Mesoporous Silica Nanocontainers Research Articles

NIR-Controlled Treatment of Multidrug-Resistant Tumor Cells by Mesoporous Silica Capsules Containing Gold Nanorods and Doxorubicin.

Multidrug resistance (MDR) is identified as a major impediment to the efficient chemotherapy of cancer, and considerable endeavors have been devoted to reverse MDR containing structuring varieties of multifunctional nanocarriers. Here, a specially light-activated hollow mesoporous silica nanocontainer with an in situ-synthesized Au nanorod (AuNR) core and a surface-modified hairpin structure DNA gatekeeper is reported for treating MDR tumor cells. In this system, the AuNR only fills part of the space in hollow mesoporous silica due to its controllable size, and the remaining space is used to load enough DOX. By controlling the near-infrared (NIR) laser intensity and exposure duration, the configuration of hairpin-structured DNA (Tm = 51.4 °C) can change reversibly and then trigger the controllable intracellular release of DOX, leading to a significantly enhanced chemotherapeutic efficacy and adjustable photothermal treatment for multidrug-resistant cancer cells. The in vitro experiments showed that this system could effectively overcome the MDR of HepG2-adm cells (a MDR cell line of human hepatocarcinoma cells) by the increased concentration of DOX intracellularly and the photothermal conversion of AuNRs, even at a low concentration (e.g., 30 μg mL-1). Therefore, this NIR-triggered chemo-photothermal synergistic treatment system can be used as a promising efficient strategy in reversing the multidrug resistance for cancer therapy.

Dendrimer like mesoporous silica nano container (DMSN) based smart self healing coating for corrosion protection performance

A new generation smart self-healing coating possessing both passive matrix functionality and rapid response to local changes in the environment is of great industrial importance. In the present work, a stimulus responsive smart self -healing anticorrosion coating was developed based on acrylic resin, incorporated with Dendrimer like Mesoporous Silica Nanoparticles (DMSN) loaded inside with 8-hydroxyquinoline inhibitor. FESEM and TEM analysis showed that the dendrimer like mesoporous silica (DMS) nanoparticles synthesized were of spherical and fibrous form with size less than 200 nm. The BET surface area, pore volume and average pore diameter of the nanoparticles were found to be 1322.4 m2 g−1, 1.39 cc/g and 4.2 nm respectively. The corrosion protection performance of the coatings was evaluated via Electrochemical Impedance Spectroscopy (EIS) in 3.5 % NaCl. The acrylic coating with dendrimer like silica nano containers showed improved and long-term corrosion protection than the coating without nano containers. The smart self-healing property of the coating was studied by Scanning Vibrating Electrode Technique (SVET). The SVET showed a smartness activity of DMSN by release of inhibitor triggered by corrosion phenomena in the defect area. Further, to reassert the smartness of the coating, impedance mapping of the surface was carried out at a fixed frequency.

Mesoporous silica particles based on complex micelles of poorly water-soluble compounds. One simple step to multidrug carriers

Curcumin, a natural water-insoluble compound of high biological activity, has been solubilized in the micelles of an antiseptic miramistin. As a result, curcumin water solubility increased up to 80 times. Miramistin micelles with the solubilized curcumin have been used as a hybrid template for the one-pot synthesis of mesoporous silica nanocontainers (MSNs) from tetraethoxysilane (TEOS) and their loading with these two drugs. The obtained MSNs are of a prolonged shape and ordered porous structure with a high amount of encapsulated drugs. It is found that the drug content in MSNs depends on the miramistin-to-TEOS ratio as well as the temperatures of both the solubilization of curcumin and the synthesis of MSNs. Kinetics of miramistin and curcumin release from the MSNs into the aqueous media with different pH values has been studied. Drugs release rate increases in acidic medium (pH 4.9) in comparison to neutral medium. We believe that the obtained MSNs loaded with two bioactive compounds may provide enhanced bioavailability of curcumin and, therefore, turn to be promising to combat drug-resistant bacteria.

Ultrasensitive Controlled Release Aptasensor Using Thymine-Hg2+-Thymine Mismatch as a Molecular Switch for Hg2+ Detection.

