"On-off-on" fluorescent probes based on amino-modified zinc oxide quantum dots for Cu2+detection in snail meat

A fluorescent probe comprising amino-modified zinc oxide quantum dots (NH2-ZQDs) with stable fluorescent properties was prepared using the sol-gel method. Based on the photoinduced electron transfer (PET) and electrostatic adsorption (ESA) quenching effects of copper ions (Cu2+) on the NH2-ZQDs and the mechanism of competitive binding of Cu2+ and the NH2-ZQDs to L-methionine (L-Met), an NH2-ZQDs + Cu2+ +L-Met fluorescence quenching-recovery sensing system was designed to efficiently exclude Fe3+ interference. Thus, a novel "on-off-on" fluorescent probe was developed to specifically recognize Cu2+. The probe showed good linearity (y = 0.03102x - 0.1156, R2 = 0.9953) over 5-25 mu mol/L, with a limit of detection of 0.039 mu mol/L. It exhibited good selectivity and was successfully applied to the quantitative determination of Cu2+ in snail meat and tap water, with spiked recoveries in the range of 98.04 %-109.53 %.