Functionalized Mesoporous Silica Research Articles

Cover Image, Volume 11, Issue 1

The front cover image is based on the Focus Article Functional mesoporous silica nanoparticles for bio‐imaging applications, by Jaeyun Kim and Bong Geun Cha, https://doi.org/10.1002/wnan.1515. image

Identifying a Membrane-Type 2 Matrix Metalloproteinase-Targeting Peptide for Human Lung Cancer Detection and Targeting Chemotherapy with Functionalized Mesoporous Silica.

Membrane-type 2 matrix metalloproteinase (MT2-MMP) is critical for the aggressive lung tumor growth, progression, and metastasis. Here, to obtain the peptides in binding specifically to MT2-MMP, a phage-displayed 12 peptide library was used and the affinity of peptides toward MT2-MMP was identified by multitest methods. The results showed that a specific MT2-MMP-targeting peptide with the sequence of HHRLHSAPPPQA (MT2-AF5p) exhibited a high specificity and strong affinity against lung tumors. To further achieve specific targeting and precise therapeutic effects, MT2-AF5p was conjugated onto fluorescent mesoporous silica nanoparticles (FMSN-NH2) and loaded with doxorubicin (DOX) to construct a chemotherapeutic drug-targeting delivery system (DOX-loaded FMSN@MT2-AF5p). The DOX-loaded FMSN@MT2-AF5p achieved a boost in DOX release in an acidic environment. Most importantly, FMSN@MT2-AF5p efficiently targeted the tumor area, as seen in the fluorescent imaging ex vivo. The novel peptide-functionalized nanoparticles with a good biocompatibility are promising for clinical use as a precise targeting nanodrug for lung cancer diagnosis and therapy.

Synthesis and Characterization of Carboxyl-terminated Polyethylene Glycol Functionalized Mesoporous Silica Nanoparticles

Colloidal mesoporous silica nanoparticles functionalized with carboxy-terminated polyethylene glycol (CMS-PEG-COOH) were successfully synthesized by covalently grafting dicarboxy-terminated polyethylene glycol (HOOC-PEG-COOH) on the surface of the amino functionalized CMS nanoparticles with amide bond as a cross linker. Moreover, the structural and particle properties of CMS-PEG-COOH were characterized by nuclear magnetic resonance spectroscopy (1H-NMR), transmission electron microscopy (TEM), dynamic light scattering (DLS), nitrogen adsorption-desorption measurements, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The nanomaterials presented a relatively uniform spherical shape morphology with diameters of about 120 nm,and favorable dispersibility in weak acid solution. The CMS-PEG-COOH exhibited no changes in the state of amorphous, while the mesopores sizes of 5.25 nm might provide the nanomaterials with large capacity for the loading and releasing of drugs. So the results indicated that CMS-PEG-COOH might be a critical nanomaterial for drug delivery system in the future.

