Pores Of Mesoporous Silica Research Articles

A robust ROS generation nanoplatform combating periodontitis via sonodynamic/chemodynamic combination therapy

Periodontitis is a popular bacteria-induced chronic disease with the absence of effective and noninvasive therapeutic strategies. Sonodynamic therapy (SDT), proved to be promising against infections of bacteria especially multidrug-resistant species by producing reactive oxygen species (ROS), has been considered as tremendous potential in antibacterial application for periodontitis treatment. However, the low quantum yield of ROS remains a significant challenge for SDT. In this study, a novel nano-sonosensitizer was prepared for robust ROS generation via growing TiO2 on dendritic large pore mesoporous silica nanoparticles (DLMSNs) followed by deposition of Ag (DT-Ag) and modifying with the quaternary ammonium chitosan (DT-Ag-CS+). In vitro antibacterial effects of DT-Ag-CS+ were investigated in porphyromonas gingivalis (P. gingivalis) which is a well-recognized periodontal pathogenic bacterium, and in vivo anti-periodontitis effects were evaluated using Wistar rats with ligature-induced periodontitis. The obtained DT-Ag-CS+ exhibited excellent SDT and chemodynamic therapy (CDT) performances both in vitro and in vivo, owing to the deposition of noble metal Ag, and greater chance to penetrate into bacterial cells due to the highly positive-charged CS+ on the surface of DT-Ag. Altogether, a multifunctional DT-Ag-CS+ nano-sonosensitizer has shown promising clinical application for combining SDT and CDT against periodontitis.

Biomimetic nanotherapeutics based on oxygen supply and ultrasmall Cu-Se-Au alloy nanoparticles for boosting radio-photothermal ablation of breast cancer

Radiotherapy (RT) is one of the important tools for clinical treatment of breast cancer. Currently, some nanoradiosensitizers have been developed for augmenting the therapeutic efficiency of RT. However, some limitations still exist for their further applications, such as oxygen dependence in hypoxic tumors, nonideal selectivity for tumors, and inevasible damages to normal tissues. To resolve these problems, a biomimetic nanoplatform was developed for efficient co-loading and precise co-delivery of oxygen and nanoradiosensitizer by taking advantage of large pore volumes and easy surface modification of dendritic large pore mesoporous silica nanoparticles (DLMSNs). The outer surfaces of DLMSNs were modified with citric acid for attaching firmly and chelating stably with ultrasmall Cu-Se-Au alloy nanoparticles possessing distinct radiosensitizing and photothermal conversion performances. The inner surfaces of DLMSNs were modified with perfluorosilane for loading perfluorohexane that has extraordinary oxygen-carrying capability to alleviate tumor hypoxia. White blood cells membranes were wrapped onto the surfaces of the resultant DLMSNs for promoting co-delivery of therapeutic agents targeting to tumor and reducing injuries to normal tissues. Biomimetic nanotherapeutic system thus prepared showed powerful suppression effects against breast cancer both in vitro and in vivo by intelligently integrating tumor-targeted delivery, oxygen supply, radiosensitizing and photothermal ablation.

One-pot synthesis of mesoporous silica-supported nano-metal oxide composites with enhanced antibacterial properties

Bacterial infections are recognized as a serious health issue in the world. Nano-zinc oxide (nano-ZnO) is considered as an antibacterial material because of its broad-spectrum bactericidal properties. In this work, a one-pot method to prepare nano-metal oxide-loaded composites based on polydopamine (PDA)-coated mesoporous silica (MSN/ZnO, MSN/CuZnO, MSN-C/ZnO, MSN-C/CuZnO) with good antibacterial properties was proposed. The results showed that the morphology of the composites had a regular spherical shape with an average particle size of 100 nm. And nano-metal oxides were formed in the pore of mesoporous silica with a diameter of 5 nm. Strikingly, the inhibition zone diameters towards E. coli of MSN-C/ZnO and MSN-C/CuZnO showed better antibacterial performance, were 35.40 ± 0.01 mm and 33.20 ± 0.01 mm, respectively. Besides, it was found that, the minimal inhibitory concentration (MIC) value of such nano-metal oxide-loaded composites were 0.625 mg/mL. Therefore, these mesoporous silica-supported nano-metal oxide composites can be used as favorable and effective antibacterial products for advanced and potential applications.

