|Part of a series of articles on|
A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At the lowest range, metal particles smaller than 1 nm are usually called atom clusters instead.
Nanoparticles are usually distinguished from microparticles (1-1000 µm), "fine particles" (sized between 100 and 2500 nm), and "coarse particles" (ranging from 2500 to 10,000 nm), because their smaller size drives very different physical or chemical properties, like colloidal properties and ultrafast optical effects or electric properties.
Being much smaller than the wavelengths of visible light (400-700 nm), nanoparticles cannot be seen with ordinary optical microscopes, requiring the use of electron microscopes or microscopes with laser. For the same reason, dispersions of nanoparticles in transparent media can be transparent, whereas suspensions of larger particles usually scatter some or all visible light incident on them. Nanoparticles also easily pass through common filters, such as common ceramic candles, so that separation from liquids requires special nanofiltration techniques.
The properties of nanoparticles often differ markedly from those of larger particles of the same substance. Since the typical diameter of an atom is between 0.15 and 0.6 nm, a large fraction of the nanoparticle's material lies within a few atomic diameters of its surface. Therefore, the properties of that surface layer may dominate over those of the bulk material. This effect is particularly strong for nanoparticles dispersed in a medium of different composition since the interactions between the two materials at their interface also becomes significant.
Nanoparticles occur widely in nature and are objects of study in many sciences such as chemistry, physics, geology, and biology. Being at the transition between bulk materials and atomic or molecular structures, they often exhibit phenomena that are not observed at either scale. They are an important component of atmospheric pollution, and key ingredients in many industrialized products such as paints, plastics, metals, ceramics, and magnetic products. The production of nanoparticles with specific properties is a branch of nanotechnology.
In general, the small size of nanoparticles leads to a lower concentration of point defects compared to their bulk counterparts, but they do support a variety of dislocations that can be visualized using high-resolution electron microscopes. However, nanoparticles exhibit different dislocation mechanics, which, together with their unique surface structures, results in mechanical properties that are different from the bulk material.
Non-spherical nanoparticles (e.g., prisms, cubes, rods etc.) exhibit shape-dependent and size-dependent (both chemical and physical) properties (anisotropy). Non-spherical nanoparticles of gold (Au), silver (Ag), and platinum (Pt) due to their fascinating optical properties are finding diverse applications. Non-spherical geometries of nanoprisms give rise to high effective cross-sections and deeper colors of the colloidal solutions. The possibility of shifting the resonance wavelengths by tuning the particle geometry allows using them in the fields of molecular labeling, biomolecular assays, trace metal detection, or nanotechnical applications. Anisotropic nanoparticles display a specific absorption behavior and stochastic particle orientation under unpolarized light, showing a distinct resonance mode for each excitable axis. 
In its 2012 proposed terminology for biologically related polymers, the IUPAC defined a nanoparticle as "a particle of any shape with dimensions in the 1 × 10−9 and 1 × 10−7 m range". This definition evolved from one given by IUPAC in 1997.
In another 2012 publication, the IUPAC extends the term to include tubes and fibers with only two dimensions below 100 nm.
According to the International Standards Organization (ISO) technical specification 80004, a nanoparticle is an object with all three external dimensions in the nanoscale, whose longest and shortest axes do not differ significantly, with a significant difference typically being a factor of at least 3.
"Nanoscale" is usually understood to be the range from 1 to 100 nm because the novel properties that differentiate particles from the bulk material typically develop at that range of sizes.
For some properties, like transparency or turbidity, ultrafiltration, stable dispersion, etc., substantial changes characteristic of nanoparticles are observed for particles as large as 500 nm. Therefore, the term is sometimes extended to that size range.
Nanoclusters are agglomerates of nanoparticles with at least one dimension between 1 and 10 nanometers and a narrow size distribution. Nanopowders are agglomerates of ultrafine particles, nanoparticles, or nanoclusters. Nanometer-sized single crystals, or single-domain ultrafine particles, are often referred to as nanocrystals.
The terms colloid and nanoparticle are not interchangeable. A colloid is a mixture which has particles of one phase dispersed or suspended within an other phase. The term applies only if the particles are larger than atomic dimensions but small enough to exhibit Brownian motion, with the critical size range (or particle diameter) typically ranging from nanometers (10−9 m) to micrometers (10−6 m). Colloids can contain particles too large to be nanoparticles, and nanoparticles can exist in non-colloidal form, for examples as a powder or in a solid matrix.
Nanoparticles are naturally produced by many cosmological, geological, meteorological, and biological processes. A significant fraction (by number, if not by mass) of interplanetary dust, that is still falling on the Earth at the rate of thousands of tons per year, is in the nanoparticle range; and the same is true of atmospheric dust particles. Many viruses have diameters in the nanoparticle range.
Nanoparticles were used by artisans since prehistory, albeit without knowledge of their nature. They were used by glassmakers and potters in Classical Antiquity, as exemplified by the Roman Lycurgus cup of dichroic glass (4th century CE) and the lusterware pottery of Mesopotamia (9th century CE). The latter is characterized by silver and copper nanoparticles dispersed in the glassy glaze.
Michael Faraday provided the first description, in scientific terms, of the optical properties of nanometer-scale metals in his classic 1857 paper. In a subsequent paper, the author (Turner) points out that: "It is well known that when thin leaves of gold or silver are mounted upon glass and heated to a temperature that is well below a red heat (~500 °C), a remarkable change of properties takes place, whereby the continuity of the metallic film is destroyed. The result is that white light is now freely transmitted, reflection is correspondingly diminished, while the electrical resistivity is enormously increased."
During the 1970s and 80s, when the first thorough fundamental studies with nanoparticles were underway in the United States (by Granqvist and Buhrman) and Japan (within an ERATO Project), researchers used the term ultrafine particles. However, during the 1990s, before the National Nanotechnology Initiative was launched in the United States, the term nanoparticle had become more common (for example, see the same senior author's paper 20 years later addressing the same issue, lognormal distribution of sizes).
Morphology and structure
Nanoparticles occur in a great variety of shapes, which have been given many informal names such as nanospheres, nanorods, nanochains, nanostars, nanoflowers, nanoreefs, nanowhiskers, nanofibers, and nanoboxes.
The shapes of nanoparticles may be determined by the intrinsic crystal habit of the material, or by the influence of the environment around their creation, such as the inhibition of crystal growth on certain faces by coating additives, the shape of emulsion droplets and micelles in the precursor preparation, or the shape of pores in a surrounding solid matrix. Some applications of nanoparticles may require specific shapes, as well as specific sizes or size ranges.
Amorphous particles typically adopt a spherical shape (due to their microstructural isotropy).
The study of fine particles is called micromeritics.
Semi-solid and soft nanoparticles have been produced. A prototype nanoparticle of semi-solid nature is the liposome. Various types of liposome nanoparticles are currently used clinically as delivery systems for anticancer drugs and vaccines.
The breakdown of biopolymers into their nanoscale building blocks is considered a potential route to produce nanoparticles with enhanced biocompatibility and biodegradability. The most common example is the production of nanocellulose from wood pulp. Other examples are nanolignin, nanochitin, or nanostarches.
Nanoparticles with one half hydrophilic and the other half hydrophobic are termed Janus particles and are particularly effective for stabilizing emulsions. They can self-assemble at water/oil interfaces and act as pickering stabilizers.
Hydrogel nanoparticles made of N-isopropylacrylamide hydrogel core shell can be dyed with affinity baits, internally. These affinity baits allow the nanoparticles to isolate and remove undesirable proteins while enhancing the target analytes.
Nucleation and growth
Impact of nucleation
Nucleation lays the foundation for the nanoparticle synthesis. Initial nuclei play a vital role on the size and shape of the nanoparticles that will ultimately form by acting as templating nuclei for the nanoparticle itself. Long-term stability is also determined by the initial nucleation procedures. Homogeneous nucleation occurs when nuclei form uniformly throughout the parent phase and is less common. Heterogeneous nucleation, however, forms on areas such as container surfaces, impurities, and other defects. Crystals may form simultaneously if nucleation is fast, creating a more monodisperse product. However, slow nucleation rates can cause formation of a polydisperse population of crystals with various sizes. Controlling nucleation allows for the control of size, dispersity, and phase of nanoparticles.
The original theory from 1927 of nucleation in nanoparticle formation was Classical Nucleation Theory (CNT). It was believed that the changes in particle size could be described by burst nucleation alone. In 1950, Viktor LaMer used CNT as the nucleation basis for his model of nanoparticle growth. There are three portions to the LaMer model: 1. Rapid increase in the concentration of free monomers in solution, 2. fast nucleation of the monomer characterized by explosive growth of particles, 3. Growth of particles controlled by diffusion of the monomer. This model describes that the growth on the nucleus is spontaneous but limited by diffusion of the precursor to the nuclei surface. The LaMer model has not been able to explain the kinetics of nucleation in any modern system.
Ostwald ripening is a process in which large particles grow at the expense of the smaller particles as a result of dissolution of small particles and deposition of the dissolved molecules on the surfaces of the larger particles. It occurs because smaller particles have a higher surface energy than larger particles. This process is typically undesirable in nanoparticle synthesis as it negatively impacts the functionality of nanoparticles.
Two-step mechanism – autocatalysis model
In 1997, Finke and Watzky proposed a new kinetic model for the nucleation and growth of nanoparticles. This 2-step model suggested that constant slow nucleation (occurring far from supersaturation) is followed by autocatalytic growth where dispersity of nanoparticles is largely determined. This F-W (Finke-Watzky) 2-step model provides a firmer mechanistic basis for the design of nanoparticles with a focus on size, shape, and dispersity control.  The model was later expanded to a 3-step and two 4-step models between 2004-2008. Here, an additional step was included to account for small particle aggregation, where two smaller particles could aggregate to form a larger particle. Next, a fourth step (another autocatalytic step) was added to account for a small particle agglomerating with a larger particle. Finally in 2014, an alternative fourth step was considered that accounted for a atomistic surface growth on a large particle.
Modeling nucleation in nanoparticles
Recent work has begun to look at modeling the early stages of nucleation as well as the rates associated with nucleation through multiscale computational modeling. This includes exploration into an improved kinetic rate equation model as well as density function studies using the phase-field crystal model.
Measuring the rate of nucleation
The classical nucleation theory explains that the nucleation rate will correspond to the driving force One method for measuring the nucleation rate is through the induction time method. This process uses the stochastic nature of nucleation and determines the rate of nucleation by analysis of the time between constant supersaturation and when crystals are first detected. Another method includes the probability distribution model, analogous to the methods used to study supercooled liquids, where the probability of finding at least one nucleus at a given time is derived.
The properties of a material in nanoparticle form are unusually different from those of the bulk one even when divided into micrometer-size particles. Many of them arise from spatial confinement of sub-atomic particles (i.e. electrons, protons, photons) and electric fields around these particles. The large surface to volume ratio is also significant factor at this scale.
The initial nucleation stages of the synthesis process heavily influence the properties of a nanoparticle. Nucleation, for example, is vital to the size of the nanoparticle. A critical radius must be met in the initial stages of solid formation, or the particles will redissolve into the liquid phase. The final shape of a nanoparticle is also controlled by nucleation. Possible final morphologies created by nucleation can include spherical, cubic, needle-like, worm-like, and more particles. Nucleation can be controlled predominately by time and temperature as well as the supersaturation of the liquid phase and the environment of the synthesis overall.
