Bombyx mori silk fibroin (SF) is known to be capable of facilitating nucleation of the hydroxyapatite crystals (HAps). To find out how SF mediates the nucleation of HAps, self‐assembly of SF in 1.5 simulated body fluid (SBF) was observed in this study through design of a co‐solution of SF and 1.5‐times SBF (SF/1.5 SBF). After the co‐solution of SF/1.5 SBF was incubated at 37.2 °C up to 7 days, SEM, X‐ray, and Fourier transform infrared (FTIR) observations indicated that nucleation of HAps was increased. In addition, the structure of SF was transited from random coil into β‐sheet indicated by FTIR spectra. The β‐sheet assembly of SF in 1.5 SBF was also supported by CD spectra. Atomic force microscopy provided detailed progress of the self‐assembly that SF incubated in 1.5 SBF was self‐assembled in the form from dot, through rod to final net. Therefore, this study suggested that nucleation of HAps of SF was controlled by its molecular self‐assembly. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013

The competitive adsorption properties of the heavy metal ions Pb(II), Cu(II), and Cd(II) ions in binary and ternary systems on black carbon (BC) isolated from the burning residue of wheat straw were studied in batch systems. The BC samples were characterized by Fourier transform infrared spectroscopy (FTIR). Equilibrium and kinetic adsorption data showed that the selectivity of metal ions on BC followed the order of Pb(II) > Cu(II) > Cd(II). Kinetic studies were performed, and the rate kinetics was fitted well with the pseudosecond-order model. The Freundlich adsorption isotherm was applicable to the adsorption process, and its constants were evaluated.

No abstract

In order to use a simple and ecofriendly method to prepare porous silk scaffolds, aqueous silk fibroin solution (ASF) was extracted from silk gland of 7-day-old fifth instar larvae of Bombyx mori (B. mori). SDS-page analysis indicated that the obtained fibroin had a molecular weight higher than 200 kDa. The fabrication of porous scaffolds from ASF was achieved by using the freeze-drying method. The pore of porous scaffolds is homogenous and tends to become smaller with an increase in the concentration of ASF. Conversely, the porosity is decreased. The porous scaffolds show impressive compressive strength which can be as high as 6.9 ± 0.4 MPa. Furthermore, ASF has high cell adhesion and growth activity. It also exhibits high ALP activity. This implies that porous scaffolds prepared from ASF have biocompatibility. Therefore, the porous scaffolds prepared in this study have potential application in tissue engineering due to the impressive compressive strength and biocompatibility.

Research Article Hg(II) Removal from Aqueous Solutions by Bacillus subtilis BiomassThe biosorption of Hg(II) from aqueous solutions using Bacillus subtilis biomass was investigated in this study. The adsorbent was characterized by FTIR. Various factors including solution pH, initial concentration of Hg(II), contact time, reaction temperature and ionic strength were taken into account and promising results were obtained. An initial solution pH of 5.0 was most favorable for Hg(II) removal. The kinetic data was also analyzed using pseudo first order and pseudo second order equations. The results suggested that Hg(II) bioadsorption was best represented by the pseudo second order equation. Freundlich, Langmuir and Langmuir-Freundlich isotherms for the present systems were analyzed. The most satisfactory interpretation for the equilibrium data at different temperatures was given by the Langmuir-Freundlich isotherm. The effect of ionic strength on bioadsorption was significant. Bacillus subtilis biomass could serve as low cost adsorbent to remove Hg(II) from aqueous solutions, especially at lower concentrations of Hg(II) (a20 mg Hg/L).