Abstract
To date, most research regarding amino acid detection and quantification in fingermarks relies on spectrometric methods. Herein, the Sakaguchi colorimetric test was adapted to a rotationally-driven microfluidic platform and used to detect and quantify arginine in fingermarks deposited by male and female donors. A red color indicates the presence of arginine in a given sample following the reaction, and the intensity of this color is linearly proportional to the concentration. Objective detection and quantification of arginine were accomplished using image analysis software (freeware) based on this colorimetric result. The mean concentrations obtained in a blind study were 96.4 ± 5.1 µM for samples from female donors and 55.3 ± 5.3 µM for samples from males. These were not statistically different from the literature values of 94.8 µM ± 12.9 µM for females (p = 0.908) and 54.0 ± 12.6 µM for males (p = 0.914), respectively (± SEM in all cases). Conversely, the experimental means from males and female samples were statistically different from each other (p < 0.001). Objective differentiation between male and female fingermark deposits was achieved in a blind study with 93% accuracy. Additionally, the method was compatible both with samples lifted from common surfaces and with magnetically-powdered samples.
Highlights
The microfluidic device to identify biological sex sex via fingerThecreation creationofofananoptimized optimized microfluidic device to identify biological via finmark deposit analysis is detailed
Sakaguchi reaction for a microfluidic platform coupled with and optimizing the colorimetric Sakaguchi reaction for a microfluidic platform coupled an inexpensive but objective detection method employing freeware and a standard computer scanner. These were used to reliably determine the donor’s biological sex from fingermark content in ≤40 min with mean arginine concentrations that were statistically similar to those previously reported in the literature
The biological sexes of fourteen out of fifteen unknown participants were correctly designated with an inexpensive but objective detection method employing freeware and a standard computer scanner
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. In cases where fingermarks are deposited on smooth, non-porous surfaces, development is often achieved using cyanoacrylate (commonly known as superglue) vapor or vacuum-metal deposition [9] These chemical techniques discern the latent fingermark but do not provide detailed biological information about its content. Most studies in this area of fingermark analysis have been conducted using spectrophotometric methods [3,5] One such example is the successful development of chemical and enzymatic assays targeting amino acids present in fingermarks for use as biomarkers by Brunelle et al [3,4,10,11]. The intensity of the color is directly indicative of the concentration of arginine present in the sample This test is applicable in determining biological sex from fingermarks as the average concentrations of arginine in males’ and females’ sweat differ significantly. This technology can be further adapted to allow for an integrated, automated, and portable analysis system
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