(352e) Improve Sensitivity and Selectivity of Neurotransmitter Sensing through UV Plasmonics Enhanced Native Fluorescence.

Neurotransmitters (NTs) are responsible for brain neuronal communications and their dysregulation can lead to a number of disorders such as Parkinson’s disease, Alzheimer’s disease, depression and addiction. The ability to simultaneously assay multiple NTs and their metabolites at their physiological concentration is essential to understand their functional roles, the relations between these chemicals and develop interventions that may normalize their levels in pathological conditions. Conventional technologies for NT detection include electrochemical methods. Electrochemical methods cannot probe multiple NTs simultaneously in one region and cannot differentiate structurally similar molecules such as dopamine (DA) and norepinephrine (NE).

This work presents a neurotransmitter sensor based on ultraviolet plasmonic enhanced native fluorescence that promises to detect an array of NTs with high sensitivity and selectivity. Monoamine NTs have intrinsic fluorescence in the ultraviolet range of the spectrum. However, the intrinsic fluorescence intensity is low compared to fluorescence dyes. UV plasmonics has been used to enhance the native fluorescence of biomolecules. We report that UV plasmonics not only improve the detection limits by enhancing the native fluorescence; it also improves the selectivity by providing a new mechanism for molecule differentiation. Three neurotransmitters have been tested: dopamine, norepinephrine, and 3,4-dihydroxyphenylacetic acid (DOPAC). The net enhancement on an aluminum hole array with 300 nm hole spacing substrate was measured to be 50 times for all three molecules. The photobleaching rates for the 3 molecules are distinct: norepinephrine has the highest photobleaching rate, followed by dopamine and DOPAC, providing a novel differentiation mechanism. This study describes evidence that the detection and differentiation of neurotransmitters with similar structures can be achieved by UV plasmonic enhanced native fluorescence.