Urea-assisted fabrication of defect and oxygen vacancy-enriched Ce(MoO4)2 oxidase mimetics: A dual-mode sensor array for detection and recognition of phenolic antioxidants

Structurally similar phenolic compounds are involved in numerous biological processes and disease regulation, while the simultaneous determination and discrimination of them is still a great challenge. Herein, an oxygen vacancy and defect-enriched Ce(MoO₄)₂ oxidase mimetics with tunable oxidase-like activity was successfully fabricated using a combined urea-assisted hydrothermal-annealing and peroxide etching-induced surface reconstruction strategy, and the as-prepared MoCe-based oxidase mimetics was constructed as a set of colorimetric/photothermal dual-mode triple-channel array sensors for simultaneously detecting and discriminating multiple phenolic compounds. Based on the different inhibition effects of phenolic compounds on 3,3’,5,5’-tetramethylbenzidine (TMB) oxidation, diverse colorimetric/photothermal signal variations are collected as "fingerprints" on the array sensors. The constructed colorimetric/photothermal array sensors can be successfully used to detect and recognize five phenolic compounds including gallic acid, quercetin, catechin, kaempferol and caffeic acid from sea buckthorn seeds. This dual-mode array sensors not only had the low determination limits for the five phenolic compounds and high anti-interference power, but also had better self-calibration and mutual verification characteristics than the single-mode detection. The current work not only endows an ingenious means to fabricate high catalytic active Ce(MoO₄)₂ oxidase mimetics, but also exploits a high sensitive array sensor for the rapid detection and recognition of phenolic compounds from food samples.