And 3-aminopropyltriethoxysilane Research Articles

Distinctive ligand effects of functionalized magnetic microparticles immobilizing palladium acetate as heterogeneous coordination catalysts for selective oxidation of styrene to acetophenone

A series of functionalized magnetic nanoparticles immobilizing palladium acetate with different ligands, including β-diketimine, Schiff base and (3-aminopropyl)triethoxysilane (APTES), were prepared by a facile surface modification method. These prepared heterogeneous coordination catalysts were characterized by TEM, XRD, FT-IR, VSM, XPS and ICP. Fe3O4@SiO2-β-diketimine was found to be an excellent scaffold for the immobilization of palladium acetate through the complexation between palladium acetate and nitrogen atoms (and oxygen atoms). Among the three catalysts, Fe3O4@SiO2-β-diketimine-Pd(OAc)2 with the highest steric hindrance exhibited extraordinary catalytic property to undergo Wacker type reaction with a high selectivity of 94% toward the formation of acetophenone in liquid phase using H2O2 as oxidant. Meanwhile, Fe3O4@SiO2-Schiff base-Pd(OAc)2 and Fe3O4@SiO2-APTES-Pd(OAc)2 afforded 49% and 32% selectivities of acetophenone, which were just a little higher than homogeneous Pd(OAc)2 (15%). Importantly, the proposed reaction mechanism of the styrene selective oxidation reactions by ligand immobilized Pd(OAc)2 catalyst was also inferred according to the distinctive catalytic activities of the three heterogeneous coordination catalysts and reported literatures. It could be concluded that the steric hindrance of the ligand probably played an important role in the selective oxidation of styrene, and big steric hindrance of the ligand probably was beneficial to form acetophenone. Furthermore, Fe3O4@SiO2-β-diketimine-Pd(OAc)2 revealed high efficiency and stability during recycling stages.

Effect of surface functionalisation on the interaction of iron oxide nanoparticles with polymerase chain reaction

The combination of nanoparticles with the polymerase chain reaction (PCR) can have benefits such as easier sample handling or higher sensitivity, but also drawbacks such as loss of colloidal stability or inhibition of the PCR. The present work systematically investigates the interaction of magnetic iron oxide nanoparticles (MIONs) with the PCR in terms of colloidal stability and potential PCR inhibition due to interaction between the PCR components and the nanoparticle surface. Several types of MIONs with and without surface functionalisation by sodium citrate, dextran and 3-aminopropyl-triethoxysilane (APTES) were prepared and characterised by Transmission Electron Microscopy (TEM), dynamic light scattering (DLS) and Fourier Transform Infrared (FT-IR) spectroscopy. Colloidal stability in the presence of the PCR components was investigated both at room temperature and under PCR thermo-cycling. Dextran-stabilized MIONs show the best colloidal stability in the PCR mix at both room and elevated temperatures. Citrate- and APTES-stabilised as well as uncoated MIONs show a comparable PCR inhibition near the concentration 0.1mgml−1 while the inhibition of dextran stabilized MIONs became apparent near 0.5mgml−1. It was demonstrated that the PCR could be effectively carried out even in the presence of elevated concentration of MIONs up to 2mgml−1 by choosing the right coating approach and supplementing the reaction mix by critical components, Taq DNA polymerase and Mg2+ ions.

Influence of functionalized mesoporous silica in controlling azathioprine drug release and cytotoxicity properties

The present study is focused on functionalisation of mesoporous silica (or SBA-15) to control azathioprine drug release rate and its toxic effect. The mesoporous silica was functionalised by (γ-chloropropyl)triethoxysilicane and (3-aminopropyl)triethoxysilane (APTES) via hydrothermal process. The azathioprine was loaded into SBA-15 via post impregnation method. Azathioprine-loaded pristine and functionalised SBA-15 samples were characterised using UV–visible spectrophotometry and thermogravimetric analysis to measure the drug loading efficiency. The samples were also characterised by small and wide-angle powder X-ray diffraction, scanning electron microscope, transmission electron microscope, infrared spectroscopy and nitrogen adsorption/desorption analysis to study the structure, morphology, functionalisation and drug loading in detail. The maximum drug loading efficiency of 65(±1)% was achieved. In vitro azathioprine release profiles were studied in phosphate buffered saline (pH 7.4) and results suggested that the drug release amount could be controlled by functionalisation of carrier matrix SBA-15. Azathioprine-loaded APTES-functionalised material revealed lowest release amount of ~64.5% in 60 h. The toxicity of azathioprine was significantly reduced by loading the drug into the mesoporous pristine and functionalised silica. The controlled azathioprine release reduced its repeated administration and can reduce its toxicity and side effects. These outcomes recommend that the functionalised SBA-15 is an advantageous drug carrier for achieving extended release time.

