Ultrasensitive near-infrared aptasensor for enrofloxacin detection based on wavelength tunable AgBr nanocrystals electrochemiluminescence emission triggered by O-terminated Ti3C2 MXene.

Toxic-free and easily accessible electrochemiluminescence (ECL) emitter/luminophore with near-infrared (NIR) emission is highly anticipated for ECL biosensor evolution. In this study, well-dispersed AgBr nanocrystals (NCs) decorated Ti3C2 MXene nanocomposites (Ti3C2-AgBrNCs) were prepared using a simple wet chemical technique and demonstrated highly efficient NIR ECL emission. For the first time, Ti3C2-AgBrNCs displayed wavelength-tunable ECL emission with varied Ti3C2 contents. Interestingly, further experimental data revealed that the ECL emission wavelength of Ti3C2-AgBrNCs red-shifted from 550 to 665 nm as Ti3C2 content increased, which can be attributed to the surface-defect effect generated by the oxygen-containing functional groups in Ti3C2 MXene. In particular, the ECL emission at 665 nm of Ti3C2-AgBrNCs nanocomposites not only revealed a 3.5 times increased ECL intensity but also a more stable ECL signal compared to pure AgBr NCs. As a proof of concept, a direct-type NIR ECL aptasensor with signal-on strategy was constructed with the Ti3C2-AgBrNCs nanocomposites as an ECL platform and enrofloxacin (ENR) as a model analyte. The NIR ECL aptasensor exhibited high sensitivity, a wide linear range from 1.0 × 10-12 mol/L to 1.0 × 10-6 mol/L and a low detection limit (5.97 × 10-13 mol/L). This research offered a viable alternative way for producing toxic-free and efficient near-infrared ECL luminophores in bioanalysis and wavelength-tuning light-emitting devices.