Comparing Ag-O coordinated AgMOF-5 and Ag-N coordinated Ag nanosphere catalytic polymers for real time monitoring of H₂O₂ level in cancer cells

Monitoring H₂O₂ levels in live cells is essential due to its superior stability and possible severity inside the cell. The quest for a superior platform capable of detecting cellular-level hydrogen peroxide (H₂O₂) concentrations without necessitating the use of high-cost enzymes is of utmost importance. Here, the quantification of intracellular H₂O₂ concentrations has been performed using silver metal polymer-based nonenzymatic electrochemical detection. Two forms of silver metal-organic polymers are synthesized to explore its suitability as catalytic nanozyme activity for cell-level H₂O₂ detection with good accuracy. An Ag-O coordination interaction-based silver metal-organic framework, AgMOF-5 was synthesized and then transformed into a compact silver nanosphere (Ag nanosphere), rich in Ag-N coordination bond, to find the potential of individual coordination arrangement of each material in favour of the electrical conductivity, catalytic property, and sensing ability. AgMOF-5 modified Glassy Carbon Electrode (AgMOF/GCE) was found to be highly conductive while also demonstrating exceeding catalytic potential towards both commercial H₂O₂ and cell-secreted H₂O₂ with a LOD of 0.7 nM and sensitivity of 1300 μA mM^-1cm^-2. AgMOF/GCE demonstrated superior sensor characteristics like superconductivity, high stability, high reproducibility, and good selectivity upon investigation. Among many cellular byproducts of metabolism, H₂O₂ and other ROS species indicate the oxidative stress and are a key differentiator between healthy and diseased conditions. The modified GCE was used for live monitoring of H₂O₂ levels in L929, HeLa, T98G, and LN18 cell lines. The detection of higher H₂O₂ levels in glial cells established its predisposition towards increased oxidative stress. The electrochemical results of AgMOF/GCE were validated against a Phenol Red, HRPO-based live cell compatible Colourimetric detection for applicability and acceptance of AgMOF/GCE as H₂O₂ detection platform.