Large surface-area-to-volume ratio
A bulk materials (>100 nm in size) are expected to have constant physical properties (such as thermal and electrical conductivity, stiffness, density, and viscosity) regardless of its size, for nanoparticle, however, this is different: the volume of the surface layer (few atomic diameters-wide) becomes a significant fraction of the particle's volume; whereas that fraction is insignificant for particles with diameter of one micrometer or more. In other words, the surface area/volume ratio impacts certain properties of the nanoparticles more prominently than in bulk particles.
For nanoparticles dispersed in a medium of different composition, the interfacial layer — formed by ions and molecules from the medium that are within a few atomic diameters of the surface of each particle — can mask or change its chemical and physical properties. Indeed, that layer can be considered an integral part of each nanoparticle.
Suspensions of nanoparticles are possible since the interaction of the particle surface with the solvent is strong enough to overcome density differences, which otherwise usually result in a material either sinking or floating in a liquid.
Nanoparticles often develop or receive coatings of other substances, distinct from both the particle's material and of the surrounding medium. Even when only a single molecule thick, these coatings can radically change the particles' properties, such as and chemical reactivity, catalytic activity, and stability in suspension.
Diffusion across the surface
The high surface area of a material in nanoparticle form allows heat, molecules, and ions to diffuse into or out of the particles at very large rates. The small particle diameter, on the other hand, allows the whole material to reach homogeneous equilibrium with respect to diffusion in a very short time. Thus many processes that depend on diffusion, such as sintering can take place at lower temperatures and over shorter time scales inducing catalysis.
Ferromagnetic and ferroelectric effects
The small size of nanoparticles affects their magnetic and electric properties. The ferromagnetic materials in the micrometer range is a good example: widely used in magnetic recording media, for the stability of their magnetization state, those particles smaller than 10 nm are unstable and can change their state (flip) as the result of thermal energy at ordinary temperatures, thus making them unsuitable for that application.
The reduced vacancy concentration in nanocrystals can negatively affect the motion of dislocations, since dislocation climb requires vacancy migration. In addition, there exists a very high internal pressure due to the surface stress present in small nanoparticles with high radii of curvature. This causes a lattice strain that is inversely proportional to the size of the particle, also well known to impede dislocation motion, in the same way as it does in the work hardening of materials. For example, gold nanoparticles are significantly harder than the bulk material. Furthermore, the high surface-to-volume ratio in nanoparticles makes dislocations more likely to interact with the particle surface. In particular, this affects the nature of the dislocation source and allows the dislocations to escape the particle before they can multiply, reducing the dislocation density and thus the extent of plastic deformation.
There are unique challenges associated with the measurement of mechanical properties on the nanoscale, as conventional means such as the universal testing machine cannot be employed. As a result, new techniques such as nanoindentation have been developed that complement existing electron microscope and scanning probe methods. Atomic force microscopy (AFM) can be used to perform nanoindentation to measure hardness, elastic modulus, and adhesion between nanoparticle and substrate. The particle deformation can be measured by the deflection of the cantilever tip over the sample. The resulting force-displacement curves can be used to calculate elastic modulus. However, it is unclear whether particle size and indentation depth affect the measured elastic modulus of nanoparticles by AFM.
Adhesion and friction forces are important considerations in nanofabrication, lubrication, device design, colloidal stabilization, and drug delivery. The capillary force is the main contributor to the adhesive force under ambient conditions. The adhesion and friction force can be obtained from the cantilever deflection if the AFM tip is regarded as a nanoparticle. However, this method is limited by tip material and geometric shape. The colloidal probe technique overcomes these issues by attaching a nanoparticle to the AFM tip, allowing control oversize, shape, and material. While the colloidal probe technique is an effective method for measuring adhesion force, it remains difficult to attach a single nanoparticle smaller than 1 micron onto the AFM force sensor.
Another technique is in situ TEM, which provides real-time, high resolution imaging of nanostructure response to a stimulus. For example, an in situ force probe holder in TEM was used to compress twinned nanoparticles and characterize yield strength. In general, the measurement of the mechanical properties of nanoparticles is influenced by many factors including uniform dispersion of nanoparticles, precise application of load, minimum particle deformation, calibration, and calculation model.
Like bulk materials, the properties of nanoparticles are materials dependent. For spherical polymer nanoparticles, glass transition temperature and crystallinity may affect deformation and change the elastic modulus when compared to the bulk material. However, size-dependent behavior of elastic moduli could not be generalized across polymers. As for crystalline metal nanoparticles, dislocations were found to influence the mechanical properties of nanoparticles, contradicting the conventional view that dislocations are absent in crystalline nanoparticles.
Melting point depression
A material may have lower melting point in nanoparticle form than in the bulk form. For example, 2.5 nm gold nanoparticles melt at about 300 °C, whereas bulk gold melts at 1064 °C.
Quantum mechanics effects
Quantum mechanics effects become noticeable for nanoscale objects. They include quantum confinement in semiconductor particles, localized surface plasmons in some metal particles, and superparamagnetism in magnetic materials. Quantum dots are nanoparticles of semiconducting material that are small enough (typically sub 10 nm or less) to have quantized electronic energy levels.
Quantum effects are responsible for the deep-red to black color of gold or silicon nanopowders and nanoparticle suspensions. Absorption of solar radiation is much higher in materials composed of nanoparticles than in thin films of continuous sheets of material. In both solar PV and solar thermal applications, by controlling the size, shape, and material of the particles, it is possible to control solar absorption.
Core-shell nanoparticles can support simultaneously both electric and magnetic resonances, demonstrating entirely new properties when compared with bare metallic nanoparticles if the resonances are properly engineered. The formation of the core-shell structure from two different metals enables an energy exchange between the core and the shell, typically found in upconverting nanoparticles and downconverting nanoparticles, and causes a shift in the emission wavelength spectrum.
By introducing a dielectric layer, plasmonic core (metal)-shell (dielectric) nanoparticles enhance light absorption by increasing scattering. Recently, the metal core-dielectric shell nanoparticle has demonstrated a zero backward scattering with enhanced forward scattering on a silicon substrate when surface plasmon is located in front of a solar cell.
Nanoparticles of sufficiently uniform size may spontaneously settle into regular arrangements, forming a colloidal crystal. These arrangements may exhibit original physical properties, such as observed in photonic crystals.
Artificial nanoparticles can be created from any solid or liquid material, including metals, dielectrics, and semiconductors. They may be internally homogeneous or heterogenous, e.g. with a core–shell structure.
Friable macro- or micro-scale solid particles can be ground in a ball mill, a planetary ball mill, or other size-reducing mechanism until enough of them are in the nanoscale size range. The resulting powder can be air classified to extract the nanoparticles.
Breakdown of biopolymers
Biopolymers like cellulose, lignin, chitin, or starch may be broken down into their individual nanoscale building blocks, obtaining anisotropic fiber- or needle-like nanoparticles. The biopolymers are disintegrated mechanically in combination with chemical oxidation or enzymatic treatment to promote breakup, or hydrolysed using acid.
Another method to create nanoparticles is to turn a suitable precursor substance, such as a gas (e.g. methane) or aerosol, into solid particles by combustion or pyrolysis. This is a generalization of the burning of hydrocarbons or other organic vapors to generate soot.
Traditional pyrolysis often results in aggregates and agglomerates rather than single primary particles. This inconvenience can be avoided by ultrasonic nozzle spray pyrolysis, in which the precursor liquid is forced through an orifice at high pressure.
Condensation from plasma
Nanoparticles of refractory materials, such as silica and other oxides, carbides, and nitrides, can be created by vaporizing the solid with a thermal plasma, which can reach temperatures of 10,000 kelvin, and then condensing the vapor by expansion or quenching in a suitable gas or liquid. The plasma can be produced by dc jet, electric arc, or radio frequency (RF) induction. Metal wires can be vaporized by the exploding wire method.
In RF induction plasma torches, energy coupling to the plasma is accomplished through the electromagnetic field generated by the induction coil. The plasma gas does not come in contact with electrodes, thus eliminating possible sources of contamination and allowing the operation of such plasma torches with a wide range of gases including inert, reducing, oxidizing, and other corrosive atmospheres. The working frequency is typically between 200 kHz and 40 MHz. Laboratory units run at power levels in the order of 30–50 kW, whereas the large-scale industrial units have been tested at power levels up to 1 MW. As the residence time of the injected feed droplets in the plasma is very short, it is important that the droplet sizes are small enough in order to obtain complete evaporation.
Inert gas condensation
Inert-gas condensation is frequently used to produce metallic nanoparticles. The metal is evaporated in a vacuum chamber containing a reduced atmosphere of an inert gas. Condensation of the supersaturated metal vapor results in creation of nanometer-size particles, which can be entrained in the inert gas stream and deposited on a substrate or studied in situ. Early studies were based on thermal evaporation. Using magnetron sputtering to create the metal vapor allows to achieve higher yields. The method can easily be generalized to alloy nanoparticles by choosing appropriate metallic targets. The use of sequential growth schemes, where the particles travel through a second metallic vapor, results in growth of core-shell (CS) structures.
Nanoparticles can also be formed using radiation chemistry. Radiolysis from gamma rays can create strongly active free radicals in solution. This relatively simple technique uses a minimum number of chemicals. These including water, a soluble metallic salt, a radical scavenger (often a secondary alcohol), and a surfactant (organic capping agent). High gamma doses on the order of 104 gray are required. In this process, reducing radicals will drop metallic ions down to the zero-valence state. A scavenger chemical will preferentially interact with oxidizing radicals to prevent the re-oxidation of the metal. Once in the zero-valence state, metal atoms begin to coalesce into particles. A chemical surfactant surrounds the particle during formation and regulates its growth. In sufficient concentrations, the surfactant molecules stay attached to the particle. This prevents it from dissociating or forming clusters with other particles. Formation of nanoparticles using the radiolysis method allows for tailoring of particle size and shape by adjusting precursor concentrations and gamma dose.
Nanoparticles of certain materials can be created by "wet" chemical processes, in which solutions of suitable compounds are mixed or otherwise treated to form an insoluble precipitate of the desired material. The size of the particles of the latter is adjusted by choosing the concentration of the reagents and the temperature of the solutions, and through the addition of suitable inert agents that affect the viscosity and diffusion rate of the liquid. With different parameters, the same general process may yield other nanoscale structures of the same material, such as aerogels and other porous networks.
The nanoparticles formed by this method are then separated from the solvent and soluble byproducts of the reaction by a combination of evaporation, sedimentation, centrifugation, washing, and filtration.Alternatively, if the particles are meant to be deposited on the surface of some solid substrate, the starting solutions can be by coated on that surface by dipping or spin-coating, and the reaction can be carried out in place.
Electroless deposition provides a unique opportunity for growing nanoparticles onto surface without the need for costly spin coating, electrodeposition, or physical vapor deposition. Electroless deposition processes can form colloid suspensions catalytic metal or metal oxide deposition. The suspension of nanoparticles that result from this process is an example of colloid. Typical instances of this method are the production of metal oxide or hydroxide nanoparticles by hydrolysis of metal alkoxides and chlorides.
Besides being cheap and convenient, the wet chemical approach allows fine control of the particle's chemical composition. Even small quantities of dopants, such as organic dyes and rare earth metals, can be introduced in the reagent solutions end up uniformly dispersed in the final product.
