Colorimetric Detection of Dopamine Based on Iodine-mediated Etching of Gold Nanorods

A colorimetric analytical method, with wavelength change as a response, was developed for highly sensitive determination of dopamine (DA) based on gold nanorods (AuNRs). Even though AuNRs were unable to be etched by KIO 3 , however, they surrendered to I 2 generated from IO 3 - in the presence of DA. This could result in a blue shift of their absorption peak of longitudinal localized surface plasma resonance (LSPR), accompanied by obvious color change of solution from wine red to blue. Under the optimum conditions such as KIO 3 concentration of 0.7 mmol/L, reaction temperature at 50 °C, pH 2.6 and incubation time of 6 min, the amount of blue shift of AuNRs absorption wavelength was linear to DA concentration in the range of 0.80–60.0 μmol/L and the detection limit was 0.62 μmol/L (3σ/k). Furthermore, the common substances in urine did not interfere in the determination and the DA recovery rate in actual urine samples ranged from 103.0% to 110.8%.