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.
Brahim
Sean
S
Department of Chemical Engineering, Virginia Commonwealth University, P.O. Box 843038, 601 West Main Street, Richmond, Virginia 23284-3038, USA.
Narinesingh
Dyer
D
Guiseppi-Elie
Anthony
A
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