Inexpensive Route to Reclaimable Biomass-Derived Magnetic DNA Nanoparticles Exhibiting Multifunctional Nanozyme Activity via Visible-Light-Induced Reactive Oxygen Species Regulation

Imparting light-sensitive, multifaceted, and contrasting activity to biomass-derived nanoparticles is a far-fetched proposition, rarely achieved due to limited chemical diversity hindering effective surface chemistry. This has been successfully achieved here through a controlled hydrothermal pyrolytic synthesis of a magnetic nanoparticle, Fe-DNA Dot, derived from onion genomic DNA doped with Fe(III). The presence of redox-active Fe(III) on the surface enables the Fe-DNA Dot to respond to low-intensity visible white light (40 W LED), triggering nanozyme activity across a broad range of substrates via the generation of reactive oxygen species (ROS). Interestingly, the same Fe-DNA Dot was found to scavenge ROS in the dark, efficiently driving reverse reactions, thanks to its rich array of surface functionalities. The presence of Fe ions imparts ferromagnetic properties, enabling easy recovery of the nanozyme after the reaction using an externally applied magnetic field, such as a simple bar magnet. The inherent fluorescence of Fe-DNA Dot allows for visual tracking during recovery, while the presence of dangling DNA strands on their surface offers an alternative retrieval method via simple ethanol precipitation. Their easy synthesis, sensitivity to visible light, intrinsic fluorescence, and magnetic properties, combined with convenient reclaimability, make the Fe-DNA Dot a sustainable and biocompatible enzyme mimic, well-suited for diverse chemical and biochemical transformations on the go.