A label-free and ultrasensitive fluorescent sensor for dopamine detection based on double-stranded DNA templated copper nanoparticles

Abstract A novel and label-free fluorescent sensing strategy have been developed for simple, rapid and ultrasensitive detecting dopamine by using double-stranded DNA (ds-DNA) templated copper nanoparticles (CuNPs) as the fluorescent indicator. Fluorescent CuNPs were formed within several minutes in the mild conditions by using random ds-DNA as templates. The fluorescence intensity of ds-DNA templated CuNPs was found to be quenched effectively with the increasing concentration of dopamine, due to the formation of photo-induced electron transfer process between dopamine and CuNPs. Under the optimized conditions, the fluorescent sensor exhibited highly sensitive detection of dopamine by flourescence intensity decreasing with addition of dopamine in the range of 0.1–10,000 nM and with a detection limit of 20 pM. The strategy showed excellent selectivity toward dopamine over interfering substances at a 100-fold higher concentration. In addition, the label-free method was successfully applied in the detection of dopamine in dopamine hydrochloride injection samples. Furthermore, this method did not need any fluorescence dye label, complex DNA sequence design, and sophisticated experimental techniques. Thus, the strategy would be expected to have potential applications in biotechnology and clinical diagnosis.