Synthesis and hydration properties of pH-sensitive p(HEMA)-based hydrogels containing 3-(trimethoxysilyl)propyl methacrylate.
An amphiphilic hydrogel network was synthesized from a cross-linked poly(2-hydroxyethyl methacrylate) backbone copolymerized with the monomers 3-(trimethoxysilyl)propyl methacrylate (PMA) and dimethylaminoethyl methacrylate (DMAEMA) using tetraethylene glycol diacrylate (TEGDA) as cross-linker and using the radical initiator system comprising N,N,N',N'-tetramethylethylenediamine and ammonium peroxydisulfate. The degree of hydration of hydrogel slabs was investigated as functions of varying monomer compositions and cross-link density and as a function of pH and ionic strength of the bathing medium. As much as a 45% increase in hydration was observed for hydrogels containing 15 mol % DMAEMA upon reducing the pH of the bathing medium from 8.0 to 2.0. This confirms the pH-modulated swelling of amine-containing hydrogels. Increasing the concentration of TEGDA cross-linker from 3 to 12 mol % in a 10 mol % DMAEMA-containing hydrogel resulted in only a 10% reduction in the degree of hydration of the gel. There was, however, a 40-50% reduction in the degree of hydration of a 15 mol % DMAEMA hydrogel upon increasing the molar composition of PMA from 0 up to 20 mol %. The presence of PMA confers hydrophobic character that reduces hydration and introduces additional cross-links that reduce network mesh size. The water content of the hydrogel was consistently higher in buffers of lower ionic strength. The reversible pH-dependent swelling observed in these studies, along with the control of cross-link density afforded by the PMA component, endows these biocompatible materials with potential for use in pH-controlled drug delivery of more hydrophobic drugs and present new compositions for in vitro and in vivo biocompatibility studies.
Department of Chemical Engineering, Virginia Commonwealth University, P.O. Box 843038, 601 West Main Street, Richmond, Virginia 23284-3038, USA.
Sean
S
Brahim
Dyer
D
Narinesingh
Anthony
A
Guiseppi-Elie
D000179:Acrylates / Q000138:chemical synthesis / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008689:Methacrylates / Q000138:chemical synthesis* / Q000737:chemistry; D011102:Polyhydroxyethyl Methacrylate / Q000138:chemical synthesis* / Q000737:chemistry; D017655:Silicon Compounds / Q000138:chemical synthesis* / Q000737:chemistry
D000179:Acrylates; D008689:Methacrylates; D017655:Silicon Compounds; D011102:Polyhydroxyethyl Methacrylate; C032704:tetraethylene glycol diacrylate; C049840:2-(dimethylamino)ethyl methacrylate