Graphene–ZnO Nanohybrid Synthesis via Wheat Germ Lipase Exfoliation for Environmentally Compatible Antimicrobial Applications

A graphene-supported ZnO bionanohybrid material (G@WG-ZnO) was prepared through an aqueous synthesis approach using immobilized wheat germ lipase (WG) as a natural biotemplate. The strategy enabled the in-situ formation of ZnO nanoparticles within the graphene-based material. X-ray diffraction, surface and elemental analyses confirmed the formation and incorporation of ZnO, with a Zn content of approximately 6 wt.%. The re-sulting G@WG–ZnO bionanohybrid exhibited significantly enhanced antibacterial activity compared with G@WG, which showed no detectable inhibition under the tested conditions, producing inhibition zones of 13.2 ± 2.0 and 9.8 ± 1.5 mm against Shewanella oneidensis and Staphylococcus aureus , respectively. The larger inhibition zone observed for S. oneidensis indicates a greater susceptibility of the Gram-negative strain to the nanohybrid, while the inhibition zones were comparable to those obtained with ZnO nanoparticles alone at a comparable ZnO amount. In addition, the G@WG–ZnO bionanohybrid reduced the growth of the sulfate-reducing bacterium Desulfovibrio vulgaris by 92 %, indicating potential relevance for controlling microbiologically influenced corrosion (MIC). Ecotoxicological assessments showed a moderate response in Daphnia magna and no acute toxicity in Vibrio fischeri exposed to the leachates at the tested concentrations. Overall, these findings support immobilized WG as a biotemplate for the aqueous synthesis of graphene-supported ZnO nanohybrid material and demonstrate that ZnO incorporation provides antibacterial activity comparable to that of ZnO nanoparticles alone, highlighting the potential of the resulting nanohybrid for aquatic microbial control and MIC-related applications.