Twin Applications of Tetra-Functional Epoxy Monomers for Anticorrosion and Antifouling Studies

This paper reports the development and characterization of nano-hybrid coatings using tetraglycidyl 2,2-bis(4-(4-amine phenoxy)phenyl)propane (TGBAPPP) and 3-aminopropyltriethoxysilane (APTES) functionalized ZnO as nano-reinforcement. The nano-hybrid coatings were cured by aromatic and aliphatic curing agents. The effect of the ZnO-APTES and curing agents on the corrosion and fouling resistant properties of these coatings was studied by electrochemical impedance, antifouling tests and toxicity test. It shows the tetraglycidyl epoxy nano-hybrid coatings have a better set of coating properties when compared to di-functional epoxy nano-hybrid coatings. The best results were obtained for ZnO-APTES loaded TGBAPPP with curing agent Aradur 140. These observations clearly indicate the synergistic effect of curing agent and nano-reinforcing effect of ZnO-APTES towards corrosion resistance.

Mesoporous silica nanoparticles for efficient rivastigmine hydrogen tartrate delivery into SY5Y cells

Rivastigmine hydrogen tartrate (RT) is a molecule with both hydrophilic and hydrophobic properties used for the treatment of the Alzheimer’s disease. In this work, the larger pore size of mesoporous silica nanoparticles (P1-MSN) was synthesized and then, P1-MSN were functionalized by succinic anhydride (S-P1-MSN) and 3-aminopropyltriethoxysilane (APTES) (AP-CO-P1-MSN) using the grafting and co-condensation methods, respectively. A new method was used for the functionalization of P1-MSN by succinic anhydride at room temperature. Nanoparticles were characterized by special instrumental analysis and loaded by RT. Maximum entrapment efficiency and RT loading percentage into P1-MSN, AP-CO-P1-MSN and S-P1-MSN were respectively obtained as 21.26 and 25.5%, 41.5 and 49.8%, and 11.9 and 14.28% for 24 h. In the simulated gastric and body fluids, the release rate of RT-loaded AP-CO-P1-MSN (AP-CO-P1-MSN-RT) was lower than that of other RT-loaded nanoparticles. In oral pathway, the sustained release of RT was observed in AP-CO-P1-MSN-RT. Moreover, no cytotoxicity effect was observed for P1-MSN, but the cells treated by AP-CO-P1-MSN showed a reduction in SY5Y cell viability due to easy entrance of these nanoparticles and their accumulation in different parts of the cell as observed by TEM.

A novel fabrication of a high performance SiO2-graphene oxide (GO) nanohybrids: Characterization of thermal properties of epoxy nanocomposites filled with SiO2-GO nanohybrids

In this study it has been aimed to enhance the thermal resistance of epoxy coating through incorporation of SiO2-GO nanohybrids. SiO2-GO nanohybrids were synthesized through one-step sol-gel route using a mixture of Tetraethylorthosilane (TEOS) and 3-Aminopropyl triethoxysilane (APTES) silanes. The SiO2-GO nanohybrids were prepared at various hydrolysis times of 24, 48 and 72h. Then 0.2wt.% of GO and SiO2-GO nanohybrids were separately incorporated into the epoxy coating. Results revealed that amino functionalized SiO2 nanoparticles with particle size around 20–30nm successfully synthesized on the basal plane of GO. Results showed significant improvement of dispersion and interfacial interactions between nanohybrids and epoxy composite arising from covalent bonding between the SiO2-GO and the epoxy matrix. It was found that the thermal resistance of SiO2-GO nanohybrids and SiO2-GO/Epoxy nanocomposite was noticeably higher than GO and epoxy matrix, respectively.

