Abstract：
This study devised a label-free electrochemical immunosensor for the quantitative detection of alpha-fetoprotein (AFP). 3-Polythiophene acetic acid (3-PTAA) nanoparticles were anchored onto a few-layer graphene (FLG) nanosheet, and the resulting nanocomposite was utilized as the immunosensor platform. The AFP antibody (anti-AFP) was immobilized on 3-PTAA@FLG via a covalent interaction between the amine group of anti-AFP and the carboxylic group of 3-PTAA via ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS) coupling. FLG is largely responsible for providing electrochemical signals, whereas 3-PTAA nanoparticles are well-known for their ability to be compatible with biological molecules in neutral aqueous solutions. Moreover, the carboxyl group present in 3-PTAA effectively binds anti-AFP through EDC/NHS conjugation. Owing to good dispersibility and higher surface area of 3-PTAA, it is very convenient for casting the polymer directly on the electrode substrate followed by immobilization of anti-AFP. Thus, it is feasible to regulate the activity of AFP proteins and control the spatial distribution of the immobilized anti-AFP proteins. The electrochemical sensing performance was assessed via cyclic voltammetry and electrochemical impedance spectroscopy. For an increase in the bioconjugate concentration, the results demonstrated a surge in charge-transfer resistance and a consequent decline in the current response. This approach effectively detected AFP at an extended dynamic range of 0.0001-250 ng/mL with a detection limit of 0.047 pg/mL. Furthermore, the sensing capacity of the immunosensor for AFP detection has been demonstrated to be steady in real human serum cultures. Our approach exhibits good electrochemical performance in terms of reproducibility, selectivity, and stability, which would surely impart budding applications in the clinical diagnosis of several other tumor markers.
摘要：
本研究设计了一种用于定量检测甲胎蛋白（AFP）的无标记电化学免疫传感器。3-聚噻吩乙酸（3-PTAA）纳米颗粒锚定在几层石墨烯（FLG）纳米片上，并将所得纳米复合材料用作免疫传感器平台。AFP抗体(抗AFP)通过抗AFP的胺基和3-PTAA的羧基之间的共价相互作用经由乙基-3-(3-二甲基氨基丙基)碳二亚胺(EDC)/N-羟基琥珀酰亚胺(NHS)偶联固定在3-PTAA@FLG上。FLG主要负责提供电化学信号，而3-PTAA纳米颗粒以其与中性水溶液中的生物分子相容的能力而闻名。此外，存在于3-PTAA中的羧基通过EDC/NHS缀合有效地结合抗AFP。由于3-PTAA具有良好的分散性和较高的表面积，将聚合物直接浇铸在电极基底上,然后固定抗AFP是非常方便的。因此，调控AFP蛋白的活性和控制固定化抗AFP蛋白的空间分布是可行的。通过循环伏安法和电化学阻抗谱评估电化学传感性能。为了增加生物缀合物浓度，结果表明，电荷转移电阻激增，电流响应随之下降。这种方法在0.0001-250ng/mL的扩展动态范围内有效地检测了AFP，检出限为0.047pg/mL。此外，用于AFP检测的免疫传感器的传感能力已被证明在真实的人血清培养物中是稳定的。我们的方法在重现性方面表现出良好的电化学性能，选择性,和稳定性,这肯定会在其他几种肿瘤标志物的临床诊断中赋予新的应用。
