Abstract

Background: Picosecond laser can produce laser-induced optical breakdown for photo-rejuvenation clinically.On the other hand, polymer dots (PDs) can promote vascular proliferation, thereby facilitating skin repair and inhibiting inflammation via epithelial-mesenchymal transition.Our study examined a novel approach to reverse photo-damage in nude mice by combining a 755-nm picosecond laser with bioactive PDs.Study Design/Materials and Method: Twelve 6-week-old BALB/c nude mice irradiated with UVB were divided into four groups: (1) UVB, (2) UVB + PEG1000, (3) UVB + PDs + PEG1000, and (4) UVB + Laser + PDs + PEG1000.All mice were subjected to UVB irradiation for 10 weeks.Immunohistochemical analysis, enzyme-linked immunosorbent assay, and Masson's trichrome (MT) staining were conducted to analyze the collagen content, epidermal thickness, and protein levels related to photo-damage repair in the mice.Results: MT staining revealed a notable 30% increase in collagen retention in the UVB + Laser+ PD group by day 11.The MMP-9 levels in the UVB + PD + PEG1000 group on day 11 were reduced by 4.2%, compared with 9.3% in the UVB group on day 1 (p = 0.03).Furthermore, IL-6 levels were substantially decreased in all treatment groups compared with the UVB group on day 1, indicating a notable reduction in inflammation (p < 0.001).Meanwhile, Smad2/3 signaling in the UVB + PD + PEG1000 group on day 11 reached 2.8%, compared with 1.3% in the UVB group on day 1, suggesting an enhanced activation of skin repair. Conclusion:The combination of the 755-nm picosecond laser with bioactive PDs provides a therapeutic strategy for reversing photo-damage.This strategy, not only bolstering collagen production but also promoting a novel pathway for skin repair and aging reversal, merits further exploration for clinical applications.