Functionalized Mesoporous Silica Research Articles

Functionalized Mesoporous Silica for Highly Selective Sensing of Iron Ion in Water

In this study, we examined the highly selective sensing of Fe3+ ions in water using metal complex-functionalized mesoporous silica materials. Metal complex-functionalized mesoporous silica materials were synthesized on the mesoporous surface of SBA-15 via complexation process between Eu3+ and aminosilane groups. Mesoporous silica, SBA-15, and the Eu3+-complex functionalized SBA-15 were characterized using X-ray diffraction (XRD), transmittance electron microscopy (TEM), nitrogen sorption behavior, and Fourier transform infrared (FTIR) spectroscopy. The sensing behavior of the Eu3+-complex functionalized SBA-15 was studied using various metal ions (Fe3+, Cu2+, Cr3+, Co2+, Hg2+, Pb2+, and Zn2+) aqueous solutions. Photoluminescence intensity (λ = 612 nm) of the Eu3+-complex functionalized SBA-15 was dependent on the different interactions between metal ions and Eu3+-complexes. Photoluminescence intensity at λ = 612 nm of the Eu3+-complex functionalized SBA-15 decreased to near zero and proved the highly selective sensing effect of Fe3+. Therefore, the Eu3+-complex functionalized SBA-15 can be considered an excellent candidate for sensing iron ions in water.

Functionalized Mesoporous Silica Nanoparticles as Delivery Systems for Doxorubicin: Drug Loading and Release

Functionalized nanoparticles have played a major role in the field of targeted therapy, owing to their ability to control the release and for the selective delivery of entrapped materials to tumours. In this work, we described the loading capacity and in vitro release kinetics of mesoporous silica nanoparticles (MSNs), functionalized with Poly-L-Histidine and Tamoxifen. The model drug Doxorubicin (DOX) was successfully encapsulated into MSN-based systems, using the technique of solvent immersion. A post-surface grafting loading method was investigated on functionalized systems, with DOX loading content determined using HPLC. Dialysis bag diffusion was employed to investigate the release kinetics of DOX-loaded-systems at pH 7.4 and 5. The amount of DOX released from native MSNs systems over a 72 h period at pH 5 was approximately 40%; and at pH 7.4 ≈ 30%. A moderate pH dependent release behaviour was observed with both our functionalized systems: DOX@MSN-PLH and DOX@MSN-PLH-TAM; with approximately 5% of DOX released from DOX@MSN-PLH-TAM at pH 7.4 and about 9% released at pH 7.4 over 72 h. The maximal cumulated release of DOX molecules from DOX@MSN-PLH after 72 h was ≈18% at pH 7.4 and ≈23% at pH 5, respectively. The outcome of this work offers a promising contribution towards building future stimuli-responsive nano-drug delivery systems.

Preparation of Functionalized Mesoporous Silica as a Novel Carrier and Immobilization of Laccase.

Amino-modified mesoporous silica (SBA-15-NH2) was prepared by hydrothermal method, which is a kind of excellent carrier for enzyme immobilization. The structure of SBA-15 was characterized by SEM and FTIR, which proved that amino group was successfully attached to the surface of SBA-15. The carrier had good mesoporous structure proved by nitrogen adsorption and desorption test. Using SBA-15-NH2 as the carrier, the optimal conditions of laccase immobilization by two different cross-linking methods were explored. At the same time, the properties of the immobilized enzyme and free enzyme were compared. The results showed that the activity of immobilized laccase by two-step method (2977.5 U/g) was much higher than that by one-step method (239.5 U/g). The optimal conditions were as follows: free laccase (35°C, pH=4.5), two-step immobilized laccase (40°C, pH=4.0), one-step immobilized laccase (35°C, pH=4.0). The two-step method was more adaptable to temperature. The pH adaptation range of the immobilized enzyme is wider, and the thermal stability is greatly enhanced. After five cycles of repeated reaction, the residual enzyme activity of two-step and one-step methods was 56% and 43% of the original. The treatment of simulated wastewater containing 2,4-dichlorophenol (2,4-DCP) by immobilized laccase was also studied. Under optimum conditions (40°C, pH=5.0, 20 mg/L), the removal of 2,4-DCP reached 89.06%. The immobilized laccase is really effective for treatment of 2,4-DCP-containing wastewater.

