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Silver nanoparticles (Ag NPs) were biosynthesized using konjac glucomannan (KGM), κ-carrageenan (CRG) and inulin as reducing and capping agent through one-spot method. The structure and morphology of Ag NPs were investigated using UV-visible spectroscopy, transmission electron microscopy, Fourier transform infrared and X-ray powder diffraction. The catalysis and antibacterial properties were also evaluated. Results showed that Ag NPs fabrication was influenced by the incubation temperature and polysaccharide category. CRG displayed a stronger reduction of Ag+ than KGM, and the lowest was inulin. A High incubation temperature promoted the reduction of Ag NPs. As for Ag100 NPs, the kapp of Ag NPs based on CRG, inulin, and KGM were 5.80×10-2 s-1, 2.14×10-2 s-1, and 2.16×10-2 s-1 respectively. Bacteriostatic test showed excellent antimicrobial activity of Ag NPs for Escherichia coli and Staphylococcus aureus. Thus, natural polysaccharide could be effective reducing and stabilizing agents for Ag NPs biosynthesis. The excellent antibacterial and catalytic properties may facilitate their use in medical, food, and biological applications.

Biomimetic synthesis of calcium carbonate (CaCO 3) with various sizes and morphologies using organic matrix has become an interesting hotspot. CaCO 3 was synthesised by the reaction of Na 2 CO 3 and CaCl 2 in the presence of xanthan gum (XG). The results showed that the fresh mineralised CaCO 3 /XG were microspheres with large surface area and porosity. The original CaCO 3 /XG microspheres transformed to brick-like CaCO 3 after ageing 7 days at 4°C. During the morphology transformation, CaCO 3 spheres rearranged by attaching to XG molecular, and transformed from a macroscopic view of CaCO 3 microspheres to a hexahedral structure related with the XG uncoiled single chains re-associating into loose several-fold helix. The study demonstrated that environmental effect coupled XG could be one feasible approach to regulate the structure of CaCO 3 .