Au@Ag nanoparticles: an analytical tool to study the effect of tyrosine on dopamine levels.

The neurotransmitter dopamine (DA) plays important roles in the human body, including regulatory functions, movement, memory and motivational control. The direct intake of DA is impossible as it cannot cross the blood-brain barrier (BBB) efficiently. Notably, l-tyrosine works as a precursor of DA in the human brain. Herein, we report an analytical method that strongly supports the hypothesis that the intake of tyrosine (Tyr)-rich food enhances DA levels. For this analysis, citrate-coated gold-core silver-shell nanoparticles (Au@Ag NPs) were synthesized. The interaction of DA with the Au@Ag NPs was investigated using multiple spectroscopic techniques, and different thermodynamic parameters were evaluated to assign the binding mechanism. Real sample analysis with Tyr-rich food was also conducted to study the effect of Tyr on DA levels. Analytical studies were performed to verify the outcomes of the present work. The limit of detection of the Au@Ag NPs-DA system for Tyr was found to be 1.64 mM. This study can contribute to development in the fields of medicine and pharmaceuticals, particularly in regard to neuromedicine. One of the major advantages of this investigation is that it will fuel research interest in the supplementation of neurotransmitters and help categorize Tyr as a dietary precursor of dopamine.