Fig. 4: Fabrication and characterization of the MN-MP/aUCP1 patch.

a Schematic illustration of MN patch fabrication. Representative digital photographs of MN patch (b) and MP/aUCP1 loaded MN patch (c). d SEM image of the MN-MP/aUCP1 patch (Scale bar: 200 µm). e Mechanical strength of the MN patches with different concentrations of HA and schematic diagram of the corresponding testing device. f H&E staining of mouse skin exhibits penetration of single MN (Scale bar: 100 µm). g Top: demonstration of the MN tips pressed into the skin for different times (Scale bar: 200 µm). Bottom: Skin recovery after MN treatment showing slight irritation (Scale bar: 5 mm). h Fluorescence images of MN patch containing aUCP1-ICG and Cy3-loaded MP nanosheets (Scale bars: 200 µm). i In vivo fluorescence images of aUCP1 (aUCP1-ICG) and MP/aUCP1 (MP loaded aUCP1-ICG) delivered by subcutaneous injection (InJ) or MN patches inserting in the inguinal region. j Quantification of fluorescence intensity during the 3-day treatment period. Data are presented as means ± SD (n = 3 mice per group). Ex vivo organ fluorescence biodistribution (k) and corresponding fluorescence intensity quantitative analysis in organs (l) explanted from mice at 24 h after subcutaneous InJ or MN patches delivery of aUCP1 and MP/aUCP1. Data are presented as means ± SD (n = 3 biologically independent samples). The experiments for d–g and h were repeated three times independently with similar results. Statistical differences for j and l were calculated using two-tailed unpaired student’s t-test. n.s., not significant, *P < 0.05, **P < 0.01, and ****P < 0.0001. Source data are provided as a Source Data file.