Tao Zaiyou, Liu Hongmei, Chen Yanran, He Shaoying, Yang Baomin
Kunming University of Science & Technology, Kunming, 650500, Yunnan, People's Republic of China.
Mikrochim Acta. 2025 May 12;192(6):348. doi: 10.1007/s00604-025-07178-x.
Chiral recognition plays a crucial role in the fields of chemistry, biomedicine, and food science. In this study, β-cyclodextrin-modified silver nanoparticles (β-CD@AgNPs) with enhanced chiral binding ability were successfully prepared using the reduction method and utilized for the selective recognition of tryptophan (Trp) enantiomers, one of the representatives of non-polar amino acids. Interestingly, the β-CD@AgNPs with L-Trp system exhibited a red color (with a new ultraviolet-visible (UV-vis) absorption peak at around 550 nm), while no change occurred with D-Trp. Compared with unmodified silver nanoparticles (AgNPs), the recognition results of chiral Trp by β-CD@AgNPs were reversed. β-CD@AgNPs were also used to recognize non-polar (phenylalanine (Phe), valine (Val) and leucine (Leu)), polar (tyrosine (Tyr) and serine (Ser)), and basic (histidine (His)) and acidic (aspartic acid (Asp)) amino acids, respectively. It was found that β-CD@AgNPs demonstrated high selectivity only for Trp among non-polar amino acids. Furthermore, the recognition mechanism was studied through calculations, and it indicated that the binding energy strength between L-Trp and β-CD@AgNPs (-2540.76 kcal/mol) was higher than that between D-Trp and β-CD@AgNPs (-2326.91 kcal/mol). Owing to the significant electronegativity of the β-CD cavity, the indole ring of L-Trp exhibited susceptibility to electrostatic interactions, leading to enhanced adsorption within the β-CD cavity. This effect consequently improved the aggregation capability of the β-CD@AgNPs. Finally, β-CD@AgNPs were used for determining the enantiomeric excess (ee%) of Trp. A favorable linear relationship between the UV-vis absorption intensity and the ee% of Trp was established (R = 0.959). This study provided an effective method for exploring the chiral recognition mechanism of amino acid enantiomers based on nanomaterials.
手性识别在化学、生物医学和食品科学领域发挥着至关重要的作用。在本研究中，采用还原法成功制备了具有增强手性结合能力的β-环糊精修饰银纳米颗粒（β-CD@AgNPs），并将其用于选择性识别非极性氨基酸代表之一的色氨酸（Trp）对映体。有趣的是，含有L-Trp体系的β-CD@AgNPs呈现红色（在550 nm左右有一个新的紫外可见（UV-vis）吸收峰），而D-Trp体系则无变化。与未修饰的银纳米颗粒（AgNPs）相比，β-CD@AgNPs对手性Trp的识别结果相反。β-CD@AgNPs还分别用于识别非极性（苯丙氨酸（Phe）、缬氨酸（Val）和亮氨酸（Leu））、极性（酪氨酸（Tyr）和丝氨酸（Ser））以及碱性（组氨酸（His））和酸性（天冬氨酸（Asp））氨基酸。结果发现，β-CD@AgNPs在非极性氨基酸中仅对Trp表现出高选择性。此外，通过计算研究了识别机制，结果表明L-Trp与β-CD@AgNPs之间的结合能强度（-2540.76 kcal/mol）高于D-Trp与β-CD@AgNPs之间的结合能强度（-2326.91 kcal/mol）。由于β-CD空腔具有显著的电负性，L-Trp的吲哚环表现出对静电相互作用的敏感性，导致其在β-CD空腔内的吸附增强。这种效应进而提高了β-CD@AgNPs的聚集能力。最后，β-CD@AgNPs用于测定Trp的对映体过量值（ee%）。建立了UV-vis吸收强度与Trp的ee%之间良好的线性关系（R = 0.959）。本研究为基于纳米材料探索氨基酸对映体的手性识别机制提供了一种有效方法。
