具有不同粒径和相同表面结构纳米银颗粒的制备及表征

具有不同粒径相同表面结构AgNPs（nano-silver，纳米银）的可控合成是开展AgNPs毒性研究和风险评估的基础，也是材料制备领域的难点之一.采取化学还原的方法，使用AgNO₃（硝酸银）作为反应前体，使用TSC（trisodium citrate，柠檬酸三钠）和NaBH₄（sodium borohydride，硼氢化钠）作为稳定剂及还原剂，通过优化剂量比和反应条件等合成参数，一步式原位反应生成不同粒径的AgNPs.利用TEM（透射电子显微镜）、UV-Vis（紫外可见分光光谱）、ICP-MS（电感耦合等离子体质谱）、FT-IR（傅里叶转换红外光谱）和DLS（动态光散射）等技术综合表征了合成纳米颗粒的形貌和结构性质.结果表明:①TEM结果显示，3种AgNPs均为球形且粒径分别为12、25和33 nm.②UV-Vis表征结果显示，所得产物在391~408 nm之间有较强吸收，说明合成产物为AgNPs.③利用ICP-MS测试样品中未反应的ρ（Ag+），得出该制备方法具有高产率（>99%）.④DLS结果证实了合成的AgNPs在水溶液中带负电荷且具有较窄的粒度分布.⑤FT-IR结果显示，所制备的AgNPs表面结构一致，具有碳碳双键、酯基、羧基和羟基等官能团，在材料制备的过程中，溶液的初始配比、反应时间及环境条件都会对反应结果产生很大影响.研究显示，通过化学还原方法制备的AgNPs具有方法简便、重现性好、产率高和单分散性的特点，所制备的系列AgNPs颗粒表面结构一致，具有良好的化学稳定性. 

Preparation and Characterization of Nano-Silver with Different Particle Sizes and Uniform Surface Coating

The controllable synthesis of AgNPs (nano-silver) with the same surface structures and different particle sizes is the basis for researching the AgNPs toxicity and risk assessment, which is one of the challenge in the material preparation. Chemical reduction was carried out by using silver nitrate (AgNO₃) as the reaction precursor, trisodium citrate (TSC) and sodium borohydride (NaBH₄) as stabilizers and reducing agents. One-step in-situ reaction to generate AgNPs with different particle sizes could be obtained through controlled synthesis parameters such as the dose ratio and the reaction conditions. Transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), inductively coupled plasma mass spectrometry (ICP-MS), Fourier transform infrared spectroscopy (FT-IR) and dynamic light scattering (DLS) were used to characterize the morphology and structural properties of the nanoparticles. The results showed that:(1) According to the TEM, it was found that the three AgNPs were spherical and had particle sizes of 12, 25 and 33 nm, respectively. (2) The UV-visible spectroscopy results show that the obtained product had strong absorption between 391 and 408 nm, indicating that the synthesized product was AgNPs. (3) The concentration of the unreacted silver ions, calculated by the results gained from ICP-MS, demonstrated the high yield of the preparation method (>99%). (4) DLS results confirmed that the synthetic AgNPs were negatively charged in aqueous solution and had a narrow particle size distribution. (5) FTIR shows the uniform surface structure of the AgNPs, which have the same functional groups such as carbon-carbon double bonds, ester, carboxyl and hydroxyl groups. In the preparation processes, the initial ratio of the solution, the reaction time and the environmental conditions had a great influence on the reaction results. This study indicated that the preparation process by the chemical reduction method was easy,reproducible and high yield. The series of AgNPs had uniform surface structure and good chemical stability.