The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous Catalyst in Organic Synthesis

The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous Catalyst in Organic Synthesis

Molecular dynamic simulations and quantum chemical calculations of adsorption process using amino-functionalized silica

Present study focused on the adsorption behavior of two cationic dyes (Neutral Red (NR) and Rhodamine B (RB)) on mesoporous silica (MPS) and amino-functionalized MPS with N1-(3-Trimethoxysilylpropyl) diethylenetriamine linker (TAF/MPS). In order to provide more details about adsorption mechanism of dyes on the adsorbents surface, the molecular dynamics (MD) simulations were employed. A very promising simulation approach for adsorption of NR and RB dyes by functionalized and bare MPS adsorbents were obtained by MD results. The obtained results of quantum chemical calculations confirmed the highest adsorption energy for TAF/MPS-water-RB configurations, while the MPS-water-NR had the lowest adsorption energy. According to the results, functionalization of MPS with amino groups led to improvement in adsorption affinity of both dyes. The Sigma profiles demonstrated higher RB adsorption on both adsorbent while lower HOMO–LUMO energy gap was observed for RB dye compared to NR dye. Based on the energies of the HOMO and LUMO, other quantum chemical descriptors were calculated for different dyes, water and adsorbent configurations. These descriptors include: hardness (η), softness (σ), chemical potential (μ), nucleophilicity (ɛ) and electrophilicity index (ω). It was observed that the chemical reactivity, softness, and polarizability of RB dye were more than that of NR dye. The results of this study provide deeper atomic/molecular understanding into the adsorption mechanism of dye molecules on adsorbent surface which could help to get new insights about interactions of molecules. Moreover, MD simulation can be a very useful approach in term of cost-efficient and time saving for predicting the adsorption behavior of structures.

The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous Catalyst in Organic Synthesis

Mesoporous silica nanomaterials provide an extraordinary advantage for making new and superior heterogeneous catalysts because of their surface silanol groups. The functionalized mesoporous SBA-15, such as acidic, basic, BrÖnsted, lewis acid, and chiral catalysts, are used for a wide range of organic syntheses. The importance of the chiral ligands, which were immobilized on the SBA-15, was mentioned in this review to achieve chiral products as valuable target molecules. Herein, their synthesis and application in different organic transformations are reviewed from 2016 till date 2020.

Molecular modeling investigation on mechanism of cationic dyes removal from aqueous solutions by mesoporous materials

Currently, mesoporous silica (MPS) adsorbents as promising material have been widely used for toxic dyes removal from wastewater but understanding the detail of adsorption mechanism still remains a big challenge. This work presents an approach for design and simulation of the cationic dyes removal through MPS and an amino-functionalized MPS (3-Aminopropyl triethoxysilane, MPS-APTES) structures in aqueous solution. The adsorption of methylene blue and malachite green dyes on the MPS and functionalized MPS were comprehensively analyzed using quantum mechanics method. The results showed that the adsorption energy of compounds was increased as follows: MPS-APTES-water-malachite green, MPS-APTES-water-methylene blue, MPS-water-malachite green and MPS-water-methylene blue structures. An improvement in adsorption of both dyes was observed in presence of amino groups in the surface of MPS. The HOMO and LUMO energy levels were calculated for dyes and adsorbents-water-dyes configurations. Other impressive quantum chemical descriptors, such as chemical potential (μ), global hardness (η), global softness (σ), polarizability and electrophilicity index (ω) were calculated using ionization energy (I) and electron affinity (A) energies. It was observed that the softness and chemical reactivity of MPS-APTES-dye systems were higher than MPS-dyes; moreover MPS-APTES-water-malachite green structure had more softness and chemical reactivity compared to MPS-APTES-water-methylene blue. As a result, the electron transfer of studied dyes on MPS-APTES structure was more facile compared to MPS structure which was in accordance with the low ∆EGAP and electrophilicity index of MPS-APTES-dyes compounds. The quantum calculations demonstrated that amino functionalization of MPS provides higher reactivity for adsorption of organic pollutants in comparison to MPS. In particular, this study shows that the theoretical molecular calculation is highly recommended for cost and time saving as this approach offers an evaluation of process feasibility before any practical analysis.

