And 3-aminopropyltriethoxysilane Research Articles

Covalent binding of glutathione on magnetic nanoparticles: Application for immobilizing small fragment ubiquitin-like-specific protease 1

Magnetic nanoparticles bound with glutathione (GSH) are useful for diagnostics, enzyme immobilization, and affinity precipitation by using the strong and specific interaction of GSH with glutathione S-transferase (GST)-fused proteins. Our studies revealed that GSH-bound magnetic nanoparticles could be obtained using the covalent bond linkage of GSH and nanoparticles to promote the stability of bound GSH. To yield this conjugate, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared and modified using tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES), which introduced amino groups that were then activated with maleic anhydride (MA) for covalent binding of GSH. After MA was used to activate the amino-grafted SPION for 24 h, the yield of GSH conjugation increased over 4 days from 37 % to 74 % of the original amine density on the surface as the incubation of GSH with MA-activated SPION. These GSH-bound magnetic nanoparticles, designated as SPION@silica-GSH with approximately 103 nmol GSH/mg particles, were ready for coupling with GST-fused protein through the GSH–GST affinity interaction. A GST-tagged small fragment of ubiquitin-like-specific protease 1 (sfULP1) was used as the model protein for immobilization on SPION@silica-GSH. ULP1 is a small ubiquitin-like modifier (SUMO) protease. Results indicated that this immobilized GST-sfULP1 could retain 87 % ± 5 % enzyme activity of free protease before immobilization and could catalyze the cleavage of the SUMO-fused peptide (SUMO-GLP-1) to obtain glucagon-like peptide-1, a peptide hormone for type 2 diabetes therapy.

Gaining thermochromic property of quartz lamel surface and functionalization

The aim of this study was to obtain functional features by coating the quartz lamella with a sol-gel technique. Smart functional material was developed by including microencapsulated thermochromic pigments in coatings. Using anatase powder titanium (IV) oxide with additions in different ratios, the coatings were applied to the quartz lamel surfaces by dip-coating technique. The sol formulation was made using the initial precursors Tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES). Tetraethoxysilane was added to the structure of the coatings to increase the adhesion of the coatings to the substrate. Thermochromic coatings were synthesized by reacting polyvinylpyrrolidone in aqueous solution with tetraethoxysilane. The structural and thermochromic performance of coatings prepared with the sol-gel dip-coating method was systematically characterized and its functionality was determined. In this study, the effects of the addition of titanium (IV) oxide on the phase composition, transition temperature, and surface morphology of the coatings were investigated. The result obtained showed that the formed anatase phase increased as the titanium (IV) oxide content increased. Exothermic and endothermic transition temperatures for the undoped sample ranged from 34.6 °C to 26.5 °C, while 3 g titanium (IV) oxide doped sample these temperatures varied from 34.6 °C to 26.7 °C. Smooth surface coatings were prepared using polyethylene glycol. The results demonstrated that the colors of the obtained thermochromic coatings could be reversibly changed between green and white.

Improvement of Mechanical and Anticorrosion Coating Properties in Conducting Polymer Poly(Propyl Methacrylate) Embedded with Silane Functionalized Silica Nanoparticles

An excellent new nanocomposite coating consisting of poly(propyl methacrylate) (PPMA), silanes and SiO2 nanoparticles (i.e., PPMA/silane/SiO2 blend) for aluminium alloy (AA7178) protection in natural seawater is investigated by electrochemical techniques. Three different silanes namely, ethyltriethoxysilane (EES), (3-glycidyloxypropyl)triethoxysilane (GES), and (3-aminopropyl)triethoxysilane (AES) were used to prepare functionalized SiO2 nanoparticles which are incorporated into PPMA to form PPMA/EES/SiO2, PPMA/GES/SiO2, and PPMA/AES/SiO2 nanocomposites. Electrochemical impedance spectroscopy (EIS) displayed a pronounced increase in the charge transfer resistance and potentiodynamic polarisation studies showed a significant decrease in the corrosion current for the investigated nanocomposites. The resultant nanocomposites performed as an excellent passivation layer which prevents the diffusion of ions and slows down the corrosion process due to the inclusion of silane functionalized SiO2 nanoparticles to PPMA. Scanning electrochemical microscopic (SECM) studies showed very lower corrosion current at the scratch of the PPMA-silane/SiO2 nanocomposite coated aluminium alloy. Field emission-scanning electron microscopy/energy dispersive X-ray (FE-SEM/EDX) analysis displayed the formation of corrosion products as the passive layer that hinders the dissolution of aluminium alloy. Mechanical properties of the coated aluminium alloy were found to be enhanced by the inclusion of functionalized SiO2 nanoparticles to PPMA which complimented the electrochemical studies.

