See ion implantation Ion implantation-induced nanoparticle formation. Scientists have taken to naming their particles after the real-world shapes that they might represent. Nanospheres,  nanochains ,  nanoreefs,  nanoboxes  and more have appeared in the literature.
These morphologies sometimes arise spontaneously as an effect of a templating or directing agent present in the synthesis such as miscellar emulsions or anodized alumina pores, or from the innate crystallographic growth patterns of the materials themselves. Amorphous particles usually adopt a spherical shape due to their microstructural isotropy , whereas the shape of anisotropic microcrystalline whiskers corresponds to their particular crystal habit.
At the small end of the size range, nanoparticles are often referred to as clusters. Spheres , rods, fibers , and cups are just a few of the shapes that have been grown. The study of fine particles is called micromeritics. 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.
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.
Mobile Surface Analyzer – MSA
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.
Functionalization is the introduction of organic molecules or polymers on the surface of the nanoparticle. The surface coating of nanoparticles determines many of their physical and chemical properties, notably stability, solubility, and targeting.
A coating that is multivalent or polymeric confers high stability. Functionalized nanomaterial-based catalysts can be used for catalysis of many known organic reactions. An environmentally friendly and facile functionalization approach for synthesizing highly dispersed Graphene was developed. In this approach, graphenes were functionalized covalently with Gallic Acid GA in a one-pot free radical grafting method.
This cost-effective method could be used for industrial mass production.
The suspension of Gallic acid-functionalized graphene in water was test as a high performance heat transfer fluids for improved convective heat transfer in closed conduit flows. 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. 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.
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Monovalent nanoparticles, bearing a single binding site,    avoid clustering and so are preferable for tracking the behavior of individual proteins. Red blood cell coatings can help nanoparticles evade the immune system. Nanoparticles present possible dangers, both medically and environmentally. This could result in regulatory bodies, such as the FDA, missing new side effects that are specific to the nano-reformulation. Concern has also been raised over the health effects of respirable nanoparticles from certain combustion processes. Environmental Protection Agency was investigating the safety of the following nanoparticles: .
As of , the U. 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 potential and actual applications in all industries.
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 medicine, physics,    optics,    and electronics.
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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 and it has been shown to improve conversion efficiencies and to decrease laser beam divergence. Nanoparticles are being investigated as potential drug delivery system. Nanoparticles are also studied for possible applications as dietary supplements for delivery of biologically active substances, for example mineral elements.
From Wikipedia, the free encyclopedia. Particle with size between 1 and nm with an outer layer.
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IUPAC definition. Note 4 : Tubes and fibers with only two dimensions below nm are also nanoparticles. Main article: Characterization of nanoparticles.
Main article: Nanoparticle—biomolecule conjugate. See also: Health and safety hazards of nanomaterials , Particulates , and Nanotoxicology. Science portal Technology portal Biology portal. Silvera; Larson, Ronald G. Pure and Applied Chemistry. Blackwell Science. International Organization for Standardization.
Retrieved 18 January Materials Chemistry. Physical Review Letters. Bibcode : PhRvL.. Noyes Publications. Bibcode : Nanot.. Oxford University Press. Retrieved 6 December Retrieved 12 December In Sattler, Klaus D. Handbook of Nanophysics: Nanoparticles and Quantum Dots. CRC Press. Biotechnology Fundamentals. University of Pennsylvania Press.
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