Regen Biomater 2015 Sep 20;2(3):177-85. Epub 2015 Aug 20.
Department of Bioengineering and the McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA;; Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15260, USA;; Department of Chemical and Petroleum Engineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA 15261, USA;; Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261, USA;; Clinical Translational Science Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA and; The McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
Injectable thermal gels are a useful tool for drug delivery and tissue engineering. However, most thermal gels do not solidify rapidly at body temperature (37°C). We addressed this by synthesizing a thermo-sensitive, rapidly biodegrading hydrogel. Our hydrogel, poly(ethylene glycol)-co-poly(propanol serinate hexamethylene urethane) (EPSHU), is an ABA block copolymer comprising A, methoxy poly ethylene glycol group and B, poly (propanol L-serinate hexamethylene urethane). EPSHU was characterized by gel permeation chromatography for molecular weight and (1)H NMR and Fourier transformed infrared for structure. Rheological studies measured the phase transition temperature. In vitro degradation in cholesterol esterase and in Dulbecco's phosphate buffered saline (DPBS) was tracked using the average molecular weight measured by gel permeation chromatography. LIVE/DEAD and resazurin reduction assays performed on NIH 3T3 fibroblasts exposed to EPSHU extracts demonstrated no cytotoxicity. Subcutaneous implantation into BALB/cJ mice indicated good biocompatibility in vivo. The biodegradability and biocompatibility of EPSHU together make it a promising candidate for drug delivery applications that demand carrier gel degradation within months.