Čampelj Stanislav, Pobrežnik Matic, Landovsky Tomas, Kovač Janez, Martin-Samos Layla, Hamplova Vera, Lisjak Darja
"Jožef Stefan" Institute, Jamova 39, 1000 Ljubljana, Slovenia.
CNR-IOM, Democritos National Simulation Center, Istituto Officina dei Materiali, c/o SISSA, Via Bonomea 265, 34136 Trieste, Italy.
Nanomaterials (Basel). 2023 Jun 8;13(12):1822. doi: 10.3390/nano13121822.
In this study, MNPs were functionalized with pyrocatechol (CAT), pyrogallol (GAL), caffeic acid (CAF), and nitrodopamine (NDA) at pH 8 and pH 11. The functionalization of the MNPs was successful, except in the case of NDA at pH 11. The thermogravimetric analyses indicated that the surface concentration of the catechols was between 1.5 and 3.6 molecules/nm. The saturation magnetizations (M) of the functionalized MNPs were higher than the starting material. XPS analyses showed only the presence of Fe(III) ions on the surface, thus refuting the idea of the Fe being reduced and magnetite being formed on the surfaces of the MNPs. Density functional theory (DFT) calculations were performed for two modes of adsorption of CAT onto two model surfaces: plain and adsorption via condensation. The total magnetization of both adsorption modes remained the same, indicating that the adsorption of the catechols does not affect the M. The analyses of the size and the size distribution showed an increase in the average size of the MNPs during the functionalization process. This increase in the average size of the MNPs and the reduction in the fraction of the smallest (i.e., <10 nm) MNPs explained the increase in the M values.
在本研究中，在pH值为8和11的条件下，用邻苯二酚（CAT）、连苯三酚（GAL）、咖啡酸（CAF）和硝基多巴胺（NDA）对磁性纳米颗粒（MNPs）进行功能化处理。除了在pH值为11时用NDA处理的情况外，MNPs的功能化处理是成功的。热重分析表明，儿茶酚的表面浓度在1.5至3.6个分子/纳米之间。功能化MNPs的饱和磁化强度（M）高于起始材料。X射线光电子能谱分析表明，表面仅存在Fe(III)离子，从而反驳了Fe被还原并在MNPs表面形成磁铁矿的观点。对CAT在两种模型表面上的两种吸附模式进行了密度泛函理论（DFT）计算：平面吸附和缩合吸附。两种吸附模式的总磁化强度保持不变，表明儿茶酚的吸附不影响M。对尺寸和尺寸分布的分析表明，在功能化过程中MNPs的平均尺寸增加。MNPs平均尺寸的增加以及最小尺寸（即<10 nm）的MNPs比例的降低解释了M值的增加。
