Fabrication of silicon-based nickel nanoflower-encapsulated gelatin microspheres as an active antimicrobial carrier.

Local antibiotic application might mitigate the burgeoning problem of rapid emergence of antibiotic resistance in pathogenic microbes. To accomplish this, delivery systems must be engineered. Hydrogels have a wide range of physicochemical properties and can mimic the extracellular matrix, rendering them promising materials for local antibacterial agent application. Here, we synthesized antibacterial silicon (Si)-based nickel (Ni) nanoflowers (Si@Ni) and encapsulated them in gelatin methacryloyl (GelMA) using microfluidic and photo-crosslink technology, constructing uniform micro-sized hydrogel spheres (Si@Ni-GelMA). Si@Ni and Si@Ni-GelMA were characterized using X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Injectable Si@Ni-GelMA exhibited excellent antibacterial activities owing to the antibiotic effect of Ni against Pseudomonas aeruginosa, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus, while showing negligible cytotoxicity. Therefore, the Si@Ni-GelMA system can be used as drug carriers owing to their injectability, visible light-mediated crosslinking, degradation, biosafety, and superior antibacterial properties.

Injectable hyaluronic acid hydrogel encapsulated with Si-based NiO nanoflower by visible light cross-linking: Its antibacterial applications.

Bacterial infections have become a severe threat to human health and antibiotics have been developed to treat them. However, extensive use of antibiotics has led to multidrug-resistant bacteria and reduction of their therapeutic effects. An efficient solution may be localized application of antibiotics using a drug delivery system. For clinical application, they need to be biodegradable and should offer a prolonged antibacterial effect. In this study, a new injectable and visible-light-crosslinked hyaluronic acid (HA) hydrogel loaded with silicon (Si)-based nickel oxide (NiO) nanoflowers (Si@NiO) as an antibacterial scaffold was developed. Si@NiO nanoflowers were synthesized using chemical bath deposition before encapsulating them in the HA hydrogel under a mild visible-light-crosslinking conditions to generate a Si@NiO-hydrogel. Si@NiO synthesis was confirmed using scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. As-prepared Si@NiO-hydrogel exhibited enhanced mechanical properties compared to a control bare hydrogel sample. Moreover, Si@NiO-hydrogel exhibits excellent antibacterial properties against three bacterial strains (P. aeruginosa, K. pneumoniae, and methicillin-resistant Staphylococcus aureus (>99.9% bactericidal rate)) and negligible cytotoxicity toward mouse embryonic fibroblasts. Therefore, Si@NiO-hydrogel has the potential for use in tissue engineering and biomedical applications owing to its injectability, visible-light crosslink ability, degradability, biosafety, and superior antibacterial property.

Biocompatible Core-Shell-Structured Si-Based NiO Nanoflowers and Their Anticancer Activity.

Compared to most of nano-sized particles, core-shell-structured nanoflowers have received great attention as bioactive materials because of their high surface area with the flower-like structures. In this study, core-shell-structured Si-based NiO nanoflowers, Si@NiO, were prepared by a modified chemical bath deposition method followed by thermal reduction. The crystal morphology and basic structure of the composites were characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) and porosity analysis (BJT), and inductively coupled plasma optical emission spectrometry (ICP-OES). The electrochemical properties of the Si@NiO nanoflowers were examined through the redox reaction of ascorbic acid with the metal ions present on the surface of the core-shell nanoflowers. This reaction favored the formation of reactive oxygen species. The Si@NiO nanoflowers showed excellent anticancer activity and low cytotoxicity toward the human breast cancer cell line (MCF-7) and mouse embryonic fibroblasts (MEFs), respectively, demonstrating that the anticancer activities of the Si@NiO nanoflowers were primarily derived from the oxidative capacity of the metal ions on the surface, rather than from the released metal ions. Thus, this proves that Si-based NiO nanoflowers can act as a promising candidate for therapeutic applications.

