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Multifunctional, chemically modified chitosan surfaces and charged polymer brushes with protection against microbes and changes in pH
Chitosan, a cationic polysaccharide, is a biocompatible and biodegradable coating material. While chitosan has been used for drug delivery, wound dressings, and tissue materials, this material has not been fully realized as a biomaterial coating due to its limited solubility at physiological conditions. At low pH, chitosan is a water-soluble cationic polyelectrolyte, while at pH above 6.5, chitosan is uncharged and becomes insoluble in water.
Researchers at Penn and Thomas Jefferson University have developed a new formulation of chitosan by modifying the molecule with quaternary ammonium salts, enhancing solubility in water.
Grafting a thin layer of this modified chitosan and immobilizing on a surface generates resistance to biofilm formation due to the material’s enhanced microbicidal activities. Furthermore, there is a pH-dependent swelling behavior, which could be exploited to initiate drug release or control the width of channels in nanofluidic devices. The grafted chitosan has been shown to reduce bacterial colonization of S. aureus compared to silicon oxide and APTES modified silicon oxide surfaces.