Enhanced Dark-Field Hyperspectral Imaging and Spectral Angle Mapping for Nanomaterial Detection in Consumer Care Products and in Skin Following Dermal Exposure

Abstract

Consumer personal care products, and cosmetics containing nanomaterials (NM), are increasingly available in the Canadian market. Current Canadian regulations do not require product labeling for ingredients that are present in the nanoscale. As a result, unless voluntarily disclosed, it is unclear which products contain NM. The enhanced dark-field hyperspectral imaging (EDF-HSI) coupled with spectral angle mapping (SAM) is a recent technique that has shown much promise for detection of NM in complex matrices. In the present study, EDF-HSI was used to screen cosmetic inventories for the presence of nano silver (nAg), nano gold (nAu), and nano titanium dioxide (nTiO 2 ). In addition, we also assessed the potential of EDF-HSI as a tool to detect NM in skin layers following application of NM products in vitro on commercially available artificial skin constructs (ASCs) and in vivo on albino hairless SKH-1 mouse skin. Spectroscopic analysis positively detected nAu (4/9 products) and nTiO 2 (7/13 products), but no nAg (0/6 products) in a subset of the cosmetics. The exposure of ASCs for 24 h in a Franz diffusion cell system to a diluted cosmetic containing nTiO 2 revealed penetrance of nTiO 2 through the epidermal layers and was detectable in the receptor fluid. Moreover, both single and multiple applications of nTiO 2 containing cosmetics on the dorsal surface of SKH-1 mice resulted in detectable levels of trace nTiO 2 in the layers of the skin indicating that penetrance of NM was occurring after each application of the product. The current study demonstrates the sensitivity of EDF-HSI with SAM mapping for qualitative detection of NM present in cosmetic products per se and very low levels in complex biological matrices on which these products are applied.

A methodology for developing key events to advance nanomaterial-relevant adverse outcome pathways to inform risk assessment

“…materials with engineered properties) such as composites, ceramics, biomaterials, polymers, and others. Because of their numerous applications, the production of MNs and other advanced materials has increased and the availability of nano-enabled consumer products on the market is also on the rise (Boyadzhiev et al 2020). Consequently, exposure to these substances in occupational settings and throughout the lifecycle of the MNs is expected to increase.…”

Critical Review: Uptake and Translocation of Organic Nanodelivery Vehicles in Plants

“…Other microscopy methods that have been reported include optical light microscopy, , X-ray microscopy, atomic force microscopy (AFM), and hyperspectral-enhanced dark field microscopy (DF-HIS). ,,,, DF-HIS detects a target molecule’s spectral signature at a submicrometer, typically ∼10 nm, plane resolution, allowing organic NDVs containing a detectable probe to be imaged nondestructively on different plant tissue layers. − Non-microscopy-based imaging techniques, such as magnetic resonance imaging (MRI) and photoacoustic (PA) imaging, have also been used to track organic NDVs.…”

“…Quantitative methods are less often used than qualitative, image-based ones, being typically indirect (tissue extracts or digestates are analyzed as opposed to the actual plant), destructive, and requiring extensive sample preparation in which alterations, contaminations, and errors can be introduced. , Despite these challenges, quantitative methods are powerful tools for measuring the bulk concentration of NDVs, or some compound therein, within plant tissues, which provides an overview of the total biodistribution of organic NDVs following uptake and translocation. As with qualitative methods, demonstrating retention of the tracer probe within the NDV is critical for correlating its localization with the NDVs.…”

What to Expect When Expecting in Lab: A Review of Unique Risks and Resources for Pregnant Researchers in the Chemical Laboratory

“… 145 , 150 There are some studies on dermal exposure, mainly focusing on metal oxide nanoparticles in cosmetics, with the general conclusion that nanoparticles do not pass through human skin immediately or with short duration exposures, but with repeated exposure can penetrate deeper into the skin and become internalized (e.g., 4.7–6.1% 4 mm diameter titania nanoparticle cosmetic applied directly to skin of pigs for 22 days resulted in skin penetration, 60 days of exposure resulted in internalization). 140 , 151 , 152 Therefore, avoidance of skin contact and appropriate PPE are recommended. ENMs in powder form can become aerosolized and may be suspended for extended periods of time, resulting in inhalational exposure.…”

“…Safety guidelines for nanomaterials are lagging behind more traditional chemicals for the general researcher, with a 2010 survey of university and public research laboratories worldwide showing 90% of respondents being unaware of local or national regulations for safe handling of nanomaterials and almost three-quarters reporting having little or no awareness of internal or lab scale rules . Since then, the EU and the US have issued guidance on nano safety practices through ECHA and NIOSH, respectively, but recent surveys in other regions continue to show a lack of awareness of nanomaterial-specific safety and health policy plans. , Guidelines on ENM exposure specific to pregnant researchers are further lagging, although the routes of ENMs exposure are well-established including dermal and via inhalation. , There are some studies on dermal exposure, mainly focusing on metal oxide nanoparticles in cosmetics, with the general conclusion that nanoparticles do not pass through human skin immediately or with short duration exposures, but with repeated exposure can penetrate deeper into the skin and become internalized (e.g., 4.7–6.1% 4 mm diameter titania nanoparticle cosmetic applied directly to skin of pigs for 22 days resulted in skin penetration, 60 days of exposure resulted in internalization). ,, Therefore, avoidance of skin contact and appropriate PPE are recommended. ENMs in powder form can become aerosolized and may be suspended for extended periods of time, resulting in inhalational exposure .…”