Spectroscopic insight into the interaction of dopamine with spherical gold nanoparticles

Abstract Dopamine (DA) is a monoamine neurotransmitter of phenethylamine and catecholamine families, which is present in the central nervous system (CNS) and its periphery. Since DA is associated with several functions in the brain and body (motivational salience, reward, motor control, paracrine messenger, etc.), any imbalance in the DA level can trigger several neurodegenerative and other diseases. On the other hand, the spherical gold nanoparticles (AuNPs) can be used for drug delivery in several parts of the body. In addition, AuNPs also has the potentiality to penetrate through the blood-brain barrier and interact with the central nervous system without causing any toxicity. In view of many applications, it is important to look into the interaction between DA and AuNPs for a potential drug delivery model in DA related diseases. Here, we have used the steady-state and time-resolved spectroscopic tools to investigate the binding interaction of DA with Gold nanoparticles (AuNPs). The nature of the quenching mechanism is confirmed through both steady-state and time-resolved fluorescence measurements. The binding constants along with the number of binding sites were estimated from the steady-state fluorescence measurements. The distance between DA and AuNPs was calculated using Forster's theory to verify the possibility of fluorescence resonance energy transfer (FRET) from DA to AuNPs.