Latest progress on the typical mesoporous Si-based solid acid catalysts

Serious environment and safety issues by the wide application of inorganic mineral acids have attracted worldwide attention from fundamental science and application point of view. Under such circumstances, the development of the solid acid catalysts is a very hot topic currently. The ideal solid acid catalysts possess appropriate Bronsted and Lewis acidic nature, good porosity, high stability and unique morphology. Among them, the morphological nanostructure of catalysts is one of the important factors that can have a profound influence on their catalytic performance. Compared with a number of other supports of the solid acid catalysts, the silica-based materials are considered as promising candidates because of their diverse composition, physicochemical property and morphology as well as excellent porosity property. Among them, mesoporous silica-based materials possess lager pore compared with the microporous silica materials (e.g., ZSM-5, H-beta, etc.). They enable to catalyze reactions efficiently involving bulky substrates and/or products, and facilitate mass transfer. Meanwhile, the larger pore favors the dispersion of the active sites and hinders the accumulation of coke on the surface to avoid pore blocking. As a result, one of the important strategies to prepare novel solid acid catalysts is to immobilize the active sites on mesoporous silica materials. The as-prepared mesoporous silica-based solid acid catalysts have shown great potential for application in the field of environment, energy and industrial catalysis. In this paper, the latest progress on the morphology-controlled preparation of mesoporous silica−based materials and their applications in catalysis are summarized. In the case of the silica-based materials, it can be dated back to the early 1990s, and Mobil Company synthesized various M41S materials firstly (MCM-41, MCM-48 and MCM-50) by using the alkyl quaternary ammonium salt cationic surfactant as the template agent. Compared with the amorphous silica materials, M41S possess ordered mesoporous structure, uniform pore size (2‒5 nm), large pore volume and BET surface area (1000 m2 g-1). Subsequently, various SBA materials (such as SBA-15 and SBA-16) with large pore size were prepared successfully. It has attracted wide attention to functionalize the silica materials by incorporating the active sites and maintaining the morphological structure. With the development of silica-based materials, periodic mesoporous organosilicas (PMO) were synthesized by surfactant-directed sol-gel method, which opened a new pathway to prepare functional mesoporous silica materials. Up to now, a number of functionalized organosilica materials have been reported and exhibited great potential in the fields of catalysis, sensing, chromatography analysis, metal adsorption and bio-pharmacy etc. Herein, the mesoporous silica-based solid acid catalysts by the morphology-controlled preparation of functionalized organosilicas showed highly ordered, tubular or hollow spherical nanostructure by P123-directed sol-gel co-condensation. The as-prepared mesoporous silica-based solid acid catalysts possessed hydrophobic surface, excellent porosity property and strong Bronsted acidic nature. Moreover, the catalysts with well-defined morphology exhibited high catalytic performance for synthesis of the biomass-derived platform molecules or high value-added chemicals. Owing to the accelerated diffusion, transmission and improved accessibility of substrates to active sites, the mesoporous silica-based solid acid catalysts with hollow nanosphere morphology showed the highest activity compared with the tubular or ordered analogues. On the other hand, the covalent bond between active sites and silica framework can avoid the leaching issue of the solid acid catalysts. In addition, the hydrophobic character of alkyl-containing organosilica can reduce acid sites deactivation associated with adsorption of polar byproducts, which can improve the stability of as-prepared catalysts. To summarize, this review aims to provide important reference value for development of novel solid acid catalysts.

Palladium nanoparticles immobilized on Schiff base‐functionalized mesoporous silica as a highly efficient and magnetically recoverable nanocatalyst for Heck coupling reaction

A new magnetically recoverable nanocatalyst was prepared by functionalization of mesoporous silica (SBA‐15) with a Schiff base ligand, and then immobilization of palladium nanoparticles on it using a simple procedure. This heterogeneous catalyst was fully characterized using appropriate analyses and its catalytic efficiency was investigated in Heck reaction using iodo‐, bromo‐ and chlorobenzene derivatives and styrene, with the aim of synthesizing stilbene derivatives, a class of compounds with a variety of pharmacological properties. Some of the characteristics of this nanocatalyst include good dispersion of palladium nanoparticles on the SBA‐15 support, easy separation, catalyses the production of stilbene derivatives in a short time with excellent yields even for bromo‐ and chlorobenzene, and preservation of its catalytic activity after eight reaction cycles.

Mesoporous Silica Nanoparticles for Dual-Mode Chemo-Sonodynamic Therapy by Low-Energy Ultrasound.

