Conventional affinity assays used for carbohydrate antigen (CA125) detection are still problematic due to the heterogeneity in the structure and molecular nature of CA125. This makes the conventional antibody based immunoassay difficult to detect CA125 levels accurately in clinical samples which demands the need for the development of new affinity-based detection without compromising specificity and sensitivity. In this study, for the specific detection of CA125, a unique hybrid affinity biosensor involving DNA aptamers and monoclonal antibodies in a sandwich assay format was developed. To suppress the electrode biofouling from interfering blood proteins, CA125 in human blood/serum samples were specifically captured and transferred to the electrode using monoclonal antibodies conjugated magnetic beads (MBs). The affinity binding between CA125 and the protein binding aptamer was investigated using electrochemical methods and computational modelling. Two different electrochemical detection modalities, viz., electrocatalytic activity of signaling enzymes conjugated to MBs and utilizing external redox probe in the solution, have been evaluated for monitoring the immuno-complex formation CA125 detection. In human serum samples, a sensitivity of 0.017 mA U mL^-1 and the detection limit of 0.08 U mL^-1 for CA125 is demonstrated. The immunosensor was able to detect CA125 levels with a broad clinical range of 2 U/mL to 100 U/mL.

由于CA125的结构和分子性质的异质性，用于碳水化合物抗原（CA125）检测的常规亲和力测定法仍然存在问题。这使得常规的基于抗体的免疫测定法难以准确地检测临床样品中的CA125水平，这需要开发新的基于亲和力的检测方法而又不损害特异性和敏感性。在这项研究中，对于CA125的特异性检测，开发了一种独特的杂交亲和力生物传感器，涉及夹心测定形式的DNA适体和单克隆抗体。为了抑制电极生物污染干扰血液蛋白，使用单克隆抗体偶联磁珠（MBs）专门捕获了人血液/血清样品中的CA125，并将其转移到电极上。CA125和蛋白质结合适体之间的亲和力绑定使用电化学方法和计算模型进行了研究。两种不同的电化学检测方式即，已评估了与MBs偶联并利用溶液中外部氧化还原探针的信号酶的电催化活性，以监测免疫复合物形成CA125的检测。在人血清样品中，CA125的灵敏度为0.017 mA U mL ^-1，检出限为0.08 U mL ^-1。免疫传感器能够在2 U / mL至100 U / mL的广泛临床范围内检测CA125水平。