Carboxyethylsilanetriol Sodium Salt Research Articles

A novel zwitterionic magnetic nanocomposite developed for non-invasive speciation analysis of inorganic chromium

3-(2-Aminoethylamino)propyltriethoxysilane and carboxyethylsilanetriol sodium salt were grafted on silica-coated Fe3O4 nanoparticles via sol-gel process to prepare novel amine- and carboxyl-bifunctionalized magnetic nanocomposites (SMNPs-(NH2 + COOH)). After well characterized, this doubly functionalized material was used as magnetic solid-phase extraction (MSPE) adsorbent to separate and enrich inorganic chromium species followed by inductively coupled plasma-mass spectrometry detection. The optimization of MSPE operation parameters including pH was conducted. It is reasonably elucidated that the adsorption mechanisms of zwitterionic SMNPs-(NH2 + COOH) towards chromium species are electrostatic and/or coordination interactions. Cr(VI) and Cr(III) can be adsorbed around pH 3.0 and around 10.0 respectively with strong anti-interference ability not only from other co-existing ions but also from the two labile species each other, and eluted by dilute nitric acid solution. With a 15-fold enrichment factor, the limits of detection of Cr(VI) and Cr(III) were 0.008 and 0.009 μg L−1, respectively, profiting from the maximum adsorption capacities of 7.52 and 6.11 mg g−1. The just one magnetic extraction matrix based speciation scheme possesses excellent convenience and friendliness to Cr(VI) and Cr(III) without any oxidation or reduction prior to capture of these two species. This protocol has been successfully applied to the speciation analysis of inorganic chromium in real-world environmental water samples.

Synthesis and adsorption performance of functionalized chitosan and carboxyethylsilanetriol hybrids

A novel adsorbent from cationic chitosan derivative and anionic silica precursor was fabricated to remove methylene blue (MB). The hybrid material was prepared from N-guanidinium chitosan acetate (GChi) and carboxyethylsilanetriol sodium salt by a simple ionic interaction followed by sol–gel approach. Multiple characterization methods were used to analyze the morphology and the structure of the well-prepared functionalized material. Batch experiments were conducted to optimize the various operational parameters. The Langmuir isotherm was used to fit the data, and it predicted monolayer adsorption with a maximum capacity of 334 mg g−1. A pseudo-second-order equation fit the adsorption process well. Chitosan/silica hybrids containing carboxylic groups are efficient and cost-effective adsorbents for cationic dyes adsorption from aqueous solutions.

Development of a novel amine- and carboxyl-bifunctionalized hybrid monolithic column for non-invasive speciation analysis of chromium

A novel amine- and carboxyl-bifunctionalized organic-inorganic hybrid monolithic column (A&C-HMC) was synthesized via one-pot co-condensation of N-(2-aminoethyl)-3-aminopropyltriethoxysilane, carboxyethylsilanetriol sodium salt and tetramethoxysilane with cetyltrimethylammonium bromide and polyethylene glycol 6000 as binary porogens in this work. The introduction of the binary porogens controllably improved the morphology and pore structure of A&C-hybrid monolith (HM) and made the active sites of amine and carboxyl groups more prolific, compared with the monolith prepared with either of porogens. It is found that Cr(VI) and Cr(III) can be selectively adsorbed on A&C-HM under different pH ranges, and eluted by aqueous nitric acid solution completely. The A&C-HMC was used as needle-solid phase microextraction (SPME) matrix for direct separation and enrichment of inorganic chromium species coupled with inductively coupled plasma mass spectrometer without any oxidation/reduction treatment. Various parameters of SPME operation and analytical performance were investigated systematically, and the adsorption mechanism was also discussed and explained in depth. In view of the advantages of facile preparation, low cost, excellent speciation selectivity and high adsorption capacity to Cr(VI) and Cr(III), the A&C-HMC based SPME protocol is a promising alternative for non-disturbed speciation analysis of inorganic chromium in real environmental water samples.

