Cleansing-induced changes in skin measured by in vivo confocal raman spectroscopy

Physiological effects of appropriate washing on xerotic skin

BACKGROUND

Daily skin care is important for treatment of skin diseases, but few studies have reported on appropriate washing methods.

AIM

This study aimed to provide guidance on washing techniques and examine changes in skin condition after using the recommended washing technique and foaming-type skin cleanser in patients with atopic or asteatotic dermatitis.

METHODS

An internet-based questionnaire survey on skin symptoms and cleaning methods was conducted. Further, a left-right comparative, nonrandomized trial was performed in 19 patients with asteatotic or atopic dermatitis and xerosis. Participants were instructed to wash with a cotton towel and their normal cleanser during Weeks 1-4 and with bare hands or a cotton towel and the recommended foaming-type cleanser during Weeks 5-8.

RESULTS

The survey revealed that the degree of lathering differed depending on the cleaning tool. In the trial, scores for erythema, desquamation, and xerosis in the lower legs were significantly reduced after 4 weeks compared with scores at the start. Between Weeks 4 and 8, scores for erythema, xerosis, and pruritus in the inner forearm on the side washed with bare hands and scores for xerosis, pruritus, and excoriation on the side washed with a cotton towel were significantly reduced. A significant increase was noted in stratum corneum ceramide content on both left and right inner forearms, whereas a significant decrease was noted in stratum corneum thymus and activation-regulated chemokine level ratios in the lower legs on both sides.

CONCLUSIONS

Xerotic skin disease symptoms can be improved using appropriate body washing methods.

Optical Methods for Non-Invasive Determination of Skin Penetration: Current Trends, Advances, Possibilities, Prospects, and Translation into In Vivo Human Studies

Information on the penetration depth, pathways, metabolization, storage of vehicles, active pharmaceutical ingredients (APIs), and functional cosmetic ingredients (FCIs) of topically applied formulations or contaminants (substances) in skin is of great importance for understanding their interaction with skin targets, treatment efficacy, and risk assessment-a challenging task in dermatology, cosmetology, and pharmacy. Non-invasive methods for the qualitative and quantitative visualization of substances in skin in vivo are favored and limited to optical imaging and spectroscopic methods such as fluorescence/reflectance confocal laser scanning microscopy (CLSM); two-photon tomography (2PT) combined with autofluorescence (2PT-AF), fluorescence lifetime imaging (2PT-FLIM), second-harmonic generation (SHG), coherent anti-Stokes Raman scattering (CARS), and reflectance confocal microscopy (2PT-RCM); three-photon tomography (3PT); confocal Raman micro-spectroscopy (CRM); surface-enhanced Raman scattering (SERS) micro-spectroscopy; stimulated Raman scattering (SRS) microscopy; and optical coherence tomography (OCT). This review summarizes the state of the art in the use of the CLSM, 2PT, 3PT, CRM, SERS, SRS, and OCT optical methods to study skin penetration in vivo non-invasively (302 references). The advantages, limitations, possibilities, and prospects of the reviewed optical methods are comprehensively discussed. The ex vivo studies discussed are potentially translatable into in vivo measurements. The requirements for the optical properties of substances to determine their penetration into skin by certain methods are highlighted.

Challenges and opportunities for small volumes delivery into the skin

Each individual's skin has its own features, such as strength, elasticity, or permeability to drugs, which limits the effectiveness of one-size-fits-all approaches typically found in medical treatments. Therefore, understanding the transport mechanisms of substances across the skin is instrumental for the development of novel minimal invasive transdermal therapies. However, the large difference between transport timescales and length scales of disparate molecules needed for medical therapies makes it difficult to address fundamental questions. Thus, this lack of fundamental knowledge has limited the efficacy of bioengineering equipment and medical treatments. In this article, we provide an overview of the most important microfluidics-related transport phenomena through the skin and versatile tools to study them. Moreover, we provide a summary of challenges and opportunities faced by advanced transdermal delivery methods, such as needle-free jet injectors, microneedles, and tattooing, which could pave the way to the implementation of better therapies and new methods.