Large pore mesoporous silica nanomaterials for application in delivery of biomolecules

Mesoporous Silica Nanoparticle-Coated Microneedle Arrays for Intradermal Antigen Delivery

PURPOSE

To develop a new intradermal antigen delivery system by coating microneedle arrays with lipid bilayer-coated, antigen-loaded mesoporous silica nanoparticles (LB-MSN-OVA).

METHODS

Synthesis of MSNs with 10-nm pores was performed and the nanoparticles were loaded with the model antigen ovalbumin (OVA), and coated with a lipid bilayer (LB-MSN-OVA). The uptake of LB-MSN-OVA by bone marrow-derived dendritic cells (BDMCs) was studied by flow cytometry. The designed LB-MSN-OVA were coated onto pH-sensitive pyridine-modified microneedle arrays and the delivery of LB-MSN-OVA into ex vivo human skin was studied.

RESULTS

The synthesized MSNs demonstrated efficient loading of OVA with a maximum loading capacity of about 34% and the lipid bilayer enhanced the colloidal stability of the MSNs. Uptake of OVA loaded in LB-MSN-OVA by BMDCs was higher than that of free OVA, suggesting effective targeting of LB-MSN-OVA to antigen-presenting cells. Microneedles were readily coated with LB-MSN-OVA at pH 5.8, yielding 1.5 μg of encapsulated OVA per microneedle array. Finally, as a result of the pyridine modification, LB-MSN-OVA were effectively released from the microneedles upon piercing the skin.

CONCLUSION

Microneedle arrays coated with LB-MSN-OVA were successfully developed and shown to be suitable for intradermal delivery of the encapsulated protein antigen.

A Pathogen-Specific Cargo Delivery Platform Based on Mesoporous Silica Nanoparticles

We present a synthetic approach to a highly pathogen-selective detection and delivery platform based on the interaction of an antibody nanovalve with a tetrasaccharide from the O-antigen of the lipopolysaccharide (LPS) of Francisella tularensis bacteria, a Tier 1 Select Agent of bioterrorism. Different design considerations are explored, and proof-of-concept for highly pathogen-specific cargo release from mesoporous silica nanoparticles is demonstrated by comparisons of the release of a signal transducer and model drug by LPS from F. tularensis vs Pseudomonas aeruginosa and by F. tularensis live bacteria vs the closely related bacterium Francisella novocida. In addition to the specific response to a biowarfare agent, treatment of infectious diseases in general could benefit tremendously from a delivery platform that releases its antibiotic payload only at the site of infection and only in the presence of the target pathogen, thereby minimizing off-target toxicities.

Adsorption and release of ampicillin antibiotic from ordered mesoporous silica

In this work the adsorption and the release of ampicillin - a β-lactam penicillin-like antibiotic - from MCM-41, SBA-15, and (amino functionalized) SBA-15-NH₂ ordered mesoporous silica (OMS) materials were investigated. The silica matrices differ for their pore size (SBA-15 vs. MCM-41) mainly, and also for surface charge (SBA-15 and MCM-41, vs. SBA-15-NH₂). OMS samples were characterized through small-angle X-rays scattering (SAXS), transmission electron microscopy (TEM), N₂ adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and potentiometric titrations. The quantification of immobilized and released ampicillin was monitored by mean of UV-Vis spectroscopy. Experimental adsorption isotherms evidenced that ampicillin's loading is not related to the pore size (d_BJH) of the adsorbent. Indeed the maximal loadings were 237mg/g for SBA-15 (d_BJH=6.5nm), 278mg/g for MCM-41 (d_BJH=2.2nm), and 333mg/g for SBA-15-NH₂ (d_BJH=5.6nm). Loading seems, instead, to be related to the surface charge density (σ) of the sorbent surface. Indeed, at pH 7.4 ampicillin drug is negatively charged and likely prefers to interact with SBA-15-NH₂ (σ_SBA-15-NH2=+0.223Cm^-2) rather than the slightly negatively charged silicas (σ_SBA-15=-0.044Cm^-2 and σ_MCM-41=-0.033Cm^-2). Similarly, ampicillin release is affected by interfacial interactions. Indeed, we found a burst release from pure silica samples (SBA-15 and MCM-41), whereas a sustained one from SBA-15-NH₂ sample. We explain this behavior as a result of an attractive interaction between the protonated amino group of SBA-15-NH₂ and the negatively charged carboxylate group of ampicillin. In summary, in order to obtain a sustained drug release, the chemical nature of the matrix's surface plays a role which is more important than its textural features. SBA-15-NH₂ matrix is hence a suitable candidate for local sustained release of antibiotic drugs.

Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

Fabrication of colloidal crystals composed of pore-expanded mesoporous silica nanoparticles prepared by a controlled growth method

Colloidal crystals composed of mesoporous silica nanoparticles (MSNs) are expected to have various applications because of their unique hierarchical structures and tunable functions. The expansion of the mesopore size is important for introducing guest species which cannot be accommodated by using conventional colloidal crystals of MSNs; however, the preparation of MSNs with a controllable pore size, suitable for the fabrication of colloidal crystals, still remains a challenge. In this study, we fabricated colloidal crystals composed of pore-expanded MSNs using a sophisticated particle growth method to control the pore size of colloidal MSNs while retaining their monodispersity high enough to form colloidal crystals. By adding triisopropylbenzene (TIPB) only during the growth process with the stepwise addition of tetrapropoxysilane (TPOS), the particle size can be tuned from 60 nm to 100 nm, while the pore size can be tuned from 3 nm to ten plus several nm which is the largest size among the previous MSNs capable of forming colloidal crystals. These novel colloidal crystals should contribute to the expansion of nanomaterials science.

Cellular Internalization and Biocompatibility of Periodic Mesoporous Organosilica Nanoparticles with Tunable Morphologies: From Nanospheres to Nanowires

This work describes the sol-gel syntheses of para-substituted phenylene-bridged periodic mesoporous organosilica (PMO) nanoparticles (NPs) with tunable morphologies ranging from nanowires to nanospheres. The findings show the key role of the addition of organic co-solvents in the aqueous templates on the final morphologies of PMO NPs. Other factors such as the temperature, the stirring speed, and the amount of organic solvents also influence the shape of PMO NPs. The tuning of the shape of the PMO nanomaterials made it possible to study the influence of the particle morphology on the cellular internalization and biocompatibility.

Dendritic Mesoporous Silica Nanospheres Synthesized by a Novel Dual-Templating Micelle System for the Preparation of Functional Nanomaterials

Highly monodisperse, dendritic, and functionalized mesoporous silica nanospheres (MSNs) with sub-200 nm size were synthesized in a one-pot sol-gel reaction, by a dual-templating micelle system consisting of a partially fluorinated short-chain anionic fluorocarbon surfactant and cetyltrimethylammonium bromide. This kind of anionic fluorocarbon surfactant works simultaneously as a swelling agent to enlarge the pore of the MSNs, an ion-pair agent to the structure-directing silane in the preparation of amine-functionalized MSNs, and a surface tension reducing agent to make the system thermodynamically more stable for producing more uniform MSNs. The particle size and the morphology of the resultant MSNs can be fine-tuned by changing the amount of the fluorocarbon surfactant added and the ratio of the functional group containing organosilane to tetraethoxysilane. Subsequently, the as-prepared MSNs were used as base materials for the preparation of drug delivery nanomaterials through the surface grafting of a pH-sensitive drug-conjugated polymer and fluorescent nanomaterials through the embedding of europium(III) complex or the immobilization of large molecule fluorescein isothiocyanate-bovine serum albumin.