Cellulose Nanofiber Composite with Bimetallic Zeolite Imidazole Framework for Electrochemical Supercapacitors.

Cellulose nanofiber (CNF) and hybrid zeolite imidazole framework (HZ) are an emerging biomaterial and a porous carbonous material, respectively. The composite of these two materials could have versatile physiochemical characteristics. A cellulose nanofiber and cobalt-containing zeolite framework-based composite was prepared using an in-situ and eco-friendly chemical method followed by pyrolysis. The composite was comprised of cobalt nanoparticles decorated on highly graphitized N-doped nanoporous carbons (NPC) wrapped with carbon nanotubes (CNTs) produced from the direct carbonization of HZ. By varying the ratio of CNF in the composite, we determined the optimal concentration and characterized the derived samples using sophisticated techniques. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the functionalization of CNF in the metallic cobalt-covered N-doped NPC wrapped with CNTs. The CNF-HZNPC composite electrodes show superior electrochemical performance, which is suitable for supercapacitor applications; its specific capacitance is 146 F/g at 1 A/g. Furthermore, the composite electrodes retain a cycling stability of about 90% over 2000 charge-discharge cycles at 10 A/g. The superior electrochemical properties of the cellulose make it a promising candidate for developing electrodes for energy storage applications.

Electron transfer interpretation of the biofilm-coated anode of a microbial fuel cell and the cathode modification effects on its power.

Biofilm-coated electrodes and outer cell membrane-mimicked electrodes were examined to verify an extracellular electron transfer mechanism using Marcus theory for a donor-acceptor electron transfer. Redox couple-bound membrane electrodes were prepared by impregnating redox coenzymes into Nafion films on carbon cloth electrodes. The electron transfer was believed to occur sequentially from acetate to nicotinamide adenine dinucleotide (NAD), c-type cytochrome, flavin mononucleotide (FMN) (or riboflavin (RBF)) and the anode substrate. Excellent polarisation and power density characteristics were contributed by the modification of the cathode with a high-surface-area ordered mesoporous carbon or a hollow core-mesoporous shell carbon. The maximum power density of the microbial fuel cell (MFC) could be improved by a factor of two mainly due to the accelerated electron consumption by modifying the cathode surfaces within three-dimensionally interconnected mesoporous carbon particles, and the anode was coated with a mixed culture of anaerobic bacteria.

Silicon core-mesoporous shell carbon spheres as high stability lithium-ion battery anode.

An innovative and simple synthesis strategy of silicon nanoparticle (Si NP) core covered by mesoporous shell carbon (MSC) structure is demonstrated. The Si core@MSC (SCMSC) composite is developed for addressing the issues for Si anode material in lithium ion batteries (LIBs) such as high volume expansion and low electrical conductivity. Significant improvement in the electrochemical performance for the SCMSC anode is observed compared with bare Si anode. The SCMSC composite delivers an initial specific capacity of 2450 mAh g-1 at 0.166 A g-1 with Coulombic efficiency of 99.2% for 100 cycles. Compared to bare Si anode, the SCMSC anode exhibits much higher Li storage capacity, superior cyclability, and good rate capability, highlighting the advantages of hierarchical MSC in the SCMSC structure.

Synthesis of Water-Dispersible Single-Layer CoAl-Carbonate Layered Double Hydroxide.

Despite extensive study on single-layer layered double hydroxides (SL-LDHs) with NO3- counterions, SL-LDHs with CO32- counterions (CO32- SL-LDHs) have never been prepared before. Herein, a CoAl-CO32- SL-LDH which stays stable in water and powdery state is first synthesized using ethylene glycol as a reaction medium. The SL-LDH, with thickness of ∼0.85 nm, is composed of one Co(Al)O6 layer sandwiched between two CO32- layers. The SL-LDH powder shows high specific surface area (∼289 m2/g) and excellent electrocatalytic oxygen evolution efficiency. This work provides the first simple way to prepare CO32- SL-LDHs and will open an avenue for synthesizing other SL-LDHs.