Easily recyclable and highly active rice roll-like Au/SiO2 nanocatalysts from inverse miniemulsion

Rice roll-like (RR-like) Au/SiO2 nanocatalysts (NCs) were synthesized through simultaneous sol–gel process of tetramethoxysilane and 3-aminopropyltriethoxysilane (APTES) and in situ reduction of gold salt in inverse miniemulsions. APTES played an important role in formation of RR-like SiO2 nano-supports, reduction of gold salts to narrowly size-distributed sub–10nm Au nanoparticles (NPs), and improved attachment of Au NPs to the SiO2 nano-supports. The prepared RR-like Au/SiO2 NCs displayed a pH-dependent, reversible colloidal stability in water, which facilitated to recycle them through tuning the pH value of the dispersion. Most importantly, the catalytic activity of the RR-like Au/SiO2 NCs towards reduction of p-nitrophenol was about 7–9 times higher than that of the raspberry-like Au/SiO2 NCs reported in our previous paper (Colloids Surf. A, 489, 2016, 223–233). The formation mechanism of the RR-like Au/SiO2 NCs was also discussed.

Preparation and Characterization of Modified Silica-Epoxy Hybrid Ceramic Coatings

Hybrid sol-gel processing of inorganic-organic nanocomposites has been of a great interest over the last decades for being advantageous compared to the conventional addition methods of nanoparticles. In this study, a three-component system was adopted experiencing the design and preparation of different hybrid ceramic coatings based on Diglycidyl ether of Bisphenol A (Epoxy) and 3-Glycidyloxypropyl trimethyloxysilane (GLYMO) by sol-gel technique. The obtained hybrid coatings were cured using different hardeners, Diethylene triamine (DETA) as an organic linker and 3-Aminopropyl triethoxysilane (APTES) as an inorganic/organic linker. Microstructure assessment and the morphology of the prepared hybrids was investigated using FTIR and scanning electron microscopy (SEM) respectively. Mechanical properties (adhesion, and hardness) were determined. The degree of hydrophilicity of the hybrids was assigned depending on the contact angle measurements. Moreover, the thermal properties were investigated using thermogravimetric analysis (TGA). The results showed that the silica content plays an important role in determining the morphology as well as the mechanical, physical, and thermal properties of the coatings. The results showed an improvement in most of the properties of the hybrid coatings with increasing the silica content up to a certain extent. However, further increase in the silica content, leads to a clear deterioration.

Synthesis of quaternized chitosan-coated magnetic nanoparticles for oil-water separation

In this letter, we reported successful development of a class of novel quaternized chitosan (QC)-coated magnetic nanoparticles (MNPs) for oil-water separation. Fe3O4 MNPs were coated with silica and 3-aminopropyltriethoxysilane (APTES), followed by QC grafting to yield QC-coated MNPs. Results showed that Fe3O4 and Fe3O4@SiO2 MNPs exhibited negligible oil-water separation effect and APTES coating onto Fe3O4@SiO2 MNPs could only improve its separation efficiency under acidic condition. However, QC-coated MNPs not only exhibited excellent oil-water separation performance at various pH levels, but also could be reused up to 8 times without showing significant decrease in separation efficiency. Results suggested QC-coated MNP could potentially be used as a class of promising materials for oil-water separation.

Biosilica from Living Diatoms: Investigations on Biocompatibility of Bare and Chemically Modified Thalassiosira weissflogii Silica Shells.

In the past decade, mesoporous silica nanoparticles (MSNs) with a large surface area and pore volume have attracted considerable attention for their application in drug delivery and biomedicine. Here we propose biosilica from diatoms as an alternative source of mesoporous materials in the field of multifunctional supports for cell growth: the biosilica surfaces were chemically modified by traditional silanization methods resulting in diatom silica microparticles functionalized with 3-mercaptopropyl-trimethoxysilane (MPTMS) and 3-aminopropyl-triethoxysilane (APTES). Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses revealed that the –SH or –NH2 were successfully grafted onto the biosilica surface. The relationship among the type of functional groups and the cell viability was established as well as the interaction of the cells with the nanoporosity of frustules. These results show that diatom microparticles are promising natural biomaterials suitable for cell growth, and that the surfaces, owing to the mercapto groups, exhibit good biocompatibility.

