Probing the single neurotransmitters with the WGM microcavity-hybridized plasmonic nanospiked antennas

TL;DR

This paper introduces an ultra-sensitive WGM sensor hybridized with plasmonic nanospiked antennas capable of detecting and discriminating single neurotransmitter molecules at attomolar concentrations, advancing neuroscience diagnostics.

Contribution

The study presents a novel optoplasmonic WGM sensor that achieves single-molecule detection and discrimination of neurotransmitters at unprecedented sensitivity levels.

Findings

Detects neurotransmitters at 10 aM concentration

Discriminates between GABA and glutamate molecules

Correlates resonance shifts with molecular polarizability

Abstract

Discerning the neurotransmitter dysregulation is a hallmark of neurological disorders and diseases, including Alzheimer's, Parkinson's, and multiple sclerosis. The concentration of neurotransmitters in the synaptic cleft is particularly low, ranging from nM to fM, which makes it challenging to accurately monitor changes over the course of a clinical trial using existing sensing techniques. By means of an advanced whispering gallery mode (WGM) sensor hybridized with plasmonic nanospiked antennas, we detect and discriminate between different neurotransmitters at the single-molecule level. Our results show that the sensor can detect neurotransmitters with exceptional sensitivity down to 10 aM and discriminate between structurally similar neurotransmitters, such as GABA and glutamate, over a large number of detection events. Furthermore, we find that the average WGM resonance shift, induced by a neurotransmitter binding to the sensor, strongly correlates with molecular polarizability values obtained from electronic structure calculations. These findings establish the optoplasmonic WGM sensors as potential biosensor platform in different avenues of neuroscience by detecting and discriminating neurotransmitters as well as investigating their dynamics at ultra low-level concentrations, plausibly contributing to deeper understanding of brain function and neurological disorders.