3-aminopropyl Silane Research Articles

Binding behavior of receptor binding domain of the SARS-CoV-2 virus and ivermectin

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), sparked an international debate on effective ways to prevent and treat the virus. Specifically, there were many varying opinions on the use of ivermectin (IVM) throughout the world, with minimal research to support either side. IVM is an FDA-approved antiparasitic drug that was discovered in the 1970s and was found to show antiviral activity. The objective of this study is to examine the binding behavior and rates of association and dissociation between SARS-CoV-2 receptor binding domain (RBD), IVM, and their combination using aminopropylsilane (APS) biosensors as surrogates for the hydrophobic interaction between the viral protein and human angiotensin-converting enzyme 2 (ACE2) receptors to determine the potential of IVM as a repurposed drug for SARS-CoV-2 prevention and treatment. The IVM, RBD, and combination binding kinetics were analyzed using biolayer interferometry (BLI) and validated with multiple in silico techniques including protein–ligand docking, molecular dynamics simulation, molecular mechanics-generalized Born surface area (MM-GBSA), and principal component analysis (PCA). Our results suggest that with increasing IVM concentrations the association rate with the hydrophobic biosensor increases with a simultaneous decrease in dissociation. Significant kinetic changes to RBD, when combined with IVM, were found only at a concentration a thousand times the approved dosage with minimal changes found over a 35-min time period. Our study suggests that IVM is not an effective preventative or treatment method at the currently approved dosage.

Speciation of Hexavalent Chromium in Aqueous Solutions Using a Magnetic Silica-Coated Amino-Modified Glycidyl Methacrylate Polymer Nanocomposite

A new magnetic amino-functionalized polymeric sorbent based on glycidyl methacrylate was synthesized and used in the separation of chromium Cr(VI) oxyanions sorption from aqueous solutions in a static batch system. The kinetic and isothermal parameters of the sorption process were determined. The experimental data were best fitted by a pseudo-second-order model with R2 = 0.994 and χ2 = 0.004. The sorption process of Cr(VI) removal by amino-functionalized sorbent was controlled by both intraparticle diffusion and liquid film diffusion. The equilibrium results showed that the sorption process is best described by the Freundlich model, followed closely by the Sips isotherm model, with a maximum sorption capacity of 64 mg/g. Quantum chemical modeling revealed that the sorption sites on the sorbent surface are fragments with diethylenetriamine and aminopropyl silane groups that coated the magnetic nanoparticles. The calculations showed that Cr(VI) oxyanions (Cr2O72-, CrO42- and HCrO4-) bind to both sorption sites, with diethylenetriamine centers slightly favored. The X-ray photoelectron spectroscopy (XPS) spectra demonstrate that the chromium bound to the sorbent in the form of Cr(III), indicating that the Cr(VI) can be converted on the surface of the sorbent to a less harmful form Cr(III) due to the sorbent's chemical composition.

Synthesis and Surface Modification of Iron Oxide Nanoparticles for the Extraction of Cadmium Ions in Food and Water Samples: A Chemometric Study

In this project, a prompt, efficient, and effective method for Cd2+ ions extraction from different food and water samples using magnetic dispersion-based solid phase extraction by functionalized iron oxide nanoparticles was proposed. Iron oxide nanoparticles were synthesized through the co-precipitation method followed by functionalization with tetraethyl orthosilicate (TEOS) and 3-aminopropyl silane (APTES) to obtain Fe3O4@SiO2@APTES. This composite was characterized through different techniques, including vibrating sample magnetometer, dynamic light scattering, zeta potential, FTIR, SEM, XRD, and BET. Variables studied were pH, temperature, sorbent amount, sonication time, and sample and eluent volume affecting the sorption efficacy of freshly synthesized sorbent. Plackett–Burman design was utilized for the identification of significant factors for microextraction of target analyte, while the central composite design was utilized for the optimization of significant factors. Detection and quantification limits obtained were 0.17 and 0.58 μgL−1, respectively, with an enhancement factor of 83.5. Under optimum conditions, Fe3O4@SiO2@APTES showed good stability even after >80 adsorption/desorption cycles run while maintaining over 96% analyte recoveries. The developed method was validated by assessing certified reference materials and standard addition methodology for Cd2+ detection in real samples. To confirm the precision, repeatability (RSDr) and reproducibility (RSDR) were calculated and found as <3.0 (n = 7) and <7.5 (n = 15), respectively. Furthermore, in accordance with the ISO/IEC 17025 recommendations, the validation was also confirmed through a “bottom-up” approach while considering all possible uncertainties in data.