Synergistic effect between a novel silane-containing hyperbranched polyphosphamide and ammonium polyphosphate on the flame retardancy and smoke suppression of polypropylene composites

A novel hyperbranched polyphosphamide with abundant terminal groups of silane (HBPPA-Si) was synthesized from phosphorus oxychloride (POCl3), 4, 4′-diaminodiphenylmethane (DDM) and (3-aminopropyl) triethoxysilane (APTES), which had high thermal stability with a residual weight of 44.0 wt% at 800°C in nitrogen atmosphere. By incorporating 25 wt% of APP and HBPPA-Si with an optimum mass ratio of 1:1 into polypropylene (PP) composites, the PP/APP/HBPPA-Si composite reached V-0 rating at the UL-94 test and also obtained a maximum LOI value of 27.5%. Meanwhile, their peak heat release rates (PHRR), total heat release (THR), and total smoke production (TSP) reduced dramatically by 72.5%, 35.8%, and 62.7% respectively, when compared with virgin PP. The improved flame retardancy and smoke suppression of PP/APP/HBPPA-Si composite were ascribed to their excellent synergistic effect working efficiently in both condensed-phase and gas-phase actions. It is noticeable that the high-quality and high-quantity char residue possessing thermal-stable P- and Si-containing cross-linked structures can shield the underlying polymeric materials from further hydrolysis and simultaneously insulate the volatile fuel and heat transfer. Moreover, the weak polar silane shell of HBPPA-Si improved the interfacial compatibility of APP within the PP matrix, leading to enhanced mechanical properties with increasing HBPPA-Si concentration.

Synthesis, characterization and desalination study of polyvinyl chloride-co-vinyl acetate/cellulose acetate membranes integrated with surface modified zeolites

Novel mixed matrix membranes of polyvinyl chloride-co-vinyl acetate/cellulose acetate (PVCA/CA) infused with nano-particles of both pristine zeolite (p-zeolite) and 3-aminopropyl triethoxysilane (APTS) functionalized zeolite (f-zeolite) were synthesized by dissolution casting method for desalination application. MMMs were then characterized using FTIR, SEM, contact angle and DMA analysis. FTIR and TGA analysis were also carried out for zeolite particles to confirm the surface functionalization. The loading effect of zeolite (1, 3 and 5 wt. %) and the impact of APTS functionalization on dispersion, morphological structure, thermo-mechanical properties and hydrophilicity were also analyzed. Desalination performance of the membranes was evaluated using 2000 ppm NaCl solution at 6 bar pressure. SEM analysis demonstrated that APTS functionalization improved the uniformity of the zeolite nano-particles in the membrane and a noticeable reduction in undesirable microscopic voids. Higher hydrophilicity was attained with the inclusion of f-zeolite nanoparticles, as confirmed by contact angle measurement analysis. It was found that the membrane infused with 5 wt. % of f-zeolite exhibited substantial improvements in storage modulus, glass transition temperature and cross-link density. Membranes infused with f-zeolite demonstrated enhanced transport mechanism without showing trade-off between water flux and salt rejection. In particular, inclusion of 5 wt. % f-zeolite, resulted in achieving the highest salt rejection of 99.56% with water flux increment of ~24% in comparison to the neat PVCA/CA membrane. Finally, the membranes were tested for anti-fouling properties using flux recovery ratio test. Thus, the newly developed PVCA/CA membranes embedded with APTS f-zeolite can be exploited for high performance desalination applications. • Zeolite infused CA/PVCA blend is a promising material for reverse osmosis membranes. • f-zeolite infused membranes exhibit better properties compared to p -zeoilte membranes. • APTS f-zeolite greatly improves the dispersion quality leading to a densified membrane microstructure. • 5 wt % APTS f-zeolite infused membrane greatly enhances the desalination capacity. • Storage modulus, T g and crosslink density also improve with APTS-f-zeolite infusion.

