A novel biopolymer/rectorite nanocomposite with antimicrobial activity

Rectorite (REC), a type of layered silicate, was used to prepare the intercalated nanocomposites with quaternized chitosan (HTCC). Characterization by XRD and TEM revealed that HTCC were intercalated into the intergallery of REC. Moreover, it was confirmed from FT-IR, XRD and ζ-potential analyses that interaction between HTCC and REC took place. Two in vitro antimicrobial assays indicated that all the nanocomposites exhibited strong inhibition against Gram-positive bacteria, Gram-negative bacteria and Fungi under weak acid, water and weak basic condition, particularly against Gram-positive bacteria. Moreover, with increasing the amount or the interlayer distance of organic REC, the antimicrobial activity was stronger. The lowest minimum inhibition concentration values of the nanocomposites against Staphylococcus aureus and Bacillus subtilis were less than 0.00313% (w/v) in all media tested, and the killing rate on S. aureus reached more than 90% in 30 min. The mechanism of the antimicrobial action was briefly discussed.