1,4-Diazabicyclo [2.2.2] Octane Functionalized Mesoporous Silica SBA-15 (SBA-15@DABCO): a Novel Highly Selective Adsorbent for Selective Separation/Preconcentration of Cr(VI) from Environmental Water Samples

1,4-Diazabicyclo [2.2.2] Octane Functionalized Mesoporous Silica SBA-15 (SBA-15@DABCO): a Novel Highly Selective Adsorbent for Selective Separation/Preconcentration of Cr(VI) from Environmental Water Samples

One-Pot Hydrothermal Synthesis of Functionalized Mesoporous Silica for Effective Removal of Pb(II) Ion

There is a huge scope for the removal of heavy metal ions from aqueous solutions. In this study, mesoporous silica materials, (MSMs), functionalized with (3-Mercaptopropyl) trimethoxysilane, (MPTS/MSMs), were prepared and used for adsorption of Pb(II) ions from aqueous solutions. The synthesis of MPTS/MSMs adsorbent was done using one-pot hydrothermal method by immobilizing 3-Mercaptopropyl trimethoxysilane onto mesoporous silica surface. The structure and properties of the adsorbent were explored using different techniques such as FT-IR, XRD, SEM, TEM, TGA, and N2 adsorption-desorption isotherms. The adsorption applicability of prepared nanostructure for removal of the Pb(II) ions from the aqueous solution was investigated and the results showed a good selectivity in the absorption of Pb(II) ions over other ions in aqueous solution. The effect of different parameters including the solution pH, Pb(II) concentration, sorbent amount, ion interfering effect, and the contact time onto the removal efficiency of the adsorbent was investigated systematically. The maximum adsorption efficiency (~ 97%) was found for the solutions with pH = 6, the best contact time was seen as 30 min for 50 mg L−1 of the analyte under the optimal conditions. The adsorbent was triumphantly used for the removal of Pb (II) ions from the three real water samples, including tap water, well water, and lake water with the removal efficiency of > 95%.

The Synthesis and Application of Functionalized Mesoporous Silica SBA-15 as Heterogeneous Catalyst in Organic Synthesis

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Fluorine-Free Transparent Superhydrophobic Nanocomposite Coatings from Mesoporous Silica

In recent decades, there has been a growing interest in the development of functional, fluorine-free superhydrophobic surfaces with improved adhesion for better applicability into real-world problems. Here, we compare two different methods, spin coating and aerosol-assisted chemical vapor deposition (AACVD), for the synthesis of transparent fluorine-free superhydrophobic coatings. The material was made from a nanocomposite of (3-aminopropyl)triethoxysilane (APTES) functional mesoporous silica nanoparticles and titanium cross-linked polydimethylsiloxane with particle concentrations between 9 to 50 wt %. The silane that was used to lower the surface energy consisted of a long hydrocarbon chain without fluorine groups to reduce the environmental impact of the composite coating. Both spin coating and AACVD resulted in the formation of superhydrophobic surfaces with advancing contact angles up to 168°, a hysteresis of 3°, and a transparency of 90% at 550 nm. AACVD has proven to produce more uniform coatings with concentrations as low as 9 wt %, reaching superhydrophobicity. The metal oxide cross-linking improves the adhesion of the coating to the glass. Overall, AACVD was the more optimal method to prepare superhydrophobic coatings compared to spin coating due to higher contact angles, adhesion, and scalability of the fabrication process.

