Fe/Mo-doped carbon dots as a bifunctional nanozyme for self-validating colorimetric and fluorometric sensing of hydroquinone

Bimetallic Fe/Mo-doped carbon dots (Fe/Mo-CDs) have been developed as a high-performance nanozyme to construct a self-validating dual-mode (colorimetric/fluorometric) platform for hydroquinone (HQ) detection. The Fe/Mo-CDs exhibited strong peroxidase-like activity, catalyzing H 2 O 2 -mediated TMB oxidation to generate oxTMB, which simultaneously yields a colorimetric signal and quenches the fluorescence of Fe/Mo-CDs through a confirmed FRET process. The introduction of HQ competitively scavenges the essential reactive oxygen species, inhibiting oxTMB formation and triggering synchronous signal inversion in both channels. This endogenous self-validating function enables favorable analytical performance, with wide linear ranges and ultralow detection limits (0.03 µM for colorimetric; 0.016 µM for fluorometric). Successful application in commercial creams with satisfactory recoveries underscores its strong potential for accurate and reliable screening in complex samples. This work not only presents a sensitive sensor for HQ but also offers a novel design strategy for developing intelligent, self-validating biosensing systems. Section Graphical abstract The alternative text for this image may have been generated using AI.