Synthesis and Hydration Properties of pH-Sensitive p(HEMA)-Based Hydrogels Containing 3-(Trimethoxysilyl)propyl Methacrylate

Abstract

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.

Microspheres Containing Cibacron Blue F3G-A and Incorporated Iron Oxide Nanoparticles as Biomarker Harvesting Platforms

“…The resultant pellets were blotted quickly with a soft tissue to remove any remaining surface droplets and weighed (recorded as wet weight). The degree of hydration of the particles, in terms of percentage of total mass of hydrated particles attributable to water, was calculated from the average masses of the particles dry (W dry ) and hydrated (W wet ) using Equation 1 below [15].…”

Polyplex Formation Influences Release Mechanism of Mono- and Di-Valent Ions from Phosphorylcholine Group Bearing Hydrogels

“…Highly hydratable cross-linked polymers, or hydrogels, have become a mainstay in biological and biomedical applications [1] due to their desirable properties engendered by controllable high degree of hydration [2,3], cell and tissue biocompatibility [4] and high potential for molecular engineering [5] relative to other materials. A canonical example of a hydrogel, poly(2-hydroxyethyl methacrylate) (pHEMA), was first used in contact lenses for its optical clarity, dimensional stability, mechanical properties and biologically benign nature [6].…”

“…The culmination of this early work, using pHEMA as the drug delivery polymer, was the combination of two explicitly derived drug release models which describe diffusion controlled (Fickian or Case I) and polymer relaxation controlled (Case II) release; Equations (1) and (2), respectively. In general, polymeric hydrogels that do not exhibit appreciable relaxation or for which the polymer segmental relaxation time is much smaller than the characteristic diffusion time for solvent transport, experimentally display standard Fickian diffusion.…”

“…In this case, solvent transport is controlled by a simple concentration gradient and water uptake by the polymeric hydrogel exhibits the characteristic t 1/2 dependence, with the resulting swelling also exhibiting t 1/2 dependence, Equation (1). When hydrogel segmental relaxation is the dominant mechanism involved in solvent transport, then a time-independent hydration is observed and the swelling will depend linearly on time t, Equation (2). Mathematically, these two release mechanisms have been shown to be a function of t 1/2 and t (zero order), for planar hydrogel geometries, which can be used to differentiate release mechanisms based on experimental observation.…”

2-(Dimethylamino)ethyl Methacrylate/(2-Hydroxyethyl) Methacrylate/α-Tricalcium Phosphate Cryogels for Bone Repair, Preparation and Evaluation of the Biological Response of Human Trabecular Bone-Derived Cells and Mesenchymal Stem Cells

“…Poly(dimethyl aminoethyl methacrylate) (PDMAEMA) is a polymer that possess pH sensitivity [13], widely used for gene transfection [14,15]. PDMAEMA can be easily synthesized by radical polymerization and is therefore relatively simple to be modified by copolymerization.…”