基于碳量子点/羧基化石墨相氮化碳复合材料的电化学发光适体传感器检测牛奶中林可霉素

Determination of lincomycin in milk by electrochemiluminescence aptasensor based on carbon quantum dots/carboxyl functionalized graphene-like carbon nitride composites

中文关键词:  碳量子点  羧基化石墨相氮化碳  林可霉素  电化学发光  适体传感器  牛奶

英文关键词:carbon quantum dots  carboxyl functionalized graphene-like carbon nitride  lincomycin  electrochemiluminescence  aptasensor  milk

中文摘要:

      目的 构建一种高灵敏的核酸电化学发光(electrochemiluminescence, ECL)适体传感器检测牛奶中的林可霉素(lincomycin, LIN)残留。方法 以壳聚糖为交联剂, 在玻碳电极(glassy carbon electrode, GCE)表面固定羧基化石墨相氮化碳(carboxylated functionalized graphite-like carbon nitride, C-g-C3N4)和碳量子点(carbon quantum dots, CQDs), 制得CQDs/C-g-C3N4/GCE。电极活化后, 将LIN的适配体(Apt-DNA)和二茂铁标记的DNA (Fc-DNA)修饰至电极表面, 构建新型的电化学发光适体传感界面。采用循环伏安和交流阻抗对传感器的构建过程及电化学性能进行考察, 同时对传感器的电化学发光行为进行分析, 并应用于牛奶中LIN的检测。结果 CQDs和C-g-C3N4之间能产生强烈的协同效应, 复合材料不仅能提供大量的活性催化位点, 而且能促进S2O82?还原成大量的SO4??, CQDs/C-g-C3N4复合材料修饰电极的发光信号达13606 a.u., 分别是CQDs/GCE和C-g-C3N4/GCE发光信号的24.2和5.6倍。当LIN不存在时, 由于二茂铁的猝灭作用, Fc-DNA/Apt-DNA/ CQDs/C-g-C3N4/GCE产生较弱的发光信号; 当适体传感器经LIN培育后, 由于Apt-DNA与LIN的高特异性结合, 导致部分Fc-DNA从电极表面脱落, 发光信号恢复。在最佳条件下, 电化学发光强度与LIN质量浓度对数在0.10 ng/mL~100.00 μg/mL范围内呈现良好的线性关系, 检出限为0.03 ng/mL (S/N=3)。传感器对LIN具有良好的特异性识别能力, 应用于牛奶中LIN的检测, 加标回收率为93.5%~104.0%, 相对标准偏差为2.9%~4.1%。结论 制备的Fc-DNA/Apt-DNA/CQDs/C-g-C3N4/GCE适体传感界面可用于牛奶中LIN残留的高灵敏检测。

英文摘要:

      Objective To develop a highly sensitive electrochemiluminescence (ECL) aptasensor for the determination of lincomycin (LIN) in milk. Methods Carboxylated functionalized graphite-like carbon nitride (C-g-C3N4) and carbon quantum dots (CQDs) were assembled onto the glass carbon electrode (GCE) to form CQDs/C-g-C3N4/GCE with chitosan as cross-linker. After the CQDs/C-g-C3N4/GCE was activated, the aptamer DNA (Apt-DNA) and the ferrocene-labeled DNA probe (Fc-DNA) were modified to the electrode surface, therefore, a novel ECL aptasensing interface was established. The cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the construction process and electrochemical performance of the sensor. Meantime, the ECL process of the sensor was also analyzed and applied to the detection of LIN in milk. Results There was a strong synergistic effect between CQDs and C-g-C3N4, the composite could not only provided more available catalytic active sites, but also facilitated the reduction of S2O82? to produce more SO4?? . Accordingly, the enhanced ECL intensity was acquired, the ECL intensity of CQDs/C-g-C3N4 system was 13606 a.u., the ECL signal of CQDs/C-g-C3N4/GCE was 24.2 times over CQDs/GCE, 5.6 times over C-g-C3N4/GCE. In the absence of LIN, the ECL signal was quenched effectively by Fc-DNA and a decreased ECL emission was acquired. On the contrary, in the presence of LIN, LIN was specifically bond with Apt-DNA, and Fc-DNA was detached from the aptasensor surface because of the deformation of Apt-DNA, resulting in an effectively enhanced ECL signal. A good linear correlation could be obtained between the ECL intensity and the logarithmic of LIN mass concentration in a range from 0.10 ng/mL to 100.00 μg/mL with a limit of detection of 0.03 ng/mL (S/N=3). The sensor showed good response specificity for LIN, the recoveries of LIN in milk were 93.5%?104.0%, and the relative standard deviations were 2.9%?4.1%. Conclusion The aptasensor has high sensitivity and is suitable for the determination of LIN in milk.