Fig. 5: Characterization of drug delivery performance of microorganism micro-engine microneedles (MM-MNs).

a Double-layer microneedles with an outer layer loaded with Rhodamine dye and an inner layer containing Poly(ethylene glycol) diacrylate (PEGDA) loaded with E.A.. Created with BioRender.com/e13d275. b Digital microscope image of RMM-MNS. Scale bar, 3 mm (Left); 500 μm (Right). c The release of rhodamine over time in simulated body fluid. Mean ± SD of n = 3 independent samples. d Confocal microscopy imaging of the penetration depth of Rhodamine dye released by microneedles loaded with different concentrations of glucose into the skin. Scale bar, 500 μm. e Fluorescence intensity of Rhodamine dye diffusion at different depths beneath the skin released by microneedles loaded with varying concentrations of glucose. Mean ± SD of n = 3 independent samples. Two-sided Student’s t test. f Double-layer microneedles with an outer layer loaded with Calcipotriol and an inner layer containing PEGDA loaded with E.A. Created with BioRender.com/e13d275. g Determination of the concentration of Carpotriol in the skin’s surface and subcutaneous tissue by high-performance liquid Chromatography (HPLC). Mean ± SD of n = 6 independent samples. Two-sided Student’s t test. h Changes in caprotriol concentration in skin surface and subcutaneous tissue over time as determined by HPLC. Mean ± SD of n = 6 independent samples. Two-sided Student’s t test. A representative image of four biologically independent samples from each group is shown in (b) and (d).