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We report on a green procedure for the synthesis and stabilization of gold nanoparticles (AuNPs) from chlorauric acid (HAuCl4) with the use of a β-glucan known as Lentinan (LNT) without external reducing or stabilizing agents in aqueous medium. LNT adopted triple helical conformation in water, which was first denatured into single chains (s-LNT) at a high temperature of 140 °C before mixing with HAuCl4. Results from UV-vis absorption spectroscopy, transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) spectra suggested that AuCl4(-) was rapidly reduced to AuNPs by s-LNT. Moreover, the as-prepared AuNPs could be converted into nanobelt, spherical nanoparticles, and nanowire morphology simply by controlling the s-LNT concentration, reaction time, and temperature. In particular, the AuNPs nanowire was confirmed as the most stable shape in water, which was predominately ascribed to the hydrophobic cavity in the helical center of the renatured triple helical LNT (r-LNT) from s-LNT. Namely, AuNPs were entrapped in the hydrophobic cavity of r-LNT to form nanowire with an outer layer of water-soluble r-LNT, leading to stable dispersion of AuNPs. All the data demonstrated that the β-glucan of s-LNT can be used as a reducing and stabilizing agent to synthesize and disperse AuNPs in water. The whole process of reduction and stabilization was free of organic solvent and thus very safe, which is important for the potential application of AuNPs in biotechnology and biomedicine.

Novel protein-based nanocomposites were well prepared by in vivo synthesis and co-precipitation of soy protein isolate (SPI) with calcium carbonate (CaCO3) in an aqueous solution. The resultant CaCO3 in the nanocomposites was identified as calcite- and aragonite-type, respectively. The morphology and structure of the CaCO3/SPI composites were investigated by means of wide-angle X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, and high-resolution transmission electron microscopy. The results revealed that the polymorph and the size of CaCO3 in the nanocomposites were dependent on its content, pH, and the conformation of soy protein. At the content of more than 5%, CaCO3 was changed into calcite crystal with the preference of growing along (104) plane. However, at lower content of less than 5%, CaCO3 preferred to form aragonite in the composite as a result of the modulation by soy protein. The aragonite nanocrystals were arrayed in the direction of (111) plane and self-assembled along beta-sheet planes of soy protein polypeptides. The mechanical properties, thermal stability, and water resistance of the CaCO3/SPI nanocomposites were significantly improved as a result of the nanosized effects. Interestingly, the aragonite/SPI nanocomposite exhibited higher tensile strength (about 50 MPa) than that of calcite/SPI, owing to a good compatibility and strong interaction between aragonite and soy protein polypeptides. This work provided a simple pathway to develop the soy protein-based bio-hybrid materials with high mechanical strength and valuable information on their structure-properties relationship.

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Two water-soluble polysaccharides (PV-W, PV-B) were isolated and purified from fruiting bodies of P. vaninii Ljup (a traditional Chinese medicine) by hot water and sodium hydroxide, respectively. The chemical structure was analyzed by FT-IR, GC-MS analysis and 13C NMR spectra. The results illustrated that PV-W was a heteropolysaccharide, mainly composed of mannose, glucose, arabinose and galactose. PV-B was a β-1, 3-D-glucan branched with β-1, 6-D-glucose. The results of viscometry proved that PV-W and PV-B could be molecularly dispersed in water without aggregation. The results of SEC-MALLS-RI indicated that the two polysaccharides with the similar Mw but different chain conformation. PV-W was a stable chain with globular shape, while PV-B was a more expanded flexible random coils conformation. MTT assay indicated that PV-B showed higher inhibition effect on HepG2 and HeLa cells than PV-W in vitro. This work provided the important information of active components from traditional Chinese medicines and its potential applications in the food and medicine industry.