Antibacterial performance, microstructure, optical, and magnetic characteristic of eco-friendly magnetite/carbon dots ferrofluids synthesized utilizing plants extract

The development of eco-friendly antibacterial agents has become essential in addressing environmental and health concerns. This research highlighted the fabrication of magnetite (Fe₃O₄)/carbon dots (CDots) ferrofluids via the green synthesis method using Moringa oleifera (MO) leaf extract and watermelon peel carbon source. The diffractograms of Fe₃O₄/CDots revealed cubic inverse spinel structures. The crystallite sizes of Fe3O4/CDots ranged from 10.1 to 7.2 nm, where the values reduced with the increasing CDots concentrations. The FeO functional group emerging in the ferrofluids confirmed that Fe3O4 remained intact after fabrication. Additionally, the emergence of the CC, CO, and C-O-C groups validated the CDots attachment on the Fe₃O₄ surface. Furthermore, the introduction of CDots influenced the magnetization saturation and coercivity, where the values ranged from 29.2 to 38.3 emu/g and 59 to 65 Oe, respectively. The antimicrobial activity of the ferrofluids was evaluated against Escherichia coli (E.Coli). The bacteria reduction was up to 82 %, demonstrating enhanced antibacterial efficacy resulting from the synergistic interaction between the Fe₃O₄ nanoparticles and CDots. Further, the presence of CDots significantly improved the creation of reactive oxygen species (ROS) when exposed to visible light, resulting in efficient bacterial inactivation. Moreover, the magnetic nature of Fe₃O₄ facilitated the easy separation and recovery of the ferrofluids after application. The reusability investigation indicated that the Fe₃O₄/CDots ferrofluids retained their photocatalytic antibacterial performance over three cycles. Hence, the green-synthesized Fe3O4/CDots ferrofluid represents a promising alternative for environmentally sustainable antibacterial applications, with potential uses in wastewater treatment and medical devices.