3D FeMoO4/Fe7S8 nanosheet flower composites as highly active peroxidase-like nanozymes for colorimetric sensing enrofloxacin in environmental water samples

Background Emerging pollutants such as enrofloxacin (ENR) pose a serious threat to the ecosystem and public health due to their resistance to degradation and tendency to accumulate in the environment. Although existing antibiotic detection techniques have considerable application value, they suffer from high costs, complex operation procedures, or insufficient sensitivity. Therefore, there is an urgent need to develop a new detection method that is simple, rapid, low-cost, and environmentally friendly to efficiently monitor antibiotic pollution in environmental water bodies and safeguard public health. Results In this work, inspired by the superior catalytic activity of three-dimensional (3D) composite nanomaterials, we rationally designed and synthesized FeMoO 4 /Fe 7 S 8 nanosheet flower composites (3D FeMoO 4 /Fe 7 S 8 NSFs) as a novel peroxidase-mimicking nanozyme for the sensitive colorimetric detection of ENR. The as-synthesized NSFs exhibit outstanding intrinsic peroxidase-like activity, enabling their direct integration into a colorimetric sensing platform. Critically, the synergistic redox coupling between Mo 6+ /Mo 4+ and the Fe 2+ /Fe 3+ couple facilitates rapid electron transfer, thereby promoting efficient activation of peroxymonosulfate (PMS) to generate reactive oxygen species—including hydroxyl radicals (·OH), sulfate radicals (·SO 4 − ), singlet oxygen ( 1 O 2 ), and superoxide radicals (·O 2 − ), which collectively drive the oxidation of chromogenic substrates without requiring external enzymatic or chemical initiators. This mechanism underpins a robust, single-step colorimetric assay that overcomes key limitations of conventional methods, such as stringent temperature control, prolonged reaction times, and narrow pH operational windows, thus enabling rapid, reliable ENR quantification. The optimized sensing platform delivers a wide linear range (0.500–70.0 μM), a low detection limit (LOD) of 0.150 μM (S/N = 3), and a total assay time of only 5 min. Significance This system breaks through the limitations of traditional methods in terms of temperature, time, and pH conditions, and successfully generates free radicals and non-free radical active substances by activating PMS, thereby achieving rapid and efficient detection of antibiotics. This innovation provides a highly promising new strategy for the identification of fluoroquinolone (FQs) antibiotics and shows broad application prospects in the field of environmental pollutant detection and monitoring.