Ultrafine V2O5-anchored 3D N-doped carbon nanocomposite with augmented dual-enzyme mimetic activity for evaluating total antioxidant capacity
Qi Wang, Yongli Ding, Randy A. Dahlgren, Yue Sun, Jingjing Gu, Yuhao Li, Tingting Liu, Xuedong Wang, Xuedong Wang
Abstract
Total antioxidant capacity (TAC) can be evaluated by detecting the content of antioxidants , such as ascorbic acid , based on the enzyme-mimetic activity of nanomaterials . Herein, we fabricated a 3D-V 2 O 5 /NC nanocomposite using a self-templating strategy, which achieved ultrafine particles (∼2.5 nm), a porous carbon layer, large specific surface area (152.4 m 2 /g), N-doping and heterogeneous structure. The strong catalytic activity of 3D-V 2 O 5 /NC resulted from the integrated effect between the ultrafine structure of V 2 O 5 nanoparticles and the 3D porous nitrogen-doped carbon framework, effectively increasing the number of active sites. This nanozyme presented a higher catalytic activity than its components or precursors in the nanocomposite (e.g., VN/NC, NC , V 2 O 5 , and VO 2 /g-C 3 N 4 ). ROS scavenging experiments confirmed that the dual enzyme-like activity of 3D-V 2 O 5 /NC (catalase-like and oxidase-like) resulted from their co-participation of ‧O 2 − , h + and ‧OH, among which ‧O 2 − played a crucial role in the catalytic color reaction. By virtue of the 3D-V 2 O 5 /NC nanoenzyme activity and TMB as a chromogenic substrate, the mixed system of 3D-V 2 O 5 /NC + TMB + H 2 O 2 provided a low detection limit (0.03 μM) and suitable recovery (93.0–109.5%) for AA. Additionally, a smartphone-based colorimetric application was developed employing "Thing Identify" software to evaluate TAC in beverages. The colorimetric sensor and smartphone-detection platform provide a better or comparable analytical performance for TAC assessment in comparison to commercial ABTS test kits. The newly developed smartphone-based colorimetric platform presents several prominent advantageous, such as low cost, simple/rapid operation, and feasibility for outdoor use.