PH responsive selective protein adsorption by carboxylic acid functionalized large pore mesoporous silica nanoparticles SBA-1

Cubic mesoporous silica nanoparticles (MSNs) with the SBA-1 moiety, functionalized with carboxylic acid (COOH) groups as well as enlarged mesopores, are successfully synthesized using tetraethyl orthosilicate (TEOS) and carboxyethylsilanetriol sodium salt (CES) as silica sources, complexes formed by polyacrylic acid (PAA) and hexadecylpyridinium chloride (CPC) as templates, and trimethylbenzene (TMB) as pore expander. The successful incorporation of organic functionalities are confirmed by 13C and 29Si solid-state NMR. The structural properties of cubic mesostructures are characterized by powder XRD, N2 adsorption-desorption isotherms, and TEM measurements. The prepared MSNs exhibit a remarkably high adsorption capacity of 1138 mg g−1 at pH 8.2 when they are used as the supports to immobilize papain. Both factors of the large pore size of the support and the favorable electrostatic attractions between the carboxylate groups on the adsorbent surface and the papain molecules play important roles in reaching such a high adsorption capacity. The immobilized papain possesses better thermal stability, pH tolerance, and heat resistance in comparison to the free papain. The materials are also used for selective adsorption of a single protein (papain) from the binary mixture of two different types of proteins (papain and hemoglobin). Our results demonstrate that proteins such as papain and hemoglobin with different isoelectric points and shapes can be effectively separated from their binary mixture by simply tuning the pH of the buffer.

Cage like ordered carboxylic acid functionalized mesoporous silica with enlarged pores for enzyme adsorption

Cubic FDU-12 type mesoporous silicas with enlarged pores and carboxylic acid (–COOH) functionality in the pore channels (denoted as LP-FTC-x) are synthesized using tetraethyl orthosilicate (TEOS) and carboxyethylsilanetriol sodium salt (CES) as silica sources, Pluronic F127 triblock copolymer as template, and trimethylbenzene (TMB) as pore expander, and utilized them as supports for enzyme immobilization. When the –COOH content is increased from 0 to 30%, the pore size of LP-FTC-x decreases from 23.6 to 11.1 nm, and its particle size decreases from around 2 μm to 600–800 nm. The material exhibits a high papain adsorption capacity (895 mg g−1) with a low leaching rate at pH 8.2 due to the well-defined surface chemistry in the pore channel. The adsorption kinetics and isotherms follow the pseudo-second-order model and the Langmuir isotherm model, respectively. The excellent structural properties of LP-FTC-x are also advantageous for enhancement in stability of enzyme toward the temperature, solution pH, and incubation time variations.

Functionalization of cubic mesoporous silica SBA-16 with carboxylic acid via one-pot synthesis route for effective removal of cationic dyes

In this work, we demonstrate that a high density of COOH groups loading, up to 60mol% based on silica, is successfully incorporated into SBA-16 via a one-pot synthesis route, which involves co-condensation of carboxyethylsilanetriol sodium salt (CES) and tetraethylorthosilicate (TEOS) templated by Pluronic F127 and P123 in an acidic medium. A variety of characterization techniques are performed to confirm quantitative incorporation of carboxylic groups into ordered cubic mesostructures. These functionalized materials are used to effectively remove two cationic dyes methylene blue (MB) and phenosafranine (PF) with the maximum adsorption capacities of 561 and 519mgg−1, respectively, at pH 9. The zeta potential results reveal that the electrostatic interactions between cationic dye molecule and negatively charged surface of the adsorbent play a crucial role in their high adsorption capacities. For a binary component system consisting of MB and PF, competitive adsorption of these two dyes is observed with adsorption capacity values slightly lower than those of the corresponding single dye systems. The dye adsorbed material can be easily regenerated by simple acid washing and be reused for five times with MB removal efficiency still up to 98.6%, showing its great potentials in environmental remediation.