Low-energy ultrasound (LEUS), exhibiting obvious advantages as a safe therapeutic strategy, would be promising for cancer therapy. We had synthesized a LEUS-responsive targeted drug delivery system based on functional mesoporous silica nanoparticle for cancer therapy. Paclitaxel (PTX) was loaded in mesoporous silica nanoparticles with a hydrophobic internal channel, and folic acid (FA) functionalized β-Cyclodextrin (β-CD) was capped on the surface of the nanoparticles (DESN), which acted as a cancer-targeting moiety and solubilizer. The existence of a hydrophobic internal channel in the DESN was beneficial to the storage of hydrophobic PTX, along with the enhancement of the cavitation effect produced by mild low-energy ultrasound (LEUS, ≤1.0 W/cm2, 1 MHz). The DESN showed significantly enhanced cavitation effect, selective targeting, and achieved a rapid drug release under mild LEUS. To investigate the in vivo antitumor efficacy of the DESN upon LEUS irradiation, we established a 4T1 mammary tumor model. The DESN were confirmed to be of great biodegradability/biocompatibility. The tumor growth was significantly inhibited when the mice were treated with DESN (10 mg/kg) + LEUS with the relative tumor volume reduced to 4.72 ± 0.70 compared with the control group (V/V0 = 17.12 ± 2.75). The DESN with LEUS represented excellent inhibiting effect on tumor cell in vivo. This work demonstrated that DESN mediating dual mode chemo-sonodynamic therapy could be triggered by extracorporeal remote control, may suggest a promising clinical application in cancer therapy.

Improving Continuous Flow Singlet Oxygen Photooxygenation Reactions with Functionalized Mesoporous Silica Nanoparticles

AbstractContinuous flow photochemistry relying on photosensitizers faces two main challenges: 1) Photodegradation (bleaching) and 2) the downstream removal of the photosensitizer. Rose bengal (RB) is a common photosensitizer utilized for photooxygenation reactions with singlet oxygen (1O2), but is notoriously sensitive to photobleaching and difficult to remove from reactor effluents. The heterogenization of photosensitizers on mesoporous silica nanoparticles (MSNs) is arguably a viable option for such applications. Herein, we report on the use of RB covalently incorporated into MSNs (RB@MSNs) for photooxygenation reactions under continuous flow conditions. RB@MSNs enable the 1O2 photooxygenation of various organic substrates upon irradiation with 540 nm LEDs. A series of organic substrates were evaluated including methionine, α‐terpinene, 2‐furoic acid, triphenylphosphine, citronellol and cyclopentadiene. These results emphasize an improved resistance to photobleaching, and the possibility to use RB@MSNs as an easily recoverable catalyst, which could be removed from the reactor effluent either a) by centrifugation or b) by in‐line membrane filtration.

Selective Immobilization of Highly Valent Radionuclides by Carboxyl Functionalized Mesoporous Silica Microspheres: Batch, XPS, and EXAFS Analyses

The removal of radionuclides on natural inorganic materials is a pursuing issue for many nuclear-related processes requiring remediation of radioactive wastewater. However, the current natural adsorbents with low cost and great biocompatibility suffer from limitations in removal efficiency, regeneration capability, or/and operation conditions. Herein, silicon dioxide (SiO2) as the major ingredient of clay minerals was modified by carboxyl groups to improve its adsorption affinity for highly valent radionuclides. The batch experiments for U(VI) capture showed that the carboxyl-modified mesoporous silica (SiO2-COOH) microspheres had fast sorption velocity and were exceptionally capable in efficiently sequestering U(VI) under various relevant interferences. The resulting SiO2-COOH possessed great potential for controlled loading of highly valent radionuclides in a selective adsorption order of U(VI) > Th(IV) > trivalent ions > divalent ions > Cs(I). The XPS and EXAFS analyses further confirmed that the inter...

Synthesis of Amine Functionalized Mesoporous Silicas Templated by Castor Oil for Transesterification

ABSTRACTMesoporous silicas were synthesized via a surfactant-templated sol-gel route using castor oil as the templating agent under acidic medium. The resulting silicas were subsequently amine functionalized with 3-aminopropyltriethoxysilane (NH2-MTS), [3-(2-aminoethylamino)-propyl]trimethoxysilane (NN-MTS), and [3-(diethylamino)propyl]trimethoxysilane(DN-MTS) to introduce surface basicity. Surface physicochemical properties were characterized by field emission gun scanning electron microscopy (FEGSEM), nitrogen porosimetry, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). As-synthesised materials exhibit type IV adsorption-desorption isotherms characteristic of mesoporous structures. Clusters of spherical shaped materials were observed by FEGSEM, suggesting growth of silica occurs within colloidal dispersions. High-resolution N 1s XP spectra and DRIFT spectra confirmed the presence of amine groups in the organo-amine functionalised mesoporous silicas. The amine functionalised mesoporous silicas were active for the transesterification of tributyrin with methanol, with conversion found to increase from NH2-MTS< NN-MTS< DN-MTS.

