A nanoparticle is a microscopic particle whose size is measured in nanometres. Nanoparticles are thus larger than angstroms (Å), but smaller than micrometres. At the small end of the size range, nanoparticles are often referred to as clusters (cluster (physics)).
Metal, dielectric, and semiconductor nanoparticles have been formed, as well as hybrid structures (e.g., core-shell nanoparticles). Nanospheres, nanorods, and nanocups are just a few of the shapes that have been grown. Semiconductor quantum dots and nanocrystals are types of nanoparticles.
Nanoparticle characterization is necessary to establish understanding and control of nanoparticle synthesis and applications. Characterization is done by using a variety of different techniques, mainly drawn from materials science. Common techniques are electron microscopy, Atomic force microscopy, x-ray photoelectron spectroscopy, fourier transform infra red spectroscopy (FTIR).
Nanoparticle research is currently an area of intense scientific research, due to a wide variety of potential applications in biomedical, optical, and electronic fields.
In biomedical applications nanoparticles are used as drug carriers or imaging agents. For this purpose the nanoparticle may have a hollow structure providing a central reservoir that can be filled with anticancer drugs, detection agents, or chemicals, known as reporters, that can signal if a drug is having a therapeutic effect. The surface of a nanoparticle can also be adorned with various targeting agents, such as antibodies, drugs, imaging agents, and reporters. Most nanoparticles are constructed to be small enough to pass through blood capillaries and enter cells.

The term "nanoparticle" was found in the following pages:

Instrument database: Elemental Scientific Inc. (ESI) - microFAST Single Cell
5th Workshop on Field-Flow Fractionation – Mass Spectrometry (FFF-MS) | EVISA's Agenda of Events
Tribute to Jacques Buffle: founding father of dynamic metal speciation analysis | EVISA's News
Impressions from the European Winter Conference on Plasma Spectrochemistry that took place February 3-8, 2017 in Pau (France) | EVISA's News
Link database: nanoComposix: Gold Nanoparticles: Physical Properties
Characterization and Speciation of Gold and Silver Nanoparticles by MEKC-ICP-MS | EVISA's News
Agilent is introducing the second generation of Triple Quadrupole ICP-MS system: The 8900 | EVISA's News
Determination of Thallium Species in Food Samples by Microextraction and Graphite Furnace Atomic Absorption Spectrometry | EVISA's News
Directory of scientists: C. Derrick Quarles Jr.
Special issue on "Advances in speciation techniques and methodology" available | EVISA's News
Instrument database: Postnova Analytics GmbH - AF2000 MT – Mid Temperature aqueous/organic Asymmetric Flow FFF
Single particle detection by ICP-MS: From particles via ion clouds to signals | EVISA's News
Instrument database: Postnova Analytics GmbH - AF2000 FOCUS Asymmetric Flow Field-Flow Fractionation
Directory of scientists: Spiros A. Pergantis
Journals database: Journal of Nanoparticle Research
Directory of scientists: Jérôme F.L. Duval
Link database: nanoComposix: Silver Nanoparticles: Physical Properties