Fabrication of Dimensional and Structural Controlled Open Pore, Mesoporous Silica Topographies on a Substrate.

Open pore mesoporous silica (MPS) thin films and channels were prepared on a substrate surface. The pore dimension, thickness and ordering of the MPS thin films were controlled by using different concentrations of the precursor and molecular weight of the pluronics. Spectroscopic and microscopic techniques were utilized to determine the alignment and ordering of the pores. Further, MPS channels on a substrate surface were fabricated using commercial available lithographic etch masks followed by an inductively coupled plasma (ICP) etch. Attempts were made to shrink the channel dimension by using a block copolymer (BCP) hard mask methodology. In this regard, polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymer (BCP) thin film forming perpendicularly oriented PEO cylinders in a PS matrix after microphase separation through solvent annealing was used as a structural template. An insitu hard mask methodology was applied which selectively incorporate the metal ions into the PEO microdomains followed by UV/Ozone treatment to generate the iron oxide hard mask nanopatterns. The aspect ratio of the MPS nanochannels can be varied by altering etching time without altering their shape. The MPS nanochannels exhibited good coverage across the entire substrate and allowed direct access to the pore structures.

Highly Precise and Sensitive Polymerase Chain Reaction Using Mesoporous Silica-Immobilized Enzymes.

A highly precise and sensitive technology that enables DNA amplification/detection from minimal amounts of nucleic acid is expected to find applicability in genetic testing involving small amounts of samples. The use of a free enzyme in conventional DNA amplification techniques, such as the polymerase chain reaction (PCR), frequently causes side reactions (i.e., nonspecific DNA amplification) when ≤103 substrate DNA molecules are present, thereby preventing selective amplification of the target DNA. To address this issue, we have developed a novel DNA amplification system, mesoporous silica-enhanced PCR (MSE-PCR), which involves the immobilization of a thermostable DNA polymerase from Thermococcus kodakaraensis (KOD DNA polymerase) into highly ordered nanopores of the mesoporous silica to control the reaction environment around the enzyme. In the MSE-PCR system using immobilized KOD DNA polymerase, such nonspecific DNA amplification was remarkably inhibited under the same conditions. Furthermore, the optimization of mesoporous silica pore sizes enabled selective and efficient DNA amplification from DNA substrates at the single-molecule level, i.e., one ten-thousandth of the amount of substrate DNA required for a DNA amplification reaction using a free enzyme. The results obtained in this study have shown that the nanopores of mesoporous silica can inhibit nonspecific reactions in DNA amplification, thereby considerably improving the specificity and sensitivity of the DNA polymerase reaction.

Reversible ionic liquids (RevILs) for the preparation of thermally stable SBA-15 supported gold nanoparticle catalysts

Reversible ionic liquids (RevILs) are ionic liquids that can be switched between molecular and ionic forms via two stimuli, and they can assist in the synthesis of colloidal gold nanoparticles. The RevIL-stabilized gold nanoparticles are deposited in the pores of SBA-15 mesoporous silica via incipient wetness without the functionalization of the SBA-15 surface. The location of nanoparticles inside the pores was confirmed by transmission electron microscopy technique and by a measured increase in the thermal stability of the nanoparticles in SBA-15 compared to non-porous silica. The porous gold catalysts are active in the selective oxidation of benzyl alcohol without calcination due to the absence of the ligands on the gold surface after deposition. Additionally, they are more active than the non-porous gold catalysts, indicating that the pore geometry enhances catalytic performance. Ultimately, the catalysts prepared by RevIL technique are thermally stable and active and show fine control over particle size.

Near-infrared responsive nanocomposite hydrogels made from enzyme-coated carbon nanotubes@ large pore mesoporous silica for remotely triggered drug delivery

