Department of Chemistry, Temple University, Philadelphia, PA 19122, United States.
J Colloid Interface Sci. 2010 Jan 15;341(2):215-23. doi: 10.1016/j.jcis.2009.09.035. Epub 2009 Sep 23.
The interaction of ascorbic acid with ferrihydrite nanoparticles with and without adsorbed phospholipid has been investigated with atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), density functional theory (DFT) cluster calculations, and batch geochemical methods. Both batch geochemical rate measurements and in situ AFM showed that ferrihydrite particles dissolved in the presence of ascorbic acid over a period of hours. The area-normalized dissolution rate derived from AFM measurements of isolated ferrihydrite particles was relatively constant over the period of dissolution and was faster than the dissolution rate derived from batch reaction methods. Results from ATR-FTIR interpreted in view of theoretical calculations suggested that exposure of ferrihydrite to ascorbic acid led to an adsorbed monodentate ascorbate surface complex. Ferrihydrite dissolution was suppressed if particles were exposed to an organic lipid prior to or during exposure to ascorbic acid. AFM analysis of the lipid layer showed that its thickness was close to 7 nm, the expected value for lipid assembled into a bilayer structure.
采用原子力显微镜（AFM）、衰减全反射傅里叶变换红外光谱（ATR-FTIR）、密度泛函理论（DFT）团簇计算和批量地球化学方法研究了抗坏血酸与带和不带吸附磷脂的水铁矿纳米颗粒的相互作用。批量地球化学速率测量和原位 AFM 均表明，在数小时的时间内，抗坏血酸存在下，水铁矿颗粒溶解。从 AFM 测量孤立水铁矿颗粒获得的面积归一化溶解速率在溶解过程中相对恒定，且快于批量反应方法获得的溶解速率。ATR-FTIR 的结果根据理论计算进行解释，表明暴露于抗坏血酸的水铁矿导致吸附的单齿抗坏血酸表面络合物。如果在暴露于抗坏血酸之前或期间将颗粒暴露于有机脂质，则会抑制水铁矿的溶解。对脂质层的 AFM 分析表明，其厚度接近 7nm，这是组装成双分子层结构的脂质的预期值。
