Narrow Results

Nano-selenium is ideal for selenium source materials in the fields of selenium-enriched fertilizer. However, existing nano-seleniums often suffer from low chemical stability and dispersity, limiting their widespread use. Here, a novel mesoporous Se NPs@SiO₂ nanoparticle with high dispersity is synthesized by the Stober method. The application of Se NPs@mSiO₂ nanoparticles for selenium-enriched fertilizer in Pleurotus geesteranus planting is reported. Compared with Na₂SeO₃ and Se nanoparticles, Se NPs@mSiO₂ selenium source material can enhance the stability and dispersity of Se NPs in NPK ternary compound fertilizer. Mesoporous silica-coated selenium nanoparticles also increased the adsorption of Se on plant leaves, and long-term stability for plant selenium supplements. Moreover, these Se NPs@mSiO₂ selenium source materials enable promote growth and selenium-enriched performance of P. geesteranus by high bioactivity. Implementation of core–shell structure selenium source material significantly reduces nano-selenium dose and hence cytotoxicity, providing a paradigm for promoting growth and selenium-enriched performance of plants.

Mesoporous silica composites filling densely peptide assemblies (Proteosilica) were newly synthesized as transparent films. Spiropyran guest was co-doped in the films and photo-isomerization between spiropyran form and merocyanine form was repeated by alternate irradiation of visible and UV lights. Circular dichroism (CD) active spectra were observed only for the spiropyran form in the Proteosilica with hexagonal geometry. However, the CD active behavior was absent for the spiropyran in lamellar Proteosilica. Difference in peptide assembling structures would affect chiral sensitivity of the doped spiropyran guest.

Mono- and bimetallic nanowires and particles were selectively synthesized in mesoporous silica templates, in which siliceous FSM-16 and organic–inorganic hybrid HMM-1 were used as templates. The metal nanowires and particles were characterized by several physicochemical methods. The mechanism for formation of Pt wires was studied, and migration of precursor Pt ions in the mesoporous channels is the key to the formation of the wires. The Pt wires can be isolated by dissolving silicate matrix in a good yield, and STM and HRTEM demonstrate that the wires extracted from HMM-1 has a nanonecklace structure, but the wire from FSM-16 shows a nanorod structure. The extracted Pt wires are stabilized by PPh₃. The nanowire composites show unique properties in magnetism and high catalytic performances in CO oxidation reaction.

Experimental conditions that govern the double-wall carbon nanotube (DWNT) growth during alcohol catalytic chemical vapor deposition (CCVD) have been optimized for mesoporous silica (MCM41) support materials. Catalyst pretreatment and preparation methods influence the quality of as-grown carbon nanotubes (CNTs). Catalyst pretreatment at low pressure leads to high-quality CNTs concomitant with an increase in the DWNT yield. Impregnation of metal precursors using methanol as the solvent is found to be more suitable than the aqueous solution. Influence of the precursor anion/metal ion on the DWNT yield is also studied under these optimized conditions. Thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and Raman spectroscopic methods have been employed to estimate the quality of the CNTs. It is observed that the present optimized method yields high-quality DWNTs with low amounts of side-wall defects and other carbon impurities.

Carbon nanotubes with 1–6 walls have been grown on cobalt-loaded mesoporous silica (i.e., MCM41) by using acetylene catalytic chemical vapor deposition. It is found that titanium grafting on the MCM41 pore walls prior to cobalt loading promotes the growth of nanotubes with 1–6 walls. As-grown nanotube material is found to be a mixture of single-wall carbon nanotubes (SWNTs), double-wall carbon nanotubes (DWNTs) and thin-multiwall carbon nanotubes (t-MWNTs) with 3–6 walls. Annealing of the as-grown nanotubes has reduced the amount of SWNTs in the nanotube mixture. Several structural deformations of the t-MWNTs are observed during transmission electron microscopy (TEM) analysis. Complete or partial collapse of the t-MWNTs is also found due to these structural deformations. Graphite-like domains developed at the collapsed regions stabilize these structural deformations.

Nickel nanoparticles embedded in mesoporous silica (Ni/SiO${}_2)$ were successfully synthesized by microwave-assisted in situ self-assembly method using colloidal silica, urea and nickel nitrate as precursors and glucose as carbon template, which resulted in mesoporous structure of silica through removal of template. Ni nanoparticles were uniformly well-dispersed within mesoporous silica, which were 3.5–4.0nm in diameter and had a very narrow particle size distribution. In addition, particle size of Ni nanoparticles can be controllably adjusted by microwave power. As-prepared Ni/SiO₂ catalyst exhibited better catalytic activity for reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) than Ni/SiO₂-IM catalyst, which was mainly attributed to confinement effect of mesoporous silica support. This simple and versatile method can also be extended to cover many kinds of other supported catalysts for broad applications in many other catalytic reactions in the future.

A mesoporous silica bearing uniformly distributed copper oxide nanoparticles (CuO@mesoporous SiO₂) was prepared through silica nanocasting copper metal organic frameworks (MOFs) followed by calcination. The nanocasting filled the micropores of MOFs with silica and then, the calcination removed the organic linker in MOFs and converted copper metal ions into CuO particles, resulting in the CuO@mesoporous SiO₂ architecture. The characterization results indicated that the final product basically maintained the original MOF morphology and the mesoporous silica effectively prevented the aggregation of nanoparticles. In addition, the CuO@mesoporous SiO₂ exhibited a superior activity for catalyzing the oxidation of styrene, which could be attributed to the fact that the dispersed CuO particles in mesoporous silica provided more accessible catalytic sites and better stability. This work provides a new strategy to prepare nanoparticles@mesoporous silica with adjustable morphology structure, which has a promising potential in the field of heterogeneous catalysis.