An ultrasensitive controlled release system electrochemical aptasensor (CRSEA) has been developed for supersensitive determination of mercury ions (Hg2+), using gold nanoparticle-linked specific single-stranded DNA (Au NPs-ssDNA) as a molecular gate and mesoporous silica nanocontainers (MSNs) as containers. MSNs have a rich porous structure, thus entrapping the toluidine blue (TB) molecules inside. It is worth noting that Hg2+ binds to the ssDNA with multiple thymine (T) and induces the ssDNA to form a hairpin structure, which makes the separation of the Au NPs-ssDNA from the MSNs. Eventually, the stored TB molecules were released from MSNs. The electron transfer signals of TB were detected stably by a differential pulse voltammetry (DPV) detection method, which are correlated with the concentration of Hg2+. Therefore, the wide linear range (10 pM-100 μM) and low limit of detection (2.9 pM) were obtained, and the system also displayed an apparent electrochemical signal response in real sample detection and showed a promising possibility in actual monitoring.

A self-healing coating containing curcumin for osteoimmunomodulation to ameliorate osseointegration

To enhance corrosion resistance and osseointegration of Mg-based endosseous implants, novel coatings with self-healing and osteoimmunomodulation functions were fabricated on Mg. The coatings exhibited similar three-layered structure, comprising an inner layer of MgO, an interlayer of poly-L-lactide containing curcumin loaded F-encapsulated mesoporous silica nanocontainers (cFMSNs) and an outer layer of dicalcium phosphate dehydrate, while the amounts of cFMSNs contained in the interlayers were different (thus namely 5FMSN, 10FMSN, 20FMSN). Localized-electrochemical impedance spectroscopy, electrochemical and immersion tests were used to investigate self-healing property and corrosion resistance of the coatings, moreover, curcumin release, immunomodulation effects and osseointegration of these coatings were also assayed, together with cFMSNs-free coating (0FMSN). Due to the cFMSNs functioning as corrosion inhibitor, cFMSNs-contained coatings exhibited obvious self-healing property to enhance protection to Mg in vitro and in vivo compared to 0FMSN, and the enhancements were more pronounced with cFMSNs increase. cFMSNs-contained coatings sustainably released curcumin, and the accumulative curcumin concentration of the 20FMSN immersed physiological saline (PS) was 1.51 μM after 10 days of immersion, which was higher than those of the PS immersing 10FMSN (1.02 μM) and 5FMSN (0.31 μM). Owing to the released curcumin, cFMSNs-contained coatings significantly modulated the immune microenvironment towards favoring osteo-differentiation and extracellular matrix mineralization of bone marrow stem cells, consequently exhibited better osseointegration compared to 0FMSN. 20FMSN exhibited higher immunomodulatory efficiency compared to 10FMSN and 5FMSN, and thus achieved the best osseointegration in vivo. Our work paves an alternative way to design coatings on Mg for realizing improved clinical performance.

Light-Induced Transport of Water and Guest Molecules in Mesoporous Silica Nanocontainer Interface

Light-Induced Transport of Water and Guest Molecules in Mesoporous Silica Nanocontainer Interface

Cytoplasmic Protein-Powered In Situ Fluorescence Amplification for Intracellular Assay of Low-Abundance Analyte.

Fluorescence amplification is critical for in situ and real-time detection of intracellular low abundance biological species. However, current intracellular amplification techniques mainly rely on synthetic nucleic acid-based nanodevices, manipulating them in living cells remains challenging. To solve this problem, herein, a new signal amplification concept named cytoplasmic protein-powered in situ fluorescence amplification (CPFA) is proposed. CPFA takes cytoplasmic protein as cell-self-power for signal amplification enabling it to operate in living cells. To establish a prototype of CPFA, an amplifiable sensor for hydroxyl radicals (•OH) was designed by entrapping the screened cytoplasmic protein-enhanced fluorophore (PBF1) inside mesoporous silica (MSN) nanocontainer with ssDNA/PTAD-based signal switch. When encountered with •OH in living cells, the ssDNA was cleaved to separate PTAD from MSN, liberating multiple copies of the loaded PBF1 to light up the fluorescence. Furthermore, these released PBF1 molecules can instantly bind with cytoplasmic proteins to amplify their fluorescence signals. Take advantage of this two-stage amplification mode, the sensor in response to •OH exhibited remarkable fluorescence enhancement (near 400-fold) in cell lysates, and the •OH was linearly determined from 0 to 800 nM with a detection limit of 6.4 pM. Moreover, this sensor can track basal level and fluctuation of •OH in living cells on account of its high sensitivity. To our knowledge, this is the first effort to use cytoplasmic protein for amplifying detection signals, which will provide a new dimension to current methodologies for low-abundance biomarkers discovery and regulation for chemical biology and medical diagnostics.

