Synthesis and characterization of Poloxamer 188-grafted heparin copolymer.

Background: Poloxamer 188 is a safe biocompatible polymer that can be used in protein drug delivery system. Aim: In this study, a new heparin-poloxamer 188 conjugate (HP) was synthesized and its physicochemical properties were investigated. HP structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and Hydrogen-1 nuclear magnetic resonance spectroscopy (H-1-NMR). Content of the conjugated heparin was analyzed using Toluidine Blue. The critical micelle concentration (CMC) of the copolymer was determined by a fluorescence probe technique. The effect of HP on the gelation of poloxamer 188 was characterized by the rheological properties of the HP-poloxamer hydrogels. Solubility and viscosity of HP were also evaluated compared with poloxamer 188. Results: From the results, the solubility of the conjugated heparin was increased compared with free heparin. The content of heparin in HP copolymer was 62.9%. The CMC of HP and poloxamer 188 were 0.483 and 0.743 mg/mL, respectively. The gelation temperature of 0.4 g/mL HP was 43.5 degrees C, whereas that of the same concentration of poloxamer 188 was 37.3 degrees C. With HP content in poloxamer 188 solution increasing, a V-shape change of gelation temperature was observed. Conclusion: Considering the importance of poloxamer 188 in functional material, HP may prove to be a facile temperature-sensitive material for protein drug-targeted therapy.