Synthesis of new type temperature and pH sensitive hydrogels using drug-based p-(methacryloyloxy)acetanilide monomer and their usage as controlled drug carrier material

Abstract

In our study, as a functional monomer, p-(methacryloyloxy)acetanilide (MOAA) was synthesized and utility in hydrogel systems with various commercial monomers after the structural characterization was analyzed. In terms of temperature sensitivity and suitability for use in biological applications, N-isopropyl acrylamide (NIPAm) monomer and pH-sensitive acrylic acid (AAc) monomer were chosen among the commercial monomers. To the best of our knowledge, p(N-isopropyl acrylamide-co-p-(p-methacryloyloxy)acetanilide) (GEL 5) and p(N-isopropyl acrylamide-co-acrylic acid-co-p-(p-methacryloyloxy)acetanilide) (GEL 8) were synthesized in the form of a film with the free radical polymerization technique for first time in the literature. The structural characterizations and surface morphologies of the hydrogels p(NIPAm) (GEL 1), p(NIPAm-co-MOAA) (GEL 5), and p(NIPAm-co-AAc-co-MOAA) (GEL 8) were investigated by using the techniques of FTIR spectroscopy and scanning electron microscope (SEM). Moreover, the thermal resistance of all three hydrogels was brightened by the thermal gravimetric analysis (TGA). Swelling behaviors in different environments of the MOAA-based hydrogels, prepared as pH and temperature-sensitive, were examined, and biomedical applications are occurred by the investigation of the usability as a controlled drug delivery material. For this purpose, sodium diclofenac (NaDc) drug, used in pain and inflammation treatment, was chosen. In vitro release of NaDc from the drug-loaded hydrogel was examined in pH 5.5 (PBS) and pH 7.4 (PBS) media. Korsmeyer-Peppas model was used in defining the drug release mechanism.

Graphical Abstract

Keywords:

• N-isopropyl acrylamide
• acrylic acid
• pH-sensitive
• temperature sensitive
• hydrogel
• controlled release

Acknowledgements

This study is derived from a part of Zeynep Güngör's PhD thesis. Zeynep Güngör is thankful to the Turkish Higher Education Council (YÖK)'s 100/2000 PhD fellowship program for supporting.