Developing heterogeneous metal nanocatalysts is highly desirable since the catalyst can be easily separated and reused for several times. In this manuscript, we have immobilized gold nanoparticles (AuNPs) on the surface of mesoporous silica (SiO${}_2)$ using simple amino acid-based phenolic chelating molecules and utilized as highly reusable catalyst for nitroarene reduction. The synthesized nanocomposites (Au@SiO₂-1 and Au@SiO₂-2) have been unambiguously confirmed using powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), high resolution-transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). Interestingly, Au@SiO₂-1 exhibited highly enhanced 4-nitrophenol reduction that was studied using absorption spectroscopy. Further catalytic activity of Au@SiO₂-1 was also explored for 2-nitroaninline and 4-nitroaniline. The reusable studies demonstrated that the catalyst did not show significant change in the activity up to ten cycles. After catalytic reactions studies confirmed the strong attachment of AuNPs on the SiO₂ matrix.

The biodegradability of inorganic nanocarriers is one of the most critical issues in their further clinical translations. In this work, a manganese-doped approach was developed to endow inorganic mesoporous silica (SiO₂) nanospheres with pH-sensitive biodegradation. Manganese-doped mesoporous silica nanospheres (MMS) were prepared by in-situ doping method, with a particle diameter of 160–175 nm and pore diameter of 3–5nm by characterization of N₂ adsorption method, powder X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectrum, field emission scanning electron microscope and transmission electron microscope techniques. Quercetin was used as the model drug to load, and MMS loaded with quercetin (MMS–QUE) was surface-modified using a carboxymethyl chitosan (MMS–QUE–CMCS) to prevent quercetin leakage. Based on the dissolution characteristics of manganese ions and the swelling behavior of carboxymethyl chitosan, the MMS–QUE–CMCS could be degraded in response to acid. The MMS–QUE–CMCS delivery system exhibited a good pH-responsive release. The cytotoxicity test showed that the MMS–QUE–CMCS had a significant biocompatibility and an enhanced cytotoxicity, thus revealing that the MMS–QUE–CMCS was a promising delivery system.

Electrochemistry has been introduced as a powerful tool in order to prepare new organometallic reagents for functionalizing of mesoporous silica. Preparation of the reagents was based on electrochemical oxidation of dihydroxybenzene derivatives in the presence of 3-(trimethoxysilyl)-1-propanethiol as a nucleophile. The mechanisms of electrochemical reactions were studied by voltammetric studies. Mesoporous silica SBA-15 was also synthesized in this work through sol-gel hydrothermal method using Genapol PF-10 as structure directing compound. The prepared mesoporous silica was characterized by FT-IR analysis and Barrett–Joiner–Halenda (BJH) pore size and Brunauer–Emmett–Teller (BET) surface area measurement methods using N₂ adsorption–desorption isotherm. Finally, the organometallic reagent was covalently grafted on the surface of mesoporous silica. Functionalizing of this material with the new reagent was confirmed by Fourier transform infrared (FT-IR) spectroscopy. The functionalized mesoporous silica by new reagent can be utilized in biological applications.

In this paper, free-radical polymerization inside magnetic mesoporous silica has been investigated in order to open a route to functional polymer–silica composite nanomaterials with well-defined mesoporosity. Proline monomers integrated with chitosan (CS) were electropolymerized into amino-functionalized magnetic mesoporous silica. The fabrication of polyproline-amino-functionalized magnetic mesoporous silica–CS nanohybrid on glassy carbon electrode (GCE) was performed using one step electrodeposition regime. Field emission scanning electron microscopy (FE-SEM) was confirmed as produced nanohybrid material containing polyproline (PPR) into the pores of magnetic (Fe₃O${}_4)$ mobile crystalline material-41 grafted with 3-aminopropyl groups (MMS) which leads to increase of surface coverage of PPR. The results indicate that PPR was successfully generated inside the pores of the amino-functionalized Mobil Composition of Matter No. 41 (nPrNH₂-MCM-41) and that the amine group was capable of protonating the polymer, producing polyproline, the most conductive one, without the addition of another acid source during the polymerization step. Therefore, it was evaluated some electrochemical aspects of the prepared nanohybrid using cyclic voltammetry, differential pulse voltammetry and linear sweep voltammetry. Finally, the electroactivity of polyproline -Fe₃O₄-nPrNH₂-MCM-41-chitosan nanohybrid (PPR-MMS-CS) modified GCE toward detection and determination of some clinically relevant small biomolecules was studied.

Mesoporous silica composites filling densely peptide assemblies (Proteosilica) were newly synthesized as transparent films. Spiropyran guest was co-doped in the films and photoisomerization between spiropyran form and merocyanine form was repeated by alternate irradiation of visible and UV lights. Circular dichroism (CD) active spectra were observed only for the spiropyran form in the Proteosilica with hexagonal geometry. However, the CD active behavior was absent for the spiropyran in lamellar Proteosilica. Difference in peptide assembling structures would affect chiral sensitivity of the doped spiropyran guest.