Evaluation of the aminosilane and colloidal silica treated red iron oxide pigment effects in styrene acrylic and polyurethane dispersion

PurposeThis study aims to perform the surface treatment of synthetic α-Fe2O3 red iron oxide pigment with hydrolysate 3-aminopropyl silane (A) and colloidal silica (CS) and investigate the effects of surface-treated pigment on the styrene acrylic (SA) emulsion and polyurethane (PU) dispersion.Design/methodology/approachFor this purpose, firstly red iron oxide particles were modified with A and CS separately in an aqueous medium. After isolation of the modified iron oxide were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Moreover, the degree of the dispersion stability of the modified pigment in coatings with SA emulsion and PU dispersion was investigated by using an oscillation rheometer. Loss (G''), storage (G') modulus, loss factor [tan(δ)] and yield stress (τ0) values were determined by performing amplitude and frequency sweep tests.FindingsThe τ0 in SA coatings decreases with the amount of used A and increases with the amount of used CS. The τ0 decreases as the amount of used A and CS in PU coatings increases. The use of CS on red iron oxide pigments causes storage modulus to increase in SA coatings at low angular frequencies, while it causes a decrease in PU coatings.Originality/valueTo the best of the authors’ knowledge, for the first time, the suspended state of the iron oxide hybrid pigment formed with CS in the coating was investigated rheologically in this study.

Polyamide‐6/cellulose nanocomposites: Influence of fiber treatment and screw rotation on nanofibrillation of jute during extrusion process

The present work studied the preparation of nanocomposites of polyamide-6 (PA6) containing nanofibrillated cellulose by melt blending in a twin screw extruder at different screw rotations to verify the fibrillation of cellulose fibers. Initially, the jute fibers were purified, hydrolyzed, and modified with titanium isopropoxide and aminopropyl silane, as well as with the two chemical modifications. They were incorporated into the polymeric matrix aiming that the shear in processing further aids in fiber fibrillation. The scanning electron microscopy analysis images of the composites showed the presence of fibers with nanodiameters dispersed in the PA6 matrix. The doubly modified fibers resulted in more fibrillation during extrusion. Increasing the screw speed of the extruder improved the degree of crystallinity for the composites with the modified fibers. The thermogravimetric measurements showed that the composite containing the doubly modified fibers increased the maximum degradation temperature. The storage modulus increased for the composites with the insertion of the treated fibers, and the glass transition temperature decreased in some composites. The composites showed higher pseudoplastic behavior, especially at high shear rates.

Binding behavior of spike protein and receptor binding domain of the SARS-CoV-2 virus at different environmental conditions

A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified as the cause of the COVID-19 pandemic that originated in China in December 2019. Although extensive research has been performed on SARS-CoV-2, the binding behavior of spike (S) protein and receptor binding domain (RBD) of SARS-CoV-2 at different environmental conditions have yet to be studied. The objective of this study is to investigate the effect of temperature, fatty acids, ions, and protein concentration on the binding behavior and rates of association and dissociation between the S protein and RBD of SARS-CoV-2 and the hydrophobic aminopropylsilane (APS) biosensors using biolayer interferometry (BLI) validated with molecular dynamics simulation. Our results suggest three conditions—high ionic concentration, presence of hydrophobic fatty acids, and low temperature—favor the attachment of S protein and RBD to hydrophobic surfaces. Increasing the temperature within an hour from 0 to 25 °C results in S protein detachment, suggesting that freezing can cause structural changes in the S protein, affecting its binding kinetics at higher temperature. At all the conditions, RBD exhibits lower dissociation capabilities than the full-length S trimer protein, indicating that the separated RBD formed stronger attachment to hydrophobic surfaces compared to when it was included in the S protein.

Using Bio-Layer Interferometry to Evaluate Anti-PEG Antibody-Mediated Complement Activation.

