Fabrication of gold-calcium phosphate composite nanoparticles through coprecipitation mediated by amino-terminated polyethylene glycol

Effect of polyethylene glycol on polysaccharides: From molecular modification, composite matrixes, synergetic properties to embeddable application in food fields

Polyethylene glycol (PEG) is a flexible, water-soluble, non-immunogenic, as well as biocompatible polymer, and it could synergize with polysaccharides for food applications. The molecular modification strategies, including covalent bond interactions (amino groups, carboxyl groups, aldehyde groups, tosylate groups, etc.), and non-covalent bond interactions (hydrogen bonding, electrostatic interactions, etc.) on PEG molecular chains are discussed. Its versatile structure, group modifiability, and amphiphilic block buildability could improve the functions of polysaccharides (e.g., chitosan, cellulose, starch, alginate, etc.) and adjust the properties of combined PEG/polysaccharides with outstanding chain tunability and matrix processability owing to plasticizing effects, compatibilizing effects, steric stabilizing effects and excluded volume effects by PEG, for achieving the diverse performance targets. The synergetic properties of PEG/polysaccharides with remarkable architecture were summarized, including mechanical properties, antibacterial activity, antioxidant performance, self-healing properties, carrier and delivery characteristics. The PEG/polysaccharides with excellent combined properties and embeddable merits illustrate potential applications including food packaging, food intelligent indication/detection, food 3D printing and nutraceutical food absorption. Additionally, prospects (like food innovation and preferable nutrient utilization) and key challenges (like structure-effectiveness-applicability relationship) for PEG/polysaccharides are proposed and addressed for food fields.

Biomimetic Catalysts Based on Au@ZnO-Graphene Composites for the Generation of Hydrogen by Water Splitting

For some decades, the scientific community has been looking for alternatives to the use of fossil fuels that allow for the planet's sustainable and environmentally-friendly development. To do this, attempts have been made to mimic some processes that occur in nature, among which the photosystem-II stands out, which allows water splitting operating with different steps to generate oxygen and hydrogen. This research presents promising results using synthetic catalysts, which try to simulate some natural processes, and which are based on Au@ZnO-graphene compounds. These catalysts were prepared by incorporating different amounts of gold nanoparticles (1 wt.%, 3 wt.%, 5 wt.%, 10 wt.%) and graphene (1 wt.%) on the surface of synthesized zinc oxide nanowires (ZnO NWs), and zinc oxide nanoparticles (ZnO NPs), along with a commercial form (commercial ZnO) for comparison purposes. The highest amount of hydrogen (1127 μmol/hg) was reported by ZnO NWs with a gold and graphene loadings of 10 wt.% and 1 wt.%, respectively, under irradiation at 400 nm. Quantities of 759 μmol/hg and 709 μmol/hg were obtained with catalysts based on ZnO NPs and commercial ZnO, respectively. The photocatalytic activity of all composites increased with respect to the bare semiconductors, being 2.5 times higher in ZnO NWs, 8.8 times higher for ZnO NPs, and 7.5 times higher for commercial ZnO. The high photocatalytic activity of the catalysts is attributed, mainly, to the synergism between the different amount of gold and graphene incorporated, and the surface area of the composites.