Development of a nanozyme-based electrochemical catalyst for real-time biomarker sensing of superoxide and nitric oxide anions released from living cells and exogenous donors.

Developing quantitative biosensors of superoxide (O2•-) and nitric oxide (NO) anion is crucial for pathological research. As of today, the main challenge for electrochemical detection is to develop high-selectivity nano-mimetic materials to replace natural enzymes. In this study, the dendritic-like morphological structure of silver organic framework (Ag-MOF) was successfully synthesized via a solvothermal strategy. Owing to the introduction of polymeric composites results in improved electrical conductivity and catalytic activity, which promotes mass transfer and leads to faster electron efficiency. For monitoring the electrochemical signals of O2•- and NO, the Ag-MOF electrode substrate was produced by drop-coating, and composites were designed by cyclic voltammetric potential cycles. The designed electrode substrates demonstrate high sensitivity, wide linear concentrations of 1 nM-1000 µM and 1 nM-850 µM, and low detection limits of 0.27 nM and 0.34 nM (S/N = 3) against O2•- and NO. Aside from that, the sensor successfully monitored the cellular release of O2•-, and NO from HepG2 and RAW 264.7 living cells and has the potential to monitor exogenous NO release from donors of Diethylamine (DEA)-NONOate and sodium nitroprusside (SNP). Additionally, the developed system was applied to the analysis of O2•- and NO in real biological fluid samples, and the results were good satisfactory (94.10-99.57 ± 1.23%). The designed system provides a novel approach to obtaining a good electrochemical biosensor platform that is highly selective, stable, and flexible. Finally, the proposed method provides a quantitative way to follow the dynamic changes in O2•- and NO in biological systems.