Low-background electrochemical biosensor for one-step detection of base excision repair enzyme

Publication date: Available online 11 November 2019Source: Biosensors and BioelectronicsAuthor(s): Min-hui Zhao, Lin Cui, Bing Sun, Quanbo Wang, Chun-yang ZhangAbstractWe develop a low-background electrochemical biosensor for one-step detection of uracil DNA glycosylase (UDG) based on the host-guest interaction and iron-embedded nitrogen-rich carbon nanotube (Fe–N–C) that mimics enzyme-mediated electrocatalysis to achieve signal amplification. In this work, Fe–N–C is initially immobilized on a glassy carbon electrode, followed by the immobilization of β–cyclodextrin (β–CD). We construct the signal probes by assembling the methylene blue (MB)-labeled hairpin DNAs onto the surface of Au nanoparticles (AuNPs) to form the MB-hairpin/AuNP probes. Due to the steric effect of AuNPs and the stem–loop structure of hairpin DNA, MB is prevented from entering the cavity of β-CD on the electrode. In contrast, UDG enables the removal of uracil from the U•A pairs in the stem of hairpin DNA probe to generate apurinic/apyrimidinic (AP) sites, leading to the assembly of MB-hairpin/AuNP probes on the electrode based on host–guest reaction between β-CD and MB. Meanwhile, L-cysteine (RSH) is oxidized by O2 to disulfide L-cystine (RSSR) and H2O2. In the presence of H2O2, Fe–N–C catalyzes the oxidation of MB to generate an amplified electrochemical signal. Notably, the Fe–N–C-catalyzed oxidation of MB is mediated by the oxidation of RSH by O2 instead of external H2O2, ...
Source: Biosensors and Bioelectronics - Category: Biotechnology Source Type: research