Surface Enhanced Spatially Offset Raman Spectroscopy Detection of Neurochemicals Through the Skull

Abstract

The ability to noninvasively detect neurotransmitters through the skull would aid in understanding brain function and the development of neurological diseases. Surface enhanced spatially offset Raman spectroscopy (SESORS) is a powerful technique that combines the sensitivity of surface-enhanced Raman spectroscopy (SERS) with the ability of spatially offset Raman spectroscopy (SORS) to probe subsurface layers. Here we present SERS measurements of neurotransmitters (melatonin, serotonin, and epinephrine) at various concentrations followed by the SESORS measurements of the neurotransmitters to a concentration as low as 100 μM in a brain tissue mimic through a cat skull. Principal components analysis was performed to distinguish between the surface bone layer and the subsurface layer, comprised of a brain tissue mimic modified with neurotransmitters, and to determine if each individual neurotransmitter could be accurately identified.

Through tissue imaging of a live breast cancer tumour model using handheld surface enhanced spatially offset resonance Raman spectroscopy (SESORRS)

“… 17 Using SESORS in a 180° back-scattering configuration, nanotags have been used in glucose sensing, 18 tracked through 6.75 mm of tissue, 19 and up to 8 mm of bone. 20 , 21 Using SESORS in a transmission geometry, bisphosphonates have been tracked in bone through 20 mm of tissue 22 and Stone et al detected signal from nanotags through 45–50 mm of tissue. 17 Several reports in the literature show the potential to target and image tumours in vivo using functionalized NPs.…”

Spatially offset Raman spectroscopy for non-invasive analysis of turbid samples

“…The first proof-of-concept studies in this area were carried out by Sharma et al [50]. Recently, the team succeeded in detecting neurotransmitters (melatonin, serotonin, and epinephrine) at various concentrations using SESORS in a brain tissue mimic through a cat skull [51].…”

Direct monitoring of light mediated hyperthermia induced within mammalian tissues using surface enhanced spatially offset Raman spectroscopy (T-SESORS)

“…The field of nanomaterials for photonics applications is rapidly expanding, with increasingly sophisticated materials being developed to monitor a plethora of physical and chemical properties, including but not limited to temperature, 1,2 pH, 3,4 redox, 3 glucose, 5 DNA 6 and proteins such as neurotransmitters, 7 with many of these being complex in vivo targets. One such active area is the development of advanced nanomaterials as therapeutics for the next generation of photothermal therapies for cancer treatment.…”