Hollowed-engineered modified Co9S8 nanomaterial with peroxidase mimetic activity for enhanced colorimetric detection of glutathione

Due to the high costs and relative instability of natural enzymes, highly efficient enzyme mimics have attracted much research interest in constructing nanozymes of biosensors. This study fabricated Co 9 S 8 nanozymes with diverse morphologies by adjusting the sulfur content in a facile and efficient solvothermal strategy using the Co-glycerate microsphere as the sacrificial template. Our findings revealed that sulfur-mediated surface reconstruction, especially at an optimal sulfur concentration, enables the fabrication of the M−Co 9 S 8 nanozyme with a hollow nanosphere structure. The nanozyme exhibits exceptional peroxidase-like activity. In the presence of H 2 O 2 , M−Co 9 S 8 nanozyme significantly enhanced the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB), resulting in a pronounced color change, thereby enabling the colorimetric sensing of glutathione (GSH). The systematic studies, including radical scavengers and electron spin resonance experiments, confirm that superoxide free radicals (·O 2 − ) play a key role in catalytic reactions and exhibit a synergistic effect with holes ( h + ). Based on these active radicals and the optimized electron transfer efficiency of the hollow porous spherical shell structure, the M−Co 9 S 8 nanozyme showed a catalytic efficiency of 5.44 times higher than that of L-Co 9 S 8 solid nanospheres with low sulfur content. The strategy demonstrated high sensitivity, excellent specificity, and robust stability. It featured a 5-order linear range and a detection limit as low as 3.16 nM for the detection of GSH, rendering it highly promising for clinical sample detection. A deeper understanding of Co 9 S 8 ′s surface reconstruction could offer crucial insights for developing high-performance nanomaterials and biosensors, broadening their potential applications in biosensing and biomedicine.