Autocatalytic synthesis of multifunctional precursors for fabricating silica microspheres with well-dispersed Ag and Co3O4 nanoparticles

Herein, an autocatalytic route to fabricate dual metal ion-equipped organic/inorganic hybrid silica, an ideal precursor for multifunctional silica-based composites integrated with well-dispersed Ag and Co₃O₄ nanoparticles was demonstrated. Significantly, by rational selection of reactants, such dual metal ion-equipped organic/inorganic hybrid silica can be synthesized through successive spontaneous reactions under near neutral conditions without an additional catalyst. Both the Ag⁺ and Co²⁺ ions are introduced into silica by chemical bonds, which favor the formation of small-sized and well-dispersed Ag and Co₃O₄ nanoparticles without aggregation in the entire silica matrix. After calcination, multifunctional silica composites equipped with well-dispersed Ag and Co₃O₄ nanoparticles were obtained. The as-obtained silica composites, as indicated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), have a spherical morphology and smooth surface. TEM tests also reveal the well dispersed fashion of Ag and Co₃O₄ nanoparticles. In addition, the obtained Ag-Co₃O₄@SiO₂ composites exhibit good catalytic performance in the reduction of methylene blue (MB) with NaBH₄ as a reducing agent, and can be readily recycled by an external magnetic field due to their superparamagnetic properties.

Silica nanofibers as a new drug delivery system: a study of the protein–silica interactions

Drug delivery from silica nanofiber based materials for intervertebral disc regenerative medicine.

Biomedical applications of natural-based polymers combined with bioactive glass nanoparticles

The combination of natural polymers with nanoparticles allowed the development of functional bioinspired constructs. This review discusses the composition, design, and applications of bioinspired nanocomposite constructs based on bioactive glass nanoparticles (BGNPs).

Au–Mesoporous silica nanoparticles gated with disulfide-linked oligo(ethylene glycol) chains for tunable cargo delivery mediated by an integrated enzymatic control unit

Acetylcholinesterase-functionalized Au–mesoporous silica capped with a thiol-responsive gate is reported.

The possibility of using magnetic nanoparticles to increase the therapeutic efficiency of Herceptin antibody

INTRODUCTION

Herceptin is an expensive humanized antibody used for the treatment of early-stage breast cancers. This antibody can cause cardiotoxicity in some patients. In this study, we evaluated the possibility of increasing the therapeutic efficacy of Herceptin by combining magnetic nanoparticles and a permanent magnet for more accumulation in the tumor site.

METHODS

Herceptin magnetic nanoparticles (HMNs) were synthesized and some of their characteristics, such as stability, magnetization, particle size by transmission electron microscopy (TEM), and dynamic light scattering (DLS) technique, were measured. The biodistribution study was checked in mice bearing breast tumor with and without a permanent magnet on the position of the tumor. The therapeutic effects of HMNs were considered in this condition.

RESULTS

The size distribution of HMNs determined by the DLS technique was 182±7 nm and the average size by TEM was 100±10 nm. The reductions of 81% and 98% in the mean tumor volume for the group that received HMNs with magnetic field were observed at 42 and 45 days after injection, respectively.

CONCLUSION

The good results in mice indicated that Herceptin-loaded iron oxide nanoparticles with external magnetic field have good potential for use in humans as a targeted drug delivery that needs more investigation.

Organosilica hybrid nanomaterials with a high organic content: syntheses and applications of silsesquioxanes

Organic-inorganic hybrid materials garner properties from their organic and inorganic matrices as well as synergistic features, and therefore have recently attracted much attention at the nanoscale. Non-porous organosilica hybrid nanomaterials with a high organic content such as silsesquioxanes (R-SiO_1.5, with R organic groups) and bridged silsesquioxanes (O_1.5Si-R-SiO_1.5) are especially attractive hybrids since they provide 20 to 80 weight percent of organic functional groups in addition to the known chemistry and stability of silica. In the organosilica family, silsesquioxanes (R-SiO_1.5) stand between silicas (SiO₂) and silicones (R₂SiO), and are variously called organosilicas, ormosil (organically-modified silica), polysilsesquioxanes and silica hybrids. Herein, we comprehensively review non-porous silsesquioxane and bridged silsesquioxane nanomaterials and their applications in nanomedicine, electro-optics, and catalysis.

