Synthesis of poly(acrylamide-co-methyl methacrylate-co-vinyl amine-co-acrylic acid) hydrogels by Hoffman degradation and their interactions with acetaminophen

Abstract

ABSTRACT:A modified poly(acrylamide-co-methyl methacrylate-co-vinyl amine-co-acrylic acid) [poly(AAm-co-MMA-co-VAm-co-AAc)] hydrogel was prepared by the Hofmann degradation of poly(acrylamide-co-methyl methacrylate) [poly(AAm-co-MMA)] copolymer. The hydrogel was characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and swelling studies. Matrices of this hydrogel with acetaminophen were prepared for application in controlled release. The physical state of the drug (acetaminophen) and its interaction with the modified polymeric hydrogel were examined in hydrogel-acetaminophen matrices with DSC. The acetaminophen in the matrices (with more than 10% drug) exhibited distinct melting endotherms because of their crystalline state. The peak temperature of these endotherms was lowered and the peaks were broadened as the concentration of acetaminophen decreased. The melting enthalpy of acetaminophen in various matrices when plotted as a function of acetaminophen concentration yielded a straight line with an intercept of 142 mg/g of matrix, which was the solubility of acetaminophen in the hydrogel at its melting temperature. FTIR spectroscopy investigations confirmed that hydrogen bonding occurred between the modified polymeric hydrogel and acetaminophen. Scanning electron microscopy studies revealed the presence of acetaminophen drug crystals of various shapes, sizes, and roughness on the surface, depending on acetaminophen loading. The controlled release of acetaminophen was tested in vitro; 67.10 and 37.2% cumulative releases were obtained for the poly(AAm-co-MMA) and poly(AAm-co-MMA-coVAm-co-AAc) hydrogel matrices, respectively. The acetaminophen release percentage for the modified hydrogel was low because of secondary interactions with acetaminophen.

A library of tunable agarose carbomer‐based hydrogels for tissue engineering applications: The role of cross‐linkers

“…The hydrogel samples were first immersed in PBS for about 24 h, then freeze‐dried, weighed ( W d ), and poured in excess PBS to achieve complete swelling at 37°C in 5% CO 2 atmosphere 30. The swelling kinetics was measured gravimetrically.…”

Characterization and Degradation Behavior of Agar–Carbomer Based Hydrogels for Drug Delivery Applications: Solute Effect

“…The hydrogel samples were first immersed in PBS for about 24 h, then freeze-dried, weighted ( W d ) and poured in excess solvent at pH = 0.5, 7.4 and 14 to achieve complete swelling at 37 °C in 5% CO 2 atmosphere; such conditions were applied since they are typical of in vitro experiments [ 21 , 36 ]. The swelling kinetics was measured gravimetrically.…”

“…The samples were removed from the solvent at regular times. Then, hydrogel surfaces were wiped with moistened filter paper in order to remove the excess of solvent and then weighed ( W t ) [ 36 , 37 ]. Swelling ratio is defined as follows:…”

Improved crystallizability and processability of ultra high molecular weight polyethylene modified by poly(amido amine) dendrimers

“…d), the band at 1717.1 cm −1 was much stronger in the spectrum of skin layer than that of the core layer; it is attributed to the stretching vibration of the carboxyl group. It was caused by a typical Hoffman degradation reaction of the CTAB occurring to some extent partially in the mixing process, as shown in Scheme . Moreover, there was no characteristic peak of carboxyl groups observed in the core layer (Fig.…”