4-Aminopyridine containing metal-2,6-pyridine dicarboxylates and complex embedded hydrogels: Synthesis, characterization and antimicrobial applications

Abstract

Hydrogels containing metal complexes with bioactive ligands have recently attracted great interest in biological applications due to good biocompatibility, water absorption, self-healing, and controlled release of drugs as well as structural diversity. Herein, to investigate the potential biological applicability of metal complex embedded hydrogels, three complexes including 2,6-pyridine dicarboxylic acid (dipicH2) and 4-aminopyridine (4-apy) were synthesized: (4-apyH)2[Mn(dipic)2]·3H2O (1), (4-apyH)2[Cu(dipic)2]·5H2O (2), (4-apyH)2[Zn(dipic)2]·3H2O (3). The complexes were characterized by X-ray single-crystal diffraction, elemental analysis, FT-IR, and thermogravimetric analysis (TGA). The complex embedded hydrogels (Mn-complex 1 hydrogel, Cu-complex 2 hydrogel, and Zn-complex 3 hydrogel) based on 2-hydroxyethyl methacrylate (HEMA) were prepared and characterized by FT-IR, thermogravimetric analysis (TGA) and Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX). The prepared metal complexes and metal complex embedded hydrogels were tested for their antimicrobial activity against three fungal species Aspergillus brasiliensis, Saccharomyces cerevisiae, Candida albicans, and two bacteria strains a Gram-negative Escherichia coli, a Gram-positive Bacillus cereus by the in vitro agar diffusion method. The antimicrobial tests indicated that all metal complex embedded hydrogels exhibit antimicrobial activity against all tested strains better than that of the control hydrogel.