LAUSR

The chitosan physical hydrogels formed under gaseous ammonia atmospheres usually have poor mechanical properties and low antibacterial activities, which limit its application as biomaterials. In the current study, CTS-Ag+/NH3 physical hydrogels with great comprehensive properties were prepared by the gelation of chitosan in the presence of AgNO3 under a gaseous ammonia atmosphere. Compared with the previously reported hydrogels made with chitosan and AgNO3, the CTS-Ag+/NH3 hydrogels were more homogeneous and transparent. In addition, the AgNO3 content in the hydrogels was decreased to 0.064-0.424wt.%. The formation mechanism and the influence of reaction conditions on the structures and properties of CTS-Ag+/NH3 physical hydrogels were characterized by FT-IR, SEM, XPS, XRD and rheological measurement. Tensile testing suggested that CTS-Ag+/NH3 physical hydrogels had a higher tensile strength than the CTS/NH3 hydrogel. Moreover, the CTS-Ag+/NH3 physical hydrogels showed excellent antibacterial activities against both gram positive and negative bacteria.