Portable smartphone platform based on Ti3C2 MQDs/CDs assembly for ratiometric fluorescence quantitative monitoring of crystal violet

Recent years have witnessed the ever-increasing achievements of Ti3C2 MXene quantum dots (Ti3C2 MQDs) and their vital contributions to fluorescent biosensing. However, the applicability and flexibility of most Ti3C2 MQDs-based sensors are limited by their emission of a single blue wavelength. To address this issue, we present a facile strategy to utilize carbon dots as the model to construct a ratiometric fluorescent sensor based on fluorescence resonance energy transfer to quantitatively monitor crystal violet. The fabricated probe exhibited dual emission at 440 and 565 nm respectively, when introducing crystal violet, the peak at 565 nm was quenched but 440 nm remained constant. Further aiming for portable, convenient, and on-site analysis, an innovative smartphone-assisted platform provides promising perspectives on the future in-situ quantitation. This work creates a general strategy for constructing the Ti3C2 MQDs-based composite fluorescent system, as well as suggests great application potential in food security monitoring.