A novel thermosensitive polypeptide hydrogel with encapsulated growth factors for biomedical applications

Abstract

Event Abstract Back to Event A novel thermosensitive polypeptide hydrogel with encapsulated growth factors for biomedical applications Ji-Yu Lin1, Po-Liang Lai2, Li-Yu Lee1, Yuan-Kai Lin1 and I-Ming Chu1 1 National Tsing Hua University, Chemical Engineering, Taiwan 2 Chang Gung Memorial Hospital, Orthopaedic Surgery, Taiwan Abstract: As a new application of a thermosensitive hydrogel for biomedical applications, Poly-peptide hydrogel, Poloxamer (PLX)-b-poly (L-alanine-lysine) (Lys-Ala-PLX-Ala-Lys) aqueous solution that undergoes sol-gel transition as the temperature increases. We designed a positive charged polymer could encapsulate growth factor, drug, cell etc… We observed at low concentration as 3.0 -7.0 wt% has the sol-gel transition behavior. Through the Circular Dichroism, could realize conformation changes from the peptide as temperature increase. Using TEM observed micelles aggregation and SEM to characterize its polymer morphology. The results show that we have successfully synthesized a thermosensitive polymer having a positive charged, it demonstrates a high potential as an injectable material for tissue engineering. Experimental: Poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol)bis(2-aminopropyl ether) (PLX, M n =900) (4.00 g) was dissolved in 20 mL of toluene, and residual water was removed by azeotropic distillation to a final volume of approximately 5 mL. Anhydrous chloroform/N, N-dimethylformamide (2/1 v/v, 32 mL) was added under reflux in a nitrogen atmosphere. NCA-Lys (3.26 g), and NCA-Ala (4.198 g) were added to the reaction system and stirred at 40°C for 24 h in a dry nitrogen atmosphere. The product was precipitated in cooled diethyl ether (500 mL) and dried under vacuum to yield Lys-Ala-PLX-Ala-Lys. Result: Fig : (1) Phase diagram of the Lys-Ala-PLX-Ala-Lys aqueous solutions determined by the test tube inverting method. Photos are Lys-Ala-PLX-Ala-Lys aqueous solutions (3.0 wt %- 7.0wt %) at gel state. (2) Increases in storage modulus (G′) and loss modulus (G′′) of the PAL-PLX-PAL aqueous solutions (4.0 wt%) during the sol-to-gel transition. Conclusion: The present study reports a new biocompatible thermosensitive hydrogel system prepared by incorporating an oligopeptide block into the conventional poloxamer amphiphilic block copolymer. The sol−gel transition as mediated by the secondary-structure unit of the oligopeptide block tailored via the functional group has been investigated. This research was financially supported by a grant from Ministry of Science and Technology and Chang Gung Memorial Hospital. We gratefully acknowledge Prof. Po-Liang Lai for their kind technical assistance with in vitro experiments