The purpose of this study was to develop a Bio-layer interferometry (BLI) system that could be an alternative approach for the direct evaluation of anti-polyethylene glycol (PEG) immunoglobulin M (IgM)-mediated complement activation of the accelerated blood clearance (ABC) phenomenon. Complement activation is well known to play an important role in the clearance of PEGylated and non-PEGylated nanomedicines following intravenous injection. This complement system is also thought to be responsible for the ABC phenomenon wherein repeated injections of PEGylated products are bound by anti-PEG antibodies. This study used three different sources of anti-PEG antibodies: HIK-M09 monoclonal antibodies (mAbs); HIK-M11 mAbs; and antiserum containing polyclonal anti-PEG IgMs. 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-n-[methoxy (polyethylene glycol)-2000] (mPEG2000-DSPE) was immobilized as an antigen on aminopropyl silane biosensor chips of BLI. All anti-PEG IgMs in the sources increased the signals (thickness of the layer around the sensor tip) regarding binding of anti-PEG antibodies to PEG on the chips. In all anti-PEG IgM sources, further increases in the signals were observed when incubated in naïve mouse serum, which is a complement source, but not in heat inactivated (56 °C, 30 min) mouse serum, which abolishes complement activity. These findings show that the complement activation mediated via anti-PEG IgMs, which occurred on the sensor chips, was detected via BLI analysis. The complement activation induced by all anti-PEG IgM sources was confirmed via conventional enzyme-linked immunosorbent assay (ELISA), which is the conventional mode for detection of complement activation. Our study results show that BLI is a simple alternative method for the detection of complement activation.

Au nanoparticles supported on piranha etched halloysite nanotubes for highly efficient heterogeneous catalysis

Halloysite nanotubes (HNTs) can be conveniently used as scaffolds to load catalytic units, to enable efficient heterogeneous catalytic processes. In this contribution, we report a facile strategy to prepare a composite system based on Au nanoparticles (NPs) supported on piranha-etched HNTs. The resulting nano-system was characterized by FTIR, XPS and nitrogen physisorption to highlight its surface properties and porosity. Compared to the non-treated reference HNTs, the increase of hydroxyl groups on the etched HNTs walls allowed to graft a double amount of 3-aminopropyl silane (5.7 wt% vs. 2.8 wt%) and, consequently, to load 15.5 wt% more gold NPs. On the other hand, the interaction of the amino groups with Au NPs stabilizes positively charged NPs, thus leading to excellent catalytic activity and stability. The resulting nano-hybrid can catalyse the reduction of 4-nitrophenol to 4-aminophenol with a kinetic rate constant 53% higher than the reference reaction. In addition, it can be reused for 8 times without significant loss of activity. The supported system also demonstrates its potential in the oxidation of a sugar-derived molecule, i.e., furfural, which is converted into furoic acid with turnover frequency (TOF) 25% higher than the reference.

Versatile nanografting pathway to functionally embellished fluorogenic small-molecule on two-dimensional inorganic surfaces

Nanografting as a pathway to create functionalized two-dimensional inorganic surfaces capable of immobilizing fluorogenic substituted-fluorene dye is demonstrated. Of particular importance is that the self-assembled monolayer of 3-aminopropyltriethoxysilane is successfully modified with 9H-fluorene-9-carbonyl chloride carbonyl chloride via amide coupling reactions. Physico-chemical properties of self-assembled monolayer are studied by water contact angle (WCA) measurements, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The optical properties were determined by photoluminescence spectroscopy. The WCA and AFM data suggest that employing the same functionalization protocol on two different surfaces, (SiO2/Si) and GaN/Al2O3 respectively, may lead to different but meaningful results. XPS results confirm fluorene dye covalently attached onto two-dimensional inorganic surfaces via self-assembled monolayer of aminopropyl silane.

Encapsulation and controlled release of an antimalarial drug using surface functionalized mesoporous silica nanocarriers.

Herein, we report the encapsulation and release of antimalarial drug quinine (QN) using three nanocarriers, including MCM-41 (1), and its 3-aminopropyl silane (aMCM-41 (2)) and 3-phenylpropyl silane (pMCM-41 (3)) surface functionalized derivatives. The pH and thermal optimization effects on QN adsorption and release from 1, 2 and 3 were investigated.

Effect of surface treatment on tribological characteristic of ferrite nanoparticles epoxy composites

In this investigation, surface treatment of ferrite nanoparticles were efficiently prepared by using amino propyl silane (APS). XRD which is a spectral analysis technique used for investigate the morphology and chemical structure of treated and normal ferrite nanoparticles. Ferrite nanoparticles epoxy composites were prepared by Modified ferrite nanoparticles (MFNs) with varying weight percentage and ferrite nanoparticles (FNs). XRD shown that MFNs was effectively modified with highly crystalline structure and silane surface treatment decreased the average particle size of FNs to ∼ 16.48 nm. Surface treatment of FNs enhanced the homogeneous dispersion of ferrite in epoxy resin and improved interfacial adhesiveness between MFNs and epoxy. Tribological property of Modified ferrite nanoparticles epoxy composite (MFNEs) compare to cured epoxy and normal ferrite nanoparticles epoxy composites (FNEs) has been enhanced due to surface treatment.