Roles of nanostructures and carboxylic acid functionalization of ordered cubic mesoporous silicas in lysozyme immobilization

Cage-type cubic mesoporous silicas FDU-12 functionalized with a tunable content of carboxylic acid (–COOH) groups, ranging from 0 to 50 mol% based on silica, were used for immobilization of lysozyme. The particle size of –COOH functionalized FDU-12 was highly dependent on the relative amount of carboxyethylsilanetriol sodium salt (CES) and tetraethoxysilane (TEOS) in the reaction mixture. The particle size was around 200 nm for the materials prepared with the CES/(TEOS + CES) molar ratio of 20%–30%. The combination of –COOH functionalization and nanoscale dimension significantly enhanced the lysozyme adsorption capacity of the prepared materials. A remarkably high adsorption capacity of 895 mg g−1 at 37 °C (pH 9.6) was attained with the FDU-12 nanostructure functionalized with 30 mol% of –COOH groups. Meanwhile, the structural stability of lysozyme was unaltered after immobilization. A very low leaching rate was observed, indicating that protein molecules were tightly adsorbed onto the –COOH functionalized FDU-12 nanostructures due to the strong electrostatic interactions between the adsorbent and the lysozyme molecule. The zeta potentials of the materials also correspond well to their adsorption capacities observed. The enzymatic activity of the immobilized lysozyme was also examined as a function of the –COOH contents present on the mesopore surface of the materials.

Indirect immunofluorescence detection of E. coli O157:H7 with fluorescent silica nanoparticles

A method of fluorescent nanoparticle-based indirect immunofluorescence assay using either fluorescence microscopy or flow cytometry for the rapid detection of pathogenic Escherichia coli O157:H7 was developed. The dye-doped silica nanoparticles (NPs) were synthesized using W/O microemulsion methods with the combination of 3-aminopropyltriethoxysilane (APTES) and fluorescein isothiocyanate (FITC) and polymerization reaction with carboxyethylsilanetriol sodium salt (CEOS). Protein A was immobilized at the surface of the NPs by covalent binding to the carboxyl linkers and the surface coverage of Protein A on NPs was determined by the Bradford method. Rabbit anti-E. Coli O157:H7 antibody was used as primary antibody to recognize E. coli O157:H7 and then antibody binding protein (Protein A) labeled with FITC-doped silica NPs (FSiNPs) was used to generate fluorescent signal. With this method, E. Coli O157:H7 in buffer and bacterial mixture was detected. In addition, E. coli O157:H7 in several spiked background beef samples were measured with satisfactory results. Therefore, the FSiNPs are applicable in signal-amplified bioassay of pathogens due to their excellent capabilities such as brighter fluorescence and higher photostability than the direct use of conventional fluorescent dyes.

Effect of carboxylic acid of periodic mesoporous organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems

This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (–COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and 13C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed.

Ordered cubic mesoporous silica KIT-5 functionalized with carboxylic acid groups for dye removal

Cubic cage-type KIT-5 mesoporous silica functionalized with carboxylic acid (–COOH) groups, ranging from 0 to 45 mol% based on silica, were synthesized via co-condensation of tetraethyl orthosilicate (TEOS) and carboxyethylsilanetriol sodium salt (CES) in the presence of Pluronic F127 in acidic media. The materials thus obtained were characterized by powder X-ray diffraction, nitrogen sorption, transmission electron microscopy, FTIR, thermogravimetric analysis, acid–base titration, and solid-state NMR measurements. The –COOH functionalized KIT-5 was used to adsorb different types of dyes such as phenosafranine (PF), methylene blue (MB), orange II (OII) and rhodamine B (RhB). The –COOH functionalized KIT-5 materials exhibited excellent adsorption capacities for cationic PF and MB, and amphoteric RhB in comparison to pure silica KIT-5, but the opposite for anionic OII. The adsorption was highly dependent on the electrostatic interaction between the adsorbent and the dye molecules. External mass transfer and intra-particle diffusion collectively control the adsorption process.