Ion implantation may be used to treat the surfaces of dielectric materials such as sapphire and silica to make composites with near-surface dispersions of metal or oxide nanoparticles.
Many properties of nanoparticles, notably stability, solubility, and chemical or biological activity, can be radically altered by coating them with various substances — a process called functionalization. Functionalized nanomaterial-based catalysts can be used for catalysis of many known organic reactions.
For biological applications, the surface coating should be polar to give high aqueous solubility and prevent nanoparticle aggregation. In serum or on the cell surface, highly charged coatings promote non-specific binding, whereas polyethylene glycol linked to terminal hydroxyl or methoxy groups repel non-specific interactions. By the immobilization of thiol groups on the surface of nanoparticles or by coating them with thiomers high (muco)adhesive and cellular uptake enhancing properties can be introduced.
Nanoparticles can be linked to biological molecules that can act as address tags, directing them to specific sites within the body specific organelles within the cell, or causing them to follow specifically the movement of individual protein or RNA molecules in living cells. Common address tags are monoclonal antibodies, aptamers, streptavidin, or peptides. These targeting agents should ideally be covalently linked to the nanoparticle and should be present in a controlled number per nanoparticle. Multivalent nanoparticles, bearing multiple targeting groups, can cluster receptors, which can activate cellular signaling pathways, and give stronger anchoring. Monovalent nanoparticles, bearing a single binding site, avoid clustering and so are preferable for tracking the behavior of individual proteins.
It has been shown that catalytic activity and sintering rates of a functionalized nanoparticle catalyst is correlated to nanoparticles' number density
Coatings that mimic those of red blood cells can help nanoparticles evade the immune system.
The chemical processing and synthesis of high-performance technological components for the private, industrial, and military sectors requires the use of high-purity ceramics (oxide ceramics, such as aluminium oxide or copper(II) oxide), polymers, glass-ceramics, and composite materials, as metal carbides (SiC), nitrides (Aluminum nitrides, Silicon nitride), metals (Al, Cu), non-metals (graphite, carbon nanotubes), and layered (Al + aluminium carbonate, Cu + C). In condensed bodies formed from fine powders, the irregular particle sizes and shapes in a typical powder often lead to non-uniform packing morphologies that result in packing density variations in the powder compact.
Uncontrolled agglomeration of powders due to attractive van der Waals forces can also give rise to microstructural heterogeneity. Differential stresses that develop as a result of non-uniform drying shrinkage are directly related to the rate at which the solvent can be removed, and thus highly dependent upon the distribution of porosity. Such stresses have been associated with a plastic-to-brittle transition in consolidated bodies, and can yield to crack propagation in the unfired body if not relieved.
In addition, any fluctuations in packing density in the compact as it is prepared for the kiln are often amplified during the sintering process, yielding inhomogeneous densification. Some pores and other structural defects associated with density variations have been shown to play a detrimental role in the sintering process by growing and thus limiting end-point densities. Differential stresses arising from inhomogeneous densification have also been shown to result in the propagation of internal cracks, thus becoming the strength-controlling flaws.
Inert gas evaporation and inert gas deposition are free many of these defects due to the distillation (cf. purification) nature of the process and having enough time to form single crystal particles, however even their non-aggreated deposits have lognormal size distribution, which is typical with nanoparticles. The reason why modern gas evaporation techniques can produce a relatively narrow size distribution is that aggregation can be avoided. However, even in this case, random residence times in the growth zone, due to the combination of drift and diffusion, result in a size distribution appearing lognormal.
It would, therefore, appear desirable to process a material in such a way that it is physically uniform with regard to the distribution of components and porosity, rather than using particle size distributions that will maximize the green density. The containment of a uniformly dispersed assembly of strongly interacting particles in suspension requires total control over interparticle forces. Monodisperse nanoparticles and colloids provide this potential.
Nanoparticles have different analytical requirements than conventional chemicals, for which chemical composition and concentration are sufficient metrics. Nanoparticles have other physical properties that must be measured for a complete description, such as size, shape, surface properties, crystallinity, and dispersion state. Additionally, sampling and laboratory procedures can perturb their dispersion state or bias the distribution of other properties. In environmental contexts, an additional challenge is that many methods cannot detect low concentrations of nanoparticles that may still have an adverse effect. For some applications, nanoparticles may be characterized in complex matrices such as water, soil, food, polymers, inks, complex mixtures of organic liquids such as in cosmetics, or blood.
There are several overall categories of methods used to characterize nanoparticles. Microscopy methods generate images of individual nanoparticles to characterize their shape, size, and location. Electron microscopy and scanning probe microscopy are the dominant methods. Because nanoparticles have a size below the diffraction limit of visible light, conventional optical microscopy is not useful. Electron microscopes can be coupled to spectroscopic methods that can perform elemental analysis. Microscopy methods are destructive and can be prone to undesirable artifacts from sample preparation, or from probe tip geometry in the case of scanning probe microscopy. Additionally, microscopy is based on single-particle measurements, meaning that large numbers of individual particles must be characterized to estimate their bulk properties.
Spectroscopy, which measures the particles' interaction with electromagnetic radiation as a function of wavelength, is useful for some classes of nanoparticles to characterize concentration, size, and shape. X-ray, ultraviolet–visible, infrared, and nuclear magnetic resonance spectroscopy can be used with nanoparticles. Light-scattering methods using laser light, X-rays, or neutron scattering are used to determine particle size, with each method suitable for different size ranges and particle compositions. Some miscellaneous methods are electrophoresis for surface charge, the Brunauer–Emmett–Teller method for surface area, and X-ray diffraction for crystal structure, as well as mass spectrometry for particle mass, and particle counters for particle number. Chromatography, centrifugation, and filtration techniques can be used to separate nanoparticles by size or other physical properties before or during characterization.
Health and safety
Nanoparticles present possible dangers, both medically and environmentally. Most of these are due to the high surface to volume ratio, which can make the particles very reactive or catalytic. They are also thought to aggregate on phospholipid bilayers and pass through cell membranes in organisms, and their interactions with biological systems are relatively unknown. However, it is unlikely the particles would enter the cell nucleus, Golgi complex, endoplasmic reticulum or other internal cellular components due to the particle size and intercellular agglomeration. A recent study looking at the effects of ZnO nanoparticles on human immune cells has found varying levels of susceptibility to cytotoxicity. There are concerns that pharmaceutical companies, seeking regulatory approval for nano-reformulations of existing medicines, are relying on safety data produced during clinical studies of the earlier, pre-reformulation version of the medicine. This could result in regulatory bodies, such as the FDA, missing new side effects that are specific to the nano-reformulation. However considerable research has demonstrated that zinc nanoparticles are not absorbed into the bloodstream in vivo.
Concern has also been raised over the health effects of respirable nanoparticles from certain combustion processes. Preclinical investigations have demonstrated that some inhaled or injected noble metal nano-architectures avoid persistence in organisms. As of 2013 the U.S. Environmental Protection Agency was investigating the safety of the following nanoparticles:
- Carbon nanotubes: Carbon materials have a wide range of uses, ranging from composites for use in vehicles and sports equipment to integrated circuits for electronic components. The interactions between nanomaterials such as carbon nanotubes and natural organic matter strongly influence both their aggregation and deposition, which strongly affects their transport, transformation, and exposure in aquatic environments. In past research, carbon nanotubes exhibited some toxicological impacts that will be evaluated in various environmental settings in current EPA chemical safety research. EPA research will provide data, models, test methods, and best practices to discover the acute health effects of carbon nanotubes and identify methods to predict them.
- Cerium oxide: Nanoscale cerium oxide is used in electronics, biomedical supplies, energy, and fuel additives. Many applications of engineered cerium oxide nanoparticles naturally disperse themselves into the environment, which increases the risk of exposure. There is ongoing exposure to new diesel emissions using fuel additives containing CeO2 nanoparticles, and the environmental and public health impacts of this new technology are unknown. EPA's chemical safety research is assessing the environmental, ecological, and health implications of nanotechnology-enabled diesel fuel additives.
- Titanium dioxide: Nano titanium dioxide is currently used in many products. Depending on the type of particle, it may be found in sunscreens, cosmetics, and paints and coatings. It is also being investigated for use in removing contaminants from drinking water.
- Nano Silver: Nano Silver is being incorporated into textiles, clothing, food packaging, and other materials to eliminate bacteria. EPA and the U.S. Consumer Product Safety Commission are studying certain products to see whether they transfer nano-size silver particles in real-world scenarios. EPA is researching this topic to better understand how much nano-silver children come in contact with in their environments.
- Iron: While nano-scale iron is being investigated for many uses, including “smart fluids” for uses such as optics polishing and as a better-absorbed iron nutrient supplement, one of its more prominent current uses is to remove contamination from groundwater. This use, supported by EPA research, is being piloted at a number of sites across the United States.
As of 2016, the U.S. Environmental Protection Agency had conditionally registered, for a period of four years, only two nanomaterial pesticides as ingredients. The EPA differentiates nanoscale ingredients from non-nanoscale forms of the ingredient, but there is little scientific data about potential variation in toxicity. Testing protocols still need to be developed.
As the most prevalent morphology of nanomaterials used in consumer products, nanoparticles have an enormous range of potential and actual applications. Table below summarizes the most common nanoparticles used in various product types available on the global markets.
Scientific research on nanoparticles is intense as they have many potential applications in pre-clinical and clinical medicine, physics, optics, and electronics. The U.S. National Nanotechnology Initiative offers government funding focused on nanoparticle research.|The use of nanoparticles in laser dye-doped poly(methyl methacrylate) (PMMA) laser gain media was demonstrated in 2003 and it has been shown to improve conversion efficiencies and to decrease laser beam divergence. Researchers attribute the reduction in beam divergence to improved dn/dT characteristics of the organic-inorganic dye-doped nanocomposite. The optimum composition reported by these researchers is 30% w/w of SiO2 (~ 12 nm) in dye-doped PMMA. Nanoparticles are being investigated as potential drug delivery system. Drugs, growth factors or other biomolecules can be conjugated to nano particles to aid targeted delivery. This nanoparticle-assisted delivery allows for spatial and temporal controls of the loaded drugs to achieve the most desirable biological outcome. Nanoparticles are also studied for possible applications as dietary supplements for delivery of biologically active substances, for example mineral elements.
Clay nanoparticles, when incorporated into polymer matrices, increase reinforcement, leading to stronger plastics, verifiable by a higher glass transition temperature and other mechanical property tests. These nanoparticles are hard, and impart their properties to the polymer (plastic). Nanoparticles have also been attached to textile fibers in order to create smart and functional clothing.
Liquid properties tuner
Being smaller than the wavelengths of visible light, nanoparticles can be dispersed in transparent media without affecting its transparency at those wavelengths. This property is exploited in many applications, such as photocatalysis.
Asphalt modification through nanoparticles can be considered as an interesting low-cost technique in asphalt pavement engineering providing novel perspectives in making asphalt materials more durable.
Nanoscale particles are used in biomedical applications as drug carriers or imaging contrast agents in microscopy. Anisotropic nanoparticles are a good candidate in biomolecular detection. Moreover, nanoparticles for nucleic acid delivery offer an unprecedented opportunity to overcome some drawbacks related to the delivery, owing to their tunability with diverse physico-chemical properties, they can readily be functionalized with any type of biomolecules/moieties for selective targeting.