Modification of the wood‐plastic composite for enhancement of formaldehyde clearance and the 3D printing application

AbstractAs the formaldehyde is one of the main indoor pollutants, the purpose of this study is to effectively remove indoor formaldehyde pollution by using environmentally friendly 3D printing ornaments. The wood 3D printing filaments cellulose/polylactic acid composite (Cellu/P) was selected as the starting material, and 3‐aminopropyltriethoxysilane (APTES) was used for chemical modification to obtain a series of cellulose composite materials with amino groups. The modified composite materials (APTES@Cellu/P) were characterized by Fourier transform infrared, X‐ray diffraction, scanning electron microscope, energy dispersive spectroscopy, thermogravimetric analysis, and mechanical tests, and a formaldehyde removal experiment was performed. The feasibility of 3D printing was evaluated, and the process of 3D printing‐functionalized customized ornaments was proposed, and then a school emblem was used for modeling, printing, and surface modification. Compared with the commercially traditional activated carbon, 3D printing‐customized ornaments of APTES@Cellu/P material has a better formaldehyde removal effect, and can even avoid the secondary pollution that is common to the activated carbon.

Cross-Linked SPEEK–PEG–APTEOS-Modified CaTiO3 Perovskites for Efficient Acid–Base Cation-Exchange Membrane Fuel Cell

Nanocomposite membranes are synthesized by the combination of sulfonated poly(ether ether ketone) (SPEEK), poly(ethylene glycol) (PEG), and 3-aminopropyl triethoxysilane (APTEOS)-modified CaTiO3. From thermogravimetric analysis (TGA) and mechanical and Arrhenius studies, it is seen that the covalent cross-linking of PEG with SPEEK exhibits a lower weight loss (91.84 wt %) at 120 °C than SPEEK (88.19 wt %). Moreover, higher activation energy (Ea) and tensile stress values are obtained in the order of 26.23 kJ/mol and 23.32 MPa, respectively. The APTEOS-modified CaTiO3 nanoparticles impregnated into the SPEEK/PEG membrane cause the acid–base proton hopping mechanism (HSO3/NH2) and induce a more compact structure. The nanocomposite membranes possess exceptional proton conductivity, thermal, oxidative, and physicochemical properties than SPEEK. Further, 6 wt % functionalized CaTiO3 in the SPEEK/PEG membrane manifests the highest values of proton conductivity, current density, and power density at 80 °C in 100% RH of 65.32 mS cm–1, 403 mA cm–2, and 90 mW cm–2 with an open-circuit voltage (OCV) of 0.90 V, respectively. This membrane retains 95.37 wt % original weight during 3 h of the Fenton test.

Hydrothermal synthesis and characterization of magnetic Fe3O4 and APTS coated Fe3O4 nanoparticles: physicochemical investigations of interaction with DNA.

Magnetic nanoparticles (MNPs) especially iron oxide (Fe3O4) NPs have quite extensively been used for in vivo delivery of biomolecules and drugs because of their high bioconjugation efficiency. In this study, Fe3O4 NPs and (3-Aminopropyl) triethoxysilane (APTS) coated Fe3O4 NPs were synthesized and their interaction with Calf thymus (Ct) DNA has been studied in order to understand their usage in biomedical applications. Hydrothermal method was used for the NPs synthesis. Characterization of NPs was done using techniques like UV-Visible spectroscopy, FTIR spectroscopy, FE-SEM, EDAX, Zeta Sizer and powder XRD. Further, interaction studies of NPs with Ct-DNA were investigated using various physicochemical techniques. In UV-Visible studies, hypochromicity with binding constant 3.2 × 105 M-1 was observed. Binding constants calculated using fluorescence studies were found to be k = 3.2 × 104 M-1, 2.9 × 104 M-1 at 293 and 323 K respectively. Results of UV-Visible and fluorescence studies were in correlation with other techniques like UV-TM and CD. All studies suggested alteration in DNA conformation on interaction with surface engineered Fe3O4 NPs, stabilizing DNA-NPs conjugate via partial intercalation and electrostatic interactions. This study may facilitate our understanding regarding the physicochemical properties and DNA-binding ability of APTS-Fe3O4 NPs for their further application in magnetosensitive biosensing and drug delivery. Iron oxide based magnetic nanoparticles are well known for their excellent bio-conjugation efficiency and therefore APTS-Fe3O4 NPs were synthesized via very simple and benign hydrothermal method. Further, the interaction of APTS-Fe3O4 NPs with calf thymus DNA was studied using various physicochemical techniques to explore their potential in biomedical applications.