The design of smart nanocomposite supramolecular scaffolds for tissue engineering or anticancer applications, able to release drugs under external fields is currently a challenge. Such architectures require not only strong interactions between the polymer matrix and externally responsive nanomaterials, but also an efficient strategy for the loading and release of drugs. Herein, we address an original approach to trigger the self-assembly of peptide hydrogel from enzyme-coated carbon-based nanocomposites which act as initiators and cross-linking points of the resulting nanocomposite hydrogel. Carbon nanotubes (CNTs), chosen given their photothermal behavior under near infrared (NIR) light, were coated with large pore (>10 nm) mesoporous silica (CNT@LPMS) which are very suitable for a high loading of enzymes. Then, based on an original isobutyramide (IBAM)-mediated coating, a huge amount of alkaline phosphatase (AP) (>100% wt) was immobilized within the large pores allowing the localized growth of peptide nanofibrous network resulting in supramolecular hydrogel. The incorporation of Doxorubicin (DOX) during the hydrogelation process leads to a reservoir material of anti-cancer agents whose release is photothermally triggered by the NIR light-induced hyperthermia temperature. Combination of rheological studies and molecular simulations indicate an original mechanism in which DOX is included within the peptide nanofibers.

Assemblies of two multimeric enzymes using mesoporous silica microspheres toward cascade reaction fields

A highly efficient, rapid cascade reaction system with coupled enzyme reactions is developed using mesoporous silica microspheres having a large pore diameter of 24.5 nm as an immobilization scaffold for two multimeric enzymes. The simultaneous adsorption of glucose oxidase and catalase on the pores of the mesoporous silica microspheres cause aggregation of the two enzymes, resulting in extremely low adsorbed amounts of the enzymes. The present study overcomes this limitation by immobilizing the two enzymes sequentially on the mesoporous silica pores, which significantly increases the decomposition ratio of hydrogen peroxide (an intermediate product). The localization and assembly of the two enzymes encapsulated in the mesopores were confirmed by labeling with fluorescent dyes for direct visualization and by detection of the fluorescence resonance energy transfer between the two enzymes, respectively, under a confocal laser scanning microscope field. The activity in the cascade reaction by the dual enzyme–mesoporous silica composite was significantly improved via the dense arrangement of the two enzymes on the surface of the mesoporous silica microspheres.

Simple Preparation of Large Pore Mesoporous Silica Nanospheres and Their Protein Sequestration Ability

AbstractA simple and efficient method for the preparation of large pore MSNs is Ca ion‐etching of the as‐prepared mesoporous silica nanospheres (MSNs) containing ammonium‐based organic template. In this facile process, the generation of new large mesopores through the partial collapse of several mesopores and template removal through cation‐exchange occurred simultaneously. We found that CaCl2 could also act as a good etching source. Template‐free cubic phase MSN (cMSN) with large pores could be obtained by treating CaCl2 under mild conditions in high yield. Both surface area and pore volume increased in the order Ca(NO3)2‐treated cMSN<CaCl2‐treated cMSN (Ca‐cMSN)<calcined cMSN, while the pore size increased in the order calcined cMSN<Ca‐cMSN<Ca(NO3)2‐treated cMSN. Compared to the calcined sample, the large pore cMSN (Ca‐cMSN) showed good adsorption capacities for proteins.

A heterogeneous mesoporous catalyst based on anchored copper: Schiff base complex into SBA-15 for the synthesis of benzimidazoles from orthoesters

In this article, we report the synthesis of 2-substituted benzimidazoles via condensation of 1,2-phenylenediamines and orthoesters using a heterogeneous catalyst based on anchored copper-Schiff base complex into SBA-15 (Cu/SBA-15) as a modified nanoporous material. The catalyst has been prepared via a postsynthesis grafting method and the 2D hexagonal mesoporous structures of this hybrid have been confirmed by small-angle X-ray scattering, transmission electron microscopy, N2 adsorption–desorption isotherms and Fourier transform infrared spectroscopy. Our results show that the benzimidazole heterocycles were obtained in good to excellent yields under solvent-free conditions in the presence of entitled catalyst. The mesoporous silica pore walls of the catalyst create some advantages such as high specific surface area, good to excellent yields of the benzimidazole products, non-toxicity and reusability.

Construction of a redox-responsive drug delivery system utilizing the volume of AS1411 spatial configuration gating mesoporous silica pores.

