Oxygen Vacancy‐Engineered PEGylated MoO3−x Nanoparticles with Superior Sulfite Oxidase Mimetic Activity for Vitamin B1 Detection

Sulfite oxidase (SuO_x) is a molybdenum‐dependent enzyme that catalyzes the oxidation of sulfite to sulfate to maintain the intracellular levels of sulfite at an appropriate low level. The deficiency of SuO_x would cause severe neurological damage and infant diseases, which makes SuO_x of tremendous biomedical importance. Herein, a SuO_x mimic nanozyme of PEGylated (polyethylene glycol)‐MoO_3?x nanoparticles (P‐MoO_3?x NPs) with abundant oxygen vacancies created by vacancy‐engineering is reported. Their level of SuO_x‐like activity is 12 times higher than that of bulk‐MoO₃. It is also established that the superior increased enzyme mimetic activity is due to the introduction of the oxygen vacancies acting as catalytic hotspots, which allows better sulfite capture ability. It is found that vitamin B1 (VB1) inhibits the SuO_x mimic activity of P‐MoO_3?x NPs through the irreversible cleavage by sulfite and the electrostatic interaction with P‐MoO_3?x NPs. A colorimetric platform is developed for the detection of VB1 with high sensitivity (the low detection limit is 0.46 µg mL^?1) and good selectivity. These findings pave the way for further investigating the nanozyme which possess intrinsic SuO_x mimicing activity and is thus a promising candidate for biomedical detection.