title: Rapid and precise release from nano-tracted poly(N-isopropylacrylamide) hydrogels containing linear poly(acrylic acid).
abstract: We investigated the rapid and precise molecular release from hydrogels in response to dual stimuli. To achieve precise on/off drug release using thermoresponsive poly(N-isopropylacrylamide) hydrogels, we prepared nano-structured semi-IPNs, which consisted of thermosensitive PNIPAAm networks penetrated by pH-responsive poly(acrylic acid) (PAAc) linear chains and perforated to create nano-tracts as a molecular pathway. The present nano-tracted semi-IPNs show a rapid deswelling response to both temperature and pH. Model drug releases were investigated when simultaneous changes in temperature and pH were applied. We observed that the cationic drug was rapidly released and then abruptly discontinued from the nano-tracted semi-IPNs in response to the dual stimuli, and clear release and stopping cycles were repeatedly observed on successive steps. Moreover, the release rates and amount of drug released were controllable by the deswelling speed of the gels and the PAAc content inside the gels. This novel release system using the nano-tracted semi-IPNs may be useful for the high performance, pulsed release of molecules.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Taka-Aki
authors.initials: TA
authors.lastname: Asoh
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kaneko
authors.forename: Michiya
authors.initials: M
authors.lastname: Matsusaki
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Akashi
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000179:Acrylates / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D002412:Cations / Q000737:chemistry; D004337:Drug Carriers; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D015394:Molecular Structure; D053769:Nanocapsules / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000178:Acrylamides; D000179:Acrylates; D002412:Cations; D004337:Drug Carriers; D020100:Hydrogels; D053769:Nanocapsules; C067295:N-isopropylacrylamide; C036658:acrylic acid