Surfactant-free synthesis of hollow mesoporous carbon spheres and their encapsulated Au derivatives using biopolymeric chitosan

Hollow carbon spheres derived from self-assembled chitosan/poly(γ-glutamic acid) nanoparticles for oil-in-water emulsion separation

With the rapid science and technology advancement, the oil-water separation in oily wastewater has become an urgent problem, especially the emulsified oil-water mixtures. Hollow carbon spheres (HCSs) have tremendous potential in separating oil-water emulsions due to their rich porous channels and high surface-to-volume ratio. In this work, as-prepared chitosan/poly(γ-glutamic acid) nanoparticles crosslinked by Ni2+ (Ni2+/CS/γ-PGA NPs) were used as carbon precursor to fabricate HCSs. This strategy separated the formation process of the biomolecular microspheres and the carbonization process. Especially, the Ni2+/CS/γ-PGA NPs were fabricated from the self-assembly of chitosan and γ-PGA in aqueous solution and the crosslinking of Ni2+ via the electrostatic interactions, facilitating the formation of biomolecular microspheres and making the usable of biomolecule-based carbon precursors diversity. After lyophilization, Ni2+/CS/γ-PGA NPs powder was obtained, which was then carbonized in a tube furnace under N2 atmosphere. During the carbonization process, the nickel species aggregated together to form the core of nickel@carbon nanoparticles, and carbon formed the shell. At last, nickel nanoparticles were removed from the carbon framework by hydrochloric acid, obtaining HCSs with super-hydrophobicity and lipophilicity. The as-prepared HCSs exhibited excellent separation performance in oil-in-water emulsions.

Ultrasensitive catechin electrochemical sensor based on uniform ordered mesoporous carbon hollow spheres (MCHSs) advanced carbon-based conductive materials

Fabrication of an electrochemical catechin sensor composed of mesoporous carbon hollow spheres (MCHSs) and its application in actual sample detection. The MCHSs were obtained using a simple one-pot method without a surfactant.

Electrospun nanofibers enhance trehalose synthesis by regulating gene expression for Micrococcus luteus fermentation

In this study, mesoporous polyacrylonitrile (PAN)/thermoplastic polyurethane (TPU) blended nanofibers were prepared to immobilize Micrococcus luteus for enhancing the conversion of trehalose. The images of SEM showed the cells were adsorbed on the surface and pores due to the unique pore structure. The results of contact angle, Zeta potential and water holding ratio exhibited the good hydrophilicity and stability of PAN/TPU-P2. Besides, it was indicated that the biomass and immobilization efficiency were increased to 0.633 g/L and 0.153 g/g, respectively. It was the most noteworthy that the trehalose yield could reach 23.46 g/L, which was 71.62 % higher than that of the control in the multi-batch fermentation. Moreover, the reactive oxygen species (ROS) level was decreased to 12.8 % while the enzyme concentration was increased to 11.176 mg/mL. Meanwhile, it was also found that PAN/TPU-P2 immobilization substantially increased the expression of target gene MtreY by 3.500 times. In other words, the mechanism by which immobilized cells increased trehalose yield was that PAN/TPU-P regulated gene expression of MtreY. Therefore, this research provided theoretical foundation for the metabolic regulation of sufficient trehalose production by immobilized cells.

A self-crosslinking procedure to construct yolk–shell Au@microporous carbon nanospheres for lithium–sulfur batteries

An efficient self-crosslinking procedure to reasonably construct porous shells is reported for the synthesis of yolk–shell Au@microporous carbon nanospheres.