Ethane‐Bridged Periodic Mesoporous Organosilicas Functionalized with High Loadings of Carboxylic Acid Groups: Synthesis, Bifunctionalization, and Fabrication of Metal Nanoparticles

Well-ordered periodic mesoporous organosilicas (PMOs) functionalized with high contents of carboxylic acid (COOH) groups, up to 85 mol % based on silica, were synthesized by co-condensation of 1,2-bis(triethoxysilyl)ethane (BTEE) and carboxyethylsilanetriol sodium salt (CES) under acidic conditions by using alkyl poly(oxyethylene) surfactant Brij 76 as a structure-directing agent. A variety of techniques including powder X-ray diffraction (XRD), nitrogen adsorption/desorption, Fourier-transformed infrared (FTIR), transmission electron microscopy (TEM), (13) C- and (29) Si solid-state nuclear magnetic resonance (NMR) were used to characterize the products. The materials thus obtained were used as an effective support to synthesize metal nanoparticles (Ag and Pt) within the channel of 2D hexagonal mesostructure of PMOs. The size and distribution of the nanoparticles were observed to be highly dependent on the interaction between the carboxylic acid functionalized group and the metal precursors. The size of Pt nanoparticles reduced from 3.6 to 2.5 nm and that of Ag nanoparticles reduced from 5.3 to 3.4 nm with the increase in the COOH loading from 10 to 50 %.

Synthesis and characterization of large pore cubic mesoporous silicas functionalized with high contents of carboxylic acid groups and their use as adsorbents

Well-ordered cubic FDU-12 type mesoporous silicas functionalized with various contents of carboxylic acid group (COOH), up to 40mol% based on silica, were synthesized via co-condensation of tetraethyl orthosilicate (TEOS) and carboxyethylsilanetriol sodium salt (CES) under acidic conditions using Pluronic F127 triblock copolymer as template. The materials thus obtained were characterized by a variety of techniques including powder X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM), 13C and 29Si solid-state nuclear magnetic resonance (NMR) measurements. The materials were used as adsorbents for removal of methylene blue (MB) in aqueous solutions and as an antidote for intoxication of herbicide paraquat (PQ). Due to the COOH functionalization, three-dimensional pores, high surface areas, and electrostatic interactions between the adsorbent and the adsorbates, the prepared adsorbents possessed very high adsorption capacities and extremely rapid rates for MB and PQ adsorption. The kinetic regression results revealed that the overall adsorption process was controlled by external mass transfer and intra-particle diffusion jointly. The Langmuir isotherm model showed better fit with the experimental adsorption data than the Freundlich isotherm model, implying a monolayer adsorption mechanism. The present results show that the prepared COOH functionalized cubic mesoporous silicas have great potentials for removing pollutants and herbicides from aqueous solutions in environmental and clinical applications.

Synthesis, Bifunctionalization, and Remarkable Adsorption Performance of Benzene‐Bridged Periodic Mesoporous Organosilicas Functionalized with High Loadings of Carboxylic Acids

Highly ordered benzene-bridged periodic mesoporous organosilicas (PMOs) that were functionalized with exceptionally high loadings of carboxylic acid groups (COOH), up to 80 mol % based on silica, have been synthesized and their use as adsorbents for the adsorption of methylene blue (MB), a basic dye pollutant, and for the loading and release of doxorubicin (DOX), an anticancer drug, is demonstrated. These COOH-functionalized benzene-silicas were synthesized by the co-condensation of 1,4-bis(triethoxysilyl) benzene (BTEB) and carboxyethylsilanetriol sodium salt (CES), an organosilane that contained a carboxylic acid group, in the presence of non-ionic oligomeric surfactant Brij 76 in acidic medium. The materials thus obtained were characterized by a variety of techniques, including powder X-ray diffraction (XRD), nitrogen-adsorption/desorption isotherms, TEM, and (13)C and (29)Si solid-state NMR spectroscopy. Owing to the exceptionally high loadings of COOH groups, their high surface areas, and possible π-π-stacking interactions, these adsorbents have very high adsorption capacities and extremely rapid adsorption rates for MB removal and for the controlled loading/release of DOX, thus manifesting their great potential for environmental and biomedical applications.

