Amine-rich carbon nanodots as a fluorescence probe for methamphetamine precursors†
Amine-functionalized carbon dots (A-CDs) were synthesized by one-step hydrothermal reaction of urea and citric acid. The purified CD sample exhibits a surface states dominated fluorescence emission with a quantum yield of 30%. The A-CDs demonstrate excellent sensitivity toward methamphetamine pre-precursor and precursor, and a remarkable selectivity against common drug cutting agents (diluents) such as aspirin, paracetamol, etc. The specific selectivity of CDs towards such type of drug precursor molecules is first time reported, which appears to be related to the spatial distribution of the surface functional groups. The fluorescence-based sensing mechanism is revealed by a detailed analysis on the static and dynamic fluorescence behaviour. We further demonstrated an immobilization strategy for fabricating solid-state sensors, and the retained sensitivity of the A-CDs after immobilization. The study reveals the potential of the use of a CDs as an effective sensing probe for illicit drugs, which is in demand.