Handheld detection strategy: Real-time on-site assay of Mn(VII) and GSH integrating ratiometric fluorescent carbon dots paper strip, smartphone, and 3D-printed accessory

Handheld detection platform integrating ratiometric fluorescent N,P co-doped carbon dots (N,P-CDs) paper strip, smartphone, and 3D-printed accessory corroborates its efficacy for visual quantitative detection of Mn(VII) and GSH via a continuous fluorescence color shift. N,P-CDs were synthesized by hydrothermal treatment of 1,8-diaminonaphthalene, phosphoric acid, and formamide. Inspiringly, with increasing Mn(VII) concentrations, blue emission of N,P-CDs decreases gradually at 445 nm and a ratio rising orange band emerges at 600 nm under 340 nm excitation, which concurrently exhibits continuous fluorescence color variation of blue, purplish blue, purplish pink, pink, to orange. Subsequent addition of GSH renders orange fluorescence of N,[email protected](VII) gradually quench but blue peak slightly enhance, accompanied by the fluorescence color successively returning from orange to blue. The RGB values of the resulting images were precisely defined by a color recognition application within the smartphone, and the R/B values could be employed for Mn(VII) and GSH quantification with linear ranges of 0 − 40 μM and 0 − 28 μM, respectively, as well as limits of detection of 24.49 nM and 21.41 nM, respectively. It is solicitously anticipated that our research will provide novel insight for the development of effective sensing protocol and the enlargement of practical application prospect.