Human skin-inspired design of sticky and strain-gradient artificial epineurium (SSGAE) and its tissue-adhesion characteristics. (IMAGE)

Korea University College of Medicine

Human skin-inspired design of sticky and strain-gradient artificial epineurium (SSGAE) and its tissue-adhesion characteristics.

Caption

A) Schematic description of the SSGAE composed of one hydrophilic wet-adhesive and two hydrophobic elastomers (low modulus (LM-E) and high modulus (HM-E)) (left panel) corresponding to three layers (e.g., hypodermis, dermis, and epidermis) of human skin (right panel). B) Versatile properties of the SSGAE: Janus hydrophilic/hydrophobic surfaces (i), optical transparency (ii), and self-healing property (iii, iv). C) Schematic illustrations of overall procedures of neurorrhaphy using traditional sutures (top) versus the SSGAE (bottom) which is feasible in both rat and monkey nerves. The orange dashed box shows the robust SSGAE-nerve interface enabled by immediate adhesion followed by its self-fixing property. D) The nerve-to-nerve bridging mechanism of the SSGAE through rapid swelling from pre-gel to adhesive hydrogels and strain dissipation through multivalent hydrogen bonds in sutureless neurorrhaphy. E) Plot of ex vivo adhesion strength of four different structures: (i) the SSGAE with middle layer of PDMS-MPU0-IU1, top layer of PDMS-MPU0.4-IU0.6, (ii) PDMS coated with wet-adhesive, iii) HM-E coated with wet-adhesive film (the SSGAE with PDMS-MPU0.4-IU0.6), and (iv) LM-E coated with wet-adhesive film (the SSGAE with PDMS-MPU0-IU1) (n = 3). F) Representative shear stress–strain curve of the SSGAE without using backing substrate at an elongation rate of 20 mm/min, showing efficient strain dissipation in a dynamic mode mimicking in vivo environment. Scale bar of 1 cm for inset photos. G) Adhesive strength of the single-sided SSGAE compared to that of commercial medical glues, Kwik-Cast, Kwik-Sil, Greenplast Q, and Tisseel (n = 3). H) Comparison of the adhesive strength of double-sided SSGAEs to that of commercial medical glues (e.g., Kwik-Cast, Kwik-Sil, Greenplast Q, and Tisseel), NHS-based adhesive, and mussel-inspired hydrogels (n = 3). All data are expressed as the mean ± s.d. Comparisons of the SSGAE with others were conducted using a one-way ANOVA (Dunnett's test, ns = not significant, **p < 0.01, ****p < 0.0001).

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