Titanium dioxide nanoparticles imparts what is known as the self-cleaning effect, which lend useful water-repellant and antibacterial properties to paints and other products. Zinc oxide nanoparticles have been found to have superior UV blocking properties and are widely used in the preparation of sunscreen lotions, being completely photostable though toxic.
Compounds by industrial area
- Carbon quantum dot
- Ceramic engineering
- Colloidal crystal
- Colloidal gold
- Colloid-facilitated transport
- Gallium(II) selenide
- Icosahedral twins
- Indium(III) selenide
- Magnetic immunoassay
- Magnetoelastic filament a.k.a. magnetic nanochain
- Magnetic nanoparticles
- Nanocrystalline silicon
- Nanoparticle deposition
- Nanoparticle tracking analysis
- Patchy particles
- Photonic crystal
- Platinum nanoparticle
- Quantum dot
- Self-assembly of nanoparticles
- Silicon quantum dot
- Silver Nano
- Sol–gel process
- Synthesis of nanoparticles by fungi
- Transparent material
- Upconverting nanoparticles
- U.S. Environmental Protection Agency (): "Module 3: Characteristics of Particles Particle Size Categories". From the EPA Website.
- Vert, M.; Doi, Y.; Hellwich, K. H.; Hess, M.; Hodge, P.; Kubisa, P.; Rinaudo, M.; Schué, F. O. (2012). "Terminology for biorelated polymers and applications (IUPAC Recommendations 2012)". Pure and Applied Chemistry. 84 (2): 377 410. doi:10.1351/PAC-REC-10-12-04. S2CID 98107080.
- Vert, Michel; Doi, Yoshiharu; Hellwich, Karl-Heinz; Hess, Michael; Hodge, Philip; Kubisa, Przemyslaw; Rinaudo, Marguerite; Schué, François (11 January 2012). "Terminology for biorelated polymers and applications (IUPAC Recommendations 2012)". Pure and Applied Chemistry. 84 (2): 377–410. doi:10.1351/PAC-REC-10-12-04. S2CID 98107080.
- Torres-Torres, C; López-Suárez, A; Can-Uc, B; Rangel-Rojo, R; Tamayo-Rivera, L; Oliver, A (24 July 2015). "Collective optical Kerr effect exhibited by an integrated configuration of silicon quantum dots and gold nanoparticles embedded in ion-implanted silica". Nanotechnology. 26 (29): 295701. Bibcode:2015Nanot..26C5701T. doi:10.1088/0957-4484/26/29/295701. ISSN 0957-4484. PMID 26135968. S2CID 45625439.
- Shishodia, Shubham; Chouchene, Bilel; Gries, Thomas; Schneider, Raphaël (31 October 2023). "Selected I-III-VI2 Semiconductors: Synthesis, Properties and Applications in Photovoltaic Cells". Nanomaterials. 13 (21): 2889. doi:10.3390/nano13212889. ISSN 2079-4991. PMC 10648425. PMID 37947733.
- Chae, Seung Yong; Park, Myun Kyu; Lee, Sang Kyung; Kim, Taek Young; Kim, Sang Kyu; Lee, Wan In (August 2003). "Preparation of Size-Controlled TiO 2 Nanoparticles and Derivation of Optically Transparent Photocatalytic Films". Chemistry of Materials. 15 (17): 3326–3331. doi:10.1021/cm030171d.
- Jacques Simonis, Jean; Koetzee Basson, Albertus (2011). "Evaluation of a low-cost ceramic micro-porous filter for elimination of common disease microorganisms". Physics and Chemistry of the Earth, Parts A/B/C. 36 (14–15): 1129–1134. Bibcode:2011PCE....36.1129S. doi:10.1016/j.pce.2011.07.064.
- Silvera Batista, C. A.; Larson, R. G.; Kotov, N. A. (9 October 2015). "Nonadditivity of nanoparticle interactions". Science. 350 (6257): 1242477. doi:10.1126/science.1242477. PMID 26450215.
- Cai, Wei; Nix, William D. (September 2016). Imperfections in Crystalline Solids. Cambridge Core. doi:10.1017/cbo9781316389508. ISBN 9781107123137. Retrieved 21 May 2020.
- Chen, Chien-Chun; Zhu, Chun; White, Edward R.; Chiu, Chin-Yi; Scott, M. C.; Regan, B. C.; Marks, Laurence D.; Huang, Yu; Miao, Jianwei (April 2013). "Three-dimensional imaging of dislocations in a nanoparticle at atomic resolution". Nature. 496 (7443): 74–77. Bibcode:2013Natur.496...74C. doi:10.1038/nature12009. PMID 23535594. S2CID 4410909.
- Guo, Dan; Xie, Guoxin; Luo, Jianbin (8 January 2014). "Mechanical properties of nanoparticles: basics and applications". Journal of Physics D: Applied Physics. 47 (1): 013001. Bibcode:2014JPhD...47a3001G. doi:10.1088/0022-3727/47/1/013001.
- Khan, Ibrahim; Saeed, Khalid; Khan, Idrees (November 2019). "Nanoparticles: Properties, applications and toxicities". Arabian Journal of Chemistry. 12 (7): 908–931. doi:10.1016/j.arabjc.2017.05.011.
- Carlton, C.E.; Rabenberg, L.; Ferreira, P.J. (September 2008). "On the nucleation of partial dislocations in nanoparticles". Philosophical Magazine Letters. 88 (9–10): 715–724. Bibcode:2008PMagL..88..715C. doi:10.1080/09500830802307641. S2CID 40776948.
- "Anisotropic Nanostructures". Mirkin. Retrieved 22 August 2021.
- Sajanlal, Panikkanvalappil R.; Sreeprasad, Theruvakkattil S.; Samal, Akshaya K.; Pradeep, Thalappil (16 February 2011). "Anisotropic nanomaterials: structure, growth, assembly, and functions". Nano Reviews. 2: 5883. doi:10.3402/nano.v2i0.5883. ISSN 2000-5121. PMC 3215190. PMID 22110867.
- Knauer, Andrea; Koehler, J. Michael (2016). "Explanation of the size dependent in-plane optical resonance of triangular silver nanoprisms". Physical Chemistry Chemical Physics. 18 (23): 15943–15949. Bibcode:2016PCCP...1815943K. doi:10.1039/c6cp00953k. PMID 27241479.
- MacNaught, Alan D.; Wilkinson, Andrew R., eds. (1997). Compendium of Chemical Terminology: IUPAC Recommendations (2nd ed.). Blackwell Science. ISBN 978-0865426849.
- Alemán, J. V.; Chadwick, A. V.; He, J.; Hess, M.; Horie, K.; Jones, R. G.; Kratochvíl, P.; Meisel, I.; Mita, I.; Moad, G.; Penczek, S.; Stepto, R. F. T. (1 January 2007). "Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)". Pure and Applied Chemistry. 79 (10): 1801–1829. doi:10.1351/pac200779101801. S2CID 97620232.
- "ISO/TS 80004-2: Nanotechnologies Vocabulary Part 2: Nano-objects". International Organization for Standardization. 2015. Retrieved 18 January 2018.
- Fahlman, B. D. (2007). Materials Chemistry. Springer. pp. 282 283. ISBN 978-1-4020-6119-6.
- Pais, A. (2005). Subtle is the Lord: The Science and the Life of Albert Einstein. Oxford University Press. ISBN 978-0-19-280672-7. Retrieved 6 December 2016.
- Simakov, S. K. (2018). "Nano- and micron-sized diamond genesis in nature: An overview". Geoscience Frontiers. 9 (6): 1849–1858. Bibcode:2018GeoFr...9.1849S. doi:10.1016/j.gsf.2017.10.006.
- Simakov, S. K.; Kouchi, A.; Scribano, V.; Kimura, Y.; Hama, T.; Suzuki, N.; Saito, H.; Yoshizawa, T. (2015). "Nanodiamond Finding in the Hyblean Shallow Mantle Xenoliths". Scientific Reports. 5: 10765. Bibcode:2015NatSR...510765S. doi:10.1038/srep10765. PMC 5377066. PMID 26030133.
- Plane, John M. C. (2012). "Cosmic dust in the earth's atmosphere". Chemical Society Reviews. 41 (19): 6507–6518. Bibcode:2012ChSRv..41.6507P. doi:10.1039/C2CS35132C. PMID 22678029.
- Zook, Herbert A. (2001). "Spacecraft Measurements of the Cosmic Dust Flux". In Peucker-Ehrenbrink, B.; Schmitz, B. (eds.). Accretion of Extraterrestrial Matter Throughout Earth's History. Boston, MA: Springer. pp. 75–92. doi:10.1007/978-1-4419-8694-8_5. ISBN 978-1-4613-4668-5.
- "Nanotechnology Timeline | Nano". www.nano.gov. Retrieved 12 December 2016.
- Reiss, Gunter; Hutten, Andreas (2010). "Magnetic Nanoparticles". In Sattler, Klaus D. (ed.). Handbook of Nanophysics: Nanoparticles and Quantum Dots. CRC Press. pp. 2 1. ISBN 9781420075458.
- Khan, Firdos Alam (2012). Biotechnology Fundamentals. CRC Press. p. 328. ISBN 9781439820094.
- Faraday, Michael (1857). "Experimental relations of gold (and other metals) to light". Phil. Trans. R. Soc. Lond. 147: 145 181. Bibcode:1857RSPT..147..145F. doi:10.1098/rstl.1857.0011.
- Beilby, George Thomas (31 January 1904). "The effect of heat and of solvents on thin films of metal". Proceedings of the Royal Society of London. 72 (477–486): 226–235. Bibcode:1903RSPS...72..226B. doi:10.1098/rspl.1903.0046.
- Turner, T. (1908). "Transparent Silver and Other Metallic Films". Proceedings of the Royal Society A. 81 (548): 301–310. Bibcode:1908RSPSA..81..301T. doi:10.1098/rspa.1908.0084. JSTOR 93060.
- Granqvist, C.; Buhrman, R.; Wyns, J.; Sievers, A. (1976). "Far-Infrared Absorption in Ultrafine Al Particles". Physical Review Letters. 37 (10): 625 629. Bibcode:1976PhRvL..37..625G. doi:10.1103/PhysRevLett.37.625.
- Hayashi, C.; Uyeda, R & Tasaki, A. (1997). Ultra-fine particles: exploratory science and technology (1997 Translation of the Japan report of the related ERATO Project 1981 86). Noyes Publications.
- Kiss, L B; Söderlund, J; Niklasson, G A; Granqvist, C G (1 March 1999). "New approach to the origin of lognormal size distributions of nanoparticles". Nanotechnology. 10 (1): 25–28. Bibcode:1999Nanot..10...25K. doi:10.1088/0957-4484/10/1/006. S2CID 250854158.
- Agam, M. A.; Guo, Q (2007). "Electron Beam Modification of Polymer Nanospheres". Journal of Nanoscience and Nanotechnology. 7 (10): 3615–9. doi:10.1166/jnn.2007.814. PMID 18330181.
- Kralj, Slavko; Makovec, Darko (27 October 2015). "Magnetic Assembly of Superparamagnetic Iron Oxide Nanoparticle Clusters into Nanochains and Nanobundles". ACS Nano. 9 (10): 9700–7. doi:10.1021/acsnano.5b02328. PMID 26394039.