One-Pot Hydrothermal Synthesis of Functionalized Mesoporous Silica for Effective Removal of Pb(II) Ion

There is a huge scope for the removal of heavy metal ions from aqueous solutions. In this study, mesoporous silica materials, (MSMs), functionalized with (3-Mercaptopropyl) trimethoxysilane, (MPTS/MSMs), were prepared and used for adsorption of Pb(II) ions from aqueous solutions. The synthesis of MPTS/MSMs adsorbent was done using one-pot hydrothermal method by immobilizing 3-Mercaptopropyl trimethoxysilane onto mesoporous silica surface. The structure and properties of the adsorbent were explored using different techniques such as FT-IR, XRD, SEM, TEM, TGA, and N2 adsorption-desorption isotherms. The adsorption applicability of prepared nanostructure for removal of the Pb(II) ions from the aqueous solution was investigated and the results showed a good selectivity in the absorption of Pb(II) ions over other ions in aqueous solution. The effect of different parameters including the solution pH, Pb(II) concentration, sorbent amount, ion interfering effect, and the contact time onto the removal efficiency of the adsorbent was investigated systematically. The maximum adsorption efficiency (~ 97%) was found for the solutions with pH = 6, the best contact time was seen as 30 min for 50 mg L−1 of the analyte under the optimal conditions. The adsorbent was triumphantly used for the removal of Pb (II) ions from the three real water samples, including tap water, well water, and lake water with the removal efficiency of > 95%.

Galactose Functionalized Mesoporous Silica Nanoparticles As Delivery Vehicle in the Treatment of Hepatitis C Infection.

DNA and RNA based antiviral strategies using nonviral vectors have shown better potential over the viral pathway due to the fewer chances of gene recombination and immunogenicity. In this work a mesoporous silica nanoparticle (MSN) based carrier system has been used for targeted delivery of shDNA molecule against the conserved 5'-untranslated region (UTR) in the RNA of a hepatitis C virus to inhibit its replication. The MSNs coated with amine and galactose could specifically target liver cells. Significant reduction (about 94%) of viral RNA level was achieved in HCV-JFH1 infectious cell culture compared to the control RNA levels directed the successful delivery and action of the shDNA. This study showed that Gal-AMSN can be used as a synthetic delivery vector to deliver the shDNA effectively for the treatment of HCV infection.

Folic Acid/Methotrexate Functionalized Mesoporous Silica Nanoflakes from Different Supports: Comparative Study

Herein, we present a facile synthesis route for the mesoporous silica nanoflakes on two types of templates and evaluate their potential as potential drug delivery systems. Silica materials are attractive due to their biocompatibility, low cytotoxicity, high surface area, and tunable pores. In addition, they can be multifunctionalized. These properties were used to create multifunctional drug delivery systems combining folic acid as a target molecule and methotrexate (MTX) as an anticancer drug. The silica nanoflakes were formed using graphene oxide and double-layered hydroxide as templates, respectively. After the removal of matrices, the silica flakes were functionalized by folic acid and loaded with methotrexate. The differences in drug release performance and structural stability were analyzed with respect to the detailed physicochemical characterization of the produced silica nanoflakes.

Synthesis of alkyl-functionalized magnetic for fluoroquinolones removal: Adsorption performance and mechanism studies in single and binary systems

The functionalized mesoporous silica (FMS) and core-shell magnetic functionalized mesoporous silica (MMS) were synthesized on the basis of unfunctionalized mesoporous silica (UMS) via alkyl modification and one-pot reaction. Its adsorption properties to enrofloxacin (ENR), pefloxacin (PEF) and ciprofloxacin (CIP) were systematically investigated in single and binary systems. The results indicated the adsorption performance of MMS is five times higher than UMS. Batch adsorption experiments demonstrated the MMS had a higher adsorption capacity and adsorption efficiency for FQs, with the maximum adsorption capacities of 201.52 mg g-1 for CIP, 275.46 mg g-1 for PEF and 286.35 mg g-1 for ENR. Meanwhile, over 80% and 90% removals were achieved within 5 min and 10 min. Experiment results also presented that: MMS was able to reach the maximum adsorption capacity around pH 7.0 and maintain high adsorption capacity at a high concentration of humic acid. Besides, MMS showed the selective adsorption to three FQs in the binary adsorption experiments. The reusability experiment suggested the MMS possess excellent stability. H-bonding, electrostatic interaction and hydrophobic interaction were the main driving force between three FQs and MMS. Moreover, the adsorbent can be readily separated from water solution by an external magnet. These obtained results could be used for adsorbent design in considering of the properties of the adsorbates and the reuse of adsorbents.