Enhancing corrosion protection properties of sol-gel coating by pH-responsive amino-silane functionalized graphene oxide-mesoporous silica nanosheets

Amino-silane functionalized graphene oxide-ordered mesoporous silica nanocontainer was synthesized to load corrosion inhibitor benzotriazole, and the synthesized two-dimensional composite was named as fGS-BTA. Its compatibility and dispersion stability in sol solution was prominently reinforced by amino-silane functionalization. Meanwhile, amino-silane as pH-driven “nanogate” suppressed the premature leakage of inhibitor, which endowed fGS-BTA nanocomposite the stimuli-responsive release under alkaline condition. Electrochemical impedance spectroscopy of intact and scratched sol-gel coating filled with fGS-BTA nanosheets showed the enhanced barrier property and the active protection capacity.

An investigation on the corrosion behavior of the epoxy coating embedded with mesoporous silica nanocontainer loaded by sulfamethazine inhibitor

In this study, mesoporous silica served as the host for an eco-friendly corrosion inhibitor. This material could adsorb and release corrosion inhibitor in different aqueous media. A composite coating was prepared by embedding 1 wt. % mesoporous silica loaded with sulfamethazine (MSInh) as the corrosion inhibitor into the epoxy film to protect mild steel as substrate. Anti-corrosion properties of the solution containing MSInh and corrosion protection function of composite coating were assessed by electrochemical impedance spectroscopy. Results showed the higher corrosion protection of epoxy/mesoporous silica loaded with inhibitor (MSInh) in NaCl solution for one month of immersion in comparison with epoxy/mesoporous silica and epoxy coatings. Charge transfer resistance of epoxy, epoxy/MS, and epoxy/MSInh after 30 days of immersion estimated 6, 15, and 80 kΩ cm2, respectively. The results revealed the higher corrosion resistance of epoxy/MSInh which confirmed the barrier effect of mesoporous silica against corrosive species and corrosion inhibiting effect of the released sulfamethazine molecules.

Anti-corrosion behavior of epoxy composite coatings containing molybdate-loaded mesoporous silica

In this study, mesoporous silica nanocontainers (MS) were successfully synthesized, functionalized and loaded with sodium molybdate as a corrosion inhibitor (MSInh). The epoxy composite coatings were applied on the mild steel substrates by embedding 1 wt. % mesoporous silica with (E/MSInh) or without (E/MS) inhibitor. Characterization of the synthesized mesoporous silica loaded with molybdate demonstrated the pH-dependence of molybdate release from E/MSInh. According to the results, by increasing the pH from 1 to 14, a 160 times increase in the molybdate concentration in the solution was observed. The corrosion behavior of the composite coatings was assessed by the electrochemical impedance spectroscopy and the electrochemical noise analysis. Charge transfer resistance decreased from 4 × 107 to 3.1 × 104 Ω cm2 and from 2.2 × 106 to 2 × 103 Ω cm2 for E/MSInh and E/MS during the immersion time, respectively. The results revealed the higher corrosion resistance of E/MSInh during 56 days of immersion in 3.5 wt. % NaCl solutions in comparison to E/MS which confirms the proper corrosion inhibiting effect of the released molybdate ions.

Encapsulation and Release of Essential Oils in Functional Silica Nanocontainers.