Acid-base high temperature proton exchange membranes prepared from phosphonic acid functionalized siloxane

One kind of acid-base high temperature proton exchange membranes has been prepared from amino trimethylene phosphonic acid (ATMP), epoxycyclohexyethyltrimethoxysilane (EHTMS), and 3-aminopropyltriethoxysilane (APTES) by sol-gel process. The structural characteristics of these membranes with different amount of APTES were investigated by FT-IR, XRD, and SEM. These membranes showed excellent dimensional stability in water with the contribution of flexible ionic network structure and were thermally stable up to about 200 °C. In addition, the proton conductivity of the membranes increased with increasing temperature over the range of 20 to 140 °C, up to a maximum of 2.63 × 10−2 S cm−1 at 140 °C under anhydrous condition. The high proton conductivity was attributed to the formation of hydrogen bond network through the synergistic effect of N and P. The activation energy value of membranes became lower from 0.46 to 0.30 eV because of the acid-base pairs. The variable-temperature FT-IR further proved the formation of hydrogen bond network in the membrane.

Synthesis and stability of IR-820 and FITC doped silica nanoparticles

Fluorescent silica nanoparticles (NPs) have potential in biomedical applications as diagnostics and traceable drug delivery agents. In this study, we have synthesized fluorescent dye grafted silica NPs in two step process. First, a stable method to synthesize various sizes of silica NPs ranging from 20 to 52, 95, 210 and 410nm have been successfully demonstrated. Secondly, as-synthesized silica NPs are readily grafted with some fluorescent dyes like IR-820 and fluorescein isothiocyanate (FITC) dyes by simple impregnation method. IR-820 and FITC dyes are ‘activated’ by (3-mercaptopropyl)trimethoxysilane (MPTMS) and (3-aminopropyl)triethoxysilane (APTS) respectively prior to the grafting on silica NPs. UV–vis spectroscopy is used to test the stability of dye grafted silica NPs. The fluorescent dye grafted silica NPs are quite stable in aqueous solution. Also, a new type of dual dye-doped hybrid silica nanoparticles has been developed. The combination of microscopic and spectroscopic techniques shows that the synthesis parameters have significant effects on the particle shape and size and is tuneable from a few nanometers to a few hundred nanometers. The ability to create size controlled nanoparticles with associated (optical) functionality may have significant importance in bio-medical imaging.

The chemiluminescence immunoassay for aflatoxin B1 based on functionalized magnetic nanoparticles with two strategies of antigen probe immobilization.

A rapid and sensitive chemiluminescence immunoassay (CLIA) based on magnetic nanoparticles (MNPs) was developed to detect aflatoxin B1 (AFB1), which is a potent carcinogen in nature. We prepared monodisperse MNPs (300nm in diameter) according to the solvothermal synthesis reaction and the MNPs were coated with silica by the Stöber method. Triethox was used as a one-step carboxylation reagent, and 3-aminopropyltriethoxysilane (APTES) an amination reagent, to modify the MNPs. We prepared two types of solid phase antigens using the above synthesized functionalized MNPs coupled with the later prepared AFB1-oxime active ester and the purchased BSA-AFB1 respectively. 2',6'-dimethylcarbonylphenyl-10-sulfopropylacridinium-9-carboxylate 4'-N-hydroxysuccinimide (4'-NHS) ester (NSP-DMAE-NHS), as a novel luminescent reagent, was used to label anti-AFB1 antibodies. The two CLIA calibration curves based on the two types of solid phase antigens were obtained and compared. The acquired limit of detection (LOD) was about 0.001ng/mL for the two functionalized MNPs-based immunoassays, and the half maximal inhibitory concentration (IC50 ) was 0.51ng/mL for the MNPs-AFB1-based method and 0.72ng/mL for the MNPs-BSA-AFB1-based method.

