Study of thermoluminescence (TL) and optically stimulated luminescence (OSL) from α-keratin protein found in human hairs and nails: potential use in radiation dosimetry

Abstract

The thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of human nails and hairs containing α-keratin proteins have been investigated. For the present studies, black hairs and finger nails were selectively collected from individuals with ages between 25 and 35 years. The collected hairs/nails were cut to a size of < 1 mm and cleaned with distilled water to remove dirt and other potential physical sources of contamination. All samples were optically beached with 470 nm of LED light at 60 mW/cm(2) intensity and irradiated by a (60)Co γ source. The hair and nail samples showed overlapping multiple TL glow peaks in the temperature range from 70 to 210 ° C. Continuous wave (CW)-OSL measurements of hair samples at a wavelength of 470 nm showed the presence of two distinct OSL components with photoionization cross section (PIC) values of about 1.65 × 10(-18) cm(2) and about 3.48 × 10(-19) cm(2), while measurements of nail samples showed PIC values of about 6.98 × 10(-18) cm(2) and about 8.7 × 10(-19) cm(2), respectively. This difference in PIC values for hair and nail samples from the same individual is attributed to different arrangement of α-keratin protein concentrations in the samples. The OSL sensitivity was found to vary ± 5 times among nail and hair samples from different individuals, with significant fading (60% in 11 h) at room temperature. The remaining signal (after fading) can be useful for dose estimation when a highly sensitive OSL reader is used. In the absorbed dose range of 100 mGy-100 Gy, both the TL and OSL signals of hair and nail samples showed linear dose dependence. The results obtained in the present study suggest that OSL using hair and nail samples may provide a supplementary method of dose estimation in radiological and nuclear emergencies.

Forensic determination of hair deposition time in crime scenes using electron paramagnetic resonance

“…Melanins capture a large fraction of UV‐visible radiation resulting in the formation of free radicals which could be stabilized by resonance, thereby preventing the propagation of this chain reaction into the keratin matrix [28,29]. Natural melanin and melanin‐like pigments are characterized by a persistent radical signal due to the presence of exceptionally stable free radicals [30–32] which can be detected by electron paramagnetic resonance spectroscopy (EPR; [33–55]). While most of these studies were performed by evaluating stable radical signals present in human hair, few followed the decay of the signals with time (for example [49]) and mainly after gamma‐ or UV‐irradiation of hair [34,38,39,41,43,48–51,56].…”

“…(B) EPR spectrum of black hair (B1), synthetic melanin standards of eumelanin (B2) and pheomelanin (B3) and simulations of pheomelanin spectrum (B4) [Color figure can be viewed at wileyonlinelibrary.com] detected by electron paramagnetic resonance spectroscopy (EPR; ). While most of these studies were performed by evaluating stable radical signals present in human hair, few followed the decay of the signals with time (for example [49]) and mainly after gamma-or UV-irradiation of hair [34,38,39,41,43,[48][49][50][51]56]. In this regard, earlier articles about radiation-induced radicals in human nails and hair focused on the possible application of stable radical signals for retrospective dosimetry [49,[57][58][59][60], besides their use for assessing quality and/or degradation in petrochemical and food sciences [61][62][63][64][65][66].…”