Hollow Mesoporous Silica Nanospheres Research Articles

A Molecular Switch-Integrated Nanoplatform Enables Photo-Unlocked Antibacterial Drug Delivery for Synergistic Abscess Therapy.

Drug delivery systems (DDSs) capable of sequential multistage drug release are urgently needed for antibacterial applications. Herein, a molecular switch-integrated, photo-responsive nanoplatform is reported based on hollow mesoporous silica nanospheres (HMSN) loaded with silver nanoparticles(Ag NPs), vancomycin (Van), and hemin (HAVH) for bacteria elimination and abscess therapy. Upon near-infrared (NIR) light irradiation, the molecular switch, hemin, can effuse from the mesopores of HMSN, triggering the release of pre-loaded Ag+ and Van, which enables photothermal-modulated drug release and synergistic photothermal-chemo therapy (PTT-CHT). The HAVH_NIR irreversibly disrupts the bacterial cell membrane, facilitating the penetration of Ag+ and Van. It is found that these compounds restrain the transcription and translation of ribosomes and lead to rapid bacterial death. Furthermore, hemin can effectively inhibit excessive inflammatory responses associated with the treatment, promoting accelerated wound healing in a murine abscess model. This work presents a new strategy for antibacterial drug delivery with high controllability and extendibility, which may benefit the development of smart multifunctional nanomedicine for diseases not limited to bacterial infections.

Rational Synthesis of Monodisperse Hollow Mesoporous Silica Nanospheres for Selective Adsorption

AbstractMonodisperse hollow mesoporous silica nanospheres with large cavity (62 nm) in the inner core, small mesopores in the outer shell, and high specific surface area of 373 m2/g are successfully synthesized via one‐step dual‐template synthetic approach utilizing dodecyl sulfobetaine and sodium dodecyl benzenesulfonate as double templates. The architectures including particles sizes, outer shell thickness, and hollow structure could be effective regulated by simple adjusting the volume proportion of alcohols in the solution. Besides, the functions of alcohols in determining the critical micelle concentration and polarity of the synthesis system are elaborated. Owing to introduction of amino active sites in the outer shell, the prepared hollow mesoporous silica nanospheres deliver high loading capacity and favorable selectivity towards anionic dye molecules. The maximum uptake amount for methyl orange and eosin Y reaches as high as 359 mg/g and 332 mg/g, respectively.

CO2‐Induced Modulation of Si–O Bonds for Low Temperature Plastic Deformation of Amorphous Silica Nanoparticles with Enhanced Photoluminescence

Modulation of Si–O bonds under mild conditions has been a challenging issue in the field of material science, which is critical to manufacture high‐performance silica‐based optical and photonic devices. Herein, we introduce a nondestructive technique to achieve Si–O bond rearrangement, leading to plastic deformation and photoluminescence enhancement of amorphous silica nanoparticles using supercritical carbon dioxides in EtOH/H2O solution under mild temperature. Specifically, plastic deformation is achieved by treating hollow mesoporous silica nanospheres using supercritical CO2 at 40 °C under 20 MPa. Experimental and theoretical studies revealed the critical role of supercritical CO2 in the plastic deformation process, which can be intercalated into the hollow mesoporous silica nanospheres with anisotropic stresses and induces the rearrangement of Si–O bonds and transformation of ring structures. This work suggests a novel approach to engineer high‐performance nano‐silica glass components for numerous optical and photonic devices under mild condition.

Functionalized europium-doped hollow mesoporous silica nanospheres as a cell imaging and drug delivery agents

In an effort to enhance the antitumor efficacy of breast cancer treatment, the chemotherapeutic agent Paclitaxel (PTX) was encapsulated within hyaluronic acid (HA) modified hollow mesoporous silica (HMSNs). In vitro drug release assays showed that the resulting formulation, Eu-HMSNs-HA-PTX, exhibited enzyme-responsive drug release. In addition, cell cytotoxicity and hemolysis assays demonstrated the favorable biocompatibility of both Eu-HMSNs and Eu-HMSNs-HA. Notably, compared to Eu-HMSNs alone, Eu-HMSNs-HA showed enhanced accumulation within CD44-expressing cancer cells (MDA-MB-231). As anticipated, apoptosis experiments indicated that Eu-HMSNs-HA-PTX displayed significantly greater cytotoxicity toward MDA-MB-231 cells than non-targeted Eu-HMSNs-PTX and free PTX. In conclusion, Eu-HMSNs-HA-PTX demonstrated excellent anticancer effects and holds promise as a potent candidate for the efficient therapy of breast cancer.