Mesoporous silica nanoparticles functionalized with folic acid/methionine for active targeted delivery of docetaxel

Mesoporous silica nanoparticles (MSNs) are known as carriers with high loading capacity and large functionalizable surface area for target-directed delivery. In this study, a series of docetaxel-loaded folic acid- or methionine-functionalized mesoporous silica nanoparticles (DTX/MSN-FA or DTX/MSN-Met) with large pores and amine groups at inner pore surface properties were prepared. The results showed that the MSNs were successfully synthesized, having good pay load and pH-sensitive drug release kinetics. The cellular investigation on MCF-7 cells showed better performance of cytotoxicity and cell apoptosis and an increase in cellular uptake of targeted nanoparticles. In vivo fluorescent imaging on healthy BALB/c mice proved that bare MSN-NH2 are mostly accumulated in the liver but MSN-FA or MSN-Met are more concentrated in the kidney. Importantly, ex vivo fluorescent images of tumor-induced BALB/c mice organs revealed the ability of MSN-FA to reach the tumor tissues. In conclusion, DTX/MSNs exhibited a good anticancer activity and enhanced the possibility of targeted drug delivery for breast cancer.

Mesoporous Silica Nanoparticles with Large Pores for the Encapsulation and Release of Proteins

Mesoporous silica nanoparticles (MSNs) have been explored extensively as solid supports for proteins in biological and medical applications. Small (<200 nm) MSNs with ordered large pores (>5 nm), capable of encapsulating therapeutic small molecules suitable for delivery applications in vivo, are rare however. Here we present small, elongated, cuboidal, MSNs with average dimensions of 90 × 43 nm that possess disk-shaped cavities, stacked on top of each other, which run parallel to the short axis of the particle. Amine functionalization was achieved by modifying the MSN surface with 3-aminopropyltriethoxysilane or 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (AP-MSNs and AEP-MSNs) and were shown to have similar dimensions to the nonfunctionalized MSNs. The dimensions of these particles, and their large surface areas as measured by nitrogen adsorption-desorption isotherms, make them ideal scaffolds for protein encapsulation and delivery. We therefore investigated the encapsulation and release behavior for seven model proteins (α-lactalbumin, ovalbumin, bovine serum albumin, catalase, hemoglobin, lysozyme, and cytochrome c). It was discovered that all types of MSNs used in this study allow rapid encapsulation, with a high loading capacity, for all proteins studied. Furthermore, the release profiles of the proteins were tunable. The variation in both rate and amount of protein uptake and release was found to be determined by the surface chemistry of the MSNs, together with the isoelectric point (pI), and molecular weight of the proteins, as well as by the ionic strength of the buffer. These MSNs with their large surface area and optimal dimensions provide a scaffold with a high encapsulation efficiency and controllable release profiles for a variety of proteins, enabling potential applications in fields such as drug delivery and protein therapy.

Biodegradable Magnetic Silica@Iron Oxide Nanovectors with Ultra-Large Mesopores for High Protein Loading, Magnetothermal Release, and Delivery

The delivery of large cargos of diameter above 15nm for biomedical applications has proved challenging since it requires biocompatible, stably-loaded, and biodegradable nanomaterials. In this study, we describe the design of biodegradable silica-iron oxide hybrid nanovectors with large mesopores for large protein delivery in cancer cells. The mesopores of the nanomaterials spanned from 20 to 60nm in diameter and post-functionalization allowed the electrostatic immobilization of large proteins (e.g. mTFP-Ferritin, ~534kDa). Half of the content of the nanovectors was based with iron oxide nanophases which allowed the rapid biodegradation of the carrier in fetal bovine serum and a magnetic responsiveness. The nanovectors released large protein cargos in aqueous solution under acidic pH or magnetic stimuli. The delivery of large proteins was then autonomously achieved in cancer cells via the silica-iron oxide nanovectors, which is thus a promising for biomedical applications.

