We developed a novel electrochemical biosensor for uracil-DNA glycosylase (UDG) detection based on enzyme-free and substrate-free electrocatalytic signal amplification by porphyrin-based covalent-linked nanomaterial (OAPS-Por). This OAPS-Por could not only absorb much Thionine (Thi), but also possess obvious electrocatalytic activity toward the reduction of Thi without involvement of H₂O₂. Sequentially, the functionalized OAPS-Por with Thi, Au nanoparticles and single-stranded DNA (OAPS-Por/[email protected]) was ingeniously designed as the signal probe. Meantime, the hairpin DNA (hDNA) with four uracil bases was immobilized on AuNPs/GCE via an Au–S bond. When UDG was present, the uracil in hDNA was removed and hairpin structure was unfolded. Next, the signal probes binded with the unfolded hDNA by DNA hybridization. The Thi in signal probes could generated an original electrochemical signal, which could be further amplified and output due to the robust electrocatalytic activities of OAPS-Por toward Thi. As a result, the as-constructed electrochemical biosensor had a broad linear range from 0.005 to 1 U mL^-1. It also exhibited a low detection limit of 6.97 × 10^-4 U mL^-1. Moreover, this biosensor could be used to assay the inhibition of UDG (UGI) and the UDG activity in real samples (HeLa cell lysates and human blood serums), and demonstrated great prospect in clinical diagnostics and biomedical research.

我们开发了一种新型的电化学生物传感器，用于基于尿卟啉基共价连接纳米材料（OAPS-Por）的无酶和无底物电催化信号放大，用于尿嘧啶DNA糖基化酶（UDG）检测。这种OAPS-Por不仅可以吸收大量的硫氨酸（Thi），而且在不涉及H ₂ O _2的情况下对Thi的还原具有明显的电催化活性。。随后，将具有Thi，Au纳米颗粒和单链DNA（OAPS-Por / [电子邮件保护]）的功能化OAPS-Por巧妙地设计为信号探针。同时，具有四个尿嘧啶碱基的发夹DNA（hDNA）通过Au-S键固定在AuNPs / GCE上。当存在UDG时，hDNA中的尿嘧啶被去除并且发夹结构被展开。接下来，信号探针通过DNA杂交与未折叠的hDNA结合。信号探针中的Thi可以生成原始的电化学信号，由于OAPS-Por对Thi的强大电催化活性，其可以被进一步放大和输出。结果，如此构造的电化学生物传感器具有从0.005至1UmL ^-1的宽线性范围。它的检出限低至6.97×10 ^-4 U mL^-1。此外，该生物传感器可用于检测实际样品（HeLa细胞裂解物和人血清）中对UDG（UGI）的抑制和UDG活性，在临床诊断和生物医学研究中显示出广阔的前景。