Highly selective and sensitive biosensing of dopamine based on glutathione coated silver nanoclusters enhanced fluorescence

This study describes an ultrasensitive and highly selective dopamine (DA) assay that makes use of glutathione protected silver nanoclusters (GSH-AgNCs) acting as a nanoprobe. The GSH-AgNCs exhibit red fluorescence (with excitation/emission peaks at 490/645 nm), which increases on addition of DA, probably due to the hydrogen bonding interaction of the carboxyl groups of GSH-AgNCs and the amino groups of DA. The response is linear in the 20 x 10(-9) mol dm(-3) to 220 x 10(-9) mol dm(-3) DA concentration range, and the lowest limit of detection is 0.35 x 10(-9) mol dm(-3) (at an S/N ratio of 3). Potential interferents including uric acid, ascorbic acid, common metal ions, anions and some biologically relevant chemicals do not have an effect even in 100-fold higher concentrations. Furthermore, the present analytical assay was effectively utilized for the quantification of DA in spiked human urine samples.