H NMR Studies on Water Dynamics in Functionalized Mesoporous Silica

Mesoporous silica MCM-41 is prepared, for which the inner surfaces are modified by 3-(aminopropyl)triethoxysilane (APTES) in a controlled manner. Nitrogen gas adsorpition yields a pore diameter of 2.2 nm for the APTES functionalized MCM-41. ²H nuclear magnetic resonance (NMR) and broadband dielectric spectroscopy (BDS) provide detailed and consistent insights into the temperature-dependent reorientation dynamics of water in this confinement. We find that a liquid water species becomes accompanied by a solid water species when cooling through ~210 K, as indicated by an onset of bimodal Mesoporous silica MCM-41 is prepared, for which the inner surfaces are modified by 3-(aminopropyl)triethoxysilane (APTES) in a controlled manner. Nitrogen gas adsorpition yields a pore diameter of 2.2 nm for the APTES functionalized MCM-41. ²H nuclear magnetic resonance (NMR) and broadband dielectric spectroscopy (BDS) provide detailed and consistent insights into the temperature-dependent reorientation dynamics of water in this confinement. We find that a liquid water species becomes accompanied by a solid water species when cooling through ~210 K, as indicated by an onset of bimodal ²H spin-lattice relaxation. The reorientation of the liquid water species is governed by pronounced dynamical heterogeneity in the whole temperature range. Its temperature dependence shows a mild dynamic crossover when the solid water species emerges and, hence, the volume accessible to the liquid water species further shrinks. Therefore, we attribute this variation in the temperature dependence to a change from bulk-like behavior towards interface-dominated dynamics. Below this dynamic crossover, ²H line-shape and stimulted-echo studies show that water reorientation becomes anisotropic upon cooling, suggesting that these NMR approaches, but also BDS measurements do no longer probe the structural (α) relaxation, but rather a secondary (β) relaxation of water at sufficiently low temperatures. Then, another dynamic crossover at ~180 K can be rationalized in terms of a change of the temperature dependence of the β relaxation in response to a glassy freezing of the α relaxation of confined water. Comparing these results for APTES modied MCM-41 with previous findings for mesoporous silica with various pore diameters, we obtain valuable information about the dependence of water dynamics in restricted geometries on the size of the nanoscopic confinements and the properties of the inner surfaces. ²H spin-lattice relaxation. The reorientation of the liquid water species is governed by pronounced dynamical heterogeneity in the whole temperature range. Its temperature dependence shows a mild dynamic crossover when the solid water species emerges and, hence, the volume accessible to the liquid water species further shrinks. Therefore, we attribute this variation in the temperature dependence to a change from bulk-like behavior towards interface-dominated dynamics. Below this dynamic crossover, ²H line-shape and stimulted-echo studies show that water reorientation becomes anisotropic upon cooling, suggesting that these NMR approaches, but also BDS measurements do no longer probe the structural (α) relaxation, but rather a secondary (β) relaxation of water at sufficiently low temperatures. Then, another dynamic crossover at ~180 K can be rationalized in terms of a change of the temperature dependence of the β relaxation in response to a glassy freezing of the α relaxation of confined water. Comparing these results for APTES modied MCM-41 with previous findings for mesoporous silica with various pore diameters, we obtain valuable information about the dependence of water dynamics in restricted geometries on the size of the nanoscopic confinements and the properties of the inner surfaces.

