Synthesis and Characterization of Poly (VCL-HEA-IA) Terpolymer for Drug Release Applications

In the present work, poly(VCL-HEA-IA) terpolymeric hydrogels were synthesized by free radical polymerization of N-vinylcaprolactam (VCL), 2-hydroxethyl acrylate (HEA), and itaconic acid (IA) monomers using N,N'-methylene bisacrylamide (NMBA) as crosslinker and 2,2'-azobis (2-methylpropanimidamide) dihydrochloride (AMPA) as initiator. The swelling properties of these hydrogels were investigated at different pH and temperatures. Drug loading and release properties were also determined using Rhodamine B (RhB) as a model drug by UV-vis spectrophotometer at 554 nm. Drug loading capacities of hydrogels increased with increasing the ratio of hydrophilic monomer in hydrogel structure. Ionized hydrophilic groups of IA and HEA monomers increase the probability of interaction between the hydrophilic groups and the model drug in the phosphate buffer solution. To investigate the effect of different pH values on drug release, it was studied at pH 2.1, pH 5.5 and pH 7.2 in the buffer solutions at 37 degrees C. The model drug was released in proportion to 50% within the first 8 h at different pH values. At pH 7.2, the model drug was more quickly released due to the ionization of hydrophilic groups of IA and HEA. In addition, the surface morphology of drug loaded hydrogels was examined by scanning electron microscopy (SEM) which revealed uniform distribution of the drug in the hydrogel structure. It is concluded that, model drug loading capacity and release amount changed with composition of hydrogels. Maximum drug release and loading capacities were observed for hydrogel which contain the highest amount of HEA and IA monomers. Poly(VCL-HEA-IA)terpolymeric hydrogels are suitable for drug delivery applications.