Selective external surface functionalization of large-pore silica materials capable of protein loading

Differentiating the chemical properties of the external and pore surfaces of sol-gel derived mesoporous materials by selective functionalization is important to advancing their application as platforms for biological catalysis, sensing and drug delivery. Prior selective functionalization approaches to concentrating functional groups at the external surface of particles have been limited to small pores (≤5.5 nm diameter) incapable of loading large biological molecules. This work investigates the selective exterior surface functionalization by amines of larger-pored (>7 nm diameter) mesoporous silica particles, which are synthesized by dual surfactant templating and hydrothermal aging. Previously developed selective functionalization techniques rely on choice of functionalization precursor, functionalization reaction time, or pore blocking (by leaving pore templates in as-synthesized materials). The effectiveness of these strategies are compared for larger-pored materials using the precursors (3-aminopropyl)tris(methoxyethoxyethoxy)silane (APTMEES) and (3-aminopropyl)triethoxysilane (APTES). The extent of amine functionalization is determined as a function of precursor reaction time (10 or 20 min) in both as-synthesized and template-extracted materials by confocal laser scanning microscopy of the ∼10 μm diameter particles tagged with fluorescein isothiocyanate. Reaction time, regardless of pore template presence, is demonstrated to be the controlling variable for achieving selective exterior functionalization in these larger pored mesoporous materials. Under the conditions used, 10 min of functionalization with APTMEES localizes amine groups at the exterior of the particles, while 20 min functionalizes both the exterior and the interior pore surfaces. Protein accessibility within pores, before and after selective and full functionalization, is visually confirmed by confocal fluorescence imaging of Rhodamine B tagged lysozyme loaded particles.

Functionalization of Tungsten Disulfide Nanotubes with a Conformal Humin‐Like Shell

Nanostructures of transition metal dichalcogenides (TMDs) exhibit excellent tribological and mechanical properties. These properties account for the intensive study of their use as additives to polymeric matrices. Functionalization of TMD nanostructures with organic chemical moieties has not yet been widely researched. Functionalization of this nature improves the ability to integrate TMD nanostructures in such matrices. In this paper, a new method for the functionalization of WS2 inorganic nanotubes (INTs) with a conformal humin‐like shell in different thicknesses is presented. The method is based on Lewis acid‐activated thioglycosylation chemistry between the nanotube surface and the carbohydrate unit. It is shown that shell thickness can be controlled by adjusting the sugar concentration. A reaction between the functionalized nanotubes and 3‐aminopropyl‐triethoxysilane (APTES), an amine‐terminated silicate, for the addition of different surface functionalities is proposed. This pathway should help improve and expand the range of TMD nanostructure applications.

Photodetectors: Broad Detection Range Rhenium Diselenide Photodetector Enhanced by (3‐Aminopropyl)Triethoxysilane and Triphenylphosphine Treatment (Adv. Mater. 31/2016)

The effects of triphenylphosphine (PPh3 ) and (3-amino-propyl)triethoxysilane (APTES) on a rhenium diselenide (ReSe2 ) photodetector are systematically studied by J.-H. Park and co-workers on page 6711 in comparison with a conventional MoS2 device. A very high performance ReSe2 photodetector is demonstrated, which has a broad photodetection range, high photoresponsivity (1.18 × 10(6) A W(-1) ), and fast photoswitching speed (rising/decaying time: 58/263 ms).

Temperature Dependent Thermal Conductivity and Thermal Interface Resistance of Pentacene Thin Films with Varying Morphology

Temperature dependent thermal conductivities and thermal interface resistances of pentacene (Pn) thin films deposited on silicon substrates and self-assembled monolayer-modified [octadecyltrichlorosilane (OTS) and (3-aminopropyl)triethoxysilane (APTES)] silicon substrates were measured using frequency domain thermoreflectance. Atomic force microscopy images were used to derive an effective film thickness for thermal transport that accounts for surface roughness. Data taken over a temperature range of 77-300 K for various morphologies and film thicknesses show that the thermal conductivity increases with increasing Pn grain size. The sum of the substrate-Pn and Pn-gold thermal interface resistances was isolated from the intrinsic thermal resistance of the Pn films and found to be independent of surface chemistry. Corresponding Kapitza lengths of approximately 150 nm are larger than the physical thicknesses of typical Pn thin films and indicate that the interfaces play a dominant role in the total thermal resistance. This study has implications for increasing the performance and effective thermal management of small molecule electronic and energy conversion devices.

