"Fouling-Resistant Voltammetric Xylazine Sensors for Detection of the S" by Ann Holland Wemple

Date of Award

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science

Department

Biochemistry & Molecular Biol.

First Advisor

Dr. Michael Leopold

Second Advisor

Dr. Ryan Coppage

Abstract

As the opioid crisis continues to wreak havoc on a national and global scale, it is increasingly critical to develop methodologies to detect the most dangerous of these drugs as fentanyl and its derivatives have orders of magnitude higher potency than morphine. Recently, the scientific challenge for chemical detection of fentanyl and its derivatives has been complicated by both the constantly increasing synthetic variations of the drug as well as the expanded use of adulterants. One tragically consequential example is the nocuous street drug known as “Tranq” which combines fentanyl or a fentanyl derivative with the veterinary sedative Rompun®, chemically identified as xylazine (XYL). This increasingly pervasive street cocktail is exasperating the already staggering number of fentanyl-related deaths and has an acute toxicity that poses a danger to medical first-responders and complicates their assessment and treatment. Given its widespread use as an adulterant, an electrochemical XYL sensor capable of on-site operation by nonexperts as a fast-screening tool is a notable goal. This work presents a voltammetry-based sensor featuring carbon electrodes modified with carbon nanotubes and semi-permeable membranes for sensitivity and selectivity enhancements. The sensor has critical and robust fouling resistance while providing sensitivity at 950 μA/mM∙cm2, a low limit of detection (~5 ppm), and the ability to detect XYL in the presence of fentanyl and/or other non-fentanyl opioids. The demonstrated sensor can be applied to indicate XYL in powders, solutions, and in beverages that may be nefariously doped as well, ultimately allowing for immediate and critical information for on-site investigators.

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