Photoacoustics · May 12, 2026

Decoding melanin dynamics: Photoacoustic microscopy reveals differential aging of metabolic and keratinized skin zones

By Zhang Z, Chen Z, Chen Y et al.

Understanding depth-resolved distribution of melanin is crucial, yet anatomical methods fail to capture its functional state. Photoacoustic imaging at 650 nm, sensitive to epidermal melanin, bridges this gap. We developed functional zone segmentation based on depth-dependent PA intensity profiles using first-derivative analysis to define a Metabolically Active Zone (MAZ) and a Terminally Differentiated Keratinized Zone (TDZ). Five parameters (thickness, PA intensity, Local Area Maximum (LAM), Global Area Coefficient of Variation (GACoV), and Dispersion Index (DI)) reveal that the MAZ spatial architecture remains stable with age, while the TDZ records cumulative pigmentary changes. This model provides a new paradigm for non-invasive assessment of skin pigmentation and aging.

doi.org/10.1016/j.pacs.2026.100839Open accessPubMed 42199514Biomarkers