An HPLC tool for process monitoring: rare sugar D- psicose and D- fructose contents during the production through an enzymatic path

D-Psicose/allulose, a rare sugar, is an essential raw material in the pharmaceutical and food industries. It is scantly found in nature and to meet its demand in industries, D-Psicose is generated enzymatically using D-fructose as a substrate. In these conversations, it is important to monitor D-Psicose, in order to control the process, impurities, optimize the reaction time and reduce the process cost The available analytical methods have their limitations in quantifying D-psicose and D-fructose mixtures. Hence there is a need for the development of a routine, sensitive, quick and precise analytical method for D-psicose production on-line monitoring of reaction mixer. In the present work, a simplified reverse phase HPLC technique is developed and validated for the quick reaction monitoring of D-psicose from D-fructose, during enzymatic conversation procedures. The analysis is conducted at different concentrations ranging from 0.05 % to 0.5 % of the standard solutions of the D-psicose and D-fructose, by using water and Acetonitrile (at a ratio of 20:80) as eluent with a flow rate of 1.0 mL/min on isocratic HPLC-RID system with an aminopropyl silane stationary phase [ZORBAX SIL 4.6 x 150 mm, 5 µm particle size column (USP-L8)]. The applicability of this method is illustrated in reaction monitoring, where D-fructose (substrate) is converted to D-psicose (product) in the presence of the enzyme: D-Tagotose 3- epimerase. Separation of D-psicose and D-fructose is achieved within 8 minutes with a resolution ≥ 4 which is the key advantage for reaction monitoring and linearity is established with regression of ≥ 0.99. Additionally, the current method uses a simple mobile phase, without any buffers. It can be used routinely for reaction monitoring.

Investigation of Non-Thermodynamical CO<sub>2</sub> Adsorption Behavior for Amine-Modified Nanoporous Silica

Non-thermodynamical CO2 adsorption behavior for amine-modified nanoporous silica is clarified by evaluating the mobility of organic functional group inside mesopores by using pulsed NMR technique. CO2 adsorption behavior of nanoporous silica modified with amino-propyl silane (AP) changes significantly depending on the amount of AP loaded. A low AP loaded sample shows normal adsorption behavior; the amount of CO2 adsorbed decreases with increasing temperature. In contrast, a high AP loaded sample possesses non-thermodynamic CO2 adsorption behavior in which the amount of CO2 adsorbed increases with increasing temperature in within a certain temperature range. To address the mechanism, a pulsed NMR technique was employed to clarify the mobility of AP molecules, and it was found that the mobility of mobile components in a high AP loaded sample increased drastically with increasing temperature while the mobility in a low AP loaded sample remained unchanged. It is understood that the enhancement of the diffusion of CO2 inside nanopores leads to the non-thermodynamic adsorption behavior.

Edge-Functionalized Graphene Nanoribbon Chemical Sensor: Comparison with Carbon Nanotube and Graphene.

With growing focus on the use of carbon nanomaterials in chemical sensors, one-dimensional graphene nanoribbon (GNR) has become one of the most attractive channel materials, owing to its enhanced conductance fluctuation by quantum confinement effects and dense, abundant edge sites. Due to the narrow width of a basal plane with one-dimensional morphology, chemical modification of edge sites would greatly affect the electrical channel properties of a GNR. Here, we demonstrate for the first time that chemically functionalizing the edge sites with aminopropylsilane (APS) molecules can significantly enhance the sensing performance of the GNR sensor. The resulting APS-functionalized GNR has a sensitivity ((Δ R/ Rb)max) of ∼30% at 0.125 ppm nitrogen dioxide (NO2) and an ultrafast response time (∼6 s), which are, respectively, 7- and 15-fold enhancements compared to a pristine GNR sensor. This is the fastest and most sensitive gas-sensing performance of all GNR sensors reported. To demonstrate the superiority of the GNR-APS sensor, we compare its sensing performance with that of APS-functionalized carbon nanotube (CNT) and reduced graphene oxide (rGO) sensors prepared in identical synthesis conditions. Very interestingly, the GNR-APS sensor exhibited 30- and 93-fold enhanced sensitivity compared to the CNT-APS and rGO-APS sensors. This might be attributed to highly active edge sites with superior chemical reactivity, which are not present in CNT and rGO materials. Density functional theory clearly shows that the greatly enhanced gas response of GNR with edge functionalization can be attributed to the higher electron densities in the highest occupied molecular orbital levels of GNR-APS and incorporation of additional adsorption sites. This finding is the first demonstration of the importance of edge functionalization of GNR for chemical sensors.