We describe the fabrication of mesoporous silica nanocontainers (SiO2NCs) that simultaneously encapsulate different antiseptic agents. Peppermint oil (PO), thyme oil (TO), cinnamon oil (CnO), and clove oil (CO), which are known to display antibacterial properties, are loaded in the core of the silica nanocontainers that are stabilized by antiseptic surfactants. The encapsulation efficiency, surface area, and pore size are controlled by the type of oil and surfactant. The release of essential oils is further controlled by grafting oxidized hyaluronic acid on silica nanocontainers functionalized with amino groups.

Low Background Cascade Signal Amplification Electrochemical Sensing Platform for Tumor-Related mRNA Quantification by Target-Activated Hybridization Chain Reaction and Electroactive Cargo Release.

Herein a low background cascade signal amplification electrochemical sensing platform has been proposed for the ultrasensitive detection of mRNA (mRNA) by coupling the target-activated hybridization chain reaction and electroactive cargo release from mesoporous silica nanocontainers (MSNs). In this sensing platform, the 5'-phosphate-terminated DNA (5'-PO4 cDNA) complement to target mRNA is hybridized with the trigger DNA and anchor DNA on the surface of the MSNs, aiming at forming a double-stranded DNA gate molecule and sealing the methylene blue (MB) in the inner pores of the MSNs. In the presence of target mRNA, the 5'-PO4 cDNA is displaced from the MSNs and competitively hybridizes with mRNA, which led to the liberation of the trigger DNA and the opening of the MSNs pore. The liberated trigger DNA can be then immobilized onto the electrode surface through hybridization with the capture DNA, triggering HCR on the electrode surface. At the same time, the MB released from the MSNs will selectively intercalate into the HCR long dsDNA polymers, giving rise to significant electrochemical response. In addition, due to the λ-exonuclease (λ-Exo) cleavage reaction-assisted target recycling, more amounts of trigger DNA will be liberated and trigger HCR, and numerous MB are uncapped and intercalate into the HCR products. As proof of concept, thymidine kinase 1 (TK1) mRNA was used as a model target. Featured with amplification efficiency, label-free capability, and low background signal, the strategy could quantitatively detect TK1 mRNA down to 2.0 aM with a linear calibration range from 0.1 fM to 1 pM. We have also demonstrated the practical application of our proposed sensing platform for detecting TK1 mRNA in real samples, opening up new avenues for highly sensitive quantification of biomarkers in bioanalysis and clinical diagnosis.

A one-step preparation of inhibitor-loaded silica nanocontainers for self-healing coatings

We present a simple one-step method of preparing inhibitor-loaded mesoporous silica nanocontainers without extra steps such as template removal or inhibitors loading. The synthetic method is based on the high solubility of organic inhibitors in hydrophobic cores of template micelles. The resultant inhibitor (benzotriazole) and cetyltrimethyl ammonium bromide (CTAB) co-loaded silica nanocontainers had high uptake of inhibitor (∼16 wt.%) and possessed H+ ion-responsive inhibitor release property. When examined by scanning vibrating electrode technique, the coating doped with these nanocontainers exhibits effective corrosion protection property. These results suggest that the one-step synthetic method was efficient, energy-saving and organic solvents-free among others.

Ce(III) corrosion inhibitor release from silica and boehmite nanocontainers

Electrochemical impedance spectroscopy clearly appeared as a suitable technique to investigate the releasing properties of cerium (III) loaded on silica and boehmite nanocontainers. In this way the electrochemical behavior of the AA2024-T3 was evaluated by electrochemical impedance spectroscopy in a 0.045 mol L−1 NaCl solution with nanocontainers containing the inhibitor. Results show that the inhibitor release is influenced by both the chemical nature and the morphology of the nanocontainers. The lower loading and release phenomena were observed for the mesoporous silica nanocontainers, whereas the inhibitor is liberated until 168 h from dense silica nanocontainers. Boehmite nanocontainers combine a good loading ratio with a longer release until the second week of immersion.