Hierarchical hematite/TiO2 nanorod arrays coupled with responsive mesoporous silica nanomaterial for highly sensitive photoelectrochemical sensing

The photoelectrochemical (PEC) technique has resulted in substantial progress in chemical sensing applications. However the complicated photoelectrode modification procedures would enable undesired background noise and decreasing sensitivity. Hence, it is important to explore a new approach alternative to inconvenient substrate modification. Herein, inspired by the stimuli-responsive drug delivery systems, an innovative PEC system is developed for efficiently microRNA-21 (miRNA-21) tracing. Hierarchical nanocomposites based on hematite (α-Fe2O3) coated self-ordered titanium dioxide nanorod arrays (TiO2 NRAs) exhibited enhanced response to solar light, promoted charge carrier separation and transfer efficiency was adopted as photoelectrode directly. Functional mesoporous silica nanomaterial (MSN) is prepared as nanocarriers for efficient loading of Cu2+, further capped with miRNA-21 responsive capture RNA probe. Thereafter, the capture RNA probe endows the functional MSN with responsiveness to miRNA-21. With the presence of miRNA-21, this system is thus triggered and a quickly release of capped Cu2+ occurs due to the dissociation of capture RNA probe presented on the MSN surface via base-pair hybridization. The released Cu2+ was then served as electron acceptor reduced to Cu° at the counter electrode to enhance electron-hole pair separation efficiency, leading to a promoted photocurrent response. Consequently, the miRNA-21 can be accurately quantified. Taking advantage of its sensitivity and specificity, this versatile strategy demonstrates a new route for the design PEC sensing approach without any photoelectrode modification procedure, and holds great potential for biosensing and clinical diagnosis.

Enhancement Antimicrobial Activity of Clarithromycin by Amine Functionalized Mesoporous Silica Nanoparticles as Drug Delivery System

Methods: A large pore amine functionalized MSN (MSNs-NH2) is described here to facilitate delivery of clarithromycin (CLM) as an antibacterial drug and enhance the efficacy against Gram positive and Gram negative bacterial samples. Prepared particles were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), nitrogen adsorption/desorption isotherms, Fourier Transform Infrared (FT-IR) spectroscopy and X-ray Diffraction (XRD) spectroscopy. The antimicrobial activity was evaluated by agar well diffusion and broth dilution methods. Therefore, the biodistribution of FITC-MSNs was investigated by measure the NIR intensity fluorescent of fluorescent images from whole animal and dissected organs of NMRI mice. Results: The results showed that the CLM loaded MSNs-NH2 (CLM/MSNs-NH2) were successfully prepared having good payload and pH-sensitive drug release kinetics. The antimicrobial investigation against Staphylococcus aureus and Escherichia coli was showed better performance of antimicrobial activity of these nanoparticles. In vivo and ex vivo fluorescent imaging investigation on NMRI mice were shown that FITC-MSNs-NH2 accumulated in the liver and kidney and notably in lung tissue. Conclusion: The CLM/MSNs-NH2 exhibited higher antimicrobial activity and enhanced the possibility of microbial infection therapy especially at respiratory infections

IR spectroscopy study of SBA-15 silicas functionalized with the ethylthiocarbamidepropyl groups and their interactions with Ag(I) and Hg(II) ions

