Bioinspired mineralization of calcium carbonate in peptide hydrogel acting as a multifunctional three-dimensional template

Biomineralization is the process by which biominerals, minerals composed of bioinorganic matter possessing a controlled structure and orientation and a biomacromolecular assembly with an ordered structure that acts as a 3D template, are formed. In this study, we investigated the fabrication of organic/inorganic hybrid gels by bioinspired mineralization in peptide hydrogels. An Ac-(VHVEVS)3-CONH2 peptide was used as a multifunctional template with a mineral source supply capability and structural controllability that facilitates the formation of hydrogels via self-assembly. Hydrogels with varying viscoelastic strengths were prepared from the designed peptide by controlling the concentration of calcium ions added as cross-linking agents. The peptide hydrogel supplied carbonate anions as the mineral source through the hydrolysis of urea and mineralized CaCO3 with controlled morphology on the peptide network. With increases in the concentration of calcium ions added, the morphology of the mineralized CaCO3 changed from a fibrous structure to a thin film. This implies that the nucleation and growth mechanisms of CaCO3 formed by bioinspired mineralization were affected not only by the morphology and supply rate of the mineral source by the peptide network acting as a multifunctional template, but also by the viscoelastic strength of the hydrogel that served as a 3D reaction field

Heat shock protein 47 stress responses in Chinese hamster ovary cells exposed to raw and reclaimed wastewater

As wastewater reclamation and reuse becomes more widespread, risks of exposure to treated wastewater increase. Moreover, an unlimited number of pollutants can be identified in wastewater. Therefore, comprehensive toxicity assessment of treated wastewater is imperative. The objective of this study was to perform a comprehensive toxicity assessment of wastewater treatment systems using stress response bioassays. This powerful tool can comprehensively assess the toxicity of contaminants. In this study, samples from conventional activated sludge treatment, membrane bioreactors (MBRs) with different pore sizes and sludge retention times (SRTs), rapid sand filtration, coagulation, nano-filtration (NF) and reverse osmosis (RO) were investigated. The results of stress response bioassays confirmed that the secondary effluent showed higher stress response than influent indicating that biological treatment generates toxic compounds. The results obtained from molecular weight fractionation of water samples demonstrated that organic matter with a higher molecular weight fraction (>0.1μm) causes toxicity in secondary effluent. Furthermore, supernatant from MBR reactors showed toxicity regardless of SRT. On the other hand, stress response was not detected in MBR permeates except for an MBR equipped with a larger pore size membrane (0.4μm) and with a short SRT (12 days). While rapid sand filtration could not remove the toxic compounds found in secondary effluent, coagulation tests, operated at an appropriate pH, were effective for reducing stress response in the secondary effluent. Experimental findings also showed that stress response was not detected in cases of NF and RO permeate subsequent to MBR treatment