Effects of crime scene contaminants on surface‐enhanced Raman analysis of hair

Abstract

Forensic analysis of hair is important as hair is one of the most commonly examined forms of trace evidence found at crime scenes. A growing body of evidence suggests that surface‐enhanced Raman spectroscopy (SERS), a label‐free and non‐destructive analytical technique, can be used to detect and identify artificial colorants present on hair. However, hair collected at crime scenes is often contaminated by substances of biological and non‐biological origin present at such locations. In this study, we investigate the extent to which four contaminants, saliva, blood, dirt, and bleach can alter the accuracy of SERS‐based detection and identification of both permanent and semi‐permanent colorants present on hair. Our findings show that saliva and dirt reduce the intensity of the colorants' signals but do not obscure their detection and identification. At the same time, an exposure of the colored hair to bleach or the presence of blood eliminates SERS‐based analysis of artificial dyes present on such samples. We identified the procedure that can be used to remove blood contamination, which, in turn, enables identification of the hair colorants on such pre‐cleaned samples. However, bleach treatment irreversibly eliminates SERS‐based detection of artificial colorants on hair. These findings expand our understandings about the potential of SERS in forensic investigation of colorants on trace hair evidence.

Surface-enhanced Raman spectroscopy hair analysis after household contamination

“…Once the contaminant was removed, SERS could be used to detect and identify hair colourants. 16 In the current study, we investigate the extent to which this simple washing procedure could be used to remove the discussed above contaminants from hair. We found that SERS spectra acquired from cleaned SpBlu-colored hair spectra were nearly identical to the spectra acquired from uncontaminated hair (Fig.…”

“…The Kurouski group showed in 2022 that the ability to detect colourants on contaminated hair varies from contaminant to contaminant. 16 Some contaminants such as saliva and dirt did not block the underlying Raman signal, while others such as blood did. Some contaminants, like bleach, destroyed the possibility of detecting the underlying colourant even after the hair was rinsed.…”

Near-infrared excitation Raman analysis of Underlying colorants on redyed fabric

“…However, no statistically signicant accuracy was found in classication of spectra acquired from fabric contaminated In our previous study, we demonstrated that some household contaminants could obscure the readability of SERS-based identication of dye content on hair. 32 However, the gentle removal of such contaminants by water allowed for restoration of the accuracy of SERS-based sensing of dyes. One can expect that a similar approach could be used to remove paint from the colored fabric.…”

Thermoresponsive Polymer Brush-Decorated 3-D Plasmonic Gold Nanorod Arrays as an Effective Plasmonic Sensing Platform

“…Surface-enhanced Raman spectroscopy (SERS) is a versatile tool for analyzing and detecting molecular species and has been employed in a wide variety of applications, including molecular imaging of live cells, − homeland security, , criminal investigations, , environmental analysis, , food safety, , and even anti-counterfeiting. , To collect high-intensity Raman signals from analyte molecules in SERS, enhanced localized electromagnetic fields on the substrate and/or energetically effective charge-transfer processes between the substrate material and analyte molecules should be realized . Among these enhancement mechanisms, electromagnetic field enhancement, which is also called the electromagnetic (EM) mechanism, provides the largest contribution to Raman signal enhancements.…”