N,P-codoped carbon dots were synthesised using l-arginine and phosphoric acid and explored for the detection of vitamin B12 (VB12) and bioimaging.

Fifty‐four Eucommia ulmoides leaves were subjected to a hydrothermal technique to synthesize carbon dots (CDs) of 3.55 ± 1.45 nm size. The nanomaterial possessed excellent stability and strong fluorescence emission (φf 42.3%). In a neutral buffer solution, the fluorescence signals of CDs solution were enhanced by aluminium ion without interference from other ions. Degree of enhancement correlated linearly with the Al3+ content in the range 0.01–2.5 mM. Response of this method was fast and sensitive (detection limit was 23 nM). The CDs performed successfully as a sensitive sensor for trace Al3+ determination in water samples, and satisfactory results were obtained.

No abstract