Analyte-perturbed balance between reducibility and fluorescence of Ti3C2 MXene quantum dots for label-free, dual-mode detection of silver ions

Abstract

BackgroundAs an emerging and attractive low-dimensional functional materials, Ti3C2 MXene quantum dots (QDs) enlarge the toolbox of fluorescence sensing. However, monochromatic fluorescence, which only provide one single signal, is often beset by challenges such as false-positive readouts and limitations in selectivity. Consequently, to improve the sensing accuracy by means of cross-verified dual-signal authentication, the endeavor to engineer dual-mode nanoprobes based on Ti3C2 QDs, incorporating both the capability of fluorescence and an alternative sensing mechanism, emerges as a compelling avenue. ResultsHere, based on the alterations in colorimetric and fluorescent signals of Ti3C2 QDs with the addition of Ag+, we propose a dual-mode sensor obviating the necessity for nanoprobe labeling. Owing to the decent reducibility of Ti3C2 QDs, Ag+ is adsorbed and reduced, resulting in the generation of plasmonic Ag nanoparticles (NPs), which simultaneously trigger colorimetric responses of the solution and enhance the fluorescent emission of Ti3C2 QDs. The confluence of colorimetry and fluorometry within this strategy optimally harnesses the modulating role of the acquired Ag NPs on the reducing capability and fluorescence characteristics of Ti3C2 QDs. The equilibrium imparts versatility and promising prospects to this analyte-triggered label-free method, which enables a remarkable specificity and an excellent detecting limit (0.45 μM) for Ag+. SignificanceThe balance between reducibility and fluorescence of Ti3C2 QDs for dual-mode detection is inventively demonstrated. With the exemplification of a direct influence of both features of the nanoprobe via the introduction of analytes, this study opens the feasibility of the analyte-perturbed felicitous equilibrium, which endows label-free methods with versatility and promising prospects. This design may evoke more biosensing strategies with the function of double-signal mutual verification.