Small size effect-mediated mimetic activity of Cu₂O nanocubes: A switchable biosensor for simultaneous detection of...

The poor peroxidase-like activity of Cu₂O nanocubes has seriously limited further practical application in mycotoxins detection. Currently, optimizing small size effect of Cu₂O is considered to be a promising strategy to cope with this challenge. Hence, we synthesized Cu₂O nanocubes with different particle size distributions, including 30, 80, 200, 500, and 900 nm. It is noteworthy that the small size effect significantly enhances the catalytic performance of Cu₂O. Importantly, based on the marriage properties of catalytic activity and fluorescence signal from Cu₂O and carbon dots, a novel switchable biosensor was constructed for simultaneous detection of multiple mycotoxins. Concurrently, for dual-mode detection of single target, as the concentration of the target increased, resulting in a decrease in the colorimetric signal and an enhancement of the fluorescence response. Additionally, the distinct fluorescence emission peaks and non-interference characteristics of the probes enabled the biosensor to achieve simultaneous dual-target detection with high sensitivity, delivering detection limits of 5.3-7.1 × 10^-4 ng mL^-1 for multiple mycotoxins. Meanwhile, the excellent analytical capacity of the biosensor enabled the successful detection of the targets in wheat flour and cornmeal samples, demonstrating the bright prospect of the platform for the convenient and intuitive detection of multiple bio-molecules in real samples.