Mechanically Enhanced Nested-Network Hydrogels as a Coating Material for Biomedical Devices

Publication date: Available online 12 February 2018
Source:Acta Biomaterialia
Author(s): Zhengmu Wang, Hongbin Zhang, Axel J. Chu, John Jackson, Karen Lin, Chinten James Lim, Dirk Lange, Mu Chiao
Well-organized composite formations such as hierarchical nested-network (NN) structure in bone tissue and reticular connective tissue present remarkable mechanical strength and play a crucial role in achieving physical and biological functions for living organisms. Inspired by these delicate microstructures in nature, an analogous scaffold of double network hydrogel was fabricated by creating a poly(2-hydroxyethyl methacrylate) (pHEMA) network in the porous structure of alginate hydrogels. The resulting hydrogel possessed hierarchical NN structure and showed significantly improved mechanical strength but still maintained high elasticity comparable to soft tissues due to a mutual strengthening effect between the two networks. The tough hydrogel is also self-lubricated, exhibiting a surface friction coefficient comparable with polydimethylsiloxane (PDMS) substrates lubricated by a commercial aqueous lubricant (K-Y Jelly) and other low surface friction hydrogels. Additional properties of this hydrogel include high hydrophilicity, good biocompatibility, tunable cell adhesion and bacterial resistance after incorporation of silver nanoparticles. Firm bonding of the hydrogel on silicone substrates could be achieved through facile chemical modification, thus enabling the use of this hydrogel as a versatile coating material for biomedical applications.Statement of SignificanceIn this study, we generated a tough hydrogel by crosslinking HEMA monomers in alginate hydrogels and forming a well-organized structure of hierarchical nested network (NN) which is rarely observed before. Different from most reported stretchable alginate-based hydrogels, the NN hydrogel showed higher compressive strength but retained comparable softness to alginate counterparts. This work further demonstrated the good integration of the tough hydrogel with silicone substrates through chemical modification and micropillar structures. Moreover, other functions such as low surface friction, biocompatibility, tunable cell adhesion abilities, and antibacterial properties could be achieved in the hydrogel, indicating great promise of the hydrogel as a versatile coating material for biomedical applications.

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