title: Preparation and theophylline delivery applications of novel PMAA/MWCNT-COOH nanohybrid hydrogels.
abstract: A series of nanohybrid hydrogels was designed and developed based on a hydrogen bond self-assembly of poly(methacrylic acid) (PMAA) networks and carboxyl-functionalized multi-walled carbon nanotubes (MWCNT-COOH). The nanohybrid hydrogels show low micropore densities and large mesh sizes with an increase in MWCNT-COOH content. Particularly, the hydrogels containing 10 wt% MWCNT-COOH was observed to collapse at pore walls because of large holes, which is believed to be responsible for high swelling. The ability of the MWCNT-COOH to self-associate with PMAA or water molecules via hydrogen-bonding interactions and an additional electrostatic repulsion govern both pH response of the network and drug release. Increasing pH values causes equilibrium swelling ratios and accumulative release to be elevated. On the other hand, modified mechanical behavior can be obtained under a low content of the MWCNT-COOH in that the high MWCNT-COOH filling effects the formation of PMAA gel networks. Swelling and controlled release profiles of theophylline could be modulated by changing pH values, introducing the MWCNT-COOH and adjusting the proportions of the MWCNT-COOH component.
authors.affiliation: Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an 710062, P R China.
authors.forename: Chang-Hu
authors.initials: CH
authors.lastname: Zhang
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: Luo
authors.forename: Ya-Shao
authors.initials: YS
authors.lastname: Chen
authors.forename: Qing-Bo
authors.initials: QB
authors.lastname: Wei
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Fan
mesh_terms: D002021:Buffers; D002264:Carboxylic Acids / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D004337:Drug Carriers / Q000138:chemical synthesis / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D019563:Mechanics; D053761:Nanocomposites / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry*; D016062:Porosity; D017550:Spectroscopy, Fourier Transform Infrared; D013806:Theophylline / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D002021:Buffers; D002264:Carboxylic Acids; D003432:Cross-Linking Reagents; D004337:Drug Carriers; D020100:Hydrogels; D037742:Nanotubes, Carbon; D010710:Phosphates; D011109:Polymethacrylic Acids; D014867:Water; C030613:polymethacrylic acid; D013806:Theophylline