- Choy J.H.; Jang E.S.; Won J.H.; Chung J.H.; Jang D.J. & Kim Y.W. (2004). "Hydrothermal route to ZnO nanocoral reefs and nanofibers". Appl. Phys. Lett. 84 (2): 287. Bibcode:2004ApPhL..84..287C. doi:10.1063/1.1639514.
- Sun, Y; Xia, Y (2002). "Shape-controlled synthesis of gold and silver nanoparticles". Science. 298 (5601): 2176–9. Bibcode:2002Sci...298.2176S. doi:10.1126/science.1077229. PMID 12481134. S2CID 16639413.
- Murphy, C. J. (13 December 2002). "MATERIALS SCIENCE: Nanocubes and Nanoboxes". Science. 298 (5601): 2139–2141. doi:10.1126/science.1080007. PMID 12481122. S2CID 136913833.
- Dufresne, Alain (June 2013). "Nanocellulose: a new ageless bionanomaterial". Materials Today. 16 (6): 220–227. doi:10.1016/j.mattod.2013.06.004.
- Le Corre, Déborah; Bras, Julien; Dufresne, Alain (10 May 2010). "Starch Nanoparticles: A Review". Biomacromolecules. 11 (5): 1139–1153. doi:10.1021/bm901428y. PMID 20405913.
- Luchini, Alessandra; Geho, David H.; Bishop, Barney; Tran, Duy; Xia, Cassandra; Dufour, Robert L.; Jones, Clinton D.; Espina, Virginia; Patanarut, Alexis; Zhou, Weidong; Ross, Mark M.; Tessitore, Alessandra; Petricoin, Emanuel F.; Liotta, Lance A. (January 2008). "Smart Hydrogel Particles: Biomarker Harvesting: One-Step Affinity Purification, Size Exclusion, and Protection against Degradation". Nano Letters. 8 (1): 350–361. Bibcode:2008NanoL...8..350L. doi:10.1021/nl072174l. PMC 2877922. PMID 18076201.
- Gommes, Cedric J. (2019). "Ostwald ripening of confined nanoparticles: Chemomechanical coupling in nanopores". Nanoscale. 11 (15): 7386–7393. doi:10.1039/C9NR01349K. PMID 30938749. S2CID 91189669.
- Thanh, N. T.; MacLean, N.; Mahiddine, S. (2014). "Mechanisms of nucleation and growth of nanoparticles in solution". Chem. Rev. 114 (15): 7610–7630. doi:10.1021/cr400544s. PMID 25003956.
- Kulkarni, Samir A.; Kadam, Somnath S.; Meekes, Hugo; Stankiewicz, Andrzej I.; Ter Horst, Joop H. (2013). "Crystal Nucleation Kinetics from Induction Times and Metastable Zone Widths". Crystal Growth & Design. 13 (6): 2435-2440. doi:10.1021/cg400139t.
- Volmer, M.; Weber, A. Z. (1927). "Nucleus Formation in Supersaturated Systems". Zeitschrift für Physikalische Chemie. 125: 236-242.
- LaMer, Viktor K.; Dinegar, Robert H. (1950). "Theory, Production and Mechanism of Formation of Monodispersed Hydrosols". Journal of the American Chemical Society. 72 (11): 4847-4854. doi:10.1021/ja01167a001.
- Watzky, Murielle A.; Finke, Richard G. (1997). "Transition Metal Nanocluster Formation Kinetic and Mechanistic Studies. A New Mechanism when Hydrogen is the Reductant: Slow, Continuous Nucleation and Fast Autocatalytic Surface Growth". J. Am. Chem. Soc. 119 (43): 10382-10400. doi:10.1021/ja9705102.
- Whitehead, Christopher B.; Özkar, Saim; Finke, Richard G. (2019). "LaMer's 1950 Model for Particle Formation of Instantaneous Nucleation and Diffusion-Controlled Growth: A Historical Look at the Model's Origins, Assumptions, Equations, and Underlying Sulfur Sol Formation Kinetics Data". Chem. Mater. 31 (18): 7116-7132. doi:10.1021/acs.chemmater.9b01273. S2CID 202880673.
- Whitehead, Christopher B.; Özkar, Saim; Finke, Richard G. (2021). "LaMer's 1950 model for particle formation: a review and critical analysis of its classical nucleation and fluctuation theory basis, of competing models and mechanisms for phase-changes and particle formation, and then of its application to silver halide, semiconductor, metal, and metal-oxide nanoparticles". Mater. Adv. 2: 186-235. doi:10.1039/d0ma00439a.
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Ostwald ripening". doi:10.1351/goldbook.O04348
- Kulkarni, Samir A.; Kadam, Somnath S.; Meekes, Hugo; Stankiewicz, Andrzej I.; Ter Horst, Joop H. (2013). "Crystal Nucleation Kinetics from Induction Times and Metastable Zone Widths". Crystal Growth & Design. 13 (6): 2435-2440. doi:10.1021/cg400139t.
- Watzky, Murielle A.; Finke, Richard G. (1997). "Transition Metal Nanocluster Formation Kinetic and Mechanistic Studies. A New Mechanism when Hydrogen is the Reductant: Slow, Continuous Nucleation and Fast Autocatalytic Surface Growth". J. Am. Chem. Soc. 119 (43): 10382-10400. doi:10.1021/ja9705102.
- Hornstein, Brooks J.; Finke, Richard G. (2004). "Transition-Metal Nanocluster Kinetic and Mechanistic Studies Emphasizing Nanocluster Agglomeration: Demonstration of a Kinetic Method That Allows Monitoring of All Three Phases of Nanocluster Formation and Aging". Chem. Mater. 16 (1): 139-150. doi:10.1021/cm034585i.
- Besson, Claire; Finney, Eric E.; Finke, Richard G. (2005). "A Mechanism for Transition-Metal Nanoparticle Self-Assembly". J. Am. Chem. Soc. 127 (22): 8179–8184. doi:10.1021/ja0504439. PMID 15926847.
- Besson, Claire; Finney, Eric E.; Finke, Richard G. (2005). "Nanocluster Nucleation, Growth, and Then Agglomeration Kinetic and Mechanistic Studies: A More General, Four-Step Mechanism Involving Double Autocatalysis". Chem. Mater. 17 (20): 4925-4938. doi:10.1021/cm050207x.
- Finney, Eric E.; Finke, Richard G. (2008). "The Four-Step, Double-Autocatalytic Mechanism for Transition-Metal Nanocluster Nucleation, Growth, and Then Agglomeration: Metal, Ligand, Concentration, Temperature, and Solvent Dependency Studies". Chem. Mater. 20 (5): 1956-1970. doi:10.1021/cm071088j.
- Kent, Patrick D.; Mondloch, Joseph E.; Finke, Richard G. (2014). "A Four-Step Mechanism for the Formation of Supported-Nanoparticle Heterogeneous Catalysts in Contact with Solution: The Conversion of Ir(1,5-COD)Cl/γ-Al2O3 to Ir(0)~170/γ-Al2O3". J. Am. Chem. Soc. 136 (5): 1930–1941. doi:10.1021/ja410194r. PMID 24444431.
- Grammatikopoulos, Panagiotis (2019). "Atomistic modeling of the nucleation and growth of pure and hybrid nanoparticles by cluster beam deposition". Current Opinion in Chemical Engineering. 23: 164–173. doi:10.1016/j.coche.2019.04.004. S2CID 181326215.
- Thanh, Nguyen T. K.; MacLean, N.; Mahiddine, S. (2014). "Mechanisms of Nucleation and Growth of Nanoparticles in Solution". Chem. Rev. 114 (15): 7610–7630. doi:10.1021/cr400544s. PMID 25003956.
- Buzea, Cristina; Pacheco, Ivan I.; Robbie, Kevin (December 2007). "Nanomaterials and nanoparticles: Sources and toxicity". Biointerphases. 2 (4): MR17–MR71. arXiv:0801.3280. doi:10.1116/1.2815690. PMID 20419892. S2CID 35457219.
- ASTM E 2456 06 Standard Terminology Relating to Nanotechnology
- Valenti G, Rampazzo R, Bonacchi S, Petrizza L, Marcaccio M, Montalti M, Prodi L, Paolucci F (2016). "Variable Doping Induces Mechanism Swapping in Electrogenerated Chemiluminescence of Ru(bpy)32+ Core Shell Silica Nanoparticles". J. Am. Chem. Soc. 138 (49): 15935–15942. doi:10.1021/jacs.6b08239. hdl:11585/583548. PMID 27960352.
- Vekilov, Peter G. (2010). "Nucleation". Crystal Growth & Design. 10 (12): 5007–5019. doi:10.1021/cg1011633. PMC 2995260. PMID 21132117.
- Kulkarni, Samir A.; Kadam, Somnath S.; Meekes, Hugo; Stankiewicz, Andrzej I.; Ter Horst, Joop H. (2013). "Crystal Nucleation Kinetics from Induction Times and Metastable Zone Widths". Crystal Growth & Design. 13 (6): 2435-2440. doi:10.1021/cg400139t.
- Thanh, N. T.; MacLean, N.; Mahiddine, S. (2014). "Mechanisms of nucleation and growth of nanoparticles in solution". Chem Rev. 114 (15): 7610–7630. doi:10.1021/cr400544s. PMID 25003956.
- Gubin, Sergey P. (2009). Magnetic nanoparticles. Wiley-VCH. ISBN 978-3-527-40790-3.
- Vollath, Dieter; Fischer, Franz Dieter; Holec, David (23 August 2018). "Surface energy of nanoparticles – influence of particle size and structure". Beilstein Journal of Nanotechnology. 9: 2265–2276. doi:10.3762/bjnano.9.211. PMC 6122122. PMID 30202695.
- Jiang, Q.; Liang, L. H.; Zhao, D. S. (July 2001). "Lattice Contraction and Surface Stress of fcc Nanocrystals". The Journal of Physical Chemistry B. 105 (27): 6275–6277. doi:10.1021/jp010995n.
- Courtney, Thomas H. (2000). Mechanical behavior of materials (2nd ed.). Boston: McGraw Hill. ISBN 0-07-028594-2. OCLC 41932585.
- Ramos, Manuel; Ortiz-Jordan, Luis; Hurtado-Macias, Abel; Flores, Sergio; Elizalde-Galindo, José T.; Rocha, Carmen; Torres, Brenda; Zarei-Chaleshtori, Maryam; Chianelli, Russell R. (January 2013). "Hardness and Elastic Modulus on Six-Fold Symmetry Gold Nanoparticles". Materials. 6 (1): 198–205. Bibcode:2013Mate....6..198R. doi:10.3390/ma6010198. PMC 5452105. PMID 28809302.
- Oh, Sang Ho; Legros, Marc; Kiener, Daniel; Dehm, Gerhard (February 2009). "In situ observation of dislocation nucleation and escape in a submicrometre aluminium single crystal". Nature Materials. 8 (2): 95–100. Bibcode:2009NatMa...8...95O. doi:10.1038/nmat2370. PMID 19151703.
- Feruz, Yosi; Mordehai, Dan (January 2016). "Towards a universal size-dependent strength of face-centered cubic nanoparticles". Acta Materialia. 103: 433–441. Bibcode:2016AcMat.103..433F. doi:10.1016/j.actamat.2015.10.027.
