We demonstrate a facile wet chemical approach for fabricating spherical metal/metal‐oxide core@mesoporous silica shell hybrid nanoparticles with different core and shell thicknesses. Vertically aligned mesoporous silica (mSiO2) shells were fabricated over the pre‐synthesized spherical SiO2 nanoparticles through a three‐step strategy: 1) synthesis of core materials, 2) covering the core with an organic–inorganic composite layer, and 3) removing the organic template through calcinations in air. The mechanisms of hybrid structure formation are proposed. The multifunctional nature of the hybrid structures could be induced by incorporating guest ions/molecules, such as Ag, Mn, and TiO2, into the pores of an mSiO2 shell. Mn and TiO2 cluster‐ incorporated composite structures have been tested to be antioxidizing agents and effective photocatalysts through electron spin resonance, radical scavenging tests, and the photocatalytic degradation of rhodamine B. The possibility of incorporating several hetero‐element guest clusters in these mesoporous composite particles makes them highly attractive for multifunctional applications. 相似文献
A facile, reproducible, and scalable method was explored to construct uniform Au@poly(acrylic acid) (PAA) Janus nanoparticles (JNPs). The as‐prepared JNPs were used as templates to preferentially grow a mesoporous silica (mSiO2) shell and Au branches separately modified with methoxy‐poly(ethylene glycol)‐thiol (PEG) to improve their stability, and lactobionic acid (LA) for tumor‐specific targeting. The obtained octopus‐type PEG‐Au‐PAA/mSiO2‐LA Janus NPs (PEG‐OJNP‐LA) possess pH and NIR dual‐responsive release properties. Moreover, DOX‐loaded PEG‐OJNP‐LA, upon 808 nm NIR light irradiation, exhibit obviously higher toxicity at the cellular and animal levels compared with chemotherapy or photothermal therapy alone, indicating the PEG‐OJNP‐LA could be utilized as a multifunctional nanoplatform for in vitro and in vivo actively‐targeted and chemo‐photothermal cancer therapy. 相似文献
Chitosan exhibits great versatility in various biomedical fields and mesoporous silica nanoparticles have emerged as an interesting material in biomedical areas owing to their outstanding physio-chemical properties. The combination of inorganic silica and organic polymer such as chitosan, make them suitable for a wide range of biomedical applications. Here, we have explored the benefits of chitosan and silica by synthesizing chitosan-silica nanohybrid. In the synthesis of chitosan-silica (CS–Si) nanohybrid, chitosan is modified by thioglycolic acid and mesoporous silica MCM-41(Mobil Composition of Matter number 41) is functionalized by 3-(trimethoxysilyl)-1-propane thiol (TMSP). The modified chitosan and thiol functionalized MCM-41(inorganic network) is then linked through disulfide bond by oxidation process or oxidative coupling, resulting in the formation of inorganic-organic hybrid material. The hybrid material was characterized by FTIR, Raman, XRD, TGA, Zeta potential, EDX, Proton NMR and SEM techniques. The antibacterial results indicated that gram-negative (E. coli) bacteria exhibit better inhibition zone than gram-positive (B. subtilis) bacteria. The DPPH scavenging capability of synthesized hybrid was found to be 68%. The drug (quercetin) encapsulation efficiency of hybrid material was calculated to be 92.38% and more drug releases in acidic medium (pH 5.0) than at pH 7.4, so we can conclude that hybrid material shows pH-dependent drug releasing behavior. The results show that synthesized nano-hybrid material possess good antibacterial and antioxidant activities and is also a good nanocarrier for drug delivery application. 相似文献
A novel sandwich‐type electrochemiluminescence (ECL) immunosensor was developed to enable the sensitive detection of HIV‐1 antibodies. This system incorporated mesoporous silica (mSiO2) complexed with quantum dots (QDs) and nano‐gold particles, which were assembled to enhance signal detection. Magnetic beads were used by immobilizing the secondary anti‐IgG antibody. This was first employed to capture HIV‐1 antibody (Ab) to form a Fe3O4/anti‐IgG/Ab complex. A high loading and signal‐enhanced nanocomposite (hereafter referred to as Au‐mSiO2‐CdTe) was used as a HIV‐1 antigen label. The Au‐mSiO2‐CdTe nanocomposite was conjugated with the Fe3O4/anti‐IgG/Ab complex to form an immunocomplex (hereafter referred to as Fe3O4/anti‐IgG/Ab/HIV‐1/CdTe‐mSiO2‐Au). This complex could be further separated by an external magnetic field to produce ECL signals. Due to the large specific surface area and pore volume of mSiO2, the loading of the CdTe QDs was markedly increased. Thus, the loaded QDs released a powerful chemiluminescent signal with a concordantly increased sensitivity of the immunosensor. The immunosensor was highly sensitive, and displayed a linear range of responses for HIV‐1 antibody across a dilution range of 1 : 1500 through 1 : 50 with the detection limit of 1 : 4500. The immunoassay can be a promising candidate in early diagnosis of HIV infection. 相似文献