Design and preparation of biocompatible zwitterionic hydroxyapatite.

This study reports the design and preparation of zwitterionic nanocrystalline hydroxyapatite (HA) capable of inhibiting bacterial adhesion while allowing osteoblast cell colonization. The surface functionalization of HA powders was carried out by post-synthesis grafting of 3-aminopropyltriethoxysilane (APTES) and carboxyethylsilanetriol sodium salt (CES) as amine and carboxylate precursors, respectively. The successful functionalization of HA surfaces was assessed by elemental chemical analysis, FTIR, 29Si, 31P and 13C solid state CP/MAS NMR and ζ-potential measurements, and the zwitterionic nature of the synthesized HA was proved through the presence of -NH3 +/-COO- pairs on the material surfaces. With the aim of evaluating the feasibility of this functionalization strategy in HA shaped in different physical forms, HA 3D macroporous scaffolds were fabricated by rapid prototyping and then provided with zwitterionic character. The effect of the simultaneous presence of -NH3 +/-COO-zwitterionic pairs on the surface of HA on its behaviour regarding bacterial adhesion was tested using E. coli as model bacteria. The in vitro biocompatibility of these materials was investigated with cultured human HOS cells. The results indicate that it is possible to provide HA shaped in different physical forms (particles, granules, coatings, dense blocks, 3D scaffolds, etc.) with bacterial anti-adhesive properties via the "zwitterionization" process without affecting its biocompatibility. These findings open up promising expectations in many clinical fields including dentistry, maxillofacial surgery and otolaryngology, where a decrease in the bacterial adherence onto the implant surface would reduce the infection rates after implantation surgery.

One-Pot Synthesis of Mesoporous Silica Nanocarriers with Tunable Particle Sizes and Pendent Carboxylic Groups for Cisplatin Delivery

Mesoporous silica nanocarriers with tunable particle sizes and different loadings of pendent carboxylic groups were successfully prepared by a straightforward and reproducible strategy, in which carboxyethylsilanetriol sodium salt was co-condensed with tetraethoxyorthosilicate to introduce the carboxylic groups. The key in this strategy was to separate the synthesis process into two steps of the nuclei formation and particle growth. The uniform particle size and ordered structure of the synthesized nanocarriers were manifested by several techniques such as XRD, TEM, SEM, and BET. DLS measurement illustrated that nanocarriers could be well suspended in aqueous solution. The integration and content tunability of the carboxylic groups within mesoporous silica nanoparticles (MSNs) were verified by FT-IR and (29)Si NMR. The inherent carboxylic units on the obtained carboxylic group modified MSNs (MSNs-C) effectively enhanced the capture and tailored the release properties of the anticancer drug of cisplatin. The accumulation of drug in the HeLa cells was greatly enhanced due to the highly efficient platinum uptake efficiency transported by the synthesized nanocarriers. The drug encapsulated in the MSNs-C exhibited a higher antitumor activity than free cisplatin against both MCF-7 and HeLa cells.

A comparative study of in-flow and micro-patterning biofunctionalization protocols for nanophotonic silicon-based biosensors

Reliable immobilization of bioreceptors over any sensor surface is the most crucial step for achieving high performance, selective and sensitive biosensor devices able to analyze human samples without the need of previous processing. With this aim, we have implemented an optimized scheme to covalently biofunctionalize the sensor area of a novel nanophotonic interferometric biosensor. The proposed method is based on the ex-situ silanization of the silicon nitride transducer surface by the use of a carboxyl water soluble silane, the carboxyethylsilanetriol sodium salt (CTES). The use of an organosilane stable in water entails advantages in comparison with usual trialkoxysilanes such as avoiding the generation of organic waste and leading to the assembly of compact monolayers due to the high dielectric constant of water. Additionally, cross-linking is prevented when the conditions (e.g. immersion time, concentration of silane) are optimized. This covalent strategy is followed by the bioreceptor linkage on the sensor area surface using two different approaches: an in-flow patterning and a microcontact printing using a biodeposition system. The performance of the different bioreceptor layers assembled is compared by the real-time and label-free immunosensing of the proteins BSA/mAb BSA, employed as a model molecular pair. Although the results demonstrated that both strategies provide the biosensor with a stable biological interface, the performance of the bioreceptor layer assembled by microcontact printing slightly improves the biosensing capabilities of the photonic biosensor.