Synthesis of strongly fluorescent carbon quantum dots modified with polyamidoamine and a triethoxysilane as quenchable fluorescent probes for mercury(II)

This article reports on the synthesis of water dispersible carbon quantum dots (CDs) by a one-step hydrothermal method using polyamidoamine (PAMAM) and (3-aminopropyl)triethoxysilane (APTES) as a platform and passivant. The resulting CDs are highly uniform and finely dispersed. The synergistic effect between PAMAM and APTES on the surface of the CDs results in a fluorescence that is much brighter than that of CDs modified with either APTES or PAMAM only. The fluorescence of the co-modified CDs is quenched by Hg(II) ions at fairly low concentrations. Under the optimum conditions, the intensity of quenched fluorescence drops with Hg(II) concentration in the range from 0.2 nM to 10 μM, and the detection limit is 87 fM. The effect of potentially interfering cations on the fluorescence revealed a high selectivity for Hg2+. The fluorescent probe was applied to the determination of Hg(II) in (spiked) waters and milk and gave recoveries between 95.6 and 107 %, with relative standard deviation between 4.4 and 6.0 %.

Functionalized porous Si nanowires for selective and simultaneous electrochemical detection of Cd(II) and Pb(II) ions

Thiol and amino-functionalized porous Si nanowires have been demonstrated to selectively detect Cd(II) and Pb(II) with high sensitivity using square wave anodic stripping voltammetry (SWASV) analysis. Through a typical Ag-assisted chemical etching approach, uniform and porous Si nanowires have been fabricated on heavily doped Si wafer. Continuously functionalized by (3-mercaptopropyl)trimethoxysilane (MPTMS) and (3-aminopropyl)triethoxysilane (APTES), the internal and external surfaces of porous Si nanowires have been decorated with thiol and amino groups, respectively. Inspired by the intrinsic properties of porous nanostructures, their electrochemical performances toward heavy metal ions have been further evaluated. The results indicate that Cd(II) and Pb(II) can be detected with high sensitivity owing to the strong complexing capacity of thiol and amino groups. Additionally, porous Si nanowires decorated with thiol groups present different stripping behaviors from those with amino groups toward the investigated heavy metal ions, realizing the selective and simultaneous detection of Cd(II) and Pb(II). Furthermore, simultaneous detection of Cd(II) and Pb(II) has also been demonstrated without any interference and their individual high sensitivity has been fundamentally preserved. Expectedly, porous Si nanowires as an effective modifier can be further extended to selectively detect other heavy metal ions through modifying with other functional organic groups.

Influence of a Novel Magnetic Recoverable Support on Kinetic, Stability and Activity of Beta-amylase Enzyme

In this paper, covalent immobilization of beta amylase enzyme on the surface of modified magnetic nano particles (ZnFe2O4@SiO2-NH2) is reported. For doing so, at first, the magnetic nanoparticles of ZnFe2O4 were synthesized by chemical co-precipitation method and then tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxy silane (APTES) were used for modification of ZnFe2O4 nanoparticles with silica and amine groups (ZnFe2O4@SiO2-NH2). Then, the aminated surface of ZnFe2O4 nanoparticles was exposed to beta amylase immobilization using trichlorotriazine (TCT) as covalent agent. The immobilized beta-amylase enzyme was characterized by techniques such as Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDAX). The kinetics studies corroborate the Michaelis-Menten model and show much progress in the efficiency of immobilized enzyme compared to the free enzyme. Also, the thermal stability of the beta-amylase enzyme is increased after immobilization. By applying a magnetic active support, simple and facile separation of beta-amylase from the reaction mixture and higher catalytic activity is possible. The highest activity for immobilized beta-amylase enzyme is observed at pH and temperature of 7.0 and 40 °C, respectively.