The surface modification of mesoporous silica monoliths through thiol–ene chemistry is reported. First, mesoporous silica monoliths with vinyl, allyl, and thiol groups were synthesized through a sol–gel hydrolysis–polycondensation reaction from tetramethyl orthosilicate (TMOS) and vinyltriethoxysilane, allyltriethoxysilane, and (3‐mercaptopropyl)trimethoxysilane, respectively. By variation of the molar ratio of the comonomers TMOS and functional silane, mesoporous silica objects containing different amounts of vinyl, allyl, and thiol groups were obtained. These intermediates can subsequently be derivatized through radical photoaddition reactions either with a thiol or an olefin, depending on the initial pore wall functionality, to yield silica monoliths with different pore‐wall chemistries. Nitrogen sorption, small‐angle X‐ray scattering, solid‐state NMR spectroscopy, elemental analysis, thermogravimetric analysis, and redox titration demonstrate that the synthetic pathway influences the morphology and pore characteristics of the resulting monoliths and also plays a significant role in the efficiency of functionalization. Moreover, the different reactivity of the vinyl and allyl groups on the pore wall affects the addition reaction, and hence, the degree of the pore‐wall functionalization. This report demonstrates that thiol–ene photoaddition reactions are a versatile platform for the generation of a large variety of organically modified silica monoliths with different pore surfaces. 相似文献
In this study, a carbon‐controllable hierarchical micro/mesoporous carbon–silica material derived from agricultural waste rice husk was easily synthesized and utilized as filler in an epoxy matrix for electronic packaging applications. Scanning electron microscopy, thermogravimetric analysis, and N2 adsorption/desorption isotherms were used to characterize the morphology, thermal stability, carbon content, and porous structural properties, respectively, of the as‐obtained carbon–silica material, namely rice husk char (RHC ). As a filler material, the uniformly dispersed RHC filler in the epoxy/RHC composite was easily prepared through hydrogen bonding of the silanol group of silica with the epoxy matrix. For electronic packaging applications, the thermal conductivity and thermomechanical properties (storage modulus and coefficient of thermal expansion) of the epoxy/RHC composites improved with increasing carbon content. Moreover, loading of the 40% RHC filler substantially enhanced the storage modulus of the epoxy/RHC composite (5735 MPa ) compared to the epoxy with 40% commercial silica filler (3681 MPa ). Considerable commercial potential is expected for the carbon–silica composite because of the simple synthesis process and outstanding performance of the prepared packaging material. 相似文献
Three‐dimensional graphene‐supported mesoporous silica@Fe3O4 composites (mSiO2@Fe3O4‐G) were prepared by modifying mesoporous SiO2‐coated Fe3O4 onto hydrophobic graphene nanosheets through a simple adsorption co‐condensation method. The obtained composites possess unique properties of large surface area (332.9 m2/g), pore volume (0.68 cm3/g), highly open pore structure with uniform pore size (31.1 nm), as well as good magnetic separation properties. The adsorbent (mSiO2@Fe3O4‐G) was used for the magnetic solid‐phase extraction of seven pesticides with benzene rings in different aqueous samples before high‐performance liquid chromatography. The main parameters affecting the extraction such as adsorbent amount, volume of elution solvent, time of extraction and desorption, salt effect, oscillation rate were investigated. Under the optimal conditions, this method provided low limits of detection (S/N = 3, 0.525–3.30 μg/L) and good linearity (5.0–1000 μg/L, R2 > 0.9954). Method validation proved the feasibility of the developed adsorbent, which has a high extraction efficiency and excellent enhancement performance for pesticides in this study. The proposed method was successfully applied to real aqueous samples, and satisfactory recoveries ranging from 77.5 to 113.6% with relative standard deviations within 9.7% were obtained. 相似文献
