基于新型多功能金纳米粒子比色传感器的手性氨基酸快速分析体系研究

Nanoparticle-based colorimetric sensors are good candidates for rapid, real-time detection of chiral amino acid due to their simplicity and easy-operation properties. However, the drawbacks of current nanoparticle-based colorimetric sensors for chiral amino acid detection is its relatively low sensitivity and accuracy, narrow dynamic range, which restrict their application in real sample analysis. In this project, a kind of janus gold nanoparticles (AuNPs) with relatively large size will be prepared and introduced as colorimetric sensors for detection of chiral amino acid with important physiological functions, in which the stabilizing agent and chiral selector were attached to the selected area of the AuNPs surface. The oriented and controllable aggregation of AuNPs could be selectively induced by specific chiral recognition between amino acid enantiomers and chiral selector, which results in significantly improved long-term stability, accuracy and dynamic range of detection. The detection sensitivity could be improved by the use of relatively big AuNPs in a stable state. For real sample analysis, the inert, bulky ligands will be modified to the achiral recognition area of the AuNPs surface. The steric repulsion between the adjacent ligand of monolayer blocks will reduce the interaction between non-targeted molecule in real sample and AuNPs, which resulting significantly improved sensitivity and accuracy for chiral amino acid detection in real sample. This project not only has significant scientific values for the development of novel, rapid enantioanalysis strategies of amino acid enantiomers, but also would show its promising potentials in the real sample detection.

针对目前基于纳米粒子聚集的氨基酸手性比色分析方法准确度低、稳定性差、线性范围窄、灵敏度低及难于应用到实际样品检测等问题，本项目拟设计、制备一类稳定剂和手性选择剂定向修饰的具有较大尺寸的“Janus”型金纳米粒子比色传感器，发展针对具有重要生理功能的氨基酸的快速手性分析方法。通过手性选择剂与氨基酸对映体之间特异选择性手性识别作用实现金纳米粒子定向、可控聚集，从而提高方法稳定性、准确度及拓宽方法定量线性范围；在保证纳米粒子稳定性的情况下，通过增加金纳米粒子尺寸提高方法灵敏度；通过引入惰性空间位阻基团在传感器表面非手性识别区域营造一层空间位阻屏蔽层，进而避免实际样品中其它成分与金纳米粒子相互作用对方法的干扰，提高方法应用于实际样品检测的灵敏度及准确性。本项目研究内容不仅对发展新型氨基酸手性分析方法和技术具有重要的科学意义，更有助于解决实际样品中氨基酸手性分析问题，具有很强的应用价值。

针对目前基于纳米粒子聚集的氨基酸手性比色分析方法准确度低、稳定性差、线性范围窄、灵敏度低及难于应用到实际样品检测等问题，本项目拟通过制备一类稳定剂和手性选择剂定向修饰的 Janus金纳米粒子比色传感器，发展针对具有重要生理功能的氨基酸的快速手性分析方法。通过控制金纳米粒子定向、可控聚集，提高方法稳定性、准确度及拓宽方法定量线性范围；通过增加金纳米粒子尺寸提高方法灵敏度；通过引入空间位阻屏蔽层，避免实际样品非目标物的干扰，提高方法应用于实际样品检测的灵敏度及准确性。项目主要研究内容包括多功能金纳米粒子比色传感器制备、识别能力及分析方法优化和实际样品检测研究。通过项目的实施我们结合“grafting to” 和 “ligand exchange” 策略成功制备得到了PEG和识别剂半胱氨酸限定区域修饰的Janus型金纳米粒子比色传感器，并将其成功应用于老鼠脑脊液中天冬氨酸的直接比色检测。相比于传统对称性修饰的金纳米粒子比色传感器，项目制备得到的Janus型比色传感器对天冬氨酸检测的长期稳定性从5 min提高到3 h，而且线性范围也扩大了2个数量级 (1.8 nM~180 μM)。此外，通过逐步增加Janus比色传感器中金纳米粒子的尺寸（13到45 nm），方法的检测限提高了10000倍（18 µM到1.8 nM）。与传统基于金纳米粒子的比色传感器相比，该策略中由于PEG链修饰取代了金纳米粒子大部分区域的电荷，而且识别剂被限制在很小的特定区域，因此Janus型金纳米粒子比色传感器具有非常优异的抗干扰能力，基本不受其他神经递质、盐及其他氨基酸的干扰，无需前处理便可直接应用于老鼠脑脊液中天冬氨酸的比色检测。利用该方法检测出老鼠脑脊液中天冬氨酸含量为33.9 ± 1.3 μM，与文献报道数据一致，且加标回收率为（86.5 ± 7.5%），因此方法准确、可靠。项目已完成最为关键的材料制备和实际样品检测目标，正在开展将其应用于目标氨基酸手性比色分析方法研究中。该项目得到的研究成果为设计可直接应用于复杂样品检测的比色传感器开辟了一种新的路径和策略，具有重要科学意义和应用价值。