Self-assembled reduced graphene oxide–cerium oxide nanocomposite@cytochrome c hydrogel as a solid electrochemical reactive oxygen species detection platform

Abstract

Monitoring of aberrant cellular levels of reactive oxygen species (ROS) has been a challenging task due to their shorter half-life and low concentration. Herein, a hybrid alginate–polyacrylamide hydrogel was prepared via an in situ self-assembly of reduced graphene oxide–cerium oxide nanocomposite (rGO–CeO₂) and cytochrome c (Cyt c) and employed for electrochemical detection of ROS. The hydrogel platform, on one hand, provided a very large electroactive surface coverage and effectively increased the reactivity of Cyt c, and, on the other hand, integrated the rGO–CeO₂ nanocomposite for enhancing electrochemical signals and structural stability. The formation of the rGO–CeO₂@Cyt c hydrogel was confirmed through various microscopic and spectroscopic techniques. Besides, the electrochemical characteristics of rGO–CeO₂@Cyt c hydrogel-modified screen-printed electrodes were investigated through cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. For the detection of ROS, CV and DPV measurements were carried out to monitor the concentration-dependent changes in current responses. The prepared sensor exhibited a selective and excellent linear response towards hydrogen peroxide (H₂O₂), hydroxyl radical (˙OH) and superoxide anion radical (O₂˙⁻) in the desired concentration range with detection limits of 0.166 μM, 0.338 μM and 0.229 μM, respectively. Taken together, these hybrid hydrogels based on electrochemical interfaces could be potential candidates for real time assessment of intracellular ROS levels, with implications for unraveling ROS-related disease mechanisms.