Ultrasensitive Detection of Synthetic Drugs in Blood Plasma Using Hydrophobic Polymer-Modified Microneedle SERS Substrates
Description:
Surface-enhanced Raman spectroscopy (SERS) is an attractive, label-free analytical technique with highly specific molecular vibrational signatures, making it a practical method for analyzing synthetic drugs(e.g., opioids and cannabinoids). However, the concentration of intact drugs in blood plasma is exceedingly low because most drug molecules undergo fast metabolic decomposition, thus an ultrasensitive approach is required to detect undecomposed drugs in plasma as a part of forensic toxicology. This work encompasses the successful fabrication of a surface modified, plasmonic microneedle SERS substrate. We used polydimethylsiloxane (PDMS) to fabricate microneedles with few-micrometer tip diameters where the self-assembly of plasmonic gold nanorods(AuNRs) creates multiple “hot spots” due to coupling of the electromagnetic field that together increases the Raman signal of target analytes. Therefore, our construct closely resembles “tip enhanced Raman spectroscopy(TERS).” The modification of PDMS microneedles with chlorosilane results in the formation of a superhydrophobic surface, allowing drug pre-concentration at the microneedle tips via a controlled droplet evaporation method. We analyzed two synthetic drugs, alprazolam and fentanyl, using the microneedle SERS substrates. The limit of detections (LODs) are determined to be 28.0 pM and 4.16 fM, respectively. This fabrication strategy serves as a high throughput analytical detection tool as different drug types and/or analogues of a particular drug can be detected on each individual microneedle by SERS analysis. Furthermore, this exquisite SERS sensitivity allows blood plasma to be highly diluted to reduce fouling effects to analyze fentanyl and alprazolam in emergency department patient samples. Taken together, superhydrophobic surface modification and formation of multiple hot-spots from self-assembled AuNRs provide a generalized platform for SERS-based forensic toxicology drug analysis in complex real-world media.
Speaker: Vitoria Simas - Indiana University-Purdue University Indianapolis
Co-Authors
Ultrasensitive Detection of Synthetic Drugs in Blood Plasma Using Hydrophobic Polymer-Modified Microneedle SERS Substrates
Category
2023 Call for Oral Abstracts
Description
Session Number: C44-02
Session Type:
Session Date: Tuesday 3/21/2023
Session Time: 1:30 PM - 4:25 PM
Room Number: 115C
Track: Forensics & Toxicology
Category: Bioanalytical, Forensics, Nanotechnology/Nanoscience
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