Amino-decorated organosilica membranes for highly permeable CO2 capture

Membrane-based separation technologies are considered an effective process for the capture of CO2 due to advantages such as high levels of energy efficiency with inexpensive levels of investment. It remains challenging, however, to develop a membrane with high levels of both permeance and selectivity with the ability to capture CO2 in a highly efficient manner. Herein, we report amino-decorated organosilica membranes that are based on a facile and effective co-polymerization strategy that uses bis(triethoxysilyl)acetylene (BTESA) and (3-aminopropyl) triethoxysilane (APTES) precursors. This co-polymerization strategy simultaneously endows the resultant membranes with a controlled pore size and enhanced CO2-philic properties that have significantly improved CO2 separation performance. These composite membranes display CO2 permeance that ranges from 2550–3230 GPU and a range for CO2/N2 selectivity of 31–42 in the separation of CO2/N2 mixtures, which outperforms most state-of-the-art membranes and exceeds the target for post-combustion CO2 capture operations. A satisfying performance was achieved with a CO2 permeance of 8 ✕ 10−7 mol m−2 s−1 Pa−1 (2390 GPU) and CO2/CH4 selectivity of 70. The present study highlights an elegant decoration strategy for the production of membranes with ultrahigh CO2 capture capacities, which can also be extended to other organosilica precursors for target-oriented separations by varying the bridged or side-chain groups.

Highly Selective Fluorescence Sensor Based on Graphene Quantum Dots for Sulfamethoxazole Determination.

In our research, a reliable fluorescence sensor for the detection of sulfamethoxazole (SMZ) was developed. This method relies on graphene quantum dots (GQDs) entrapped in a silica molecularly imprinted polymer (GQDs@SMIP), which was synthesized by the polymerization using GQDs, SMZ, tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) as fluorescence material, template, cross-linker, and functional monomers, respectively. The GQDs@SMIP was characterized by fluorometry, Fourier-transform infrared spectroscopy, transmission and scanning electron microscopies, X-ray photoelectron spectroscopy, and powder X-ray diffraction. The GQDs@SMIP exhibited a good capacity to absorb SMZ from solution, which resulted in the quenching of the GQD fluorescence intensity. The intensity of GQDs@SMIP decreased linearly with the SMZ concentration in the range of 1 to 100 µM with a correlation coefficient of 0.99537. In addition, the fluorescence responses of GQDs@SMIP to interfering substances were investigated. The results indicated that there was no effect of interfering substances on SMZ detection. Thus, the highly selective GQDs@SMIP fluorescence sensor is an effective and promising device for SMZ detection and analysis.

Effect of Nafion and APTEOS functionalization on mixed gas separation of PEBA-FAU membranes: Experimental study and MD and GCMC simulations

Many of the mixed matrix membranes (MMMs) face the challenge of fillers agglomeration. In this paper, the gas separation performance of MMMs based on poly (ether-block-amide) (PEBA, 60 wt% PEO and 40 wt% PA6) filled with different functionalized zeolite faujasite (FAU, X-type) fillers was investigated. To improve the interfacial adherence of the fillers with PEBA chains, Nafion® and 3-aminopropyl triethoxysilane (APTEOS) were used as sulfonic acid and aminosilane functionalizing agents, respectively. Different physicochemical and morphological characterizations such as XRD, FTIR, SEM, AFM, thermal, and mechanical tests were used to characterize the prepared membranes. The prepared membranes were evaluated for single gas and mixed gas separation performances. The results showed that CO2 permeability reached to 110 and 122 Barrer for sulfonic acid- and amine-FAU (1 wt%) filled PEBA, respectively. In addition, amine-MMM (1 wt%) had better performance for CO2/N2 selectivity (117), while SO3-MMM (1 wt%) showed higher CO2/CH4 selectivity (31) due to their intrinsic properties. Molecular simulation was also carried out to study the structural and transport properties of the fabricated membranes. The solubility and diffusivity of CO2, CH4, and N2 gas molecules were studied by Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) methods, respectively. The acquired results revealed that experimental and simulation data were consistent in approach.

Computational Study of APTES Surface Functionalization of Diatom-like Amorphous SiO2 Surfaces for Heavy Metal Adsorption.