- Kulik, Andrzej; Kis, Andras; Gremaud, Gérard; Hengsberger, Stefan; Luengo, Gustavo; Zysset, Philippe; Forró, László (2007), Bhushan, Bharat (ed.), "Nanoscale Mechanical Properties – Measuring Techniques and Applications", Springer Handbook of Nanotechnology, Springer Handbooks, Springer, pp. 1107–1136, Bibcode:2007shnt.book.1107K, doi:10.1007/978-3-540-29857-1_36, ISBN 978-3-540-29857-1
- Guo, Dan; Xie, Guoxin; Luo, Jianbin (8 January 2014). "Mechanical properties of nanoparticles: basics and applications". Journal of Physics D: Applied Physics. 47 (1): 013001. Bibcode:2014JPhD...47a3001G. doi:10.1088/0022-3727/47/1/013001. ISSN 0022-3727.
- Tan, Susheng; Sherman, Robert L.; Ford, Warren T. (1 August 2004). "Nanoscale Compression of Polymer Microspheres by Atomic Force Microscopy". Langmuir. 20 (17): 7015–7020. doi:10.1021/la049597c. ISSN 0743-7463. PMID 15301482.
- Ouyang, Q.; Ishida, K.; Okada, K. (15 January 2001). "Investigation of micro-adhesion by atomic force microscopy". Applied Surface Science. 169–170 (1–2): 644–648. Bibcode:2001ApSS..169..644O. doi:10.1016/S0169-4332(00)00804-7. ISSN 0169-4332.
- Larson, Ian; Drummond, Calum J.; Chan, Derek Y. C.; Grieser, Franz (1 December 1993). "Direct force measurements between titanium dioxide surfaces". Journal of the American Chemical Society. 115 (25): 11885–11890. doi:10.1021/ja00078a029. ISSN 0002-7863.
- Kappl, Michael; Butt, Hans-Jürgen (2002). "The Colloidal Probe Technique and its Application to Adhesion Force Measurements". Particle & Particle Systems Characterization. 19 (3): 129–143. doi:10.1002/1521-4117(200207)19:3<129::AID-PPSC129>3.0.CO;2-G. ISSN 1521-4117.
- Casillas, Gilberto; Palomares-Báez, Juan Pedro; Rodríguez-López, José Luis; Luo, Junhang; Ponce, Arturo; Esparza, Rodrigo; Velázquez-Salazar, J. Jesús; Hurtado-Macias, Abel; González-Hernández, Jesús; José-Yacaman, Miguel (11 December 2012). "In situ TEM study of mechanical behaviour of twinned nanoparticles". Philosophical Magazine. 92 (35): 4437–4453. Bibcode:2012PMag...92.4437C. doi:10.1080/14786435.2012.709951. ISSN 1478-6435. S2CID 137390443.
- Buffat, Ph.; Borel, J.-P. (1976). "Size effect on the melting temperature of gold particles". Physical Review A. 13 (6): 2287–2298. Bibcode:1976PhRvA..13.2287B. doi:10.1103/PhysRevA.13.2287.
- Hewakuruppu, Y. L.; Dombrovsky, L. A.; Chen, C.; Timchenko, V.; Jiang, X.; Baek, S.; Taylor, R. A. (2013). "Plasmonic "pump probe" method to study semi-transparent nanofluids". Applied Optics. 52 (24): 6041–50. Bibcode:2013ApOpt..52.6041H. doi:10.1364/AO.52.006041. PMID 24085009.
- Wu, Jiang; Yu, Peng; Susha, Andrei S.; Sablon, Kimberly A.; Chen, Haiyuan; Zhou, Zhihua; Li, Handong; Ji, Haining; Niu, Xiaobin (1 April 2015). "Broadband efficiency enhancement in quantum dot solar cells coupled with multispiked plasmonic nanostars". Nano Energy. 13: 827–835. doi:10.1016/j.nanoen.2015.02.012. S2CID 98282021.
- Taylor, Robert A; Otanicar, Todd; Rosengarten, Gary (2012). "Nanofluid-based optical filter optimization for PV/T systems". Light: Science & Applications. 1 (10): e34. Bibcode:2012LSA.....1E..34T. doi:10.1038/lsa.2012.34.
- Taylor, Robert A.; Otanicar, Todd P.; Herukerrupu, Yasitha; Bremond, Fabienne; Rosengarten, Gary; Hawkes, Evatt R.; Jiang, Xuchuan; Coulombe, Sylvain (2013). "Feasibility of nanofluid-based optical filters". Applied Optics. 52 (7): 1413–22. Bibcode:2013ApOpt..52.1413T. doi:10.1364/AO.52.001413. PMID 23458793.
- Taylor, Robert A; Phelan, Patrick E; Otanicar, Todd P; Adrian, Ronald; Prasher, Ravi (2011). "Nanofluid optical property characterization: Towards efficient direct absorption solar collectors". Nanoscale Research Letters. 6 (1): 225. Bibcode:2011NRL.....6..225T. doi:10.1186/1556-276X-6-225. PMC 3211283. PMID 21711750.
- Valenti G, Rampazzo E, Kesarkar S, Genovese D, Fiorani A, Zanut A, Palomba F, Marcaccio M, Paolucci F, Prodi L (2018). "Electrogenerated chemiluminescence from metal complexes-based nanoparticles for highly sensitive sensors applications". Coordination Chemistry Reviews. 367: 65–81. doi:10.1016/j.ccr.2018.04.011. hdl:11585/653909. S2CID 103192810.
- Taylor, Robert; Coulombe, Sylvain; Otanicar, Todd; Phelan, Patrick; Gunawan, Andrey; Lv, Wei; Rosengarten, Gary; Prasher, Ravi; Tyagi, Himanshu (2013). "Small particles, big impacts: A review of the diverse applications of nanofluids". Journal of Applied Physics. 113 (1): 011301–011301–19. Bibcode:2013JAP...113a1301T. doi:10.1063/1.4754271.
- Ghosh Chaudhuri, Rajib; Paria, Santanu (11 April 2012). "Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications". Chemical Reviews. 112 (4): 2373–2433. doi:10.1021/cr100449n. PMID 22204603.
- Loo, Jacky Fong-Chuen; Chien, Yi-Hsin; Yin, Feng; Kong, Siu-Kai; Ho, Ho-Pui; Yong, Ken-Tye (December 2019). "Upconversion and downconversion nanoparticles for biophotonics and nanomedicine". Coordination Chemistry Reviews. 400: 213042. doi:10.1016/j.ccr.2019.213042. S2CID 203938224.
- Yu, Peng; Yao, Yisen; Wu, Jiang; Niu, Xiaobin; Rogach, Andrey L.; Wang, Zhiming (December 2017). "Effects of Plasmonic Metal Core -Dielectric Shell Nanoparticles on the Broadband Light Absorption Enhancement in Thin Film Solar Cells". Scientific Reports. 7 (1): 7696. Bibcode:2017NatSR...7.7696Y. doi:10.1038/s41598-017-08077-9. PMC 5550503. PMID 28794487.
- Whitesides, G.M.; et al. (1991). "Molecular Self-Assembly and Nanochemistry: A Chemical Strategy for the Synthesis of Nanostructures". Science. 254 (5036): 1312–1319. Bibcode:1991Sci...254.1312W. doi:10.1126/science.1962191. PMID 1962191.
- Dabbs D. M, Aksay I.A.; Aksay (2000). "Self-Assembled Ceramics". Annu. Rev. Phys. Chem. 51: 601–22. Bibcode:2000ARPC...51..601D. doi:10.1146/annurev.physchem.51.1.601. PMID 11031294. S2CID 14113689.
- Anandkumar, Mariappan; Bhattacharya, Saswata; Deshpande, Atul Suresh (2019). "Low temperature synthesis and characterization of single phase multi-component fluorite oxide nanoparticle sols". RSC Advances. 9 (46): 26825–26830. Bibcode:2019RSCAd...926825A. doi:10.1039/C9RA04636D. PMC 9070433. PMID 35528557.
- Hosseini, Mansoure; Mashreghi, Mansour; Eshghi, Hossein (2016). "Biosynthesis and antibacterial activity of gold nanoparticles coated with reductase enzymes". Micro and Nano Letters. 11 (9): 484–489. doi:10.1049/mnl.2016.0065. S2CID 89082048.
- Saito, Tsuguyuki; Kimura, Satoshi; Nishiyama, Yoshiharu; Isogai, Akira (August 2007). "Cellulose Nanofibers Prepared by TEMPO-Mediated Oxidation of Native Cellulose". Biomacromolecules. 8 (8): 2485–2491. doi:10.1021/bm0703970. PMID 17630692.
- Fan, Yimin; Saito, Tsuguyuki; Isogai, Akira (17 March 2010). "Individual chitin nano-whiskers prepared from partially deacetylated α-chitin by fibril surface cationization". Carbohydrate Polymers. 79 (4): 1046–1051. doi:10.1016/j.carbpol.2009.10.044.
- Habibi, Youssef (2014). "Key advances in the chemical modification of nanocelluloses". Chem. Soc. Rev. 43 (5): 1519–1542. doi:10.1039/c3cs60204d. PMID 24316693.
- Granqvist, C. G.; Buhrman, R. A. (1976). "Ultrafine metal particles". Journal of Applied Physics. 47 (5): 2200 2219. Bibcode:1976JAP....47.2200G. doi:10.1063/1.322870. S2CID 53659172.
- Hahn, H.; Averback, R. S. (1990). "The production of nanocrystalline powders by magnetron sputtering". Journal of Applied Physics. 67 (2): 1113 1115. Bibcode:1990JAP....67.1113H. doi:10.1063/1.345798.
- Wang, Jian-Ping; Bai, Jianmin (2005). "High-magnetic-moment core-shell-type FeCo Au AgFeCo Au Ag nanoparticles". Appl. Phys. Lett. 87: 152502. doi:10.1063/1.2089171.
- Hennes, M.; Lotnyk, A.; Mayr, S. G. (2014). "Plasma-assisted synthesis and high-resolution characterization of anisotropic elemental and bimetallic core shell magnetic nanoparticles". Beilstein J. Nanotechnol. 5: 466–475. doi:10.3762/bjnano.5.54. PMC 3999878. PMID 24778973.
- Llamosa, D.; Ruano, M.; Martínez, L.; Mayoral, A.; Roman, E.; García-Hernández, M.; Huttel, Y. (2014). "The ultimate step towards a tailored engineering of core@shell and core@shell@shell nanoparticles". Nanoscale. 6 (22): 13483–13486. Bibcode:2014Nanos...613483L. doi:10.1039/c4nr02913e. PMID 25180699.
- Michelakaki, Irini; Boukos, Nikos; Dragatogiannis, Dimitrios A; Stathopoulos, Spyros; Charitidis, Costas A; Tsoukalas, Dimitris (27 June 2018). "Synthesis of hafnium nanoparticles and hafnium nanoparticle films by gas condensation and energetic deposition". Beilstein Journal of Nanotechnology. 9: 1868–1880. doi:10.3762/bjnano.9.179. PMC 6036986. PMID 30013881.
- Belloni, J.; Mostafavi, M.; Remita, H.; Marignier, J. L.; Delcourt, A. M. O. (1998). "Radiation-induced synthesis of mono- and multi-metallic clusters and nanocolloids". New Journal of Chemistry. 22 (11): 1239 1255. doi:10.1039/A801445K.
- Brinker, C.J. & Scherer, G.W. (1990). Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing. Academic Press. ISBN 978-0-12-134970-7.