Highly Carboxylic‐Acid‐Functionalized Ethane‐Bridged Periodic Mesoporous Organosilicas: Synthesis, Characterization, and Adsorption Properties

Functionalization of periodic mesoporous organosilicas (PMOs) with high loadings of pendant organic groups to form bifunctional PMOs with ordered mesostructures remains a challenging objective. Herein, we report that well-ordered ethane-bridged PMOs functionalized with exceptionally high loadings of pendant carboxylic acid groups (up to 80 mol % based on silica) were synthesized by the co-condensation of 1,4-bis(trimethoxysilyl)ethane (BTME) and carboxyethylsilanetriol sodium salt (CES) with Pluronic P123 as the template and KCl as an additive under acidic conditions. The bifunctional materials were characterized by using a variety of techniques, including powder X-ray diffraction, nitrogen-adsorption/desorption, TEM, and solid-state (13)C and (29)Si NMR spectroscopy. Zeta-potential measurements showed that the surface negative charges increased with increasing the CES content. This property makes them potential candidates for applications in drug adsorption. The excellent adsorption capacity of these bifunctional PMOs towards an anticancer drug (doxorubicin) was also demonstrated.

Direct synthesis of bifunctional periodic mesoporous benzene-silicas functionalized with a high loading of carboxylic acid groups

Well-ordered periodic mesoporous benzene-silicas functionalized with a high loading of pendant carboxylic acid groups (up to 60 mol% based on silica) have been successfully synthesized via co-condensation of 1,4-bis(triethoxysilyl)benzene and carboxyethylsilanetriol sodium salt using Pluronic P123 as a template and KCl as an additive.

Synthesis of Carboxylic Group Functionalized Monodispersed Mesoporous Silica Spheres (MMSSs) via Costructure Directing Method

Abstract MMSSs with radially oriented porous structure were successfully synthesized by using cationic gemini surfactant as template and carboxyethylsilanetriol sodium salt (CES) as costructure-directing agent (CSDA). Particle size can be controlled by adding different cosolvent such as isopropanol, methanol, ethanol, or dimethyl sulfoxide.

Insight Into the Defects of Cage‐Type Silica Mesoporous Crystals with Fd$\bar 3$m Symmetry: TEM Observations and a New Proposal of “Polyhedron Packing” for the Crystals

Silica mesoporous crystals were synthesized by using a gemini cationic surfactant (C(18-3-1)) as the directing agent, carboxyethylsilanetriol sodium salt as the co-structure directing agent (CSDA), and varying amounts of HCl. By using transmission electron microscopy (TEM) we observed 1) a structural change from the close-packed structures of spherical micelles--face-centered cubic (Fm3m) and hexagonal close-packed (P6(3)/mmc)--to Fd3m structures with an increase of HCl and 2) a few structural defects in the crystals with Fd3m symmetry. The structure of a crystal with Fd3m symmetry is described as one of the tetrahedrally close-packed (tcp) structures consisting of 5(12) and 5(12)6(4) polyhedra. The observed TEM images of the structural defects were explained well through use of simulated TEM images by introducing new 13-15 polyhedra comprising 5(12)6(2), 5(12)6(3), 4(1)5(10)6(2), 4(2)5(8)6(5), and 4(1)5(10)6(4), which have been observed in bubbles by Matzke. The mesostructural changes and defect formation are discussed in terms of the hardness of micelles composed of surfactant/CSDA/silica species that have formed through a change of the interaction between the surfactant and CSDA, which causes the micelles to change from a regime of close-packing to one of minimum-area packing.