Organophilic carbon nanodots with multi-band emission and their application as a ratiometric and colorimetric fluorescent sensor

In this work, organophilic carbon nanodots (CNDs) were synthesized in acetone from organic extract of plant leaves. The as-prepared CNDs showed multi-band emission, and could be well dispersed in acetone and ethanol. The photoluminescence (PL) of the CNDs at 520 nm was excitation-independent. The PL in the blue region could be tuned from 420 to 480 nm through changing of the excitation wavelength. The multi-emissive CNDs were used as a ratiometric and colorimetric sensor for curcumin detection in ethanol. The blue PL of the CNDs at 420 nm was quenched by curcumin through inner filter effect. Meanwhile, the green PL at 495 nm and 535 nm were enhanced with additional fluorescence of curcumin. The value of I-535/I-420 and I-495/I-420 both increased linearly with the curcumin concentration in the range of 0-15 mu M. The fluorescence color of the mixed solution changed from blue to yellow, and the detection limit reached 36.7 nM. The sensitive and visual detection of the CNDs probe toward curcumin showed their high potential in practical applications.