Rutin as a coenzyme of Fe-doped silicon nanozyme with enhanced peroxidase-like activity for a colorimetric β-glucuronidase sensor

Coenzyme can work with a natural enzyme to achieve the enzymatic catalytic process. Inspired by nature, herein rutin was found to regulate the peroxidase-like activity of Fe-doped silicon nanodots (Fe-OSiNDs) acting as a coenzyme. To be specific, the peroxidase-like activity of Fe-OSiNDs can be activated by rutin at a low concentration (<200 µM), which accelerated the oxidation process between 3, 3′, 5, 5′-tetramethylbenzidine (TMB) and H 2 O 2 . Possibly as a reason, rutin at a low concentration could be easily attracted and oxidized by Fe 3+ in Fe-OSiNDs and then the produced Fe 2+ reacted with H 2 O 2 to form the hydroxyl radicals around the surface of Fe-OSiNDs thereby contributing to an enhancement. More interestingly, the addition of β-glucuronidase can hydrolysis rutin into quercetin and suppress the peroxidase-like activity of rutin-treated Fe-OSiNDs because quercetin is a sugar-free flavonoid with higher anti-oxidant activity than rutin. Thus, a colorimetric sensor for β-glucuronidase could be established. This sensor realizes a linear ranging from 2 to 40 nM (0.58 to 11.6 μg/mL) towards β-glucuronidase with a detection limit of 0.6 nM (0.174 μg/mL). The feasibility of this sensor for β-GUS detection in Escherichia coli has been realized. This work not only provides an interesting concept for coenzyme-dependent nanozyme and expands the promising use of silicon nanomaterials.