In Vivo Human Skin Penetration Study of Sunscreens by Confocal Raman Spectroscopy

Abstract

This research work mainly deals with the application of confocal Raman spectroscopic technique to study in vivo human skin penetration of sunscreen products, as there are a lot of controversies associated with their skin penetration. Healthy human volunteers were tested for penetration of two commercial sunscreen products into their volar forearm skin for a period of 2 h. Measurements were taken before and after application of these sunscreen products. All the confocal Raman spectra were pre-processed and then subjected to multivariate two-dimensional principal component analysis and classical least squares analysis to determine the skin penetration of these sunscreens in comparison to the "sunscreen product spectrum" which was considered as the control. Score plots of principal component analysis of confocal Raman spectra indicated clear separation between the spectra before and after application of sunscreen products. Loading plots showed the maximum differences in the spectral region from 1590 to 1626 cm where the characteristic peak of the pure sunscreen products was observed. Classical least squares analysis has shown a significant penetration to a depth of 10 μm in the volar forearm skin of healthy human volunteers for both these sunscreen products. The results confirm that the penetration of these tested sunscreen products was restricted to stratum corneum and also prove that confocal Raman spectroscopy is a simple, fast, nondestructive, and noninvasive semi-quantitative analytical technique for these studies.

A modification for the calculation of water depth profiles in oil‐treated skin by in vivo confocal Raman microscopy

“…Therefore, the shift of the surface points does not occur, indicating the correct position of the skin surface points. The effect of a shifting surface point in the treated skin should be taken into consideration by analyzing the penetration profiles of xenobiotics into the SC , where the determination of the correct surface position is very important.…”

Human skin in vivo has a higher skin barrier function than porcine skin ex vivo—comprehensive Raman microscopic study of the stratum corneum

“…Confocal Raman microscopy (CRM) is a powerful non‐invasive tool to measure depth profiles of molecular components in the SC , in which the skin components are measured depth‐dependently in vivo / ex vivo at high spatial resolution. An area of interest using CRM in dermatology is the analysis of the penetration into the skin , the skin barrier function provided by the SC , and collagen of the dermis . Our group recently introduced methods to determine the molecular properties of skin barrier function‐related parameters, such as water bonding states , ICL ordering and secondary and tertiary structures of keratin in the SC in vivo.…”

Sunscreen ingredients in plasma: a threat for drug–drug interactions and toxicity among patients living with HIV?

“…As we described, a number of recent studies are evidencing unexpectedly high levels of absorption of active ingredients of sunscreens. Moreover, other studies are clarifying details on the metabolism of these substances, rising the suspect of potential DDIs, bioaccumulation, and toxicity [19][20][21]. Consequently, a number of data gaps regarding the active substances present in sunscreens should be addressed.…”