The amorphous silica (SiO2) shell on diatom frustules is a highly attractive biomaterial for removing pollutants from aquatic ecosystems. The surface activity of silica can be enhanced by modification with organosilanes. In this work, we present an atomic-level theoretical study based on molecular dynamics and dispersion-corrected density functional theory calculations on the surface stability and adsorption of heavy metal (HM) compounds on silane- and 3-aminopropyltriethoxysilane (APTES)-covered SiO2 surfaces. Our simulations show that at low APTES coverage, the molecular adsorption of Cd(OH)2 and HgCl2 is more favorable near the modifier, compared to As(OH)3 that binds at the hydroxylated region on silica. At higher coverages, the metallic compounds are preferentially adsorbed by the terminating amino group on the surface, whereas the adsorption in the region between APTES and the oxide surface is also spontaneous. The adsorption is strongly driven by van der Waals interactions at the highly covered surface, where the consideration of dispersion corrections reduces the modifier-adsorbate interatomic distances and increases the adsorption energy by ca. 0.4-0.7 eV. The adsorption of water is favorable, although it is generally weaker than for the HM compounds. Based on our results, we conclude that the addition of APTES modifiers on silica increases the adsorption strength and provides extra binding sites for the adsorption of HM pollutants. These outcomes can be used for the design of more efficient structures of biomaterials for depollution of HMs.

Ionic liquid containing amine-based silica aerogels for CO2 capture by fixed bed adsorption

The main goal of this study is to develop an adsorption based process using amine-based silica aerogels to capture CO2 from post-combustion gases. For this purpose, silica based aerogels were synthesized by following single-step sol-gel method using tetraethyl orthosilicate (TEOS) as silica precursor and (3-Aminopropyl)triethoxysilane (APTES) as amine source in different compositions. To enhance CO2 capture performances of the prepared aerogels, amine-containing ionic liquid (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) was also used as sol agent due to high CO2 selectivity and lower viscosity. Chemical structural properties, thermal behaviors, surface area and morphologies of prepared aerogels were analyzed. CO2 capture performances of prepared aerogels were investigated in a fixed bed column of CO2 capture experimental set-up for adsorption. Results have shown that CO2 adsorption capacities of ionic liquid containing amine-based aerogels increased with the addition of amine source and ionic liquid. Among the prepared aerogels, the sample of TA0.24IL0.28 exhibited superior adsorption behavior with the maximum capacity of 243.32 mg CO2/g (5.53 mmol/g).

Experimental test and curve fitting of creep recovery characteristics of modified graphene oxide natural rubber and its relationship with temperature

The creep recovery properties of different graphene-doped rubber and the effect of temperature on them were studied. Doping graphene, especially with the surface functional group or surface microstructure, can significantly improve the creep resistance of natural rubber (NR). The permanent creep of each composite tested under the same conditions for 20 min. Graphene oxide, hydrazine hydrate reduced graphene oxide, and 3-aminopropyltriethoxysilane (APTS) grafted graphene oxide was 33%, 16%, and 51% lower than those filled with carbon black respectively. Four parameter model and Weibull distribution function used to analyze and evaluate the creep and recovery test results of composite rubber. These curve fitting results can adequately describe the influence of different types of nanofillers on the creep and recovery properties of composite rubber. The long-term creep of composites forecasted by the time-temperature superposition principle (TTSP). The results show that graphene doping can improve the creep resistance of the rubber. Besides, graphene oxide and surface-modified graphene oxide had better creep resistance than reduced graphene oxide filled natural rubber. It can see that the interfacial properties between the graphene sheet and the natural rubber matrix play an essential role in the creep and recovery properties of graphene/natural rubber composites.

Detection of TNT in sulfuric acid solution by SiNWs-FET based sensor

Since the preparation of TNT is always proceeded in acid solution, it is very difficult to accurately detect it at the production stage. Developing a TNT sensor which can work in sulfuric acid solution will be very helpful. This paper presents a TNT sensor based on SiNWs-FET which can quickly detect TNT in sulfuric acid. The detection mechanism is based on the fact that TNT molecules can selectively bond to the amino group of nanowires, which act as grid elements and modulate the conductance of the silicon nanowires, leading to the variation of SiNWs-FET drain-source current. The SiNWs-FET devices were fabricated on a (111) silicon-on-insulator wafer using controllable silicon anisotropy etching and self-limiting oxidation. The silicon nanowires were treated with oxygen plasma and 3-aminopropyltriethoxysilane (APTES) to form hydroxyl and amino groups on the surface of the nanowires, respectively. The SiNWs-FET sensor demonstrated highly sensitive detection to TNT molecule in aqueous solution with 0.1% dimethyl sulfoxide (DMSO) and sulfuric acid solutions. These experimental results show that the SiNWs-FET sensor can work stably and reliably in some harsh environment, even in high concentration of sulfuric acid. The rapid response time also reflected the advantages of SiNWs-FET sensors in TNT fast detection. In addition, the SiNWs-FET sensor showed selectivity to TNT, due to the specific bind between amino groups and nitro groups.

