Dual-mode fluorimetric and colorimetric sensors based on iron and nitrogen co-doped carbon dots for the detection of dopamine.

Determination of dopamine (DA) is crucial for its intimate relationship with clinical trials and biological environment. Herein, Fe, N co-doped carbon dots (AFC-CDs) were fabricated by optimizing precursors and reaction conditions for fluorimetric/colorimetric dual-mode sensing of DA. With synergistic influence of Förster resonance energy transfer and static quenching effect, DA significantly quenched the blue luminescence of AFC-CDs at 442 nm, the production of recognizable tan-brown complex caused evident colorimetric response, achieved the dual-mode fluorimetric/colorimetric sensing for DA. The excellent selectivity and satisfied sensitivity can be confirmed with the limit of detection at 0.29 μM and 2.31 μM via fluorimetric/colorimetric mode respectively. The reliability and practicability were proved by recovery of 94.81-101.61% in real samples. Notably, the proposed electron transfer way between AFC-CDs and DA was hypothesized logically, indicated dual-mode probe provided a promising platform for the sensing of trace DA, and could be expanded in environment and food safety.