Synthesis and Characterization of Chlorpyrifos/Copper(II) Schiff Base Mesoporous Silica with pH Sensitivity for Pesticide Sustained Release

The salicylaldehyde-modified mesoporous silica (SA-MCM-41) was prepared through a co-condensation method. Through the bridge effect from the copper ion, which also acts as the nutrition of the plant, the model drug chlorpyrifos (CH) was supported on the copper(II) Schiff base mesoporous silica (Cu-MCM-41) to form a highly efficient sustained-release system (CH-Cu-MCM-41) for pesticide delivery. The experimental results showed that the larger the concentration of the copper ion, the more adsorption capacity (AC) of Cu-MCM-41 for chlorpyrifos and the smaller its release rate. The results confirmed the existence of a coordination bond between SA-MCM-41 and copper ions as well as a coordination bond between Cu-MCM-41 and chlorpyrifos. The AC of SA-MCM-41 is 106 mg/g, while that of Cu-MCM-41 is 295 mg/g. The as-synthesized system showed significant pH sensitivity. Under the condition of pH ≤ 7, the release rate of chlorpyrifos decreased with increasing pH, whereas its release rate in weak base conditions was slightly larger than that in weak acid conditions. Meanwhile, the drug release rate of the as-synthesized system was also affected by the temperature. Their sustained-release curves can be described by the Korsmeyer-Peppas equation.

Nanoparticle Technologies in the Spinal Cord

Nanoparticles are increasingly being studied within experimental models of spinal cord injury (SCI). They are used to image cells and tissue, move cells to specific regions of the spinal cord, and deliver therapeutic agents locally. The focus of this article is to provide a brief overview of the different types of nanoparticles being studied for spinal cord applications and present data showing the capability of nanoparticles to deliver the chondroitinase ABC (chABC) enzyme locally following acute SCI in rats. Nanoparticles releasing chABC helped promote axonal regeneration following injury, and the nanoparticles also protected the enzyme from rapid degradation. In summary, nanoparticles are viable materials for diagnostic or therapeutic applications within experimental models of SCI and have potential for future clinical use.

Magnetic Core-Shell Silica Nanoparticles with Large Radial Mesopores for siRNA Delivery

A novel type of magnetic core-shell silica nanoparticles is developed for small interfering RNA (siRNA) delivery. These nanoparticles are fabricated by coating super-paramagnetic magnetite nanocrystal clusters with radial large-pore mesoporous silica. The amine functionalized nanoparticles have small particle sizes around 150 nm, large radial mesopores of 12 nm, large surface area of 411 m(2) g(-1) , high pore volume of 1.13 cm(3) g(-1) and magnetization of 25 emu g(-1) . Thus, these nanoparticles possess both high loading capacity of siRNA (2 wt%) and strong magnetic response under an external magnetic field. An acid-liable coating composed of tannic acid can further protect the siRNA loaded in these nanoparticles. The coating also increases the dispersion stability of the siRNA-loaded carrier and can serve as a pH-responsive releasing switch. Using the magnetic silica nanoparticles with tannic acid coating as carriers, functional siRNA has been successfully delivered into the cytoplasm of human osteosarcoma cancer cells in vitro. The delivery is significantly enhanced with the aid of the external magnetic field.

