Preparation and antibacterial properties of an AgBr@SiO2/GelMA composite hydrogel

Pure gelatin hydrogels lack antibacterial function and have poor mechanical properties, which restrict their application in wound dressings. In this study, nanosized silver bromide-doped mesoporous silica (AgBr@SiO2) microspheres with hollow structures were prepared by a modified Stober method. The novel microspheres can not only release silver ions to treat bacteria but also release drugs to treat skin wound. Furthermore, AgBr@SiO2 microspheres were modified with propyl methacrylate, incorporated into methacrylated gelatin (GelMA), and crosslinked by UV light to prepare AgBr@SiO2/GelMA dressings consisting of composite hydrogels. The results showed that the AgBr@SiO2 microspheres could enhance the mechanical properties of the hydrogels. With the increase in the AgBr@SiO2 concentration from 0.5 to 1 mg/mL, the dressings demonstrated effective antimicrobial activity against both Staphylococcus aureus and Escherichia coli. Furthermore, full-thickness skin wounds in vivo wound healing studies with Sprague–Dawley rats were evaluated. When treated with AgBr@SiO2/GelMA containing 1 mg/mL AgBr@SiO2, only 15% of the wound area left on day 10. Histology results also showed the epidermal and dermal layers were better organized. These results suggest that AgBr@SiO2/GelMA-based dressing materials could be promising candidates for wound dressings.

Protein Adsorption on SiO2-CaO Bioactive Glass Nanoparticles with Controllable Ca Content

Bioactive glass nanoparticles (BGNs) are emerging multifunctional building blocks for various biomedical applications. In this study, the primary aim was to develop monodispersed binary SiO2-CaO BGNs with controllable Ca content. We successfully synthesized such spherical BGNs (size ~110 nm) using a modified Stöber method. Our results showed that the incorporated Ca did not significantly affect particle size, specific surface area, and structure of BGNs. Concentrations of CaO in BGN compositions ranging from 0 to 10 mol% could be obtained without the gap between actual and nominal compositions. For this type of BGNs (specific surface area 30 m2/g), the maximum concentration of incorporated CaO appeared to be ~12 mol%. The influence of Ca content on protein adsorption was investigated using bovine serum albumin (BSA) and lysozyme as model proteins. The amount of adsorbed proteins increased over time at the early stage of adsorption (<2 h), regardless of glass composition and protein type. Further incubation of BGNs with protein-containing solutions seemed to induce a reduced amount of adsorbed proteins, which was more significant in BGNs with higher Ca content. The results indicate that the Ca content in BGNs is related to their protein adsorption behavior.

Hard carbon spheres prepared by a modified Stöber method as anode material for high-performance potassium-ion batteries

A modified Stöber method synthesizes resorcinol-formaldehyde resin-based secondary particle hard carbon spheres as anode material for high-performance potassium-ion batteries.

Development of a reusable fluorescent nanosensor based on rhodamine B immobilized in Stöber silica for copper ion detection

This work has the goal of developing and evaluating a reusable fluorescent nanosensor for detection of Cu(ii) ion in aqueous solution, based on the immobilization of rhodamine B in silica nanoparticles prepared according to a modified Stöber method.

Synthesis and Optical Characterizations of the Fluorescence Silica Nanoparticles Containing Quantum Dots

The quantum dots coated by silica is fluorescence material class with great biocompatibility, low toxicity and water-solubility, that is suitable for bioapplications. This work presents the synthesis of SiO2 coated CdTe/ZnSe (named CdTe) quantum dots (CdTe@SiO2 nanoparticles) via a wet chemmical route called modified Stöber method. The compounds tetraethylorthosilicate (TEOS) has used as precursors, aminopropyltriethoxysilane (APTES) is as electric neutralizer, and ammonium hydroxide is used as catalysts. The size of CdTe@SiO2 nanoparticles was estimated about 70 to 150 nm depending on the quantities of H2O, APTEOS, and catalysts. The emission behaviours of SiO2 coated quantum dots was effected by ratio of substances participating in the reaction and synthesis conditions. with the ratio (by volume) of suitable substances: TEOS:solution of QDs:NH4OH:APTES:H2O being 1.5:1.5x10-2:0.8x10-2:4x10-2:3x10-4:5x10-2, the prepared silica nanoparticles containing quantum dots show high fluorescence emission efficiency, the fluorescence intensity is higher than that of uncoated CdTe/ZnSe quantum dots. This is a positive result in the technique of manufacturing luminescent silica nanoparticles containing quantum dots. The results show an ability to use the CdTe@SiO2 nanoparticles for biological application.