Mesoporous structure of silica is determined by the type of template, but the introduction of functional groups during the synthesis has additional influence. The structure of SBA-15 may be violated by the introduction of long functions, such as ≡Si(CH2)3NHC(=S)NHC2H5. These ethylthiocarbamidepropyl groups can form complexes with metal ions in thiol or thione tautomeric forms. We determined that the 2D hexagonal p6 mm structure is preserved for SBA-15 with thiourea groups at maximal TEOS:trifunctional silane ratio (mol) = 10:2, which was confirmed by TEM and by the presence of an intense reflex in the small-angle region of diffractograms of the final product. It was shown that the obtained sorbents possess high kinetic characteristics. The experimental data fit pseudo-second-order kinetic equation, but the rate constants depend on the content of functional groups in the surface layer. Template Pluronic P-123 defines the porosity of functional mesoporous silica materials even at increasing content of trifunctional silane in the initial solution. Infrared spectroscopy analysis showed that thione form of thiourea ligand is prevalent on the surface of pores of mesoporous samples. However, during the sorption of silver(I) ions, there are both thione and thiol forms on the surface. Thione form is transformed into thiol with increasing concentration of mercury(II) ions in the sorption solution. Adsorption experiments showed that the SBA-15 silicas functionalized with ethylthiocarbamidepropyl groups had high selectivity for silver(I) ions and could concentrate Ag(I) ions from metal ions mixture at pH ~ 2.

Improved CO2 Sorption in Freeze-Dried Amine Functionalized Mesoporous Silica Sorbent

This work investigates the structural and CO2 sorption properties of amine-functionalized mesoporous silica prepared by a freeze-drying method. It was found that the freeze-dried samples delivered significantly higher CO2 sorption capacities up to a factor of 18 times as compared to samples prepared by the conventional oven-drying evaporation method. The improved performance of the freeze-drying method was attributed to a higher surface area and access to active amine sites for CO2 sorption. The freeze-dried samples also exhibited good stability at a relatively high sorption temperature (90 °C) and flue gas CO2 partial pressure (15 kPa). The freeze-drying method reached the best CO2 sorption capacity of 4.71 mmol g–1 for samples with 70 wt % amine loading. Higher loading (80 and 90 wt %) led to excess amine not being incorporated into the mesoporous silica structure, thus covering active sites and limiting CO2 diffusion.

Enhanced Mechanical Performance and Antioxidative Efficiency of Styrene–Butadiene Rubber via 4-Aminodiphenylamine Functionalized Mesoporous Silica

We reported newly prepared functionalized nanoparticles (RT@MS) using mesporous silica (MS) with antioxidant intermediate 4-aminodiphenylamine (RT) via the linkage of KH-560. RT@MS was used as a nanofiller to fabricate styrene–butadiene rubber (SBR) composites. Under the condition of equal antioxidant and filler components, functionalized mesoporous silica can greatly enhance the mechanical properties of SBR owing to the uniform dispersion and strong interfacial interaction between SBR and RT@MS. Besides, the antiaging behavior of SBR/RT@MS composites was systematically evaluated by thermal oxidation exothermic enthalpies and oxidation induction time before and after solvent extraction. The results indicated that RT@MS showed much better thermal and oxidative stabilities and longer service life than the most commonly used antioxidant N-isopropyl-N′-phenyl-4-phenylenediamine in SBR due to the improved migration resistance of immobilized RT.

Functional mesoporous silica nanoparticles for bio-imaging applications.

Biomedical investigations using mesoporous silica nanoparticles (MSNs) have received significant attention because of their unique properties including controllable mesoporous structure, high specific surface area, large pore volume, and tunable particle size. These unique features make MSNs suitable for simultaneous diagnosis and therapy with unique advantages to encapsulate and load a variety of therapeutic agents, deliver these agents to the desired location, and release the drugs in a controlled manner. Among various clinical areas, nanomaterials-based bio-imaging techniques have advanced rapidly with the development of diverse functional nanoparticles. Due to the unique features of MSNs, an imaging agent supported by MSNs can be a promising system for developing targeted bio-imaging contrast agents with high structural stability and enhanced functionality that enable imaging of various modalities. Here, we review the recent achievements on the development of functional MSNs for bio-imaging applications, including optical imaging, magnetic resonance imaging (MRI), positron emission tomography (PET), computed tomography (CT), ultrasound imaging, and multimodal imaging for early diagnosis. With further improvement in noninvasive bio-imaging techniques, the MSN-supported imaging agent systems are expected to contribute to clinical applications in the future. This article is categorized under: Diagnostic Tools > In vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Functional Magnetic Mesoporous Silica Microparticles Capped with an Azo-Derivative: A Promising Colon Drug Delivery Device.