Evaluation on the Stability of Amine-Mesoporous Silica Adsorbents used for CO2 Capture

Amine-mesoporous silica has been considered as a promising CO2 adsorbent with high potential for the reduction of energy consumption and CO2 capture cost; however, its stability could greatly vary with synthetic method. In this study, adsorbents prepared by impregnating different amines including polyethylenimine (PEI) and 3-aminopropyltriethoxysilane (APTES) onto mesoporous silica were used to evaluate the effect of amines selection on the stability of adsorbents used in CO2 capture process. Results revealed that APTES impregnated mesoporous silica (APTES-MPS) is more stable than PEI-impregnated mesoporous silica (PEI-MPS); APTES-MPS was thermally decomposed at ≈280 oC, while PEI-MPS was thermally decomposed at ≈180 oC only. PEI-MPS was particularly less stable when operating under dry condition; its CO2 adsorption capacity reduced by 22.1% after 10 adsorption/regeneration cycles, however, the capacity can be significantly improved in humid condition. APTES-MPS showed a greater stability with no significant reduction in CO2 capture capacity after 10 adsorption/regeneration cycles. In general, APTES-MPS adsorbent possesses a higher stability compared to PEI-MPS thanks to the formation of chemical bonds between amino-functional groups and mesoporous silica substrate.
 Keywords: Mesoporous silica; CO2 capture; Adsorption; Regeneration; Emission.

High-temperature resistance and hydrophobic polysiloxane-based polyurethane films with cross-linked structure prepared by the sol-gel process

Polysiloxane-based polyurethane films with cross-linked structure are synthesized by the sol-gel process using isophorone diisocyanate (IPDI), polydimethylsiloxane (PDMS), polycaprolactone (PCL) diol, and 3-aminopropyl triethoxysilane (ATS). After the ATS-terminated polyurethane prepolymer, a cross-linked network structure is formed through the process of dehydration and condensation. The hydrophobicity, thermal properties, surface morphology, and mechanical properties of a series of polysiloxane-based polyurethane films with cross-linked structure are further studied. Dynamic mechanical thermal analysis studies show that the crosslink density of polysiloxane-based polyurethane films with cross-linked structure is improved with the addition of ATS. Polysiloxane-based polyurethane films with cross-linked structure can not only enhance mechanical strength but also improve heat resistance and hydrophobicity. The results show that the maximum decomposition temperature of the polysiloxane-based polyurethane films with cross-linked structure reaches 475 °C, the hydrophobicity increases to 114.2°, and the mechanical strength increases to 16.7 Mpa, which are 18.75%, 7.53%, and 59.04% higher than that of the control group, respectively. This is mainly due to the cross-linked network structure formed by the sol-gel process, which limits the movement of the segment and increases the rigidity of the material. Besides, a dense protective layer is formed on the surface due to cross-linking, which prevents the infiltration of water molecules. Interestingly, with the increase of ATS, the R q value of the surface shows an increasing trend. This is in contrast to the study by Kamal Mohamed Seeni Meera et al. Who shows that the R q value decreases with increasing crosslink density. Also, it can be seen from the results of XPS characterization that Si element of the surface is increased, which is mainly due to the sol-gel phenomenon of ATS occurring on the surface of the material.

