Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, China.
School of Light Industry and Engineering, South China University of Technology, Guangzhou 510006, China.
Int J Mol Sci. 2023 Jun 24;24(13):10594. doi: 10.3390/ijms241310594.
This study proposes a label-free aptamer biosensor for the sensitive detection of malachite green(MG) using gold nanoparticles/multi-walled carbon nanotubes @ titanium dioxide(AuNPs/MWCNTs@TiO). The nanocomposite provides a large surface area and good electrical conductivity, improving current transfer and acting as a platform for aptamer immobilization. The aptamer and the complementary chain(cDNA) are paired by base complementary to form the recognition element and fixed on the AuNPs by sulfhydryl group, which was modified on the cDNA. Since DNA is negatively charged, the redox probe in the electrolyte is less exposed to the electrode surface under the repulsion of the negative charge, resulting in a low-electrical signal level. When MG is present, the aptamer is detached from the cDNA and binds to MG, the DNA on the electrode surface is reduced, and the rejection of the redox probe is weakened, which leads to an enhanced electrical signal and enables the detection of MG concentration by measuring the change in the electrical signal. Under the best experimental conditions, the sensor demonstrates a good linear relationship for the detection of MG from 0.01 to 1000 ng/mL, the limit of detection (LOD)is 8.68 pg/mL. This sensor is stable, specific, and reproducible, allowing for the detection of various small-molecule pollutants by changing the aptamer, providing an effective method for detecting small-molecule pollutants.
本研究提出了一种无标记适体生物传感器，用于使用金纳米粒子/多壁碳纳米管@二氧化钛（AuNPs/MWCNTs@TiO）灵敏检测孔雀石绿（MG）。该纳米复合材料提供了较大的表面积和良好的导电性，改善了电流转移，并作为适体固定的平台。适体和互补链（cDNA）通过碱基互补配对形成识别元件，并通过巯基固定在 AuNPs 上，cDNA 上修饰了巯基。由于 DNA 带负电荷，在负电荷的排斥作用下，电解质中的氧化还原探针在电极表面的暴露较少，导致电信号水平较低。当存在 MG 时，适体从 cDNA 上脱离并与 MG 结合，电极表面的 DNA 被还原，氧化还原探针的排斥作用减弱，导致电信号增强，通过测量电信号的变化可以检测 MG 浓度。在最佳实验条件下，该传感器对 0.01 至 1000ng/mL 的 MG 检测表现出良好的线性关系，检测限（LOD）为 8.68pg/mL。该传感器稳定、特异、重现性好，通过改变适体可以检测各种小分子污染物，为小分子污染物的检测提供了一种有效的方法。