Magnetic micro-sized mesoporous silica particles were used for the preparation of a gated material able to release an entrapped cargo in the presence of an azo-reducing agent and, to some extent, at acidic pH. The magnetic mesoporous microparticles were loaded with safranin O and the external surface was functionalized with an azo derivative 1 (bearing a carbamate linkage) yielding solid S1. Aqueous suspensions of S1 at pH 7.4 showed negligible safranin O release due to the presence of the bulky azo derivative attached onto the external surface of the inorganic scaffold. However, in the presence of sodium dithionite (azoreductive agent), a remarkable safranin O delivery was observed. At acidic pH, a certain safranin O release from S1 was also found. The pH-triggered safranin O delivery was ascribed to the acid-induced hydrolysis of the carbamate moiety that linked the bulky azo derivatives onto the mesoporous inorganic magnetic support. The controlled release behavior of S1 was also tested using a model that simulated the gastro intestinal tract.

Boron-chelating membranes based in hybrid mesoporous silica nanoparticles for water purification

Boron is a key element for some biological processes,but it becomes toxic for humans and plants in concentrations above a few ppm. We have design a new approach for boron scavenging, based in hybrid membranes of functional mesoporous silica nanoparticles immobilized in cellulose acetate. The mesoporous silica nanoparticles, with diameters around 150nm, were functionalized with vicinal diol groups that complex boron very efficiently. The functional nanoparticles were covalently immobilized in a cellulose acetate membrane using a di-terminated alkoxisilane that react with the remaining silanol groups at the nanoparticles surfaces and with the hydroxyl groups of the cellulose. The functional nanoparticles and the hybrid membranes show boron removal efficiencies of phenyl boronic acid of up to 93%. The membranes can be used in multistage filtering systems, with sequential membranes modules in continuous operation, in a cheap, simple and efficient process for boron scavenging.

Microfluidic Flow Synthesis of Functional Mesoporous Silica Nanofibers with Tunable Aspect Ratios

Microfluidic techniques open new frontiers for the controllable synthesis of functional micro/nanomaterials with desired shapes for a variety of applications. In this study, miniaturized spiral-shaped microchannel with two inlets and one outlet was specially designed for the controllable flow synthesis of mesoporous silica nanofibers (MSNFs) using one inlet flow containing cetyltrimethylammonium bromide and diluted ammonia and the other inlet flow containing diluted tetraethyl orthosilicate. The aspect ratios and diameters of MSNFs can be easily tuned by changing the flow rates and/or the concentrations of reactants. In addition, fluorescent dyes, magnetic nanoparticles, therapeutic drugs, or silver nanoparticles can be simultaneously assembled into MSNFs to make them promising functional materials in bioimaging, theranostics, and catalysis fields.

Targeting Somatostatin Receptors By Functionalized Mesoporous Silica Nanoparticles - Are We Striking Home?

The concept of delivering nanoformulations to desired tissues by means of targeting membrane receptors of high local abundance by ligands anchored to the nanocarrier has gained a lot of attention over the last decade. Currently, there is no unanimous opinion on whether surface functionalization of nanocarriers by targeting ligands translates into any real benefit in terms of pharmacokinetics or treatment outcomes. Having examined the published nanocarriers designed to engage with somatostatin receptors, we realized that in the majority of cases targetability claims were not supported by solid evidence of targeting ligand-targeted receptor coupling, which is the very crux of a targetability concept. Here, we present an approach to characterize targetability of mesoporous silica-based nanocarriers functionalized with ligands of somatostatin receptors. The targetability proof in our case comes from a functional assay based on a genetically-encoded cAMP probe, which allows for real-time capture of receptor activation in living cells, triggered by targeting ligands on nanoparticles. We elaborate on the development and validation of the assay, highlighting the power of proper functional tests in the characterization pipeline of targeted nanoformulations.