title: Role of Thermo-responsiveness and Poly(ethylene glycol) Diacrylate Cross-link Density on Protein Release from Poly(N-isopropylacrylamide) Hydrogels.
abstract: Thermo-responsive hydrogels have shown promise as injectable materials for local drug delivery. However, the phase-induced changes in polymer properties of N-isopropylacrylamide (NIPAAm) can pose additional challenges for achieving controlled protein release. In this work, thermo-responsive hydrogels derived from NIPAAm and cross-linked with poly(ethylene glycol) diacrylate (PEG-DA) were synthesized via free radical polymerization. The volume phase transition temperature (VPTT) of the hydrogels ranged from 32.9°C to 35.9°C. Below the VPTT, swelling ratios of the hydrogels decreased with cross-linker concentration, and showed a sharp drop (at least 4-fold) upon phase change. Protein encapsulation efficiency was high (84-90%) and decreased with cross-linker concentration. Release of bovine serum albumin, a model protein, at body temperature was significantly higher than at room temperature (67% at 37°C compared to 44% at 23°C after 48 h). The release kinetics of proteins from the hydrogels were initially expected to be a function of cross-link density. However, at the hydrogel compositions explored in this work, protein release did not change significantly with cross-linker mol fraction. The thermo-responsive hydrogels offer a promising platform for the localized delivery of proteins.
authors.affiliation: a Department of Chemical and Biological Engineering, Illinois Institute of Technology, 10 W. 33rd Street, Chicago, IL 60616-3793, USA.
authors.forename: Pawel W
authors.initials: PW
authors.lastname: Drapala
authors.forename: Eric M
authors.initials: EM
authors.lastname: Brey
authors.forename: William F
authors.initials: WF
authors.lastname: Mieler
authors.forename: David C
authors.initials: DC
authors.lastname: Venerus
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Kang Derwent
authors.forename: Victor H
authors.initials: VH
authors.lastname: Pérez-Luna
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D002417:Cattle; D004337:Drug Carriers / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry; D007074:Immunoglobulin G / Q000008:administration & dosage; D007700:Kinetics; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D012710:Serum Albumin, Bovine / Q000008:administration & dosage; D013696:Temperature; D044366:Transition Temperature
chemical_list: D000180:Acrylic Resins; D004337:Drug Carriers; D005609:Free Radicals; D020100:Hydrogels; D007074:Immunoglobulin G; C437167:poly(ethylene glycol)diacrylate; C052970:poly-N-isopropylacrylamide; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols