Biographene‐Based Nanozyme for Rapid Colorimetric Detection of Oxytetracycline via Peroxidase‐Mimicking Activity

Advancing sustainable graphene production is crucial to unlocking its potential in biomedicine and environmental technology. Although graphene offers exceptional electrical, mechanical, and surface properties, its large-scale utilisation is hindered by conventional synthesis methods such as chemical vapour deposition (CVD), which are costly, energy-intensive, and environmentally harmful. In this study, we report an eco-friendly, scalable, and cost-effective protein-assisted approach for exfoliating graphite into high-quality graphene in aqueous media using bovine serum albumin (BSA) as a biodegradable dispersant. BSA not only enables efficient exfoliation but also introduces abundant protein-derived functional groups, improving aqueous stability (zeta potential: -28.8 mV at pH 8) and ensuring long-term colloidal dispersion. These moieties enhance dispersibility while imparting intrinsic peroxidase-like activity under acidic conditions. Utilizing this nanozymatic activity, we developed a colorimetric sensing platform for rapid and sensitive detection of oxytetracycline (OTC). The assay is based on the inhibition of biographene-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of hydrogen peroxide, where OTC suppresses radical-mediated oxidation. The sensor exhibited high selectivity with a low detection limit of 2.66 µM and showed good biocompatibility, underscoring its biomedical potential. The green strategy enables sustainable production of functional graphene, positioning biographene as a promising material for diverse sensing applications.