Immobilization of biomolecules with a proper orientation is considered as a basis for diverse biotechnological applications. Herein, we report a host‐guest inclusion complexation between β‐cyclodextrin (β‐CD) and biotin as a versatile approach for the immobilization of biomolecules. As a practical application, a sandwich‐type electrochemical immunosensor was designed for the determination of prostate specific antigen (PSA). The immunosensor was fabricated by in situ electropolymerization of poly(N‐acetylaniline) onto a rGO‐modified Pt electrode. Then, β‐CD was covalently grafted onto the over‐oxidized polymer backbone. For improving the efficiency of the assay, AuNPs were casted on the polymeric film, on the surface of which thionine (TH) as an electron mediator was covalently immobilized. Using a host‐guest inclusion complexation between β‐CD and biotin, a β‐CD/biotin‐Ab₁/PSA/Ab₂‐horseradish peroxidase (HRP) sandwich was formed on the electrode surface. The analytical signal was produced via electrochemical reduction of TH_ox, generated by biocatalytic oxidation of the TH_red in the presence of HRP/H₂O₂. Under optimal conditions, the proposed sensor responded linearly to PSA in the range from 10.0 pg mL⁻¹ to 25.0 ng mL⁻¹, with a low detection limit of 6.7 pg mL⁻¹ (S/N=3). Kinetic parameters of the interaction of β‐CD with Ab₁ were also investigated. Finally, the applicability of the immunosensor was successfully investigated for the detection of PSA in human serum samples.

中文翻译：

---

基于生物素化抗体/环糊精包合物的前列腺特异性抗原免疫传感器：制备和电化学研究

具有适当方向的生物分子固定化被认为是各种生物技术应用的基础。本文中，我们报道了β-环糊精（β-CD）和生物素之间的宿主-客体包合复合物是固定生物分子的通用方法。在实际应用中，设计了一种夹心型电化学免疫传感器来测定前列腺特异性抗原（PSA）。免疫传感器是原位制造的聚（N-乙酰基苯胺）在rGO修饰的Pt电极上的电聚合。然后，将β-CD共价接枝到过氧化的聚合物主链上。为了提高测定效率，将AuNPs浇铸在聚合物膜上，在其表面上共价固定了作为电子介体的硫氨酸（TH）。使用β-CD和生物素之间的主客体包合络合物，在电极表面形成了β-CD/生物素-Ab ₁ / PSA / Ab _2-辣根过氧化物酶（HRP）三明治。通过在HRP / H ₂ O ₂存在下通过生物催化氧化TH_红产生的TH _ox电化学还原产生分析信号。在最佳条件下，建议的传感器在10.0 pg mL ^-1至25.0 ng mL ^-1的范围内对PSA线性响应，检测极限低至6.7 pg mL ^-1（S / N = 3）。还研究了β-CD与Ab ₁相互作用的动力学参数。最后，成功地研究了免疫传感器在人血清样品中检测PSA的适用性。