Effect of Confinement in Nanopores on RNA Interactions with Functionalized Mesoporous Silica Nanoparticles.

Amine-functionalized mesoporous silica nanoparticles (MSNPAs) are ideal carriers for oligonucleotides for gene delivery and RNA interference. This investigation examines the thermodynamic driving force of interactions of double-stranded (ds) RNA with MSNPAs as a function of RNA length (84 and 282 base pair) and particle pore diameter (nonporous, 2.7, 4.3, and 8.1 nm) using isothermal titration calorimetry, extending knowledge of solution-based nucleic acid-polycation interactions to RNA confined in nanopores. Adsorption of RNA follows a two-step process: endothermic interactions driven by entropic contribution from counterion (and water) release and an exothermic regime dominated by short-range interactions within the pores. Evidence of hindered pore loading of the longer RNA and pore size-dependent confinement of RNA in the MSPAs is provided from the relative contributions of the endothermic and exothermic regimes. Reduction of endothermic and exothermic enthalpies in both regimes in the presence of salt for both lengths of RNA indicates the significant contribution of short-range electrostatic interactions, whereas ΔH and ΔG values are consistent with conformation changes and desolvation of nucleic acids upon binding with polycations. Knowledge of the interactions between RNA and functionalized porous nanoparticles will aid in porous nanocarrier design suitable for functional RNA delivery.

Bioavailability and Dissolution Rate Enhancement of an Anticancer Drug Bicalutamide by Encapsulation into Mesoporous Silica Nanoparticles: Effects of Amine Functionalization and Caco-2 Cell Permeability Study

Abstract: Background: The present study was undertaken with the aim of dissolution rate and Bioavailability enhancement of anticancer drug Bicalutamide (BIC) via encapsulation into mesoporous silica nanoparticles (MSNs). Materials and Methods: The bare (MCM-41) and surface decorated MSNs were subjected to thorough characterization pre and post drug loading by Fourier transform infrared spectroscopy, Nitrogen sorption analysis, Differential Scanning Calorimetry, Thermogravimetric analysis, Small angle and wide angle X-ray diffraction, Scanning electron microscopy and Transmission electron microscopy. Introduction of Nitrogen post functionalization was confirmed by the elemental analysis. Synthesized MSNs were surface decorated with amine groups (AMN-MSN) and in-depth study of effect of functionalization and food on dissolution kinetics was done. Developed MSNs and AMN-MSNs were thoroughly characterized pre and post BIC loading. In vitro intestinal permeability study was performed to determine the apparent permeability of synthesized MSNs. The formulations were also investigated for their in vivo behaviour by oral administration to male Swiss albino mice and various pharmacokinetic parameters calculated. Results: A significant increase in permeability was obtained the dissolution rate and bioavailability were found to be 3.12 and 2.71 times enhanced in MCM-41 as comparison to the BIC suspension. Conclusion: Thus, MSNs could serve as an effective platform for delivering of various anti-cancer drugs and enhancing their efficiency. Key words: Bicalutamide, Functionalized Mesoporous silica nanoparticles, Dissolution, Caco-2 cells permeability, Bioavailability.

Effect of Nanoconfinement of Polyphenolic Extract from Grape Pomace into Functionalized Mesoporous Silica on Its Biocompatibility and Radical Scavenging Activity.

