Surface‐enhanced Raman spectroscopy combined with multivariate analysis for the detection and differentiation of dopamine and DOPAC in cerebrospinal fluid

Abstract Dopamine (DA) is a vital neurotransmitter for brain functions, including pleasure, memory, motivation, and movement control. Dopaminergic neuron degradation is correlated to neurological disorders such as Parkinson's disease, and changes in DA concentration are related to mental health disorders. Currently, the gold standard for monitoring DA concentrations in the brain is electrochemistry. However, although electrochemistry has high sensitivity, it has low specificity for molecules with similar molecular structures, such as DA and its metabolites. Here, we demonstrate that surface‐enhanced Raman spectroscopy (SERS), a vibrational spectroscopy that provides molecule‐specific information with excellent sensitivity, requires small sample sizes/volumes, and is non‐destructive, is optimal for the detection and differentiation of DA and its metabolites. We show that SERS combined with multivariate analysis allows for the detection and differentiation of DA and its metabolites, including 3‐O‐methyldopamine (3‐OMD), homovanillic acid (HVA), 3,4‐dihydroxyphenylacetic acid (DOPAC), and 3‐methoxytyramine (3‐MT) at physiologically relevant concentrations in artificial cerebrospinal fluid (aCSF).