- Hench, L. L.; West, J. K. (1990). "The sol-gel process". Chemical Reviews. 90: 33–72. doi:10.1021/cr00099a003.
- Klein, L. (1994). Sol-Gel Optics: Processing and Applications. Springer Verlag. ISBN 978-0-7923-9424-2. Retrieved 6 December 2016.
- Corriu, Robert & Anh, Nguyên Trong (2009). Molecular Chemistry of Sol-Gel Derived Nanomaterials. John Wiley and Sons. ISBN 978-0-470-72117-9.
- Sadri, R. (15 October 2017). "Study of environmentally friendly and facile functionalization of graphene nanoplatelet and its application in convective heat transfer". Energy Conversion and Management. 150: 26–36. doi:10.1016/j.enconman.2017.07.036.
- Prime, KL; Whitesides, GM (1991). "Self-assembled organic monolayers: model systems for studying adsorption of proteins at surfaces". Science. 252 (5009): 1164–7. Bibcode:1991Sci...252.1164P. doi:10.1126/science.252.5009.1164. PMID 2031186. S2CID 26062996.
- Liu, Wenhao; Greytak, Andrew B.; Lee, Jungmin; Wong, Cliff R.; Park, Jongnam; Marshall, Lisa F.; Jiang, Wen; Curtin, Peter N.; Ting, Alice Y.; Nocera, Daniel G.; Fukumura, Dai; Jain, Rakesh K.; Bawendi, Moungi G. (20 January 2010). "Compact Biocompatible Quantum Dots via RAFT-Mediated Synthesis of Imidazole-Based Random Copolymer Ligand". Journal of the American Chemical Society. 132 (2): 472–483. doi:10.1021/ja908137d. PMC 2871316. PMID 20025223.
- Hock, N; Racaniello, GF; Aspinall, S; Denora, N; Khutoryanskiy, V; Bernkop-Schnürch, A (2022). "Thiolated Nanoparticles for Biomedical Applications: Mimicking the Workhorses of our Body". Advanced Science. 9 (1): 2102451. doi:10.1002/advs.202102451. PMC 8728822. PMID 34773391.
- Akerman ME, Chan WC, Laakkonen P, Bhatia SN, Ruoslahti E (2002). "Nanocrystal targeting in vivo". Proceedings of the National Academy of Sciences of the United States of America. 99 (20): 12617–12621. Bibcode:2002PNAS...9912617A. doi:10.1073/pnas.152463399. PMC 130509. PMID 12235356.
- Hoshino, A; Fujioka, K; Oku, T; Nakamura, S; Suga, M; Yamaguchi, Y; Suzuki, K; Yasuhara, M; Yamamoto, K (2004). "Quantum dots targeted to the assigned organelle in living cells". Microbiology and Immunology. 48 (12): 985–94. doi:10.1111/j.1348-0421.2004.tb03621.x. PMID 15611617.
- Suzuki, KG; Fujiwara, TK; Edidin, M; Kusumi, A (2007). "Dynamic recruitment of phospholipase C at transiently immobilized GPI-anchored receptor clusters induces IP3 Ca2+ signaling: single-molecule tracking study 2". The Journal of Cell Biology. 177 (4): 731–42. doi:10.1083/jcb.200609175. PMC 2064217. PMID 17517965.
- Sung, KM; Mosley, DW; Peelle, BR; Zhang, S; Jacobson, JM (2004). "Synthesis of monofunctionalized gold nanoparticles by fmoc solid-phase reactions". Journal of the American Chemical Society. 126 (16): 5064–5. doi:10.1021/ja049578p. PMID 15099078. S2CID 24702517.
- Fu, A; Micheel, CM; Cha, J; Chang, H; Yang, H; Alivisatos, AP (2004). "Discrete nanostructures of quantum dots/Au with DNA". Journal of the American Chemical Society. 126 (35): 10832–3. doi:10.1021/ja046747x. PMID 15339154.
- Howarth, M; Liu, W; Puthenveetil, S; Zheng, Y; Marshall, LF; Schmidt, MM; Wittrup, KD; Bawendi, MG; Ting, AY (2008). "Monovalent, reduced-size quantum dots for imaging receptors on living cells". Nature Methods. 5 (5): 397–9. doi:10.1038/nmeth.1206. PMC 2637151. PMID 18425138.
- Campbell, Charles T. (20 August 2013). "The Energetics of Supported Metal Nanoparticles: Relationships to Sintering Rates and Catalytic Activity". Accounts of Chemical Research. 46 (8): 1712–1719. doi:10.1021/ar3003514. ISSN 0001-4842. PMID 23607711.
- "Nanoparticles play at being red blood cells". Archived from the original on 1 July 2011. Retrieved 1 July 2011.
- Onoda, G.Y. Jr.; Hench, L.L., eds. (1979). Ceramic Processing Before Firing. New York: Wiley & Sons. ISBN 978-0-471-65410-0.
- Aksay, I.A.; Lange, F.F.; Davis, B.I. (1983). "Uniformity of Al2O3-ZrO2 Composites by Colloidal Filtration". J. Am. Ceram. Soc. 66 (10): C 190. doi:10.1111/j.1151-2916.1983.tb10550.x.
- Franks, G.V. & Lange, F.F. (1996). "Plastic-to-Brittle Transition of Saturated, Alumina Powder Compacts". J. Am. Ceram. Soc. 79 (12): 3161 3168. doi:10.1111/j.1151-2916.1996.tb08091.x.
- Evans, A.G. & Davidge, R.W. (1969). "The strength and fracture of fully dense polycrystalline magnesium oxide". Phil. Mag. 20 (164): 373 388. Bibcode:1969PMag...20..373E. doi:10.1080/14786436908228708.
- Evans, A. G.; Davidge, R. W. (1970). "The strength and oxidation of reaction-sintered silicon nitride". J. Mater. Sci. 5 (4): 314 325. Bibcode:1970JMatS...5..314E. doi:10.1007/BF02397783. S2CID 137539240.
- Lange, F. F.; Metcalf, M. (June 1983). "Processing-Related Fracture Origins: II, Agglomerate Motion and Cracklike Internal Surfaces Caused by Differential Sintering". Journal of the American Ceramic Society. 66 (6): 398–406. doi:10.1111/j.1151-2916.1983.tb10069.x.
- Evans, A.G. (1987). "Considerations of Inhomogeneity Effects in Sintering". J. Am. Ceram. Soc. 65 (10): 497–501. doi:10.1111/j.1151-2916.1982.tb10340.x.
- Hassellöv, Martin; Readman, James W.; Ranville, James F.; Tiede, Karen (July 2008). "Nanoparticle analysis and characterization methodologies in environmental risk assessment of engineered nanoparticles". Ecotoxicology. 17 (5): 344–361. doi:10.1007/s10646-008-0225-x. PMID 18483764. S2CID 25291395.
- Powers, Kevin W.; Palazuelos, Maria; Moudgil, Brij M.; Roberts, Stephen M. (January 2007). "Characterization of the size, shape, and state of dispersion of nanoparticles for toxicological studies". Nanotoxicology. 1 (1): 42–51. doi:10.1080/17435390701314902. S2CID 137174566.
- Tiede, Karen; Boxall, Alistair B.A.; Tear, Steven P.; Lewis, John; David, Helen; Hassellöv, Martin (July 2008). "Detection and characterization of engineered nanoparticles in food and the environment" (PDF). Food Additives & Contaminants: Part A. 25 (7): 795–821. doi:10.1080/02652030802007553. PMID 18569000. S2CID 23910918.
- Linsinger, Thomas P.J.; Roebben, Gert; Solans, Conxita; Ramsch, Roland (January 2011). "Reference materials for measuring the size of nanoparticles". TrAC Trends in Analytical Chemistry. 30 (1): 18–27. doi:10.1016/j.trac.2010.09.005. hdl:10261/333681.
- "Structural, functional and magnetic ordering modifications in graphene oxide and graphite by 100 MeV gold ion irradiation". Vacuum. 182: 109700. 2020-12-01. doi:10.1016/j.vacuum.2020.109700
- Zoroddu, Maria Antonietta; Medici, Serenella; Ledda, Alessia; Nurchi, Valeria Marina; Peana, Joanna I. Lachowicz and Massimiliano; Peana, M (31 October 2014). "Toxicity of Nanoparticles". Current Medicinal Chemistry. 21 (33): 3837–3853. doi:10.2174/0929867321666140601162314. PMID 25306903. S2CID 24001137.
- Crisponi, G.; Nurchi, V.M.; Lachowicz, J.; Peana, M.; Medici, S.; Zoroddu, M.A. (2017). Chapter 18 - Toxicity of Nanoparticles: Etiology and Mechanisms, in Antimicrobial Nanoarchitectonics. ELSEVIER. pp. 511 546. doi:10.1016/B978-0-323-52733-0.00018-5. ISBN 9780323527330.
- Mnyusiwalla, Anisa; Daar, Abdallah S; Singer, Peter A (1 March 2003). "'Mind the gap': science and ethics in nanotechnology" (PDF). Nanotechnology. 14 (3): R9–R13. doi:10.1088/0957-4484/14/3/201. S2CID 663082. Archived from the original (PDF) on 26 September 2020.
- "Toxic Nanoparticles Might be Entering Human Food Supply, MU Study Finds". University of Missouri. 22 August 2013. Retrieved 23 August 2013.
- Ying, Jackie (2001). Nanostructured Materials. New York: Academic Press. ISBN 978-0-12-744451-2. Retrieved 6 December 2016.
- Noh SY, Nash A, Notman R (2020). "The aggregation of striped nanoparticles in mixed phospholipid bilayers". Nanoscale. 12 (8): 4868–81. doi:10.1039/c9nr07106g. PMID 31916561. S2CID 210119752.[permanent dead link]
- Nanotechnologies: 6. What are potential harmful effects of nanoparticles? europa.eu
- Thake, T.H.F; Webb, J.R; Nash, A.; Rappoport, J.Z.; Notman, R. (2013). "Permeation of polystyrene nanoparticles across model lipid bilayer membranes". Soft Matter. 9 (43): 10265 10274. Bibcode:2013SMat....910265T. doi:10.1039/c3sm51225h.
- Greulich, C.; Diendorf, J.; Simon, T.; Eggeler, G.; Epple, M.; Köller, M. (January 2011). "Uptake and intracellular distribution of silver nanoparticles in human mesenchymal stem cells". Acta Biomaterialia. 7 (1): 347–354. doi:10.1016/j.actbio.2010.08.003. PMID 20709196.
- Hanley, Cory; Thurber, Aaron; Hanna, Charles; Punnoose, Alex; Zhang, Jianhui; Wingett, Denise G. (December 2009). "The Influences of Cell Type and ZnO Nanoparticle Size on Immune Cell Cytotoxicity and Cytokine Induction". Nanoscale Research Letters. 4 (12): 1409–1420. Bibcode:2009NRL.....4.1409H. doi:10.1007/s11671-009-9413-8. PMC 2894345. PMID 20652105.
- Vines T, Faunce T (2009). "Assessing the safety and cost-effectiveness of early nanodrugs". Journal of Law and Medicine. 16 (5): 822–45. PMID 19554862.
- Benson, Heather AE; Sarveiya, Vikram; Risk, Stacey; Roberts, Michael S (2005). "Influence of anatomical site and topical formulation on skin penetration of sunscreens". Therapeutics and Clinical Risk Management. 1 (3): 209–218. PMC 1661631. PMID 18360561.
