纳米材料Nanomaterials

小尺寸带来特殊性质：比表面积急剧增大，表面原子比例高（5 nm 颗粒约 20–30% 的原子在表面），反应活性和催化活性增强；当尺寸接近电子的德布罗意波长时出现量子尺寸效应，能级变为分立，禁带变宽；金属纳米颗粒的表面等离子体共振使金溶胶呈红色、银溶胶呈黄色；熔点也随尺寸减小而下降。

Small size brings special properties: surface area per gram rises dramatically and a large share of atoms lie at the surface (about 20–30% for a 5 nm particle), boosting reactivity and catalytic activity; when size approaches the electron's de Broglie wavelength, quantum size effects make levels discrete and widen the band gap; surface plasmon resonance makes gold sols red and silver sols yellow; and melting points fall as size shrinks.

古罗马的莱库格斯杯和中世纪彩色玻璃中就含有金银纳米颗粒。1857 年法拉第制得红色金溶胶并研究其光学性质。1959 年费曼在演讲《底部还有很大空间》中设想在原子尺度操纵物质。1974 年谷口纪男提出 nanotechnology 一词。1981 年扫描隧道显微镜发明，1985 年发现富勒烯，1991 年表征碳纳米管，纳米科技迅速发展。

The Roman Lycurgus Cup and medieval stained glass contain gold and silver nanoparticles. In 1857 Faraday made red gold sols and studied their optics. In his 1959 talk 'There's Plenty of Room at the Bottom' Feynman imagined manipulating matter atom by atom, and Taniguchi coined the word nanotechnology in 1974. The scanning tunnelling microscope (1981), fullerenes (1985) and carbon nanotubes (characterised 1991) drove rapid growth.

纳米材料用于催化剂（汽车尾气纳米贵金属）、防晒霜（纳米 TiO₂、ZnO）、抗菌材料（纳米银）、锂电池电极、显示器（量子点）、靶向药物递送（脂质纳米粒、mRNA 疫苗）和高强度复合材料。纳米颗粒可能穿透生物屏障，其环境与健康风险是纳米毒理学研究的重点。

Nanomaterials are used in catalysts (nanoscale precious metals in converters), sunscreens (nano-TiO₂ and ZnO), antibacterial materials (nanosilver), lithium-battery electrodes, displays (quantum dots), targeted drug delivery (lipid nanoparticles, mRNA vaccines) and high-strength composites. Nanoparticles may cross biological barriers, and their environmental and health risks are the focus of nanotoxicology.