Tetrahydrocannabinol Sensing in Complex Biofluid with Portable Raman Spectrometer Using Diatomaceous SERS Substrates

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Biomarker Detection

Background:

• Cannabis use detection relies on identifying biomarkers like tetrahydrocannabinol (THC).
• Complex biological fluids present challenges for direct biomarker analysis.
• Sensitive and portable detection methods are needed for on-site forensic and medical applications.

Purpose of the Study:

• To develop and validate a portable thin-layer chromatography-surface-enhanced Raman spectroscopy (TLC-SERS) method for detecting THC and its metabolites.
• To utilize ultra-sensitive SERS substrates for trace-level biomarker detection in saliva and urine.
• To assess the feasibility of on-site sensing for cannabis exposure identification.

Main Methods:

• Development of SERS substrates using diatomaceous earth integrated with gold nanoparticles (Au NPs).
• Application of TLC coupled with SERS for analyzing saliva and urine samples.
• Utilizing porous microfluidic devices with diatomaceous earth for urine sample separation.
• Employing Principal Component Analysis (PCA) for SERS spectral data analysis.

Main Results:

• Successful detection of THC and THC metabolites in saliva using TLC-SERS with characteristic peaks at 1601 and 1681 cm⁻¹.
• Effective separation of THC from urea in urine samples via TLC using microfluidic devices.
• Demonstrated strong THC SERS signals even with moderate interference from biological molecules.
• PCA analysis showed well-clustered spectra, establishing a benchmark for THC sensing.

Conclusions:

• Portable Raman spectrometers coupled with diatomaceous SERS substrates enable on-site detection of THC in biological fluids.
• The developed TLC-SERS method offers high sensitivity and specificity for identifying cannabis exposure.
• This technology holds significant potential for forensic analysis, medical diagnosis, and public health monitoring.