N-vinylcaprolactam-based temperature and pH-sensitive graft hydrogels for controlled drug release of 5-FU: a comprehensive study on synthesis, characterization, and release kinetics

Stimuli-responsive polymers can be used for various purposes due to their amazing properties within the context of controlled release systems. In this study, the aim was to prepare hydrogels that are stimulus-responsive to temperature and pH and utilize them in drug release investigations. N-Vinyl caprolactam-based polymers were synthesized and optimized based on the swelling ratio data. Both temperature and pH sensitivity, along with their respective transition values, were determined. The best sample was selected based on 5-FU encapsulation efficiency. To enhance the swelling ratio and encapsulation values, different amounts of poly-(ethylene glycol) were added to improve water swelling ratio and 5-FU release properties. All obtained samples were characterized using water swelling ratio, SEM, FTIR, and DSC analyses. Additionally, the encapsulation and release of the 5-FU drug from the hydrogels were studied. According to the results, it was understood that it could release the 5-FU drug approximately 14% when below the transition temperature and pH value, and approximately 99% when above the transition temperature and pH value. The kinetics of the drug release were thoroughly examined. The results of thekinetic study revealed a drug release pattern consistent with Fick's law.

Graphical abstract

Synthesis and drug release route for the study