Highly sensitive determination of dopamine based on the aggregation of small-sized gold nanoparticles

Abstract

In this study, a highly selective and sensitive colorimetric method is developed for the determination of dopamine (DA) based on the aggregation of small gold nanoparticles (AuNPs). It is relied upon the size-dependent aggregation behavior of AuNPs induced by DA in the absence and presence of copper ions, offering a simple and sensitive method for detection of DA. The hydroxyl groups in the adjacent dopamine molecules induce efficiently the aggregation of 5 nm AuNPs by intermolecular hydrogen bonding, which leads to a change in color, from orange red to purple. The proposed colorimetric method gives an excellent linear range of 0.02–0.7 μM, with detection limit of 3.3 nM (3σ). This sensing strategy shows excellent characteristics for detection of DA in biological fluids.