Thermo-tunable Injectable Thermosensitive Hydrogel and its Application as Protein Carriers

Abstract

It is known that polymer chemistries determine mechanical and physical properties of hydrogels and thus its drug delivery performance. In order to achieve desired drug release behavior, triblock copolyester PCT-PEG-PCT with proper hydrogel formulation has to be synthesized. This research has demonstrated a way to adjust hydrogel mechanical and gelation properties by simply physically mixing amphiphilic copolymers with different composition to achieve desired protein carriers. Tri-block copolymer poly (CL-co-TOSUO)-PEG-poly (CL-co-TOSUO), briefed as (PCT-PEG-PCT) with different composition have been successfully synthesized. These copolymers are thermosensitive and can form hydrogels in aqueous solution. Copolymers with higher percentage hydrophobic PCT blocks show higher mechanical stiffness and yet lower solubility. To reduce the crystallinity of the hydrophobic block and soften the hydrogel, the copolymer with long PCT blocks was physically mixed with ones with shorter PCT blocks. The polymer mixture demonstrated a moderated mechanical stiffness and desired solubility. The polymer mixture also achieved a gelation temperature at 37°C, which is desirable for drug delivery. Macromolecular drug, bovine serum albumin (BSA) was used as model drug for its release study. This protein drug was successfully loaded into the polymer mixture, and the drug release study shows the polymer mixture is able to extend a stable drug release for over 48 hours. This result confirms physical mixing of PCT-PET-PCT thermosensitive copolymers can tune gel properties and improve drug delivery performance without redesigning and synthesizing new polymers.