Article ID Journal Published Year Pages File Type
1423755 Journal of Controlled Release 2015 10 Pages PDF
Abstract

In this study, we investigated the mineralization capacity and biocompatibility of injectable, dual-gelling hydrogels in a rat cranial defect as a function of hydrogel hydrophobicity from either the copolymerization of a hydrolyzable lactone ring or the hydrogel polymer content. The hydrogel system comprised a poly(N-isopropylacrylamide)-based thermogelling macromer (TGM) and a polyamidoamine crosslinker. The thermogelling macromer was copolymerized with (TGM/DBA) or without (TGM) a dimethyl-γ-butyrolactone acrylate (DBA)-containing lactone ring that modulated the lower critical solution temperature and thus, the hydrogel hydrophobicity, over time. Three hydrogel groups were examined: (1) 15 wt.% TGM, (2) 15 wt.% TGM/DBA, and (3) 20 wt.% TGM/DBA. The hydrogels were implanted within an 8 mm critical size rat cranial defect for 4 and 12 weeks. Implants were harvested at each timepoint and analyzed for bone formation, hydrogel mineralization and tissue response using microcomputed tomography (microCT). Histology and fibrous capsule scoring showed a light inflammatory response at 4 weeks that was mitigated by 12 weeks for all groups. MicroCT scoring and bone volume quantification demonstrated a similar bone formation at 4 weeks that was significantly increased for the more hydrophobic hydrogel formulations – 15 wt.% TGM and 20 wt.% TGM/DBA – from 4 weeks to 12 weeks. A complementary in vitro acellular mineralization study revealed that the hydrogels exhibited calcium binding properties in the presence of serum-containing media, which was modulated by the hydrogel hydrophobicity. The tailored mineralization capacity of these injectable, dual-gelling hydrogels with hydrolysis-dependent hydrophobicity presents an exciting property for their use in bone tissue engineering applications.

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Related Topics
Physical Sciences and Engineering Materials Science Biomaterials
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