Prolonged zero‐order BSA release from pH‐sensitive hydrogels of poly(AAc‐co‐DMAPMA) having rich nano through micro scale morphology

Abstract

AbstractNew variety of pH‐sensitive hydrogels, having macroporous interior with honey‐comb type architecture and continuous skin at the surface, have been developed by single step aqueous copolymerization of acrylic acid (AAc) and N‐[3‐(dimethylamino)propyl]‐methacrylamide (DMAPMA) in different feed ratios at 41 ± 1°C. Interlocked nanogels of ∼ 300 nm were identified as the building blocks in all of these cylindrical poly(AAc‐co‐DMAPMA) matrices (PDMAAc). The gels showed good compressive strength even at a swelling as high as 4330% (mass) at pH 7.0. Morphology of McCoy fibroblast cell line remained unchanged in direct contact with different PDMAAc gels, and cell viability (±SD) was recorded to be in the range of 105 (±3)% to 87 (±8)% after 72 h. Bovine serum albumin (BSA) loaded gels were prepared by means of equilibrium partitioning. Loading efficiency of PDMAAc gels has been found to be in the range of 210–277 mg/g dry gel. BSA release from PDMAAc gels at 37°C has been found to follow non‐Fickian diffusion mechanism in simulated gastric juice (pH 1.2), and Case II transport in simulated intestinal juice (pH 7.4). In vitro study showed that the gels are capable of retaining >95% of the loaded BSA in gastric medium through average gastric emptying period. Again, ∼ 56% BSA release was recorded in 24 h at pH 7.4, indicating prolonged BSA diffusion in intestinal condition. Constant rate of BSA diffusion was reflected from the release profiles at both the pH. Diffusion exponents also supported the same and indicated for absolute zero‐order kinetics at pH 7.4. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010