The challenge for conformal modification of the ultra-high internal surface of nanoporous silicon was tackled by electrochemical polymerisation of 2,6-dihydroxynaphthalene using cyclic voltammetry or potentiometry and, notably, after the thermal treatment (800 °C, N2, 4 h) an assembly of interconnected networks of graphene strongly adhering to nanoporous silicon matrix resulted. Herein we demonstrate the achievement of an easy scalable technology for solid state supercapacitors on silicon, with excellent electrochemical properties. Accordingly, our symmetric supercapacitors (SSC) showed remarkable performance characteristics, comparable to many of the best high-power and/or high-energy carbon-based supercapacitors, their figures of merit matching under battery-like supercapacitor behaviour. Furthermore, the devices displayed high specific capacity values along with enhanced capacity retention even at ultra-high rates for voltage sweep, 5 V/s, or discharge current density, 100 A/g, respectively. The cycling stability tests performed at relatively high discharge current density of 10 A/g indicated good capacity retention, with a superior performance demonstrated for the electrodes obtained under cyclic voltammetry approach, which may be ascribed on the one hand to a better coverage of the porous silicon substrate and, on the other hand, to an improved resilience of the hybrid electrode to pore clogging.
This paper reports the synthesis and complex characterization of nanocomposite hydrogels based on polyacrylamide and functionalized magnetite nanoparticles. Magnetic nanoparticles were functionalized with double bonds by 3-trimethoxysilyl propyl methacrylate. Nanocomposite hydrogels were prepared by radical polymerization of acrylamide monomer and double bond modified magnetite nanoparticles. XPS spectra for magnetite and modified magnetite were recorded to evaluate the covalent bonding of silane modifying agent. Swelling measurements in saline solution were performed to evaluate the behavior of these hydrogels having various compositions. Mechanical properties were evaluated by dynamic rheological analysis for elastic modulus and vibrating sample magnetometry was used to investigate the magnetic properties. Morphology, geometrical evaluation (size and shape) of nanostructural characteristics and the crystalline structure of the samples were investigated by SEM, HR-TEM and selected area electron diffraction (SAED). The nanocomposite hydrogels will be further tested for the soft tissue engineering field as repairing scaffolds, due to their mechanical and magnetization behavior that can stimulate tissue regeneration.
Aiming to address the issue of poor bioavailability of most anti-tumor medicines against colorectal cancer, we developed a targeted anticancer nanocarrier using biocarriers able to both bind and easily release their load in a controlled manner. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) carriers were obtained via the emulsification-diffusion method, loaded with 5-fluorouracil and then characterized in terms of particle morphology and size (SEM, DLS), drug uptake and release. The cytotoxic potential of the 5-fluorouracil-loaded polymer nanocarriers on human adenocarcinoma cells (HT-29 cell line) was investigated. The
in vitro
studies clearly demonstrated that while the nanocarriers themselves slightly alter HT-29 cell viability, when loaded with 5-fluorouracil they significantly decrease cell viability, suggesting that the polymer itself exhibits low cytotoxicity and the drug-loaded carrier acts in an efficient manner to kill HT-29 human adenocarcinoma cells.
This paper reports the synthesis and complex characterization of novel polymeric networks based on the crosslinking of Bombyx mori silk fibroin via poly(N-isopropylacrylamide) bridges generated by an ammonium cerium nitrate redox system. The research study gives an understanding of the polymerization mechanism in terms of the generation of radical sites, radical growth and termination reaction, as well as the involvement of modifications on silk fibroin structure and properties. The physico-chemical characterization was carried out by FTIR-ATR, X-ray photoelectron spectroscopy and RAMAN spectroscopy with unravelling the chemical modification. The structural characterization and spatial arrangement by secondary structure were carried out by X-ray diffraction and circular dichroism. The thermal behavior and thermal stability were evaluated by differential scanning calorimetry and thermogravimetric analysis. The novel complex polymer network is intended to be used in the field of smart drug delivery systems.
The fabrication of magnetically modified electrospun nanocomposite fibers based on a naturally-derived biocompatible and biodegradable polysaccharide chitosan (CS) and the hydrophilic and biocompatible poly(vinylpyrrolidone) (PVP) is reported herein. The anchoring of magnetic nanoparticles (MNPs) onto the surfaces of the electrospun PVP/CS fibers was carried out by a post-magnetization process based on chemical coprecipitation, via immersing the produced fibrous mats in an aqueous solution containing Fe(II) and Fe(III) salts at appropriate molar ratios, followed by the addition of a weak base to yield MNPs. Electron microscopy revealed the presence of continuous micron and submicron fibers surface-decorated with MNPs. The magnetically modified PVP/CS fibers exhibited superparamagnetic behavior at ambient temperature. The magnetic fibrous nanocomposite carrier was employed for the immobilization of Saccharomyces cerevisiae cells and their use for sucrose hydrolysis, and Candida rugosa lipase and its use for artificial substrate hydrolysis.
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