An aptamer-based method is described for the electrochemical determination of lysozyme. A glassy carbon electrode was modified with a nanocomposite composed of reduced graphene oxide (rGO), multi-walled carbon nanotubes (MWCNTs), chitosan (CS), and a synthesized carbon quantum dot (CQD) from CS. The composition of the nanocomposite (rGO-MWCNT/CS/CQD) warrants a high surface-to-volume ratio, high conductivity, high stability, and great electrocatalytic activity. This nanocomposite provides a suitable site for better immobilization of aptamers due to the existence of many amino and carboxyl functional groups, and remaining oxygen-related defects properties in rGO. In addition, this nanocomposite allows considerable enhancement of the electrochemical signal and contributes to improving sensitivity. The amino-linked lysozyme aptamers were immobilized on the nanocomposite through covalent coupling between the amino groups of the aptamer and the amino groups of the nanocomposite using glutaraldehyde (GLA) linker. The modified electrode was characterized by electrochemical methods including differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). In the presence of lysozyme, the immobilized aptamer selectively caught the target lysozyme on the electrode interface that leads to a decrease in the DPV peak current and an increase in Charge Transfer Resistance (R_ct) in EIS as an analytical signal. Using the obtained data from DPV and EIS techniques, two calibration curves were drawn. The anti-lysozyme aptasensor proposed has two very low LODs. These measures are 3.7 and 1.9 fmol L⁻¹ within the wide detection ranges of 20 fmol L⁻¹ to 10 nmol L⁻¹, and 10 fmol L⁻¹ to 100 nmol L⁻¹ for DPV and EIS calibration curves, respectively. The GCE/rGO-MWCNT/CS/CQD showed sensitivity, high reproducibility, specificity and rapid response for lysozyme which can be used in biomedical fields.

描述了一种基于适体的方法，用于溶菌酶的电化学测定。用由还原的氧化石墨烯（rGO），多壁碳纳米管（MWCNT），壳聚糖（CS）和由CS合成的碳量子点（CQD）组成的纳米复合材料修饰玻璃碳电极。纳米复合材料的组成（rGO-MWCNT / CS / CQD）具有高的表面体积比，高电导率，高稳定性和出色的电催化活性。由于存在许多氨基和羧基官能团，以及rGO中与氧有关的缺陷性质，这种纳米复合材料为适体的更好固定提供了合适的位点。另外，该纳米复合材料允许电化学信号的显着增强并有助于提高灵敏度。使用戊二醛（GLA）接头，通过适体的氨基和纳米复合物的氨基之间的共价偶联将氨基连接的溶菌酶适体固定在纳米复合材料上。修饰电极通过电化学方法进行表征，包括差分脉冲伏安法（DPV），循环伏安法（CV）和电化学阻抗谱（EIS）。在存在溶菌酶的情况下，固定的适体在电极界面上选择性地捕获了目标溶菌酶，从而导致DPV峰值电流的降低和电荷转移电阻的增加（修饰电极通过电化学方法进行表征，包括差分脉冲伏安法（DPV），循环伏安法（CV）和电化学阻抗谱（EIS）。在存在溶菌酶的情况下，固定的适体在电极界面上选择性地捕获了目标溶菌酶，从而导致DPV峰值电流的降低和电荷转移电阻的增加（修饰电极通过电化学方法进行表征，包括差分脉冲伏安法（DPV），循环伏安法（CV）和电化学阻抗谱（EIS）。在存在溶菌酶的情况下，固定的适体在电极界面上选择性地捕获了目标溶菌酶，从而导致DPV峰值电流的降低和电荷转移电阻的增加（R _ct）在EIS中作为分析信号。使用从DPV和EIS技术获得的数据，绘制了两条校准曲线。提出的抗溶菌酶适体传感器具有两个非常低的LOD。对于DPV和EIS校准曲线，这些测量分别在20 fmol L ^-1至10 nmol L ^-1和10 fmol L ^-1至100 nmol L ^-1的宽检测范围内，分别为3.7 fmol L ^-1和1.9 fmol L ^-1。GCE / rGO-MWCNT / CS / CQD对溶菌酶具有敏感性，高重复性，特异性和快速响应性，可用于生物医学领域。