One-step preparation of porous aminated-silica nanoparticles and their antibacterial drug delivery applications

Porous functionalized silica nanoparticles have attracted the interest of researchers as they are excellent carriers for antibacterial drug delivery applications. In this work, porous aminated-silica nanoparticles (SiO2-NH2 NPs) were prepared via one-step approach through the ammonia-catalyzed hydrolysis of tetraethylorthosilicate (TEOS) and (3-aminopropyl) triethoxysilane (APTES) in a mixed water–ethanol system. The obtained SiO2-NH2 NPs displayed a spherical morphology and relatively uniform size distribution, while the morphology and structure of SiO2-NH2 NPs were mainly determined by the order of the reagents added and the pH value of the solution. After characterization, the results showed that there were a large number of –NH2 groups on the surface of porous SiO2-NH2 NPs and that the porous SiO2-NH2 NPs had a large surface area of 476 m² g−1 with an average pore width of 4.3 nm. Through an absorbing–releasing experiment and bacterial test, those SiO2-NH2 NPs were found to exhibit efficient absorption and release of drugs as well as a pH-dependent release pattern of epirubicin-loaded SiO2-NH2 NPs. Meanwhile, SiO2-NH2@capsaicin NPs exhibited antibacterial properties. Those porous SiO2-NH2 NPs could be a candidate for drug delivery for antibacterial applications owing to their tailored porous structure and high surface area.

Organocatalytic Cascade Knoevenagel–Michael Addition Reactions: Direct Synthesis of Polysubstituted 2-Amino-4H-Chromene Derivatives

In this report, we documented novel strategy for the synthesis of bioactive polysubstituted 2-amino-4H-chromine derivatives under a heterogeneous Al-MCM-41-LDH@APTES (ALAM) catalysis. A synthetic procedure is developed to prepare Al-MCM-41-LDH@APTES (ALAM) heterogeneous basic catalysts. Mesoporous Al-MCM-41 is functionalized by known grafting chemistry via layered double hydroxide (LDH) nanosheets and (3-aminopropyl)triethoxysilane (APTES) moiety as a basic organocatalyst. The resulting catalysts contain amino group functionality on the external surface as well as inside the layers and the basicity can be tuned by the loading of APTES. The samples were fully characterized by 29Si and 13C CP/MAS NMR, infrared absorption spectroscopy, TEM, XPS, EDX, TGA, XRD, CO2-TPD, N2 adsorption isotherms measurements, and they were successfully examined for the cascade type Knoevenagel–Michael addition reactions. The product yields associated with these substrates were optimized, and key reaction parameters affecting the yields were identified. The present catalytic method is simple and robust for diversity oriented synthesis which proceeds good to excellent yields without generating any hazards waste. The broad substrate scope, excellent functional group compatibility makes this protocol highly useful towards synthesis of polysubstituted α-cyanoacrylates, α-cyanoacrylonitriles and 2-amino-4H-chromenes with an electron-donating or electron-withdrawing group. We have also successfully established a flow reaction system, gram-scale synthesis as well as catalyst recyclability up to six catalytic cycles without appreciable loss of its activity.

Preparation of ternary amino-functionalized magnetic nano-sized illite-smectite clay for adsorption of Pb(II) ions in aqueous solution.

Ternary amino-functionalized magnetic illite-smectite (AMNI/S) nanocomposites were prepared via integrating two-dimensional illite-smectite nanoflakes (NI/S), magnetite nanoparticles (Fe3O4), and 3-aminopropyltriethoxysilane (APTES). The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometry (VSM). The results show that Fe3O4 nanoparticles can be well dispersed on NI/S flakes and the hydrolyzed APTES molecules can simultaneously bond to the hydroxyl groups of Fe3O4 and NI/S. Due to the synergetic effect, magnetic NI/S composite can graft more amount of APTES molecules rather than Fe3O4 nanoparticles or NI/S alone. When the mass ratio of NI/S:Fe3O4 is 1:1, the saturation magnetization of AMNI/S-1 is 17.4emu/g, facilitating the efficient magnetic separation in aqueous solution. Also, AMNI/S-1 shows a maximal adsorption amount of Pb(II) ions of 227.8mg/g calculated by the Langmuir model. The effects of initial concentration of Pb(II) ions, pH value, adsorption time, and temperature on the adsorption amount of Pb(II) ions were investigated. The adsorption kinetic models and isotherm models were applied to analyze the adsorption of Pb(II) ions, respectively. The thermodynamic analysis reveals that the adsorption of Pb(II) onto AMNI/S-1 is spontaneous and endothermic in nature. The mechanism for the adsorption of Pb(II) ions onto AMNI/S-1 is due to the surface complexation of Fe3O4 and NI/S, and the chelation of amine groups (-NH2). AMNI/S-1 can be efficiently reused and the regenerated AMNI/S-1 remains 82.91% of initial adsorption capacity after 6-cycle adsorption/desorption process. Thus, ternary AMNI/S-1 could be used as a prospective effective adsorbent.