Antimicrobial Bioplastics: Synthesis and Characterization of Thermally Stable Starch and Lysine-Based Polymeric Ligand and Its Transition Metals Incorporated Coordination Polymer

Potato-based starch was dissolved in distilled water until paste form of starch was found. Paste form of starch polymer by the process of polycondensation reacted with an essential amino acid lysine in a basic medium. The viscous product obtained was then filtered and after a short period of drying was then coordinated with a series of transition metals as Mn(II), Co(II), Ni(II), Cu(II), and Zn(II). The synthesized polymeric ligand and its polymer metal complexes were spectroscopically characterized, thermally analyzed, and biologically evaluated. In this work, FT-IR, 1H-NMR, 13C-NMR, CHN, TGA, SEM, antimicrobial screening, and ASTM- D5338-93, a CO2 evolution method of biodegradable, studies were carried out. The confirmation of the synthesis was done with these instrumental and spectroscopic techniques. Metals-coordinated polymer complexes were found to be more thermally stable and less biodegradable than the virgin parent ligand. Metal-coordinated polymers of all metals were found to be antibacterial and antifungal, with a range of weak to mild zone of inhibition values in agar well diffusion method for antimicrobial studies. Cu(II) polymer metal complex showed the highest value of antimicrobial activity because of the highest stability constant. 1. Introduction Starch is one of the finest example of the low-cost abundant material which has got manyfold uses in various multidimensional applications. Etherification, esterification, oxidation, cross-linking, and graft copolymerization through hydroxyl groups are the various chemical modifications that are most common, while having a starch molecule as a reactant in different chemical synthesis. Adsorption capacity of the polysaccharide chain is enhanced after the introduction of amino groups. The presence of amino groups in besides hydroxyl groups is highly advantageous for conducting modification reactions [1]. Water insoluble granules of starch have broader application in enhancing the physical properties of many foods [2]. In other cases the presence of amino groups in the polysaccharide chain increases the adsorption capacity [3]. The presence of amino groups in the reaction besides of hydroxyl groups is advantageous for conducting various modification reactions. Several cross linkers such as glutaraldehyde [4–6], epichlorohydrin [7], ethylene glycol diglycidyl ether [8, 9], and oxidized cyclodextrin [10] have been used to modify the polysaccharide for application in heavy toxic metal ion removal. The classical methods for the removal of metal ions from water and wastewater include oxidation,