Space-confined growth of nanoscale metal-organic frameworks/Pd in hollow mesoporous silica for highly efficient catalytic reduction of 4-nitrophenol

The development of confined growth of metal-organic frameworks (MOFs) in a nano-space remains a challenge mainly due to the spatial size randomness and inhomogeneity of host materials and the limitation of MOF species. In this study, we developed a general “stepwise vacuum evaporation” strategy, which allows the nano-confined growth of MOFs in hollow mesoporous silica nanospheres (HMSN) by the vacuum forces and the capillary effect. A series of nanoscale MOFs including ZIF-8, ZIF-90, HKUST-1, MIL-53(Cr) and UiO-66-NH2 were confinely synthesized inside the cavities of HMSN, resulting in hierarchically porous composites with core-shell structures. Further functionalization was studied by anchoring Pd to obtain UiO-66-NH2/Pd@HMSN catalyst, which exhibited excellent activity in the catalytic reduction of 4-nitrophenol to 4-aminophenol under ambient condition.

Engineering hollow mesoporous silica supported cobalt molybdate catalyst by dissolution-regrowth strategy for efficiently aerobic oxidative desulfurization

Heterogeneous catalysts show superior separable and recyclable property in comparison with homogeneous catalysts. However, the conventional synthetic method faces the problem of uneven distribution of active sites. Here, a facile dissolution-regrowth strategy was developed to prepare hollow mesoporous silica nanospheres supported cobalt molybdate (CoMoO4/HMS) under mild conditions, simultaneously, CoMoO4 was obtained in situ. The homogenous dispersion of the active species made the catalyst manifest an outstanding desulfurization efficiency in aerobic oxidative desulfurization compared with the supported single-metal oxides catalysts or supported CoMoO4 catalyst prepared by wet impregnation. The removal efficiency of three sulfur-containing substances, such as dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene, could reach 100% by 5 h with molecular oxygen as an oxidant. Besides, the sulfur removal of DBT almost did not reduce after at least 8 cycles under the optimal reaction conditions. Through electron spin resonance spectroscopy and radical quenching experiments, O2− was determined as the main active oxygen species for sulfur oxidation. This dissolution-regrowth strategy can be used to prepare a series of supported multi-metal oxides for various applications.

Pt-NixOy heteroaggregate nanoparticles confined in hollow mesoporous silica nanospheres for enhanced hydrolysis of ammonia borane

In this work, Pt-NixOy heteroaggragate nanoparticles confined in hollow mesoporous silica nanospheres (Pt-NixOy@HMSNs) are synthesized in one-pot, which features Pt-NixOy hybrid nanoparticles inside hollow cavities of mesoporous silica nanospheres. Through adjusting the ratios of Pt2+/Ni2+ in micelles, Pt-NixOy@HMSNs with different Pt/Ni ratios are synthesized. The obtained materials were tested for hydrolysis of ammonia borane with detailed kinetic studies. Compared to Pt@HMSNs and Ni@HMSNs, Pt4-(NixOy)1/x@HMSNs show the enhanced performance in AB hydrolysis. The catalytic activity improvement is ascribed to the synergistic effect of Pt-NixOy and the void confinement, where the interfaces of Pt-NixOy greatly enhance the hydrolysis activity and the confinement of functional nanoparticles inside the central voids increases their structural and catalytic stability.