Adding Functions to Biomaterial Surfaces through Protein Incorporation

The concept of biomaterials has evolved from one of inert mechanical supports with a long-term, biologically inactive role in the body into complex matrices that exhibit selective cell binding, promote proliferation and matrix production, and may ultimately become replaced by newly generated tissues in vivo. Functionalization of material surfaces with biomolecules is critical to their ability to evade immunorecognition, interact productively with surrounding tissues and extracellular matrix, and avoid bacterial colonization. Antibody molecules and their derived fragments are commonly immobilized on materials to mediate coating with specific cell types in fields such as stent endothelialization and drug delivery. The incorporation of growth factors into biomaterials has found application in promoting and accelerating bone formation in osteogenerative and related applications. Peptides and extracellular matrix proteins can impart biomolecule- and cell-specificities to materials while antimicrobial peptides have found roles in preventing biofilm formation on devices and implants. In this progress report, we detail developments in the use of diverse proteins and peptides to modify the surfaces of hard biomaterials in vivo and in vitro. Chemical approaches to immobilizing active biomolecules are presented, as well as platform technologies for isolation or generation of natural or synthetic molecules suitable for biomaterial functionalization.

Functionalized Mesoporous Silica Nanoparticle with Antioxidants as a New Carrier That Generates Lower Oxidative Stress Impact on Cells

Mesoporous silica nanoparticles (MSNs) were covalently coated with antioxidant molecules, namely, caffeic acid (MSN-CAF) or rutin (MSN-RUT), in order to diminish the impact of oxidative stress induced after transfection into cells, thus generating safer carriers used for either drug delivery or other applications. Two cellular models involved in the entry of NPs in the body were used for this purpose: the intestinal Caco-2 and the epidermal HaCaT cell lines. Rutin gave the best results in terms of antioxidant capacities preservation during coupling procedures, cellular toxicity alleviation, and decrease of ROS level after 24 h incubation of cells with grafted nanoparticles. These protective effects of rutin were found more pronounced in HaCaT than in Caco-2 cells, indicating some cellular specificity toward defense against oxidative stress. In order to gain more insight about the Nrf2 response, a stable transfected HaCaT cell line bearing repeats of the antioxidant response element (ARE) in front of a luciferase reporter gene was generated. In this cell line, both tBHQ and quercetin (Nrf2 agonists), but not rutin, were able to induce, in a dose-dependent fashion, the luciferase response. Interestingly, at high concentration, MSN-RUT was able to induce a strong Nrf2 protective response in HaCaT cells, accompanied by a comparable induction of HO-1 mRNA. The level of these responses was again less important in Caco-2 cells. To conclude, in keratinocyte cell line, the coupling of rutin to silica nanoparticles was beneficial in term of ROS reduction, cellular viability, and protective effects mediated through the activation of the Nrf2 antioxidant pathway.

Breakable mesoporous silica nanoparticles for targeted drug delivery

"Pop goes the particle". Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery.

Large Pore-Sized Hollow Mesoporous Organosilica for Redox-Responsive Gene Delivery and Synergistic Cancer Chemotherapy

A stability-difference-selective bond-breakage strategy for the fabrication of largepore-sized hollow mesoporous organosilica nanoparticles (HMONs) is successfully developed. Moreover, surfacefunctionalized HMONs are successfully constructed to simultaneously deliver P-gp modulator siRNA and anticancer drug doxorubicin to reverse the multidrug resistance of cancer cells.

Highly efficient siRNA delivery from core-shell mesoporous silica nanoparticles with multifunctional polymer caps

A new general route for siRNA delivery is presented combining porous core-shell silica nanocarriers with a modularly designed multifunctional block copolymer. Specifically, the internal storage and release of siRNA from mesoporous silica nanoparticles (MSN) with orthogonal core-shell surface chemistry was investigated as a function of pore-size, pore morphology, surface properties and pH. Very high siRNA loading capacities of up to 380 μg per mg MSN were obtained with charge-matched amino-functionalized mesoporous cores, and release profiles show up to 80% siRNA elution after 24 h. We demonstrate that adsorption and desorption of siRNA is mainly driven by electrostatic interactions, which allow for high loading capacities even in medium-sized mesopores with pore diameters down to 4 nm in a stellate pore morphology. The negatively charged MSN shell enabled the association with a block copolymer containing positively charged artificial amino acids and oleic acid blocks, which acts simultaneously as capping and endosomal release agent. The potential of this multifunctional delivery platform is demonstrated by highly effective cell transfection and siRNA delivery into KB-cells. A luciferase reporter gene knock-down of up to 80-90% was possible using extremely low cell exposures with only 2.5 μg MSN containing 0.5 μg siRNA per 100 μL well.