A novel mercaptotetrazole‐silica hybrid monolithic column was prepared for capillary liquid chromatography, in which the thiol‐end mercaptotetrazole was mixed with hydrolyzed γ‐methacryloxypropyltrimethoxysilane and tetramethyloxysilane for the co‐polycondensation and thiol‐ene click reaction in a one‐pot process. The effects of the molar ratio of silanes, the amount of mercaptotetrazole, and the volume of porogen on the morphology, permeability and pore properties of the as‐prepared mercaptotetrazole‐silica hybrid monoliths were investigated in detail. A series of test compounds including alkylbenzenes, amides and anilines were employed for evaluating the retention behaviors of the mercaptotetrazole‐silica hybrid monolithic columns. The results demonstrated that the mercaptotetrazole‐silica hybrid monoliths exhibited hydrophobic, hydrophilic as well as ion‐exchange interaction. The run‐to‐run, column‐to‐column and batch‐to‐batch reproducibilities of the mercaptotetrazole‐silica hybrid monoliths were satisfactory with the relative standard deviations less than 1.4 (n = 5), 3.9 (n = 3) and 4.0% (n = 5), respectively. In addition, the mercaptotetrazole‐silica hybrid monolith was further applied to the separation of sulfonamides, nucleobases and protein tryptic digests. These successful applications confirmed the promising potential of the mercaptotetrazole‐silica hybrid monolith in the separation of complex samples. 相似文献
Using heterogeneous basic catalysts has a great importance in chemical reactions because of their advantages (such as easy separation and thermal stability at harsh conditions) over homogeneous catalysts. In this study, magnetic mesoporous silica nanoparticles (mSiO2) containing graphitic carbon nitride layers (mSiO2/g-C3N4(x)) were fabricated through a facile process (x signifies the amount of melamine applied during synthesis). Graphitic carbon nitride layers were decorated on mSiO2 by calcination of immobilized melamine (as graphitic carbon nitride precursor) on mSiO2 in the last step of catalyst synthesis. The structure of the prepared catalysts was confirmed using XRD, BET, FESEM, EDX, elemental mapping and TEM methods. The catalytic efficiency of the so-obtained solid base composite was investigated for the synthesis of some dihydropyranochromenes and spiro-dihydropyranochromenes under thermal and microwave conditions. Using mSiO2/g-C3N4(x) led to high yields under green conditions and in short reaction times and without a decrease in catalytic activity after four consecutive cycles. 相似文献
1,3‐Diphenyl‐1,3‐propanepione (DBM)‐functionalized SBA‐15 and SBA‐16 mesoporous hybrid materials (DBM‐SBA‐15 and DBM‐SBA‐16) are synthesized by co‐condensation of modified 1,3‐diphenyl‐1,3‐propanepione (DBM‐Si) and tetraethoxysilane (TEOS) in the presence of Pluronic P123 and Pluronic F127 as a template, respectively. The as‐synthesized mesoporous hybrid material DBM‐SBA‐15 and DBM‐SBA‐16 are used as the first precursor, and the second precursor poly(methylacrylic acid) (PMAA) is synthesized through the addition polymerization reaction of the monomer methacrylic acid. These precursors then coordinate to lanthanide ions simultaneously, and the final mesoporous polymeric hybrid materials Ln(DBM‐SBA‐15)3PMAA and Ln(DBM‐SBA‐16)3PMAA (Ln=Eu, Tb) are obtained by a sol‐gel process. For comparison, binary lanthanide SBA‐15 and SBA‐16 mesoporous hybrid materials (denoted as Ln(DBM‐SBA‐15)3 and Ln(DBM‐SBA‐16)3) are also synthesized. The luminescence properties of these resulting materials are characterized in detail, and the results reveal that ternary lanthanide mesoporous polymeric hybrid materials present stronger luminescence intensities, longer lifetimes, and higher luminescence quantum efficiencies than the binary lanthanide mesoporous hybrid materials. This indicates that the introduction of the organic polymer chain is a benefit for the luminescence properties of the overall hybrid system. In addition, the SBA‐15 mesoporous hybrids show an overall increase in luminescence lifetime and quantum efficiency compared with SBA‐16 mesoporous hybrids, indicating that SBA‐15 is a better host material for the lanthanide complex than mesoporous silica SBA‐16. 相似文献
Thiol‐click reactions lead to polymeric materials with a wide range of interesting mechanical, electrical, and optical properties. However, this reaction mechanism typically results in bulk materials with a low glass transition temperature (Tg) due to rotational flexibility around the thioether linkages found in networks such as thiol‐ene, thiol‐epoxy, and thiol‐acrylate systems. This report explores the thiol‐maleimide reaction utilized for the first time as a solvent‐free reaction system to synthesize high‐Tg thermosetting networks. Through thermomechanical characterization via dynamic mechanical analysis, the homogeneity and Tgs of thiol‐maleimide networks are compared to similarly structured thiol‐ene and thiol‐epoxy networks. While preliminary data show more heterogeneous networks for thiol‐maleimide systems, bulk materials exhibit Tgs 80 °C higher than other thiol‐click systems explored herein. Finally, hollow tubes are synthesized using each thiol‐click reaction mechanism and employed in low‐ and high‐temperature environments, demonstrating the ability to withstand a compressive radial 100 N deformation at 100 °C wherein other thiol‐click systems fail mechanically.
