Itaconic and citraconic acid directed thixotropic and self-healable supramolecular metallogels of M(ii) (M = Co, Cu, Zn, and Cd) for the growth-inhibitory potency against human pathogenic microbes

Abstract

The present work explores the biological significances of two isomeric type organic constituents including itaconic acid (IA) and citraconic acid (CA) directed supramolecular metallogels of cobalt(II), copper(II), Zinc(II), and cadmium(II). The critical distinction between these two isomers has been analyzed by the metallogel-formation strategy. These metallogels of Co(II), Cu(II), Zn(II), and Cd(II) with itaconic and citraconic acid show fascinating thixotropic features found through rheological measurements. Specially, the metallogel of Cd(II) with citraconic acid is really esteemed due to its effective self-healing property. Morphological distinctions obtained from field emission scanning electron microscopy (FESEM) analyses of the metallogels are also found in this study. The energy-dispersive X-ray spectroscopy (EDS) based investigations also support the role of diverse metal ions for the stabilization of individual metallogel systems. A few selective human pathogenic microbes, including four bacterial pathogens viz. Escherichia coli (MTCC 1667), Bacillus subtilis (MTCC 121), Listeria monocytogenes (MTCC 657), Salmonella typhimurium (MTCC 98), and two fungal pathogens Candida albicans (MTCC 183) and Aspergillus flavus (MTCC 2799) are utilized for evaluating the bio-functionality of the metallogels. The exhaustive biological studies show that the metallogels are very much potent against remarkable human pathogens. More significantly, the FESEM morphological patterns of some selective pathogens, involving a Gram −ve bacterium E. coli, a Gram +ve bacterium B. subtilis, and a mycelial fungus A. flavus, have been visualized after the preliminary treatment with the metallogels, and the microstructural textures also support the growth inhibitory effects of the metallogel systems against the pathogenic microbes.