Synthesis, characterization and slow drug delivery of hydrogels based in N-acryloyl-tris-(hydroxymethyl) aminomethane and N-isopropyl acrylamide

Abstract

In this study, new hydrogels in rod shape were prepared from N-isopropyl acrylamide (NIPA), N-acryloyl-tris-(hydroxymethyl) aminomethane (NAT) and N,N´-methylenebisacrylamide (BIS). The effect of the incorporation of NAT into poly(N-isopropyl acrylamide) (PNIPA) structures for which the monomer composition was varied from NIPA 100% to NAT 100% was explored. The rheological studies were used to test their viscoelastic properties. Swelling experiments were used to test the capacity of water absorption, the modification of the network parameters, the swelling kinetics, the temperature and pH swelling response and n (number that determines the type of diffusion of water). NAT-containing hydrogels showed values of n between 0.5 and 1, therefore the diffusion of water into the hydrogels was found to have a non-Fickian character. The elastic moduli and the equilibrium water content (EWC) measurements suggest that these materials may have a potential application as biomaterials. The structure of shrunken NIPA 100 at high temperature that maintains the drug and hinders the release was controlled by the introduction of NAT into the network, to allow a slow drug release of ibuprofen at 37 ºC and pH 7.4.