In recent years, diverse redox-responsive drug delivery systems have emerged to prevent premature drug release and reduce drug toxicity in the human body in cancer treatment. In this paper, we put forward a view of directly utilizing the spatial structure size of the AS1411 aptamer as the nano-gatekeeper on the pore openings of MCM-41 type mesoporous silica and thus constructed a redox-responsive drug delivery system named MCM-41-SS-AS1411. The particles obtained at each step were characterized by TEM, FTIR, SXRD, TGA and zeta potential measurement. The characterization data confirmed that the particles were successfully prepared. The binding amount of the aptamer was ca. 3.1 × 103 for each carrier particle averagely. The anticancer drug Dox was regarded as a drug model to investigate the redox-controlled drug release behavior by fluorescence measurements. The investigation results demonstrate that the spatial volume of aptamer AS1411 can block the mesopore, and this drug-carrier can realize controlled drug release by GSH. We hope this idea can play a prompt role in relevant research. Meanwhile, the preparation steps of this DDS are simplified.

Curcumin/Fe-SiO2 nano composites with multi-synergistic effects for scar inhibition and hair follicle regeneration during burn wound healing

The scar formation and hair follicle regeneration are closely related in the healing process of skin burn wounds. Excessive pathological fibroblasts at the scar site severely hinders the migration of hair follicle stem cells to the damaged site. Therefore, it is of great clinical significance to develop wound dressings to inhibit scar formation and promote hair follicle regeneration. In this study, inspired by the bioactivity of SiO32−, Fe3+ and Cur, we designed a new type of nano composites, Cur-Fe-mesoporous silica nanoparticles (Cur-Fe-SiO2, MFSC). On the one hand, Fe3+ doping reduced the stability of mesoporous silica, so that it can effectively release biologically active SiO32− and Fe3+. On the other hand, Fe3+ ions released on the surface of the mesoporous silica pores chelated with the Cur in the solution and resulted in significantly improved loading of Cur and the chelates showed higher biological activity as compared to Cur or Fe alone. The released bioactive components such as SiO32−, Fe3+ and Fe-Cur chelates showed synergistic activity in both inhibiting scar hyperplasia and promoting hair follicle regeneration. Our results suggest that the synergistic effects between ions and flavonoids can be used to increase the bioactivity of biomaterials, and design of nano composites with bioactive ions and flavonoids might be an effective approach to prepare materials for tissue regeneration.

Cell Membrane-camouflaged Multi-functional Dendritic Large Pore Mesoporous Silica Nanoparticles for Combined Photothermal Therapy and Radiotherapy of Cancer

Cell Membrane-camouflaged Multi-functional Dendritic Large Pore Mesoporous Silica Nanoparticles for Combined Photothermal Therapy and Radiotherapy of Cancer

Incorporation and structural arrangement of microemulsion droplets in cylindrical pores of mesoporous silica

The behaviour of microemulsion (ME) droplets in mesoporous systems is highly important for understanding the immobilisation of drugs or chemical formulations, cleaning processes or enhanced oil recovery. The loading of pores as well as the structural organisation of MEs within the pores is a relevant parameter, especially for immobilisation applications. For this reason, the uptake of microemulsions in cylindrical pores of SBA-15 was investigated via adsorption and small-angle neutron scattering (SANS). Adsorption isotherms revealed an adsorption of the microemulsion droplets based on the adsorption of surfactant as a driving force. The adapted scattering model is based on the analysis of bare SBA-15 in full contrast conditions and employs microemulsions inside of SBA-15 measured at the silica contrast matching point. Accordingly, the structural arrangement of microemulsion droplets in the pores of SBA-15 was determined in good detail. Microemulsion droplets smaller than the pore size access the pores while retaining their spherical shape and become increasingly ordered for higher loading, where the droplets arrange in a dense packing of spherical droplets in a cylindrical pore. Interestingly, microemulsion droplets larger than the pore size can easily be incorporated, but become deformed upon entering and are present as elongated rod-like structures.

Leukocyte/platelet hybrid membrane-camouflaged dendritic large pore mesoporous silica nanoparticles co-loaded with photo/chemotherapeutic agents for triple negative breast cancer combination treatment

