Spectrofluorescence of skin and hair

Abstract

There are numerous chromophores present throughout the strata of human skin, which present many challenges and opportunities to probe molecular events. Fluorescence spectroscopy is principally employed to identify important biochemical components of the skin including endogenous tryptophan, tyrosine, pepsin-digestible collagen cross-links, collagenase-digestible collagen cross-links, NADH, etc. Over the last 15 years, many advances in instrument technology have been introduced allowing for much faster data acquisition with spectrofluorometers. As a result, a series of spectrofluorescence emission scans can be generated for a range of excitation wavelengths, or vice versa (excitation scans for a range of emission wavelengths), quickly to generate excitation-emission matrices. In this work, we constructed an endogenous fingerprint of fluorescent compounds present in skin, hair and nail tissues by employing a range of excitation wavelengths from 270 to 450 nm with a resolution of 2 nm. As a result, we generated surface plots of fluorescence emission as a function of excitation and emission wavelengths. From these data, we identified the predominant fluorescent chromophores in each tissue. We examined several sources of skin including in vivo human and ex vivo pig, sheep, goat and cow skin. We also analysed various types of mature hair characterized by the degree of melanin content. These analyses provided us with a fundamental understanding of the effects of melanin distribution in hair fibres and aided with the identification of fluorophores present in hair.

Penetration of different molecular weight hydrolysed keratins into hair fibres and their effects on the physical properties of textured hair

“…One peak that is related to tryptophan has an excitation wavelength at 290 nm and an emission wavelength 335–345 nm (the exact position depending on the level of pigmentation). Furthermore, they report another peak with an excitation wavelength of 366 nm and an emission wavelength of 433 nm; this is related to tryptophan degradation products [25].…”

Which are the main fluorophores in skin and oral mucosa? A review with emphasis on clinical applications of tissue autofluorescence

“…Seventeen papers were eventually included (Fig. 4) (Breunig, Studier, & König, 2010;Dimitrow, Riemann et al, 2009, 2009bEny et al, 2015;Gillies, Zonios, Anderson, & Kollias, 2000;Krasieva et al, 2013;Laiho, Pelet, Hancewicz, Kaplan, & So, 2005;Leupold et al, 2011;Miyamoto & Kudoh, 2013;McMullen, Chen, & Moore, 2012;Na, Stender, Henriksen, & Wulf, 2011;Patalay et al, 2011;Richter, Trojahn, Dobos, Blume-Peytavi, & Kottner, 2016;Stirban, Nandrean, Negrean, Koschinsky, & Tschoepe, 2008;Sandby-Møller, Thieden, Philipsen, Heydenreich, & Wulf, 2004;Yu et al, 2012;Zhao et al, 2016).…”

“…Seven out of 17 studies on skin/epidermal fluorophores were in vivo studies performed on humans; four out of 17 studies selected were ex vivo and in vivo studies, and six out of 17 studies were ex vivo or in vitro studies (Breunig et al, 2010;Dimitrow, Riemann et al, 2009, 2009bEny et al, 2015;Gillies et al, 2000;Krasieva et al, 2013;Leopold et al, 2011;McMullen et al, 2012;Na et al, 2011;Patalay et al, 2011;Richter et al, 2016;Stirban et al, 2008;Laiho et al, 2005;Sandby-Møller et al, 2004;Yu et al, 2012;Zhao et al, 2016).…”

Spectroscopy as a tool to evaluate hair damage and protection

“…Hair fluorescence under UV has been used as a tool to evaluate hair damage . However, there is a lack of correlation between the visible excitation/emission properties of hair and the presence of oxidative damages in its structure . In this study, the researchers have associated spectroscopic and imaging fluorescence properties with the photo‐oxidation of hair, giving an emphasis to the spectral changes that occur in the visible region.…”