Small-sized and large-pore dendritic mesoporous silica nanoparticles enhance antimicrobial enzyme delivery

Small-sized silica nanoparticles with large dendritic mesopores demonstrate a superior antimicrobial enzyme delivery efficacy with long-term bacterial inhibition.

Influences of mesoporous magnesium silicate on the hydrophilicity, degradability, mineralization and primary cell response to a wheat protein based biocomposite

With the addition of bioactive m-MS,WP40 composite possessed excellent bioactivity and cytocompatibility.

Mixed anionic surfactant-templated mesoporous silica nanoparticles for fluorescence detection of Fe3+

This work demonstrates the design and synthesis of large pore mesoporous silica nanoparticles by using mixed anionic surfactants as soft templates to introduce amino group for Fe³⁺ fluorescent detection.

Novel Mesoporous Silica Materials with Hierarchically Ordered Nanochannel: Synthesis with the Assistance of Straight-Chain Alkanes and Application

The straight-chain alkane-assisted synthesis of hierarchical mesoporous silica materials (MSM) results in variable mesostructures and morphologies due to remarkably different self-assembly routes of template agent from those without the assistance of straight-chain alkanes. The textural properties, particularly pore size, channel structure, morphology, and hierarchical structure of those MSM make them demonstrate peculiar effects in the immobilization of homogeneous catalysts.

SBA-15 mesoporous silica particles loaded with cisplatin induce senescence in B16F10 cells

Nanoparticles obtained by loading of cisplatin into mesoporous silica SBA-15 (SBA-15|CP) change the phenotype of surviving B16F10 melanoma cells from malignant to senescent.

A multifunctional role of trialkylbenzenes for the preparation of aqueous colloidal mesostructured/mesoporous silica nanoparticles with controlled pore size, particle diameter, and morphology

Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size and higher hydrophobicity of TIPB than TMB induce the incorporation of TIPB into micelles without the structural change. When TMB was used as TAB, the pore size of CMSS was also enlarged while the mesostructure and particle morphology were varied. Interestingly, when tetramethoxysilane and TIPB were used, CMSS with a very small particle diameter (20 nm) with concave surfaces and large mesopores were obtained, which may strongly be related to the initial nucleation of CMSS. A judicious choice of TAB and Si sources is quite important to control the mesostructure, size of mesopores, particle diameter, and morphology.

Drug-Polymer Electrostatic Complexes as New Structuring Agents for the Formation of Drug-Loaded Ordered Mesoporous Silica

Using aminoglycoside antibiotics as drug models, it was shown that electrostatic complexes between hydrophilic drugs and oppositely charged double-hydrophilic block copolymers can form ordered mesophases. This phase behavior was evidenced by using poly(acrylic acid)-block-poly(ethylene oxide) block copolymers in the presence of silica precursors, and this allowed preparing drug-loaded mesoporous silica directly from the drug-polymer complexes. The novel synthetic strategy of the hybrid materials is highly efficient, avoiding waste and multistep processes; it also ensures optimal drug loading and provides pH-dependence of the drug release from the materials.

Bimodal mesoporous silica with bottleneck pores

Partial pseudomorphic transformation of SBA-15 yields bimodal mesoporous silica with defined bottlenecks that restrict the access to the core of the particles.

Tuning the aspect ratio of arrays of silica nanochannels

Arrays of silica nanochannels (ASNCs) with various nanochannel lengths and particle aspect ratios are reported.