RESUMEN
BACKGROUND: Recently biodegradable hydrogel has been extensively used to delivery anticancer drug and bioactive macromolecule. However, to protect the activity of the bioactive macromolecule, we need to obtain series of hydrogel which have milder hydrogelation conditions and shorter hydroglation time.OBJECTIVE: To prepare enantiomeric poly(L-Lactic acid) (PLLA)-poly(ethylene glycol (PEG)-PLLA/ poly(D-Lactic acid) (PDLA)-PEG-PDLA stereocomplex hydrogel which has shorter hydroglation time, to physically encapsulate a model drug-lysozyme and sustained release it from the hydrogel. METHODS: Triblock copolymers of PLLA-PEG-PLLA and PDLA-PEG-PDLA were synthesized by ring-opening polymerization of L(D)-lactide using PEG as the initiator and Sn(Oct)2 as the catalyst. The triblock copolymers were characterized by 1H nuclear magnetic resonance, FT-IR and X-Ray diffractometry. A hydrogel was prepared from an aqueous mixture of PLLA20-PEG227-PLLA20 and PDLA21-PEG227-PDLA21 (10 wt% concentration) at room temperature for 12 hours. X-Ray diffractometry test was used to research the gelation mechanism. The release profile of the lysozyme as a model drug from the hydrogel was tested. The morphology of the freeze-dried hydrogel was investigated by scanning electron microscope. The cytotoxicity of the hydrogel was evaluated by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide) assay.RESULTS AND CONCLUSION: Triblock copolymers of PLLA-PEG-PLLA and PDLA-PEG-PDLA were obtained. Both the PEG and PLA blocks in the copolymers could crystallize, but the crystallization of the PEG block was predominant. The stereocomplex formation between the PLLA and PDLA blocks within the hydrogel was confirmed by the X-Ray diffractometry analysis. The release profile of the lysozyme from the hydrogel exhibited a sustained-release pattern with a duration period of 7 days. The hydrogel exhibited a 3D interconnected porous structure with 50-100 μm pore size after being freeze-dried. The mouse fibroblast cell viability percentage was 99.3% after the cells contacted with the 100% extracted liquid for 72 hours.