Fig. 16. (A) Injectability of silk fibroins from a prefilled syringe and inverted vial image. Reprinted with permission from ref. 124 Copyright © 2016 American Chemical Society. (B) Silk microneedles as applied to mouse skin: (i) SEM image of an individual silk microneedle, (ii) silk microneedle patch, relative size comparison to mouse, (iii) silk microneedle patch applied to animal skin, (iv) skin after removal of microneedle patch; needle penetration marks are clearly visible. Reprinted with permission from ref. 22 Copyright © 2011 Wiley. (C) Schematic and morphology of the micro-needle fabricated with SF-combined semi-IPN hydrogel as a needle tip and SF as a base layer. Scale bar: 500 μm. (D) In vitro skin insertion capability. Mouse skin was treated (i) without or (ii) with smart hybrid micro-needles for 10 min and stained with trypan blue to indicate the formation of microchannels. Reprinted with permission from ref. 126 Copyright © 2019 American Chemical Society.