Fabrication of Metallic-Ion-Free Fullerenols as Peroxidase-Like Nanozymes to Stimulate Maize Early Growth

Although fabrication of various fullerenols as agronanozymes has undergone remarkable expansion through employing various approaches, there is a lack of knowledge regarding the understanding of metallic-ion-free fullerenols. A feasible preparation technology to fabricate metallic-ion-free fullerenols was developed by heating-treatment oversaturated fullerene using H2O2 solution in o-dichlorobenzene. It was characterized as C60(OH)36·9H2O by various measurements. Maize exposure of 50 mg/L C60(OH)36·9H2O was investigated to significantly enhance growth traits, including seed germination and seedling growth. Additionally, through the integration of ESR spectrum, radical scavenging assay, and peroxidase-like catalytic performance in vitro, DAB staining to visualize the accumulated H2O2 content in vivo as well as investigating the activation of antioxidative performance, it offers insights into the combinational action mechanism of C60(OH)36·9H2O on crop growth regulation. C60(OH)36·9H2O directly scavenged accumulated H2O2 and indirectly activated the antioxidant system to suppress the H2O2 accumulation that acts like peroxidase activity. The present study gives an updated knowledge on synthesizing metallic-ion-free fullerenols with particular emphasis to their application as potential peroxidase-like nanozymes for regulatory roles in the improvement of crop growth.