Partitioning of coomassie brilliant blue into DMAEMA containing poly(HEMA)-based hydrogels

Abstract

a b s t r a c tThe loading and release of anti-inflammatory drugs from hydrogel-coated implantable devices is a demonstrated approach in mitigating the inflammatory response of implantable devices. Poly(2-hydroxyethyl methacrylate)-based hydrogels possessing ionizable 2-(dimethylamino)ethyl methacrylate (DMAEMA) and cross-linked with varying concentrations (1, 3, 5, 7, 9 and 12 mol%) tetra(ethylene glycol) diacrylate (TEGDA) were synthesized and studied for their degree of hydration, glass transition temperature and partitioning of zwitterionic Coomassie Brilliant Blue (CBB), a zwitterionic drug surrogate known to bind to amines. Using UV-Vis spectroscopy, the partition coefficient of CBB within the hydrogels was found to average 6.69 ± 0.12 but to rise monotonically from 6.54 (1 mol%) to 6.84 (12 mol%) as a function of TEGDA mol% or cross-link density in accord with a monotonic reduction of the degree of hydration. The absence of DMAEMA was found to reduce the partition coefficient of CBB from 6.5 to 4.1. Both formulations, with and without DMAEMA (pK a = 7.5), showed an independence of pH over the physiologically relevant range, pH 5-pH 9, confirming that this difference was not due to Henderson-Hasselbalch ionization of the pendant group. The presence of DMAEMA resulted in a 1.44 fold increase in CBB loading confirming complex formation. The absence of DMAEMA still resulted in considerable partitioning of CBB into the hydrogel suggesting that the affinity between CBB and DMAEMA may not be the only relationship controlling the partition coefficient.

Biotechnical Properties of Poly(HEMA-co-HPMA) Hydrogels Are Governed by Distribution among Water States

“…The degree of hydration (DoH) of the hydrogels was determined using gravimetric analysis, as previously described with more details in the Supporting Information. 42 Briefly, hydrogel disks were weighed following equilibrium hydration (M HG ) in HEPES buffer and then weighed again once they were completely dehydrated following lyophilization (M DG ). Dehydration was accomplished by freezing hydrogels at −80 °C overnight followed by a 48 h lyophilization under 0.01 mbar at −50 °C using a FreeZone 2.5 (Labcono).…”

Dataset on hydrophobicity indices and differential scanning calorimetry thermograms for poly(HEMA)-based hydrogels

“…Partition coefficient (unit less), P = [X] organic /[X] aqueous , is the ratio of molar concentrations (mol/L) in contacting phases [4] , generally an organic phase vs the aqueous phase (page 1112, Sangster) [2] . When log P > 0, P > 1; [X] org > [X] aq and when log P < 0, P < 1; [X] org < [X] aq.…”

Impedance characterization of biocompatible hydrogel suitable for biomimetic lipid membrane applications

“…Considering this result and the impedimetric behavior of the differently cross-linked covalently tethered hydrogels, as presented above, it is clear that although the varying cross-linking ratio does not significantly change the swelling capacity, it drastically influences mass transfer, active electrode area, and electrode performance due to changes in the micro-and nanoenvironment at the electrode-hydrogel interface. Further studies on the state of bound water in hydrated hydrogels using, for instance differential scanning calorimetry [33,50], may provide possibility for more detailed correlation with EIS characterization.…”