Graphene oxide-gated mesoporous silica nanocontainers using aptamers for arsenite detection with glucometer readout

A newly portable detection sensing platform based on a graphene oxide (GO)-gated mesoporous silica nanocontainer (MSN) was designed for arsenite detection through the target-responsive release of glucose from the MSN with a glucometer readout. To construct such a biosensing system, the arsenite aptamer was initially conjugated covalently onto the mesoporous silica nanoparticles through the epoxy-amino reaction. Thereafter, the indicators (glucose molecules) were gated into the pores by using graphene oxide nanosheets, on the basis of π-stacking interactions between the nucleobases and graphene. Upon target arsenite introduction, graphene oxide was displaced from the MSN thanks to a specific reaction between the analyte and the aptamer, thus resulting in the opening of the pores to release the loaded glucose molecules, which could be determined quantitatively by using a portable personal glucometer (PGM). Based on the different affinities between graphene and the analyte for the labeled aptamer on the MSN, the amount of released glucose molecules from the pores increased with the increasing arsentite concentrations. Under optimal conditions, the GO-gated aptasensing system exhibited good PGM responses relative to arsenite concentrations within the dynamic working range of 0.01-100 ng mL-1 (ppb) at a detection limit of 2.3 pg mL-1 (ppt). The coefficients of variation (CVs) for the reproducibility of intra-assay and inter-assay were below 9.1% and 11.6%, respectively. In addition, the methodology also displayed high specificity and selectivity towards target arsenite against other ions, and was applicable for monitoring arsenite in water samples, giving well-matched results in accordance with the referenced ICP-MS.

Lectin-gated and glycan functionalized mesoporous silica nanocontainers for targeting cancer cells overexpressing Lewis X antigen.

Gated mesoporous silica nanoparticles can deliver payload upon the application of a predefined stimulus, and therefore are promising drug delivery systems. Despite their important role, relatively low emphasis has been placed on the design of gating systems that actively target carbohydrate tumor cell membrane receptors. We describe herein a new Lewis X (Lex) antigen-targeted delivery system comprising mesoporous silica nanoparticles (MSNs) loaded with ATTO 430LS dye, functionalized with a Lex derivative (1) and capped with a fucose-specific carbohydrate-binding protein (Aleuria aurantia lectin (AAL)). This design takes advantage of the affinity of AAL for Lex overexpressed receptors in certain cancer cells. In the proximity of the cells, AAL is detached from MSNs to bind Lex, and selectins in the cells bind Lex in the gated MSNs, thereby inducing cargo delivery. Gated MSNs are nontoxic to colon cancer DLD-1 cells, and ATTO 430LS dye delivered correlated with the amount of Lex antigen overexpressed at the DLD-1 cell surface. This is one of the few examples of MSNs using biologically relevant glycans for both capping (via interaction with AAL) and targeting (via interaction with overexpressed Lex at the cell membrane).

Nanocontainer-Enhanced Self-Healing for Corrosion-Resistant Ni Coating on Mg Alloy.

The ability to manipulate the functionalization of Ni coating is of great importance in improving the corrosion resistance of magnesium (Mg) alloy for many industrial applications. In the present work, MCM-41 type mesoporous silica nanocontainers (MSNs) loaded with corrosion inhibitor (NaF) were synthesized and employed as smart reinforcements to enhance the integrity and corrosion inhibition of the Ni coating. The incorporation of the F-loaded MSNs (F@MSNs) to enhance the corrosion resistant capacity of a metallic coating is reported for the first time. The mesoporous structures of the as-prepared MSNs and F@MSNs were confirmed by transmission electron microscopy (TEM), small angle X-rays scattering (SAXS), and N2 adsorption-desorption isotherms. The X-ray photoelectron spectroscopy (XPS) data demonstrated the successful immobilization of fluoride ion on the MSNs and formation of a magnesium fluoride (MgF2) protective film at the corrosion sites of the Mg alloy upon soaking in a F@MSNs-containing NaCl solution. The results from potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) for both bare Mg alloy and Ni coatings with and without F@MSNs have revealed a clear decrease in corrosion rate in a corrosive solution for a long-time immersion due to the introduction of F@MSNs. These findings open new opportunities in the exploration of self-healing metallic coatings for highly enhanced anticorrosion protection of Mg alloy.

