Nanoarticle

Nanoarticle, often used interchangeably with nanoparticle, refers to a particle whose dimensions lie in the nanometer scale, typically between 1 and 100 nanometers. As particles approach this size, their surface area to volume ratio increases dramatically and quantum effects can influence optical, electronic, and chemical behavior. Nanoarticles can be composed of a wide range of materials and may exist as discrete entities or as core–shell, alloy, or hybrid structures.

Common classes include metallic nanoparticles such as gold, silver, and platinum; metal oxides such as titanium dioxide and zinc oxide; carbon-based particles such as fullerenes, carbon dots, and graphene fragments; polymeric nanoparticles; and hybrid systems combining materials.

Properties: depending on composition and size, nanoarticles exhibit unique plasmonic, catalytic, magnetic, or optical properties. Quantum confinement can alter band gaps in semiconductors and narrow or shift absorption spectra. Surface functionalization controls stability, dispersibility, and biocompatibility.

Synthesis and stability: nanoarticles are produced by bottom-up approaches (chemical reduction, sol-gel synthesis, hydrothermal methods) or top-down methods (milling, laser ablation). Stabilization often requires ligands, polymers, or surfactants to prevent aggregation and to tailor surface chemistry.

Applications and considerations: in medicine, they serve in drug delivery, imaging, and diagnostics; in catalysis and energy, as catalysts and electrocatalysts; in electronics and sensing; and in consumer products such as cosmetics and coatings. Safety concerns include potential cytotoxicity and environmental impact, which depend on size, composition, surface coating, and release dynamics; regulatory frameworks evaluate such risks.