Triple-negative breast cancer (TNBC) is an aggressive subset of breast cancer and currently lacks effective therapeutic targets. As two main phototherapeutic methods, photothermal therapy (PTT) and photodynamic therapy (PDT) show many advantages in TNBC treatment, and their combination with chemotherapy can achieve synergistic therapeutic effects. In the present study, a biomimetic nanoplatform was developed based on leukocyte/platelet hybrid membrane (LPHM) and dendritic large pore mesoporous silicon nanoparticles (DLMSNs). A near infrared (NIR) fluorescent dye IR780 and a chemotherapeutic drug doxorubicin (DOX) were co-loaded into the large pores of DLMSNs to prepare DLMSN@DOX/IR780 (DDI) nanoparticles (NPs), followed by camouflage with LPHM to obtain LPHM@DDI NPs. Through the mediation of LPHM, LPHM@DDI NPs showed an excellent TNBC-targeting ability and very high PTT/PDT performances in vitro and in vivo. Upon NIR laser irradiation, LPHM@DDI NPs exhibited synergistic cytotoxicity and apoptosis-inducing activity in TNBC cells, and effectively suppressed tumor growth and recurrence in TNBC mice through tumor ablation and anti-angiogenesis. These synergistic effects were sourced from the combination of PTT/PDT and chemotherapy. Altogether, this study offers a promising biomimetic nanoplatform for efficient co-loading and targeted delivery of photo/chemotherapeutic agents for TNBC combination treatment.

Tetrasulfonate calix[4]arene modified large pore mesoporous silica microspheres: Synthesis, characterization, and application in protein separation

Effective protein adsorption by solid matrices from complex biological samples has attracted attention for broad application in biomedical field. Immobilization of calixarenes to solid supports is an essential process for their application in protein separation and purification. Silica is the most widely used support material in calixarene immobilization. With high concentration of polymer microspheres as templates, the large pore mesoporous silica microspheres with controllable, uniform size and structure were successfully synthesized and the resulting large pore mesoporous silica microspheres were modified with water-soluble tetrasulfonate calix[4]arene of unique hollow cavity-shaped structure. The tetrasulfonate calix[4]arene modified large pore mesoporous silica microspheres (SCLX4@LPMS) were characterized by diverse analytical techniques and their protein adsorption performance were also investigated. The obtained SCLX4@LPMS gave rise to an adsorption efficiency of >90% for cytochrome c and lysozyme within a wide pH range of 3.0–10.0 and possessed remarkably high adsorption capacity of cytochrome c (363.64 mg g−1) and lysozyme (166.11 mg g−1). The retained cytochrome c and lysozyme can be readily eluted by using phosphate buffer solution containing NaCl as a stripping reagent with the recoveries of 81% and 86% after 5 times enrichment, respectively. The SCLX4@LPMS microspheres have been applied for the selective adsorption of proteins in real samples and had the application potential in protein adsorption, drug delivery, biosensors, and other biomedical fields.

Effects of mesoporous silica particle size and pore structure on the performance of polymer-mesoporous silica mixed matrix membranes.

The fabrication of mixed matrix membranes (MMMs) has been regarded as an effective and economic approach to enhance the gas permeability and selectivity properties of conventional polymeric membranes for gas separation applications. However, the poor compatibility between polymeric matrix and inorganic filler in MMMs could lead to the generation of interfacial defects resulting in reduced gas selectivity. In this work, with the aim of studying the effect of particle size and pore structure of the filler on the performance of the resultant MMMs, nano/micro sized spherical mesoporous silicas with 2D/3D pore structure (MCM-41 and MCM-48) were synthesized and selected as fillers for the preparation of polydimethylsiloxane (PDMS)-based MMMs. The separation properties of the membranes prepared were characterized by permeability measurements for nitrogen and organic vapors (C3H6 and n-C4H10). Compared with microsized particles, nanosized fillers have better dispersion in the polymer matrix which could minimize the formation of non-selective microvoids around the particles, leading to higher vapor/N2 ideal selectivities of the MMMs, even at the high loading (15 wt%). Moreover, due to the conventional random packing orientation of the particles in the polymer, vapor permeation was severely hindered in the MMMs fabricated from mesoporous silica with 2D pore channels. The interface morphologies and gas diffusion paths in the MMMs have also been proposed. With an optimum loading of nanosized MCM-48 (3D pore structure), the vapor permeabilities and vapor/N2 ideal selectivities of the MMMs were shown to increase simultaneously, compared with the neat polymer membrane.

