Ultrathin g-C3N4/TiO2 composites as photoelectrochemical elements for the real-time evaluation of global antioxidant capacity

The antioxidants in biological organisms can scavenge excess free radicals and effectively reduce oxidative stress, which protects DNA, protein and lipids in the human body from damage, thus preventing diseases from being induced. Therefore, it is particularly significant to assay the antioxidant capacities of our habitual foods during dietary evaluation. Herein, ultrathin graphitic carbon nitride (utg-C3N4)/TiO2 composites have been introduced as sensing elements into a photoelectrochemical platform with a thin layer structured flow-cell, for the real-time assay of the global antioxidant capacity in practical samples. In this system, the two-dimensional utg-C3N4 nanosheet/TiO2 nanoparticle composite material provided a much better optoelectronic function than the individual materials. In comparison with previous reports, this photoelectrochemical strategy shows considerable advantages, including excellent anti-interference properties, a high level of stability and reproducibility, and it is also proved to be the most prompt, convenient and cost-effective method for antioxidant capacity detection up to now. Moreover, utilizing theoretical and experimental examinations, we revealed its photoelectrochemical sensing mechanism in depth. It is proposed that the developed method will pave the way for the development of excellent antioxidant assays with the advantages of photoelectrochemistry and fluidic cells. It is expected to be further applied in food quality inspections and health guides, as well as in other fields.