Removal of mercury (II) from water using magnetic nanoparticles coated with amino organic ligands and yam peel biomass

It was studied the adsorption of mercury from aqueous systems using magnetic nanoparticles (MNP) functionalized with different organic ligands, such as aminopropyl silane (MNP-APS), peptone (MNP-P), and yam peel biomass (MNP-YP). FTIR spectroscopy was used to determine the presence of chemical groups in all magnetic samples, such as amino radicals (NH2-), carboxyl (-COOH), and hydroxyl (OH-), which can contribute to the adsorption of Hg+2 ions in an aqueous solution. According to the SEM microscope, MNP-APS and MNP-P samples showed a particle size of about 45 and 70 nm, respectively. Additionally this technique allowed the visualization of these nanoparticles in the yam peel biomass. Saturation magnetization Ms was recorded with vibrating sample magnetometer equipment, from which was calculated an Ms of 66.30 emu/g for MNP-APS sample, 66.4 emu/g for MNP-P, and 26.6 emu/g for MNP-YP. Mercury adsorption was evaluated as a function of the pH. From these measurements, it was observed an increase of mercury adsorption as increasing the pH of the aqueous media, obtaining an adsorption of 94% for MNP-APS sample (pH 7.0), 87% for MNP-P (pH 7.0), and 75% for MNP-YP (pH 8.0). The adsorption kinetics showed an equilibrium time of 5 h, with adsorption capacities greater than 80% adsorption for all magnetic samples. Elovich model showed the best fit to the experimental values, while adsorption isotherms were well described with the Temkin isotherm equation, suggesting that only one active site present in the magnetic samples can be involved in the adsorption of mercury ions.

Light scattering and haze in TMOS-co-APTES silica aerogels

TMOS-co-APTES wet-gels have been used as templates for polymer crosslinked aerogels, which in turn have been used as strong materials and as starting materials for ceramic aerogels. Such wet-gels are prepared in acetonitrile (CH3CN) via co-gelation of tetramethylorthosilicate (TMOS) and 3-aminopropyl silane (APTES) in a 3:1 v/v ratio. Qualitatively, native monolithic TMOS-co-APTES aerogels appear more clear than the corresponding straight TMOS-derived materials, suggesting applications in thermally insulating daylighting. For that application, it is important to understand and minimize haze. Haze from the bulk of silica aerogels may be due to scattering from particles or pores, but study of its origin may be complicated by scattering and reflections from the surface of the monolith. In this report, using wet-gels as proxy materials for aerogels, haze from TMOS-co-APTES was investigated as a function of density, which is controlled by the amount of TMOS + APTES in the sol. The wet-gel approach to the study of haze of aerogels has the advantages of eliminating surface scattering issues from aerogel monoliths, and owing to better refractive index matching between the skeletal framework and the surrounding medium (CH3CN), bulk scattering is also reduced, facilitating study of lower-density materials. Haze from the bulk was traced to Rayleigh scattering down to 0.017 g cm−3 aerogels. The opacity of even lower-density samples (down to 0.006 g cm−3) was attributed to the Mie scattering. The scatterer size was obtained via Rayleigh’s law, and matched the secondary particle sizes of silica. The size of those particles increased as the density decreased, producing higher haze. Results suggest that in order to keep haze low at lower densities, one must keep the particle size low, for example, by increasing the rate of gelation.

The "Missing" Bicarbonate in CO2 Chemisorption Reactions on Solid Amine Sorbents.

