Synthesis, characterization and swelling behavior of high-performance antimicrobial amphoteric hydrogels from corn starch

Three novel hydrogels with high antimicrobial activity were synthesized from grafting of corn starch with 4-acrylamidobenzoic acid (4ABA) and diallyldimethylammonium chloride as cross-linkers (CLs). Three concentrations of the cross-linker (3%, 5% and 10% based on starch weight) were used to give three hydrogels designated as St-g-P4ABA/PCL3, St-g-P4ABA/PCL5 and St-g-P4ABA PCL10, respectively. The structure of the prepared hydrogels was evidenced by FTIR,H-1-NMR, XRD and SEM techniques. The thermal stability as well as the swelling behavior of the starch hydrogels was investigated, and the results revealed high thermal stability and potential swell ability in water and 9% saline solution for the hydrogels compared with the native starch. They showed a higher swelling degree in acidic, basic and neutral buffer solutions; lower degradation was observed in acidic and basic media after 96 h. Starch hydrogel's antimicrobial activity actions against various types of gram-positive bacteria, gram-negative bacteria and fungi demonstrated higher growth inhibition ability against all tested microorganisms compared to zero-native starch inhibitions. The hydrogels did not demonstrate cytotoxicity on normal human cells and can therefore be used safely in pharmaceutical applications and drug delivery systems. Graphic abstract