- Howard, V. (2009). "Statement of Evidence: Particulate Emissions and Health (An Bord Plenala, on Proposed Ringaskiddy Waste-to-Energy Facility)." Retrieved 26 April 2011.
- Pieters, N (March 2015). "Blood Pressure and Same-Day Exposure to Air Pollution at School: Associations with Nano-Sized to Coarse PM in Children". Environmental Health Perspectives. 123 (7): 737–742. doi:10.1289/ehp.1408121. PMC 4492263. PMID 25756964.
- Mapanao, Ana Katrina; Giannone, Giulia; Summa, Maria; Ermini, Maria Laura; Zamborlin, Agata; Santi, Melissa; Cassano, Domenico; Bertorelli, Rosalia; Voliani, Valerio (2020). "Biokinetics and clearance of inhaled gold ultrasmall-in-nano architectures". Nanoscale Advances. 2 (9): 3815–3820. Bibcode:2020NanoA...2.3815M. doi:10.1039/D0NA00521E. PMC 9417912. PMID 36132776.
- Cassano, Domenico; Mapanao, Ana-Katrina; Summa, Maria; Vlamidis, Ylea; Giannone, Giulia; Santi, Melissa; Guzzolino, Elena; Pitto, Letizia; Poliseno, Laura; Bertorelli, Rosalia; Voliani, Valerio (21 October 2019). "Biosafety and Biokinetics of Noble Metals: The Impact of Their Chemical Nature". ACS Applied Bio Materials. 2 (10): 4464–4470. doi:10.1021/acsabm.9b00630. PMID 35021406. S2CID 204266885.
- "Nanomaterials EPA is Assessing". Environmental Protection Agency. Retrieved 6 February 2013. This article incorporates text from this source, which is in the public domain.
- Susan Wayland and Penelope Fenner-Crisp. Reducing Pesticide Risks: A Half Century of Progress. EPA Alumni Association. March 2016.
- Tai, Yifan; Midgley, Adam C. (29 March 2022), "Nanoparticles for Cardiovascular Medicine: Trends in Myocardial Infarction Therapy", Nanopharmaceuticals in Regenerative Medicine (1 ed.), Boca Raton: CRC Press, pp. 303–327, doi:10.1201/9781003153504-17, ISBN 978-1-003-15350-4, retrieved 23 May 2022
- Gu, Xurui; Liu, Zhen; Tai, Yifan; Zhou, Ling-yun; Liu, Kun; Kong, Deling; Midgley, Adam C; Zuo, Xiao-cong (1 April 2022). "Hydrogel and nanoparticle carriers for kidney disease therapy: trends and recent advancements". Progress in Biomedical Engineering. 4 (2): 022006. Bibcode:2022PBioE...4b2006G. doi:10.1088/2516-1091/ac6e18. ISSN 2516-1091. S2CID 248688540.
- Hubler, A.; Osuagwu, O. (2010). "Digital quantum batteries: Energy and information storage in nanovacuum tube arrays". Complexity: NA. doi:10.1002/cplx.20306. S2CID 6994736.
- Stephenson, C.; Hubler, A. (2015). "Stability and conductivity of self assembled wires in a transverse electric field". Sci. Rep. 5: 15044. Bibcode:2015NatSR...515044S. doi:10.1038/srep15044. PMC 4604515. PMID 26463476.
- Hubler, A.; Lyon, D. (2013). "Gap size dependence of the dielectric strength in nano vacuum gaps". IEEE Transactions on Dielectrics and Electrical Insulation. 20 (4): 1467 1471. doi:10.1109/TDEI.2013.6571470. S2CID 709782.
- Omidvar, A. (2016). "Metal-enhanced fluorescence of graphene oxide by palladium nanoparticles in the blue-green part of the spectrum". Chinese Physics B. 25 (11): 118102. Bibcode:2016ChPhB..25k8102O. doi:10.1088/1674-1056/25/11/118102. S2CID 125102995.
- Rashidian V, M.R. (2017). "Investigating the extrinsic size effect of palladium and gold spherical nanoparticles". Optical Materials. 64: 413–420. Bibcode:2017OptMa..64..413R. doi:10.1016/j.optmat.2017.01.014.
- Omidvar, A. (2018). "Enhancing the nonlinear optical properties of graphene oxide by repairing with palladium nanoparticles". Physica E: Low-dimensional Systems and Nanostructures. 103: 239–245. Bibcode:2018PhyE..103..239O. doi:10.1016/j.physe.2018.06.013. S2CID 125645480.
- Duarte, F. J.; James, R. O. (2003). "Tunable solid-state lasers incorporating dye-doped polymer-nanoparticle gain media". Opt. Lett. 28 (21): 2088–90. Bibcode:2003OptL...28.2088D. doi:10.1364/OL.28.002088. PMID 14587824.
- Singh, BN; Prateeksha, Gupta VK; Chen, J; Atanasov, AG (2017). "Organic Nanoparticle-Based Combinatory Approaches for Gene Therapy". Trends Biotechnol. 35 (12): 1121–1124. doi:10.1016/j.tibtech.2017.07.010. PMID 28818304..
- Wang, Zhenming; Wang, Zhefeng; Lu, William Weijia; Zhen, Wanxin; Yang, Dazhi; Peng, Songlin (October 2017). "Novel biomaterial strategies for controlled growth factor delivery for biomedical applications". NPG Asia Materials. 9 (10): e435. doi:10.1038/am.2017.171.
- Jóźwik, Artur; Marchewka, Joanna; Strzałkowska, Nina; Horbańczuk, Jarosław; Szumacher-Strabel, Małgorzata; Cieślak, Adam; Lipińska-Palka, Paulina; Józefiak, Damian; Kamińska, Agnieszka; Atanasov, Atanas (11 May 2018). "The Effect of Different Levels of Cu, Zn and Mn Nanoparticles in Hen Turkey Diet on the Activity of Aminopeptidases". Molecules. 23 (5): 1150. doi:10.3390/molecules23051150. PMC 6100587. PMID 29751626.
- "The Textiles Nanotechnology Laboratory". nanotextiles.human.cornell.edu. Retrieved 6 December 2016.
- Evans, B. (January 2018). "Nano-particle drag prediction at low Reynolds number using a direct Boltzmann–BGK solution approach" (PDF). Journal of Computational Physics. 352: 123–141. Bibcode:2018JCoPh.352..123E. doi:10.1016/j.jcp.2017.09.038.
- Hafezi, F.; Ransing, R. S.; Lewis, R. W. (14 September 2017). "The calculation of drag on nano-cylinders: The calculation of drag on nano-cylinders" (PDF). International Journal for Numerical Methods in Engineering. 111 (11): 1025–1046. Bibcode:2017IJNME.111.1025H. doi:10.1002/nme.5489. S2CID 125299766.
- Cheraghian, Goshtasp; Wistuba, Michael P. (December 2020). "Ultraviolet aging study on bitumen modified by a composite of clay and fumed silica nanoparticles". Scientific Reports. 10 (1): 11216. Bibcode:2020NatSR..1011216C. doi:10.1038/s41598-020-68007-0. PMC 7343882. PMID 32641741.
- Mendes, B.B., Conniot, J., Avital, A. et al. Nanodelivery of nucleic acids. Nat Rev Methods Primers 2, 24 (2022). https://doi.org/10.1038/s43586-022-00104-y
- "Sunscreen". U.S. Food and Drug Administration. Retrieved 6 December 2016.
- Mitchnick, Mark A.; Fairhurst, David; Pinnell, Sheldon R. (January 1999). "Microfine zinc oxide (Z-Cote) as a photostable UVA/UVB sunblock agent". Journal of the American Academy of Dermatology. 40 (1): 85–90. doi:10.1016/s0190-9622(99)70532-3. PMID 9922017.
- Heim, J; Felder, E; Tahir, MN; Kaltbeitzel, A; Heinrich, UR; Brochhausen, C; Mailänder, V; Tremel, W; Brieger, J (21 May 2015). "Genotoxic effects of zinc oxide nanoparticles". Nanoscale. 7 (19): 8931–8. Bibcode:2015Nanos...7.8931H. doi:10.1039/c5nr01167a. PMID 25916659. S2CID 205976044.
- Wang, Bing; Zhang, Yuying; Mao, Zhengwei; Yu, Dahai; Gao, Changyou (1 August 2014). "Toxicity of ZnO Nanoparticles to Macrophages Due to Cell Uptake and Intracellular Release of Zinc Ions". Journal of Nanoscience and Nanotechnology. 14 (8): 5688–5696. doi:10.1166/jnn.2014.8876. PMID 25935990. S2CID 23744621.
- Gosens, I; Kermanizadeh, A; Jacobsen, NR; Lenz, AG; Bokkers, B; de Jong, WH; Krystek, P; Tran, L; Stone, V; Wallin, H; Stoeger, T; Cassee, FR (2015). "Comparative hazard identification by a single dose lung exposure of zinc oxide and silver nanomaterials in mice". PLOS ONE. 10 (5): e0126934. Bibcode:2015PLoSO..1026934G. doi:10.1371/journal.pone.0126934. PMC 4429007. PMID 25966284.
- Hanagata, N; Morita, H (2015). "Calcium ions rescue human lung epithelial cells from the toxicity of zinc oxide nanoparticles". The Journal of Toxicological Sciences. 40 (5): 625–35. doi:10.2131/jts.40.625. PMID 26354379.
- Kim, Young Hee; Kwak, Kyung A; Kim, Tae Sung; Seok, Ji Hyeon; Roh, Hang Sik; Lee, Jong-Kwon; Jeong, Jayoung; Meang, Eun Ho; Hong, Jeong-sup; Lee, Yun Seok; Kang, Jin Seok (30 June 2015). "Retinopathy Induced by Zinc Oxide Nanoparticles in Rats Assessed by Micro-computed Tomography and Histopathology". Toxicological Research. 31 (2): 157–163. doi:10.5487/TR.2015.31.2.157. PMC 4505346. PMID 26191382.
- Moridian, M.; Khorsandi, L.; Talebi, A. R. (2015). "Morphometric and stereological assessment of the effects of zinc oxide nanoparticles on the mouse testicular tissue". Bratislava Medical Journal. 116 (5): 321–325. doi:10.4149/bll_2015_060. PMID 25924642.
- Salata, OV (2004). "Applications of nanoparticles in biology and medicine". Journal of Nanobiotechnology. 2 (1): 3. doi:10.1186/1477-3155-2-3. PMC 419715. PMID 15119954.
- Jackie Y. Ying (2001). Nanostructured Materials. Academic Press. pp. 5–. ISBN 978-0-12-744451-2.
- Nanoparticles Used in Solar Energy Conversion (ScienceDaily).
- "Nanoparticles: An occupational hygiene review" by RJ Aitken and others. Health and Safety Executive Research Report 274/2004
- "EMERGNANO: A review of completed and near completed environment, health and safety research on nanomaterials and nanotechnology" by RJ Aitken and others.
- High transmission Tandem DMA for nanoparticle studies by SEADM, 2014.
- Nanohedron.com images of nanoparticles
- Lectures on All Phases of Nanoparticle Science and Technology Archived 29 August 2010 at the Wayback Machine
- ENPRA – Risk Assessment of Engineered NanoParticles EC FP7 Project led by the Institute of Occupational Medicine