Abstract
Precise measurement of particulate matter (PM) on skin is important for managing and preventing PM-related skin diseases. This study aims to directly visualize the deposition and penetration of PM into human skin using a multimodal nonlinear optical (MNLO) imaging system. We successfully obtained PM particle signals by merging two different sources, C–C vibrational frequency and autofluorescence, while simultaneously visualizing the anatomical features of the skin via keratin, collagen, and elastin. As a result, we found morphologically dependent PM deposition, as well as increased deposition following disruption of the skin barrier via tape-stripping. Furthermore, PM penetrated more and deeper into the skin with an increase in the number of tape-strippings, causing a significant increase in the secretion of pro-inflammatory cytokines. Our results suggest that MNLO imaging could be a useful technique for visualizing and quantifying the spatial distribution of PM in ex vivo human skin tissues.
Highlights
High levels of ambient particulate matter (PM) in pollutants due to industrialization and urbanization have been associated with outbreaks of human diseases
We interpret that coherent anti-Stokes Raman scattering (CARS) peak 1 corresponds to the two-dimensional (2D) band of Raman spectra in carbon nanotubes [24,25] and that CARS peak 2 indicates the C–H vibrational mode that is expected to produce a strong signal when carbon complexes such as polycyclic aromatic hydrocarbon (PAH) are hydrated
The airborne PM2.5 was validated with the standard reference material (SRM) 2786 from NIST via multimodal nonlinear optical (MNLO) imaging
Summary
High levels of ambient particulate matter (PM) in pollutants due to industrialization and urbanization have been associated with outbreaks of human diseases. PM has been reported to cause various health problems, including respiratory disease, cardiovascular diseases such as hypertension, and neurotoxicity [1,2,3,4]. Particulate matter exerts detrimental effects on human skin by inducing the acceleration of inflammatory skin diseases such as atopic dermatitis, acne, and psoriasis [6,7,8]. It should be noted that these previous reports are epidemiologic studies. Benzo(a)pyrene (BaP), a type of polycyclic aromatic hydrocarbon (PAH) in PM, enhances oxidative stress-mediated inflammatory cytokines in human keratinocytes [11]. Due to the limitations of in vitro systems, though, PM effects need to be understood in a spatial environment
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