Fig. 5
Ex vivo studies of double-layered microneedles on porcine cornea. A polymeric patch containing 3 × 3 DL-MNs was applied on the central region of porcine eye (~30 s). a, b Bright-field images of the cornea before (a) and after (b) MN insertion. Scale bars = 2 mm. c, d Bright-field images of the cornea (cross-sectional view), upon MN insertion (c) and after removal of the supporting patch (d). Scale bars = 200 µm. e Hematoxylin and eosin stained section of the cornea showing the cavity caused by DL-MN penetration. Scale bar = 100 µm. f The averaged insertion force of DL-MN into the cornea (n = 3). g–i Confocal image of embedded DL-MNs in cornea (g), the average fluorescence intensity changes (n = 4) in the region adjacent to DL-MNs (h), and confocal visualization of real-time release of IgG(680) (red colour) and IgG(488) (green colour) from DL-MN into the cornea (i). Scale bars = 100 µm. j Transmittance of the fully-hydrated DL-MN, cornea and aqueous humour at different wavelengths (n = 3). n represents the number of samples for each group
