利用贵金属纳米颗粒独特的物理特性, 设计具有信号放大功能的荧光适体传感器用于多巴胺的浓度检测。基于金属荧光增强效应通过在金纳米颗粒与荧光基团之间添加隔离层的手段实现荧光信号放大。将化学修饰了SH键的核酸适体与金纳米颗粒溶液混合, 形成稳定的Au-S键结构并与标记荧光基团的DNA互补链利用碱基互补配对原则结合。然后, 通过调节所设计的核酸适体5′所添加的碱基A的数量, 从而调节荧光基团与金纳米颗粒表面的距离。同时, 优化核酸适体与金纳米颗粒之间的浓度比以及所处的反应环境的pH值, 获得最佳的放大效率。最后对不同浓度的多巴胺进行测试。实验结果表明: 金纳米颗粒溶液与核酸适体在一定的浓度比之下, 在隔离层厚度为27个碱基A时, 最大的荧光增强倍数为2.35。多巴胺浓度检测的线性范围为20~100 nmol/L, 最低检测限为20 nmol/L。该传感器可以在纳米级有效调控隔离层厚度, 提供了一种稳定的信号放大策略。

Based on the unique physical properties of noble metal nanoparticles, a fluorescence sensor with signal amplification function was designed for detecting the concentration of dopamine. Based on the effect of metal fluorescence enhancement, the fluorescence signal was amplified by adding a spacer layer between the gold nanoparticles and fluorophore. First, the aptamer chemically modified with an SH bond was mixed with a gold nanoparticle solution to form a stable Au-S bond structure. Then, the DNA labeled with fluorescent groups were bound due to the complementary base pairing. The distance between the fluorophore and the surface of the gold nanoparticle was adjusted by changing the amount of base A. At the same time, the concentration ratio between the aptamer and gold nanoparticles and the pH of the reaction environment were optimized to obtain the best amplification efficiency. Finally, different concentrations of dopamine were tested. The experimental results indicate that at a certain concentration ratio between the gold nanoparticle solution and aptamer, the maximum fluorescence enhancement is 2.35 times at the isolation layer thickness is 27 base A. Dopamine concentration detection has a linear range of 20-100 nmol/L. The detection limit is 20 nmol/L. It can effectively regulate the isolation layer thickness at the nanometer level, providing a stable signal amplification strategy.