Qiao Zhe, Jiang Zilian, Luo Qiufen, Zhang Hongfang, Zheng Jianbin
Ministry of Education Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, Shanxi Provincial Key Laboratory of Electroanalytical Chemistry, College of Chemistry & Materials Science, Northwest University, Xi'an 710127, China.
Ministry of Education Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, Shanxi Provincial Key Laboratory of Electroanalytical Chemistry, College of Chemistry & Materials Science, Northwest University, Xi'an 710127, China.
Anal Chim Acta. 2021 Jun 1;1162:338476. doi: 10.1016/j.aca.2021.338476. Epub 2021 Apr 6.
Labeling with redox reporter is often required in developing electrochemical bioassay for most proteins or nucleic acid biomarkers. Herein, a label-free ratiometric immunosensing platform is firstly developed by integrating the antibody-conjugated nanochannels with a smart modified electrode. The electrode modifier is the composite of C, tetraoctylammonium bromide (TOA) and Prussian blue (PB). Cyclic voltammograms of the ultimate C-TOA/PB modified electrode exhibited two pairs of peaks at 0.15 V and -0.13 V, ascribing to the redox of PB and C, respectively. With the addition of K[Fe(CN)] in the electrolyte solution, the peaks of PB decreased due to the adsorption of [Fe(CN)] while the peaks of C increased because of the formation of the ternary complex (TC) C-TOA-[Fe(CN)]. As a result, the peak current ratio I/I decreased gradually with the increment of the concentration of [Fe(CN)]. For the nanochannels-based immunosensing platform, the steric hindrance of the bioconjugated nanochannels varied with the loading amount of the target CA125, and thus [Fe(CN)] passing through the channels was quantitatively affected. And the higher CA125 level was, the less [Fe(CN)] concentration was. And thus, the ratio I/I monitored at the C-TOA/PB modified electrode increased with the increase of the concentration of CA125. The ratiometric immunoassay featured a linear calibration range from 1.0 U mL to 100 U mL with a low detection limit of 0.86 U mL. In addition, the ratiometric immunosensing platform demonstrated good specificity and stability as well as acceptable accuracy in overcoming the effect of electrode passivation which was an inherent problem of electroanalysis.
在开发针对大多数蛋白质或核酸生物标志物的电化学生物测定法时，通常需要用氧化还原报告分子进行标记。在此，首次通过将抗体偶联的纳米通道与智能修饰电极相结合，开发了一种无标记的比率免疫传感平台。电极修饰剂是碳（C）、溴化四辛基铵（TOA）和普鲁士蓝（PB）的复合物。最终的C-TOA/PB修饰电极的循环伏安图在0.15 V和-0.13 V处显示出两对峰，分别归因于PB和C的氧化还原。在电解质溶液中加入K[Fe(CN)]后，PB的峰由于[Fe(CN)]的吸附而降低，而C的峰由于三元复合物（TC）C-TOA-[Fe(CN)]的形成而增加。结果，峰电流比I/I随着[Fe(CN)]浓度的增加而逐渐降低。对于基于纳米通道的免疫传感平台，生物偶联纳米通道的空间位阻随目标CA125的负载量而变化，因此穿过通道的[Fe(CN)]受到定量影响。并且CA125水平越高，[Fe(CN)]浓度越低。因此，在C-TOA/PB修饰电极上监测到的比率I/I随着CA125浓度的增加而增加。该比率免疫测定的线性校准范围为1.0 U mL至100 U mL，检测限低至0.86 U mL。此外，该比率免疫传感平台在克服电极钝化影响方面表现出良好的特异性、稳定性以及可接受的准确性，而电极钝化是电分析的一个固有问题。
