Liquid Prepolymer-Based in Situ Formation of Degradable Poly(ethylene glycol)-Linked-Poly(caprolactone)-Linked-Poly(2-dimethylaminoethyl)methacrylate Amphiphilic Conetwork Gels Showing Polarity Driven Gelation and Bioadhesion.

Amphiphilic conetwork (APCN) gels suffer from lack of direct injectability due to use of organic solvent, prolonged crosslinking/polymerization process and immiscibility between hydrophilic and hydrophobic prepolymers. On the basis of prepolymers compatibility and polarity, we report the use of an advanced prepolymer liquid system for in situ construction of APCN gels. Solid elastic poly(ethylene glycol)-linked-poly(ε-caprolactone)-linked-poly(2-dimethylaminoethyl)methacrylate (PEG-l-PCL-l-PDMA) APCN gels were formed upon addition of an appropriate amount of PDMA diluted in nonreactive sacrificial liquid PEG into a compatible blend of activated halide terminated PEG and PCL liquids. Compatibility among the prepolymers allowed favorable gelation. The polarity of the prepolymer liquid greatly influenced the gelation time. PEG-l-PCL-l-PDMA APCN gels were cytocompatible/biodegradable and showed storage modulus in the range of 50-200 kPa and bioadhesive strength of 40-90 kPa. The fluorescence experiments showed that the hydrophobic probe, pyrene was distributed in both hydrophilic and hydrophobic phases of the APCN gels. These APCNs exhibited sustained release of hydrophobic and hydrophilic drugs. Effects of polarity, composition, and molecular weight of the liquid prepolymers on the gelation time, rheological property, and swelling behavior of the APCN gels have been investigated in details.