The aim of this paper is to assess the properties of Mamaia (MM) grape pomace polyphenolic extract loaded onto pristine and functionalized MCM-41 mesoporous silica as potential ingredients for nutraceuticals or cosmetics. The chemical profile of hydroalcoholic polyphenolic extracts, prepared either by conventional extraction or microwave-assisted method, was analyzed by reverse-phase high-performance liquid chromatography with photodiode array detector (HPLC-PDA) analysis, while their radical scavenger activity (RSA) was evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl radical) and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assays. The extract-loaded materials were characterized by Fourier transform infrared (FTIR) spectroscopy, N2 adsorption-desorption isotherms, thermogravimetric analysis, as well as RSA (DPPH and ABTS assays). The polyphenols release profiles from pristine and functionalized (with mercaptopropyl, propyl sulfonic acid, cyanoethyl and propionic acid moieties) MCM-41-type supports were determined in phosphate buffer solution (PBS) pH 5.7. For selected materials containing embedded phytochemicals, cellular viability, and oxidative stress level on immortalized mouse embryonic fibroblast cell line (NIH3T3) were evaluated. A more acidic functional groups linked on silica pore walls determined a higher amount of phytochemicals released in PBS. The extract-loaded materials showed a good cytocompatibility on tested concentrations. The embedded extract preserved better the RSA over time than the free extract. The polyphenols-loaded MCM-41-type silica materials, especially MM@MCM-COOH material, demonstrated a good in vitro antioxidant effect on NIH3T3 cells, being potential candidates for nutraceutical or cosmetic formulations.

Synthesis and Testing of Functional Mesoporous Silica Nanoparticles for Removal of Cr(VI) Ions From Water

This work reports a reliable and reproducible synthesis and in situ functionalization protocol for the synthesis of amino-functionalized mesoporous silica nanoparticles (MSNs). The porous amino-functional (pSiO2-NH2) nanoparticles were fully characterized by high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and nitrogen adsorption-desorption (BET) analyses. The size of the particles was in the range of 80-200 nm with a specific surface area (SSA) of 721 m2 g-1, and the pore diameter was 31Å. The pSiO2-NH2 nanoparticles were tested for their efficiency in removing Cr(VI) ions from water. Almost quantitative removal of the ions was achieved by using the particles just within two hours. The adsorption efficiency of the particles was about 50 mg g-1. The synthesized porous silica particles can be repeatedly used as nano adsorbent for the adsorption removal of Cr(VI) ions from water. The nanoparticles can be potentially used for the selective capture, removal, and recovery of various other metal ions that can be complexed by amino groups.

Coassembled Nanoparticles Composed of Functionalized Mesoporous Silica and Pillar[5]arene‐Appended Gold Nanoparticles as Mitochondrial‐Selective Dual‐Drug Carriers

AbstractCoassembled nanoparticles composed of functionalized mesoporous silica and pillar[5]arene‐appended Au nanoparticles obtained through the formation of a host–guest complex are designed and synthesized as a mitochondrial‐selective dual‐drug delivery system. A pyridinium‐based ligand and fluorescein isothiocyanate are immobilized onto mesoporous silica to act as the mitochondria‐targeting ligand and fluorescence tracker, respectively, of a material dubbed NP‐3. Carboxylated pillar[5]arene‐capped Au nanoparticles (CP‐AuNPs) are fabricated by the templated reduction of Au3+. Interestingly, coassembled nanoparticles (NP‐1) composed of doxorubicin (DOX) loaded NP‐3 and CP‐AuNPs are then prepared via the formation of a host–guest complex between the pyridinium‐based ligand of NP‐3 and the pillar[5]arene of CP‐AuNPs. To demonstrate the effectiveness of NP‐2 and NP‐1 as mitochondrial targeting drug delivery systems, DOX and F16 are employed as model drugs. These drugs loaded onto NP‐2 and CP‐AuNPs, respectively, are selectively delivered to mitochondria, indicating the usefulness of NP‐2 and CP‐AuNPs as mitochondrial‐specific drug‐delivery carriers in cancer cells. More interestingly, the use of NP‐1 is also associated with the selective accumulation of DOX and F16 in mitochondria. The selective mitochondrial‐targeting of NP‐1 is possible by NP‐2 and F16 exposed to the cytoplasm, allowing the codelivery of the two drugs to the mitochondria.