Morphological and Structural Properties of Amino-Functionalized Fumed Nanosilica and Its Comparison with Nanoparticles Obtained by Modified Stöber Method

In industry, silica nanoparticles (NPs) are obtained by the fuming and the precipitation method. Fumed silica NPs are commonly used in the preparation of nanocomposites because they have an extremely low bulk density (160–190 kg/m3), large surface area (50–600 m2/g), and nonporous surface, which promotes strong physical contact between the NPs and the organic phase. Fumed silica has fewer silanol groups (Si–OH) on its surface than the silica prepared by the Stöber method. However, the number of –OH groups on the fumed silica surface can be increased by pretreating them with sodium hydroxide (NaOH) before further surface modification. In this study, the effectiveness of the NaOH pretreatment was evaluated on commercial fumed silica NPs with a surface area of 200 m2/g. The number of surface –OH groups was estimated by potentiometric titration. The pretreated fumed NPs, and the precipitated NPs (prepared by the Stöber method) were modified with 3-aminopropyltriethoxysilane (APTES) to obtain A200S and nSiO2-APTES, respectively. The NPs were characterized using electron dispersive scanning (EDS), scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), BET (Brunauer–Emmett–Teller) analysis, and ζ-potential. XRD confirmed the presence of the organo-functional group on the surface of both NPs. After the amino-functionalization, the ζ-potential values of the nSiO2 and A200 changed from −35.5 mV and −14.4 mV to +26.2 mV and +11.76 mV, respectively. Consequently, we have successfully synthesized functionalized NPs with interesting, specific surface area and porosity (pore volume and size), which can be attractive materials for chemical and energy industries.

Improving Interaction at Polymer–Filler Interface: The Efficacy of Wrinkle Texture

One of the main issues in preparing polymer-based nanocomposites with effective properties is to achieve a good dispersion of the nanoparticles into the matrix. Chemical interfacial modifications by specific coupling agents represents a good way to reach this objective. Actually, time consuming compatibilization procedures strongly compromise the sustainability of these strategies. In this study, the role of particles’ architectures in their dispersion into a poly-lactic acid matrix and their subsequent influences on physical-chemical properties of the obtained nanocomposites were investigated. Two kinds of silica nanoparticles, “smooth” and “wrinkled,” with different surface areas (≈30 and ≈600 m2/g respectively) were synthesized through a modified Stöber method and used, without any chemical surface pre-treatments, as fillers to produce poly-lactic acid based nanocomposites. The key role played by wrinkled texture in modifying the physical interaction at the polymer-filler interface and in driving composite properties, was investigated and reflected in the final bulk properties. Detailed investigations revealed the presence of wrinkled nanoparticles, leading to (i) an enormous increase of the chain relaxation time, by almost 30 times compared to the neat PLA matrix; (ii) intensification of the shear-thinning behavior at low shear-rates; and (iii) slightly slower thermal degradation of polylactic acid.

Structural combination of polar hollow microspheres and hierarchical N-doped carbon nanotubes for high-performance Li–S batteries

Herein, unique and novel structured microspheres with a porous SiO2 layer as a shell and well-aligned inner-grown N-doped CNTs comprising CoFe2 nanocatalyst alloy were synthesized by a modified Stöber method and chemical deposition.

Mn0.2Co0.8Fe2O4 and encapsulated Mn0.2Co0.8Fe2O4/SiO2 magnetic nanoparticles for efficient Pb2+ removal from aqueous solution

Sol-gel auto-combustion technique was used to synthesize spinel ferrite nanoparticles of Mn0.2Co0.8Fe2O4 (MCF). Using the modified Stöber method, these magnetic nanoparticles were encapsulated with silica to form the core/shell Mn0.2Co0.8Fe2O4/SiO2 (MCFS). The phase composition, morphology, particle size, and saturation magnetization of the encapsulated nanoparticles were studied using X-ray diffraction (XRD), high resolution-transition electron microscopy (HR-TEM), and vibrating sample magnetometer (VSM). HR-TEM images indicated that particle size of the nanoparticles ranged from 15 to 40 nm, and VSM measurements showed that Ms of uncoated and coated samples were 65.668 emu/g and 61.950 emu/g and the Hc values were 2,151.9 Oe and 2,422.0 Oe, respectively. The effects of metal concentration, solution pH, contact time, and adsorbent dose of the synthesized nanoparticles on lead (Pb2+) ions removal from an aqueous solution were investigated. Based on Langmuir isotherm model, the results for peak adsorption capacity of the adsorbent under optimal conditions was 250.5 mg/g and 247 mg/g for MCF and MCFS, respectively. We concluded that Pb2+ adsorption occurred via a chemisorption mechanism based on the analysis of adsorption kinetics. The adsorbents displayed consistent adsorption efficiencies following three cycles of regeneration, indicating that these magnetic nanoparticles are promising candidates for wastewater purification.