Total antioxidant activity assessment of Pleurotus ostreatus using a 3D-printed hydrogel nanozyme with peroxidase-like activity

A facile, cost-effective, and portable total antioxidant capacity (TAC) evaluation system was developed for Pleurotus ostreatus using a 3D-printed ferric coordination polymer (FCP) hydrogel nanozyme. Initially, the prepared peroxidase-like FCP nanozyme can catalyze the generation of hydroxyl radicals to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H 2 O 2 . Then, hydroxyl radicals can be neutralized by antioxidants, thereby inhibiting the TMB chromogenic reaction. Vitamin C (Vit C), vitamin E (Vit E), cysteine (Cys), and glutathione (GSH) were successfully used as reference antioxidant substrates. Moreover, a 3D-printed FCP hydrogel nanozyme was developed and incorporated into a smartphone-assisted point-of-care testing (POCT) system. TAC was evaluated by this POCT system, offering a limit of detection (LOD) as 0.34 mmol/L. The system was successfully applied to assess TAC in extracts from wild and commercially cultivated P. ostreatus . The results revealed TAC differences among these samples. Hence, this study provides a promising strategy for rapid, visual, and quantitative TAC detection in food.