Evaluating blue light impact on reconstructed human epidermis using laser speckle imaging

Abstract

Significance: Blue light exposure is ubiquitous in modern life, raising concerns about its potential impact on skin health.

Aim: We aim to explore the effects of blue light on the reconstructed human epidermis (RHE) using the speckle analysis technique.

Approach: RHE samples were irradiated with controlled doses of blue light (415 and 455 nm) at defined stages of their maturation. Following irradiation, speckle analysis was performed to assess the impact of blue light on the skin barrier.

Results: Our results demonstrate that blue light irradiation significantly alters the scattering properties of RHE. Both wavelengths induced changes in the degree of linear polarization and speckle grain size, indicating disruptions in the skin barrier's structure and organization. The effects were found to be wavelength-dependent, with 455 nm irradiation showing more pronounced changes.

Conclusions: Speckle imaging allowed detection of changes in the scattering properties of RHE. Findings suggest that blue light exposure can influence skin barrier function and may have implications for skin health and related conditions.

Keywords: barrier function; blue light; epidermal models; reconstructed human epidermis; speckle; visible light.

Fig. 1

Experimental setup for RHE model irradiation. (a) 6-Well plate containing RHE models designated for specific wavelengths: I415 for 415 nm and I455 for 455 nm exposure, with each model placed in separate wells to avoid cross-contamination. (b) Separate 6-well plate containing unirradiated control models (Ctrl). (c) Irradiation compartment with the LEDs positioned at a distance of $D=2\mathrm{cm}$ from the RHE models and (d) control compartment.

Fig. 2

Speckles image recorded using linear parallel polarized detection of the RHE standard controls (a) D17 and (b) D20 and groups with repeated incubator removals (c) R3_D17 and (d) R6_D20. RHE, reconstructed human epidermis.

Fig. 3

Comparison of speckle parameters: (a) ${\mathrm{DOP}}_{\mathrm{L}}$ and (b) dx between standard controls and groups with repeated incubator removals.

Fig. 4

Speckles image recorded using linear parallel polarized detection of the RHE: Control samples at (a) R3_D17, (d) R4_D18, and (g) R6_D20; samples irradiated with 415 nm at (b) R3_D17, (e) R4_D18, and (h) R6_D20; and samples irradiated with 455 nm at (c) R3_D17, (f) R4_D18, and (i) R6_D20.

Fig. 5

Variation of the ${\mathrm{DOP}}_{\mathrm{L}}$ for RHE samples, among R3_D17, R4_D18, and R6_D20, in both (a) absolute values and (b) relative values calculated as a ratio of each irradiated sample (I) to its corresponding control (Ctrl).

Fig. 6

Variation of the horizontal speckle grain size for RHE samples, among R3_D17, R4_D18, and R6_D20, in both (a) absolute values and (b) relative values calculated as a ratio of each irradiated sample (I) to its corresponding control (Ctrl).