title: Wound pH-responsive sustained release of therapeutics from a poly(NIPAAm-co-AAc) hydrogel.
abstract: Wound pH strongly influences residence time and activity of various growth factors during wound healing. Hence, a pH-responsive sustained release growth factor delivery system could be beneficial for effective treatment of wound. In this context, an effort was made to evaluate the potential  of a poly(N-isopropylacrylamide-co-acrylic acid) hydrogel as pH-sensitive sustained release system for wound-pH-dependent therapeutics delivery. The polymer was synthesized via radical copolymerization and influence of pH on lower critical solution temperature (LCST), microarchitechture  and swelling of the hydrogel was evaluated. Results showed a pH-dependent variation in the physical properties of the hydrogel within the wound pH range. Fluorescence recovery after photobleaching (FRAP) analysis endorsed a pH dependent restricted diffusion of the BSA in the hydrogel. Later,  release of bovine serum albumin (BSA), vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) (each 5%, w/v) from the hydrogel within the range of wound pH (pH 6.7-7.9) were examined. Analysis showed non-Fickian release of therapeutics from the hydrogel with a significant  variation in release rate and cumulative release with the increase in pH. Retention of the bioactivity of the released EGF was confirmed by studying murine dermal fibroblast cell proliferation in vitro. Finally, a growth factor (EGF or VEGF)-loaded hydrogel was applied on a murine excisional  wound model and showed augmentation of wound healing in comparison to conventional sustained release growth factor therapy.
authors: Department of Biotechnology, Indian Institute of Technology Kharagpur, India.
authors: Indranil
authors: I
authors: Banerjee
authors: Debasish
authors: D
authors: Mishra
authors: Tamal
authors: T
authors: Das
authors: Tapas K
authors: TK
authors: Maiti
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000818:Animals; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D004337:Drug Carriers / Q000737:chemistry*; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008863:Microspheres; D055585:Physical Phenomena; D011108:Polymers / Q000737:chemistry*; D011506:Proteins / Q000378:metabolism* / Q000494:pharmacology*; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D000178:Acrylamides; D004337:Drug Carriers; D020100:Hydrogels; C090629:N-isopropylacrylamide-acrylic acid copolymer; D011108:Polymers; D011506:Proteins