Surface-enhanced spatially-offset Raman spectroscopy (SESORS) for detection of neurochemicals through the skull at physiologically relevant concentrations

Abstract

Detection techniques for neurotransmitters that are rapid, label-free, and non-invasive are needed to move towards earlier diagnosis of neurological disease.

Spatially offset Raman spectroscopy

“…Other medical applications for SORS that have been investigated include non-invasive glucose 127 and low-level bioanalyte detection in brain tissue using SESORS 128 . An illustrative case study in this field is the application of SESORS for the through-skull analysis of an agarose gel containing varying concentrations of neurotransmitters and gold nanoparticles, where agarose gel was used to mimic brain tissue [128][129][130] . The limits of detection for all studied neurotransmitters were between 100 nM and 1 μM and corresponded to physiologically relevant concentrations 130 .…”

“…An illustrative case study in this field is the application of SESORS for the through-skull analysis of an agarose gel containing varying concentrations of neurotransmitters and gold nanoparticles, where agarose gel was used to mimic brain tissue [128][129][130] . The limits of detection for all studied neurotransmitters were between 100 nM and 1 μM and corresponded to physiologically relevant concentrations 130 . FiguRe 7 shows illustrative SESORS spectra from mixtures of neurotransmitters in agarose, collected through an animal skull with spatial offsets of 0 mm and 2 mm (ReF.…”

“…This study demonstrated the potential of SESORS for non-invasive in vivo monitoring of neurotransmitter concentrations 129 . The ultimate goal of this research area is the non-invasive diagnosis of neurological disorders such as Parkinson and Alzheimer diseases at an early clinical stage 130 .…”

Spatially offset Raman spectroscopy for biomedical applications

“…Using these phantoms, SESORS established limits of detection for a range of neurotransmitters at physically relevant concentrations; melatonin (100 nM); serotonin (400 nM); dopamine (1 μM); norepinephrine (400 nM); and epinephrine (800 nM). 92 In addition, the brain of a sacrificed mouse was spiked with serotonin and gold NPs to demonstrate the potential of SESORS to detect neurotransmitters through the skull, ( Fig. 4 ).…”

“…Data was acquired using a laser wavelength of 785 nm, 90 mW, t = 120 s. The SERS spectrum of 100 mM serotonin on AuNPs at pH 2, 785 nm, 5 mW, t = 30 s (purple). Reproduced from ref 92. with permission from the Royal Society of Chemistry, copyright 2020.…”