The biological performance of artificial biomaterials is closely related to their structure characteristics. Cell adhesion, migration, proliferation, and differentiation are all strongly affected by the different scale structures of biomaterials. Silk fibroin (SF), extracted mainly from silkworms, has become a popular biomaterial due to its excellent biocompatibility, exceptional mechanical properties, tunable degradation, ease of processing, and sufficient supply. As a material with excellent processability, SF can be processed into various forms with different structures, including particulate, fiber, film, and three-dimensional (3D) porous scaffolds. This review discusses and summarizes the various constructions of SF-based materials, from single structures to multi-level structures, and their applications. In combination with single structures, new techniques for creating special multi-level structures of SF-based materials, such as micropatterning and 3D-printing, are also briefly addressed.
Nanofiber unique characteristics and potential applications offer innovative strategies and opportunities for sustainable energy production, and for creative solutions to biomedical, healthcare, and environmental problems. This review summarizes the history and development of nanofiber technology, their unique properties, fabrication techniques (using spinning and nonspinning approaches), and emerging applications in energy harvesting and storage, environmental protection and improvement, and biomedical technology and healthcare.Nanofibers are currently used as electrode and membrane materials for batteries, supercapacitors, fuel cells, and solar cells. Nanofiber membranes are also successfully used for ultra-high air filtration, wastewater treatment, water purification, and blood purification at low pressure. This review will describe the different types of nanostructured fibers (e.g., solid, mesoporous, hollow, core-shell nanofibers) fabricated from natural and synthetic polymers, metal and metal oxides, carbon-based, inorganic-organic hybrid nanofibers and their potential applications. Moreover, it will highlight the current and future research needs in nanofiber-based materials to improve and broaden their applications and commercialization.
In
this study, ruthenium nanoparticles (RuNPs) were successfully
decorated on graphene nanosheets (GNSs) for the very first time by
a dry synthesis method. The resultant material (GNS-RuNPs) was used
as a nanocatalyst for the aerial oxidation of alcohols after being
optimized. The scope of the catalytic system was extended with various
aliphatic, aromatic, alicyclic, benzylic, allylic, amino, and heterocyclic
alcohols. The 0.036 mol % (5 mg) of catalyst was enough for aerial
oxidation of alcohols, the lowest amount of catalyst so far reported.
The proposed nanocatalyst is highly chemoselective, heterogeneous,
and reusable. The GNS-RuNPs were separated out from the reaction mixture
and analyzed by transmission electron microscopy (TEM), X-ray diffraction
(XRD), Raman, and scanning electron microscopy-energy dispersive spectrometry
(SEM-EDS); the results revealed that the nanocatalyst is physically
as well as chemically stable. Owing to the high stability of used
catalyst (u-GNS-RuNPs), it was further applied in
transfer hydrogenation, after suitable modifications. We obtained
ruthenium oxide nanorod hybrid GNSs (u-GNS-RuO2NRs) from u-GNS-RuNPs by simple calcination.
The catalytic activity of u-GNS-RuO2NRs
toward the transfer hydrogenation of various aromatic, alicyclic,
and heterocyclic ketones was found to be excellent.
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