Temperature-Responsive Graft Copolymer Hydrogels for Controlled Swelling and Drug Delivery

Abstract

Temperature-responsive graft copolymers of N-isopropylacrylamide and Jeffamine® M-1000 acrylamide were synthesized to provide controlled swelling without introducing degradable moieties or increasing the LCST above body temperature. Jeffamine® M-1000 caused a small LCST increase (0.24–0.27°C/wt%) and a broader sol-gel transition. Twenty wt% copolymer gels (M_w> 225 kDa) retained their initial volume after 42 days, while homopolymer gels shrank by more than 50%. Copolymer gels eluted <20% of ovalbumin over 6 days whereas homopolymer gels released >90% within 3 h. These results suggest that Jeffamine® M-1000 acrylamide is suitable for inclusion in N-isopropylacrylamide-based biomaterials to control swelling and drug release nearly independently of LCST.

Keywords:

• Drug delivery
• Graft copolymer
• N-isopropylacrylamide
• Swelling
• Temperature-responsive polymer

Acknowledgments

The authors acknowledge funding from the Arizona Biomedical Research Commission, Grant #0810, and a National Science Foundation GK-12 Down to Earth Science Graduate Fellowship (D.J.O.).