Single step coupling for multi-responsive water-based chitin/chitosan magnetic nanoparticles

Coupling of chitin whisker (CTWK) or water-soluble chitosan (WSCS) with magnetic nanoparticles (MAG) via a covalent linkage by using a silane coupling agent in an aqueous system is proposed. The use of the silane coupling agent glycidoxypropyltrimethoxy, having a trimethoxy silane as well as an epoxide functionality, allows one step coupling between CTWK or WSCS and MAG. The MAG derivatives obtained are well dispersed and their colloidal aqueous solutions can be stabilized for days. An external magnetic field initiates alignment of nano-rod structured CTWK–MAG in the direction of the magnetic field. The uniqueness of these two materials is that CTWK–MAG shows solvent polarity responsiveness whereas WSCS–MAG performs pH responsiveness. A model application study on DNA extraction confirms that WSCS–MAG with positively charged at pH 7 and with high surface area performs more Escherichia coli extraction ability for two times as compared to CTWK–MAG.