Fig. 4: Biophysicochemical properties of riboflavin (RF) microneedle array and light-induced scleral collagen cross-linking (SCXL).
From: A wireless battery-free eye modulation patch for high myopia therapy
a Affixing the integrated microneedle array of the myopic patch to the targeted treatment area. Right inset: Zoomed-in detail of microneedle array piercing sclera. b Illustration of the process of microneedle dissolving and releasing riboflavin within the sclera. Right inset: Structure of riboflavin. c Scanning electron microscopy (SEM) image of the microneedle array. Scale bar, 200 μm. d SEM image of a single microneedle. Scale bar, 50 μm. e Fluorescence image of the riboflavin drug. Scale bar, 200 μm. f Side-view fluorescence image of the drug microneedle. Scale bar, 200 μm. g Mechanical behavior of the riboflavin microneedle array under normal compressive load. Up inset: optical image of normal porcine sclera. Down inset: optical image of porcine sclera administered with a microneedle array, showing the indents caused by the penetration of microneedles. Scale bar, 2 mm. h Fluorescence images of drug release from microneedles into sclera over time (0–30 min), and changes in the corresponding quantitative analysis of the mean fluorescence intensity (a.u.). n = 5 porcine sclera per group. Scale bar: 200 μm. i Schematic representation of the SCXL process using riboflavin and blue μ-LEDs. Riboflavin and blue μ-LEDs induce extra covalent bonds between and within collagen fibers and between collagen and proteoglycans, enhancing scleral strength. j The relationship between blue light intensity and Young’s modulus. The control (CTRL) group represents the condition with no light and no drugs, while the riboflavin (RF) group represents the condition with no light but with drugs. Statistical comparisons were assessed by one-way analysis of variance (ANOVA), 95% confidence interval; ****p < 0.0001. n = 3 porcine sclera per group. Data are presented as mean values ± SD. k, l Hematoxylin and eosin (H&E) staining of the sclera before SCXL. Scale bar in (k): 200 μm; scale bar in (l): 50 μm. m, n H&E staining of the sclera after SCXL. Scale bar in (m): 200 μm; scale bar in (n): 50 μm. Source data are provided as a Source Data file.