We have identified a hydrated bicarbonate formed by chemisorption of 13CO2 on both dimethylaminopropylsilane (DMAPS) and aminopropylsilane (APS) pendant molecules grafted on SBA-15 mesoporous silica. The most commonly used sequence in solid-state NMR, 13C CPMAS, failed to detect bicarbonate in these solid amine sorbent samples; here, we have employed a Bloch decay ("pulse-acquire") sequence (with 1H decoupling) to detect such species. The water that is present contributes to the dynamic motion of the bicarbonate product, thwarting CPMAS but enabling direct 13C detection by shortening the spin-lattice relaxation time. Since solid-state NMR plays a major role in characterizing chemisorption reactions, these new insights that allow for the routine detection of previously elusive bicarbonate species (which are also challenging to observe in IR spectroscopy) represent an important advance. We note that employing this straightforward NMR technique can reveal the presence of bicarbonate that has often otherwise been overlooked, as demonstrated in APS, that has been thought to only contain adsorbed CO2 as carbamate and carbamic acid species. As in other systems (e.g., proteins), dynamic species that sample multiple environments tend to broaden as their motion is frozen out. Here, we show two distinct bicarbonate species upon freezing, and coupling to different protons is shown through preliminary 13C-1H HETCOR measurements. This work demonstrates that bicarbonates have likely been formed in the presence of water but have gone unobserved by NMR due to the nature of the experiments most routinely employed, a perspective that will transform the way the sorption community will view CO2 capture by amines.

Surface Enhanced DNP Assisted Solid-State NMR of Functionalized SiO2 Coated Polycarbonate Membranes

Abstract Surface enhanced solid-state NMR by dynamic nuclear polarization (DNP SENS) enables the characterization of the inner-pore surface functionalization of porous etched ion-track membranes exhibiting low specific surface areas compared to typical SBA- or MCM-type mesoporous silica materials. The membranes were conformally coated with a 5 nm thin SiO2 layer by atomic layer deposition. This layer was subsequently modified by aminopropyl silane linkers that allow further functionalization via the terminal amine group. The results evidence that in principle DNP SENS is a capable tool to analyze more complex porous systems, e.g. bioinspired functional etched ion-track membranes down to the molecular level. These results are relevant also for single nanopore systems, for which a direct analysis of the channel surface functionalization is not feasible by classical characterization methods. The applicability of DNP SENS to complex porous systems requires the optimization of the sample preparation and measurement parameters.

Mesoporous silica nanocarriers encapsulated antimalarials with high therapeutic performance

The use of nanocarriers in drug delivery is a breakeven research and has received a clarion call in biomedicine globally. Herein, two newly nano-biomaterials: MCM-41 encapsulated quinine (MCM-41 ⊃ QN) (1) and 3-phenylpropyl silane functionalized MCM-41 loaded QN (pMCM-41 ⊃ QN) (2) were synthesized and well characterized. 1 and 2 along with our two already reported nano-antimalarial drugs (MCM-41 ⊃ ATS) (3) and 3-aminopropyl silane functionalized MCM-41 contained ATS (aMCM-41 ⊃ ATS) (4) were screened in vitro for their activity against P. falciparium W2 strain, cytotoxicity against BGM cells and in vivo for their activity against Plasmodium bergheiNK65. 1 has the highest antimalarial activity in vivo against P. berghei NK65, (ED50: < 0.0625 mg/kg body weight) and higher mean survival time compared to the other nano biomaterials or unencapsulated drugs at doses higher than 0.0625 mg/kg body weight. This encapsulation strategy of MCM-41 ⊃ QN (1) stands very useful and effective in delivering the drug to the target cells compared to other delivery systems and therefore, this encapsulated drug may be considered for rational drug design.

Preparation of macroporous silica and its application on polysaccharide derivative based chiral stationary phase

In order to prepare 100-nm macroporous silica, spherical silica (5 μm in particle size, 10 nm in pore diameter) was treated by hydrothermal or baking methods. During hydrothermal treatment, 22 g/L NaF was added, which efficiently promoted the enlargement of pore diameters. By this method, the average pore diameter of silica reached 100 nm after heating for 48 h at 160℃ in an autoclave, but showed a poor size distribution. In the baking method, pore diameter enlargement was controlled by modifying the baking temperature, time, and the amount of double salt LiCl-NaCl added. The addition of 1.125 g LiCl·H2O and 0.75 g NaCl per 10 g silica and baking at 500℃ for 3-5 h yielded silica with 100-nm pore diameters. This method was more efficient, easier, and better in the product pore diameter distribution than hydrothermal treatment. The obtained silica was very similar to commercial Fuji-1000 gel. The macroporous silicas obtained from the hydrothermal and baking treatments were both modified with aminopropyl silane and coated by cellulose tri(3,5-dimethylphenyl carbamate) to prepare chiral stationary phases (CSPs). The CSP based on the baking-treated silica exhibited much better selectivity and resolution for enantiomers.