Preparation of new crosslinked chitosan with crown ether and their adsorption for silver ion for antibacterial activities

New di-Schiff base type crown ethers crosslinked chitosan (CCTS-1) was synthesized by the reaction of 4,4′-diformyldibenzo-18-c-6 crown ether with crosslinked chitosan. New di-secondary amine type crown ethers crosslinked chitosan (CCTS-2) was prepared by the reaction between CCTS-1 and sodium borohydride. Their structures were confirmed by Fourier transform infrared spectral analysis, X-ray powder diffraction analysis and elemental analysis. The adsorption rates by CCTS-2 for Ag+ for 1 h were 96% at pH 6.0, and Ag+ initial concentration 0.5 mmol/l. The complexes of CCTS [Bull. Chem. Soc. Jpn 60 (1987) 444], CCTS-2 and silver ion against three bacteria were studied. The bacteriostasis zone diameters of the complex of CCTS-2 and Ag+ (CCTS-2–Ag+) containing 0.00355 mmol Ag+ against Staphylococcus Aureus, Escherichia coli and Pseudomonas aeruginona are 11, 10 and 7.5 mm, respectively, while those of the complex of CCTS and Ag+ (CCTS–Ag+) under similar conditions were 11, 10 and 6.0 mm, respectively. This research will be useful for designing crosslinked-chitosan-based adsorption for preconcentration of Ag+ for medical bacteriostasis.