Large scale synthesis of self-assembled shuttlecock-shaped silica nanoparticles with minimized drag as advanced catalytic nanomotors

• Large scale synthesis of shuttlecock-shaped silica nanoparticles (SSNs) were reported. • Assembly behavior of two surfactants were finely controlled to direct the growth. • SSNs exhibited minimized drag force in motion in fluid. • SSNs based nanomotors showed high diffusibility and lipid degradation activity. The catalytic performance of nanomotors is highly dependent on their interaction with substrates, for which the motion dynamics of the nanomotors needs to be carefully manipulated via materials design. Herein, we report a facile one-step self-assembly strategy for hundred-gram scale synthesis of shuttlecock-shaped silica nanoparticles as advanced catalytic nanomotors. These asymmetric nanoparticles have a streamline conical morphology with ultra-large opening in one side. The shuttlecock-mimetic morphology endows the nanoparticles with minimized drag force during fluid motion and consequently high diffusibility, while the large open cavity ensures efficient encapsulation of lipase (a model enzyme) to provide propulsive force. These unique features collectively result in superior diffusibility, leading to significantly improved catalytic performance compared with conventional large pore mesoporous silica nanoparticles with a spherical morphology. This research provides a new conceptual design and synthetic strategy to develop high-performance nanomotors.

Fabrication of large pore mesoporous silica microspheres by salt-assisted spray-drying method for enhanced antibacterial activity and pancreatic cancer treatment.

Large-pore mesoporous silica (LPMS) microspheres with tunable pore size have received intensive interest in the field of drug delivery due to their high storage capacity and fast delivery rate of drugs. In this work, a facile salt-assisted spray-drying method has been developed to fabricate LPMS microspheres using continuous spray-drying of simple inorganic salts as pore templates and colloidal SiO2 nanoparticles as building blocks, followed by washing with water to remove the templates. More importantly, the porosity of the LPMS microspheres can be finely tuned by adjusting the furnace temperature and relative concentration of the salt to SiO2, which could lead to optimal pharmaceutical outcomes. Then, the biological roles of these LPMS microspheres were evaluated in antibacterial and cancer therapy. In this regard, rhodamine b as a probe was initially loaded inside the LPMS microspheres. The obtained particles not only showed high entrapment efficiency (up to 30%) and a pH-responsive drug release but also presented pore-size-controlled drug release performance. Then, in vitro antibacterial activities of multiple antibiotics, namely nalidixic acid, chloramphenicol, and ciprofloxacin, loaded in the LPMS particles were investigated against two pathogenic bacteria, Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The results indicated bacterial inhibition up to 70% and 20% in less than 2h for Escherichia coli and Staphylococcus aureus, respectively. This inhibition of bacterial growth was accompanied by no bacterial regrowth within 30h. Finally, the versatility of LPMS microspheres as drug carriers in pancreatic cancer treatment was explored. In this regard, a pro-apoptotic NCL antagonist agent (N6L) as an antitumor agent was successfully loaded onto LPMS microspheres. Interestingly, the resulting particles showed pore-size-dependent anticancer activity with inhibition of cancer cell growth up to 60%.

PH-sensitive and bubble-generating mesoporous silica-based nanoparticles for enhanced tumor combination therapy

Chemotherapy has been a major option in clinic treatment of malignant tumors. However, single chemotherapy faces some drawbacks, such as multidrug resistance, severe side effects, which hinder its clinic application in tumor treatment. Multifunctional nanoparticles loading with chemotherapeutic agent and photosensitizer could be a promising way to efficiently conduct tumor combination therapy. In the current study, a novel pH-sensitive and bubble-generating mesoporous silica-based drug delivery system (denoted as M(a)D@PI-PEG-RGD) was constructed. Ammonium bicarbonate (NH4HCO3; abc) and chemotherapeutic agent doxorubicin (DOX) were loaded into the pores of mesoporous silica. Indocyanine green (ICG) as a photothermal and photodynamic agent was loaded onto the polydopamine (PDA) layer surface. The synthesized nanoparticles displayed a narrow polydispersity (PDI) and small particle size as characterized through dynamic light scattering-autosizer analysis. The nanoparticles also showed high targeting efficacy through RGD modification as indicated by cellular uptake and animal studies. DOX release analysis confirmed that the nanoparticles were pH-dependent and that NH4HCO3 accelerated drug release. At the same time, the nanoparticles had obvious photothermal and photodynamic effects performed by ICG which restrained tumor growth remarkably. In summary, the multifunctional nanoparticles presented a promising system for combination therapy.