Novel Modified Chitosan/Clay Nanocomposites with Antimicrobial Activity

Abstract

Unmodified sodium montmorillonite (Na-MMT) and montmorillonite modified by poly(methylmethacrylate) (PMMA) were used to intercalate chitosan (CS) and chitosan blended with polytertahydrofuran (CS-PTHF750). Their structures were characterized by XRD, TEM and IR techniques. The results showed that CS and CS-PTHF750 chains were inserted into silicate layers. The interlayer distance of the layered silicates in the nanocomposites enlarged as the amount of polymer increased. The thermal stability of the nanocomposites is characterized by TGA. In vitro antimicrobial assay showed that pristine montmorillonite could not inhibit the growth of bacteria. Chitosan was less effective in inhibiting bacterial growth than chitosan modified by PTHF750. CS/MMT and CS-PTHF750/MMT nanocomposites had strong antimicrobial activity, particularly against Gram-positive bacteria. With the increase of the amount and the interlayer distance of the layered silicates in the nanocomposites, the nanocomposites showed a stronger antibacterial effect. None of the CS or CS-PTHF750 intercalated into PMMA-MMT significantly inhibiting all microorganisms.

Keywods: chitosan, nanocomposite, polytertahydrofurane