Enhancement of the wear resistance of epoxy coating in presence of MBT-loaded mesoporous silica nanocontainers

Abstract The impact mechanism of mesoporous 2-Mercaptobenzothiazole (MBT)-loaded silica nanocontainers (SNCs) on wear resistance of epoxy coating was investigated. Scanning electron microscopy, BET analysis, UV-Vis spectrophotometry and thermogravimetric analysis were used to characterize SNCs. Also, pin-on-disk wear test, microhardness measurement and electron microscopy were used to investigate the impact mechanism of MBT-loaded SNCs on wear resistance of epoxy coating. Results of wear analysis revealed that presence of MBT-loaded SNCs increased the coating microhardness and also decreased the friction coefficient of coating layer and thereby resulted in significant improvement of wear resistance of coating. It was concluded that the superior wear resistance of nanocomposite coatings in presence of silica nanocontainers is due to reinforcement effect and self-lubricating action of mesoporous MBT-loaded SNCs.

Engineering a tubular mesoporous silica nanocontainer with well-preserved clay shell from natural halloysite

The in situ synthesis of mesoporous nanotubes from natural minerals remains a great challenge. Herein, we report the successful synthesis of mesoporous silica nanotubes (MNTs) with a varying inner-shell thickness and a preserved clay outer shell from natural-halloysite nanotubes (HNTs). After the enlargement of the lumen diameter of the tubular aluminosilicate clay by acid leaching, uniform mesopores were introduced by a modified pseudomorphic transformation approach, while the clay outer shell was well-preserved. Using density functional theory calculations, the atomic structure evolution and the energetics during Al leaching and Si–OH condensation were studied in detail. After the leaching of Al ions from the HNTs, local structural changes from Al(Oh) to Al(V) at a medium leaching level and to Al(Td) at a high leaching level were confirmed. The calculated hydroxylation energy of two kinds of silica components in the acid-leached HNTs (the distorted two-dimensional silica source in the inner shell and the intact aluminosilicate structure in the outer shell) was 0.5 eV lower or 1.0 eV higher than that of bulk silica, which clarifies the different behavior of the silica components in the hydrothermal process. The successful synthesis of reactive MNTs from HNTs introduces a new strategy for the synthesis of mesoporous nanocontainers with a special morphology using natural minerals. In particular, MNT samples with numerous reactive Al(V) species and a specific surface area up to 583 m2/g (increased by a factor of 10) are promising drug-loading nanocontainers and nanoreactors.

Bioresponsive Release System for Visual Fluorescence Detection of Carcinoembryonic Antigen from Mesoporous Silica Nanocontainers Mediated Optical Color on Quantum Dot-Enzyme-Impregnated Paper.

An all-in-one paper-based analytical device (PAD) was successfully developed for visual fluorescence detection of carcinoembryonic antigen (CEA) on CdTe/CdSe quantum dot (QD)-enzyme-impregnated paper by coupling with a bioresponsive controlled-release system from DNA-gated mesoporous silica nanocontainers (MSNs). The assay was carried out in a centrifuge tube by using glucose-loaded MSNs with a CEA aptamer and a QD-enzyme-paper attached on the lid. Initially, single-strand complementary DNA to a CEA aptamer was covalently conjugated to the aminated MSN, and then glucose (enzyme substrate) molecules were gated into the pore with the help of the aptamer. Glucose oxidase (GOD) and CdTe/CdSe QDs were coimmobilized on paper for the visual fluorescence signal output. Upon target CEA introduction in the detection cell, the analyte specifically reacted with the immobilized aptamer on the MSN to open the pore, thereby resulting in the glucose release. The released glucose was oxidized by the immobilized GOD on paper to produce gluconic acid and hydrogen peroxide, and the latter quenched the fluorescence of CdTe/CdSe QDs, which could be determined by the naked eye on a portable smartphone and a commercial fluorospectrometer. Under optimal conditions, the PAD-based sensing system enabled sensitive discrimination of target CEA against other biomarkers or proteins in a linear range of 0.05-20 ng mL-1 with a limit of detection of 6.7 pg mL-1 (ppt). In addition, our strategy displayed high specificity, good reproducibility, and acceptable accuracy for analyzing human serum specimens with a commercial human CEA ELISA kit. Importantly, this methodology offers promise for simple analysis of biological samples and is suitable for use in the mass production of miniaturized devices, thus opening new opportunities for protein diagnostics and biosecurity.