Recently, a facile method for the synthesis of size‐monodisperse Pt, Pt3Sn, and PtSn intermetallic nanoparticles (iNPs) that are confined within a thermally robust mesoporous silica (mSiO2) shell was introduced. These nanomaterials offer improved selectivity, activity, and stability for large‐scale catalytic applications. Here we present the first study of parahydrogen‐induced polarization NMR on these Pt‐Sn catalysts. A 3000‐fold increase in the pairwise selectivity, relative to the monometallic Pt, was observed using the PtSn@mSiO2 catalyst. The results are explained by the elimination of the three‐fold Pt sites on the Pt(111) surface. Furthermore, Pt‐Sn iNPs are shown to be a robust catalytic platform for parahydrogen‐induced polarization for in vivo magnetic resonance imaging. 相似文献
Hydrophilic molecularly imprinted microspheres (MIP@SiO2) for the adsorption of water‐soluble molecules in real aqueous samples were successfully synthesized. In this strategy, a molecular imprinted polymer (MIP) was encapsulated in the hollow core of hollow mesoporous silica (HMS) particles via a ‘ship‐in‐a‐bottle’ process. As the HMS shell contains plenty of Si‐OH groups, the as‐prepared microspheres proved to be hydrophilic and could be well dispersed in water. On the other hand, the MIP encapsulated in the HMS could specifically recognize small molecules with good binding efficiency through the mesoporous silica shell. Binding experiments in real aqueous solutions showed that the MIP@SiO2 composites have excellent recognition ability for specific molecules. Thus, MIP@SiO2 are highly promising alternatives to biological receptors with great potential for many analytical applications, such as environmental, food, and clinical analyses and other areas. 相似文献
Hollow mesoporous SiO2 (mSiO2) nanostructures with movable nanoparticles (NPs) as cores, so‐called yolk‐shell nanocapsules (NCs), have attracted great research interest. However, a highly efficient, simple and general way to produce yolk‐mSiO2 shell NCs with tunable functional cores and shell compositions is still a great challenge. A facile, general and reproducible strategy has been developed for fabricating discrete, monodisperse and highly uniform yolk‐shell NCs under mild conditions, composed of mSiO2 shells and diverse functional NP cores with different compositions and shapes. These NPs can be Fe3O4 NPs, gold nanorods (GNRs), and rare‐earth upconversion NRs, endowing the yolk‐mSiO2 shell NCs with magnetic, plasmonic, and upconversion fluorescent properties. In addition, multifunctional yolk‐shell NCs with tunable interior hollow spaces and mSiO2 shell thickness can be precisely controlled. More importantly, fluorescent‐magnetic‐biotargeting multifunctional polyethyleneimine (PEI)‐modified fluorescent Fe3O4@mSiO2 yolk‐shell nanobioprobes as an example for simultaneous targeted fluorescence imaging and magnetically guided drug delivery to liver cancer cells is also demonstrated. This synthetic approach can be easily extended to the fabrication of multifunctional yolk@mSiO2 shell nanostructures that encapsulate various functional movable NP cores, which construct a potential platform for the simultaneous targeted delivery of drug/gene/DNA/siRNA and bio‐imaging. 相似文献