Pt-Nixoy Heteroaggregate Nanoparticles Confined in Hollow Mesoporous Silica Nanospheres for Enhanced Hydrolysis of Ammonia Borane

Pt-Nixoy Heteroaggregate Nanoparticles Confined in Hollow Mesoporous Silica Nanospheres for Enhanced Hydrolysis of Ammonia Borane

Rough-surface hydroxyl-group-rich hollow mesoporous silica nanospheres with nanocellulose as a template to improve the oxidation stability of bio-oil

Bio-oils are good substitutes for petrochemical oil, but their high oxygen contents result in poor oxidation stability. Therefore, anti-oxidants are essential to improve the oxidation stability of bio-oils. In this study, quantum chemistry has been used to analyze in detail the relationship between the structure and adsorption properties of bio-oils and silanol groups. A new type of rough-surface hollow mesoporous silica nanospheres (R-nCHMSNs) bearing abundant hydroxyl groups has been prepared using hydroxyl-group-rich nanocellulose as a template. In an evaluation of anti-oxidants for bio-oil, R-nCHMSNs showed excellent anti-oxidant properties. They formed hydrogen or ester bonds with oxygen-containing groups in bio-oil through their surface hydroxyl groups and wide channel structure, thus improving the oxidation stability of the bio-oil. Furthermore, the kinetics of adsorption of bio-oil on the R-nCHMSNs has been found to be in accordance with a second-order model.

Gadolinium-doped hollow silica nanospheres loaded with curcumin for magnetic resonance imaging-guided synergistic cancer sonodynamic-chemotherapy

Curcumin is a kind of anti-cancer chemotherapeutic drug and has been demonstrated to be able to produce reactive oxygen species (ROS) under the stimuli of ultrasound (US). Herein, gadolinium-doped hollow mesoporous silica nanospheres (Gd-HMSNs) loaded with curcumin (Cur) and conjugated with carboxymethyl dextran (CMD) have been facilely fabricated and applied for magnetic resonance imaging (MRI)-guided synergistic cancer sonodynamic-chemotherapy. The as-prepared multifunctional theranostic nanoplatform (Cur@Gd-HMSNs-CMD) shows high drug loading capacity, satisfactory biocompatibility, pH-responsive degradation, and US-triggered drug release. Due to the release of Gd3+ ions or oligomers during degradation, the nanoplatform Cur@Gd-HMSNs-CMD could serve as an effective contrast agent for T1-weighted MRI to guide cancer treatment. More significantly, in vivo experiments show that the Cur@Gd-HMSNs-CMD can efficiently inhibit the tumor growth by a high inhibition rate of ~85.6% under US irradiation, mainly resulting from the synergistic effect of sonodynamic-chemotherapy. This innovative “two-in-one” theranostic nanoplatform using a single drug provides a new strategy for developing “all-in-one” nanomaterials for combined cancer treatment.

Novel photothermal-responsive sandwich-structured mesoporous silica nanoparticles: synthesis, characterization, and application for controlled drug delivery

Novel thermal nanoparticles [hollow mesoporous silica nanospheres (HMSNs)–poly (N-isopropyl acrylamide-acrylic acid) PNIPAM-AA] were developed with Ag nanoparticles (AgNps) as the core, mesoporous silica nanoparticles as the layer, and thermally responsive polymers PNIPAM-AA as the shell. The AgNps had good photothermal effects, PNIPAM-AA was responsive to temperature, the combination of AgNps and PNIPAM-AA could be used as a photothermal-responsive switch for drug release, and HMSNs greatly increased the drug loading of the carrier. The samples were characterized by means of scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, and UV–Vis absorption spectra. The results showed that Ag@HMSN nanoparticles possessed a uniform diameter (330 nm), high specific surface area (822.45 m2/g), and mesoporous pore size (2.75 nm). Using ibuprofen (IBU) as a model drug, the release process was monitored under in vitro conditions to investigate its release characteristics at different temperatures. The results showed that the nanoparticles had a significant regulatory effect on IBU release.

Hollow mesoporous silica nanospheres using pentablock copolymer micelle templates

We developed hollow mesoporous silica nanospheres by a sol-gel process utilizing pentablock copolymer templates poly(lactic acid-co-glycolic acid)-b-poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(lactic acid-co-glycolic acid) (PLGA-b-PEO-b-PPO-b-PEO-b-PLGA) under acidic aqueous conditions. Four kinds of water-soluble pentablock copolymers were used as structure-tuning agents and tetraethyl orthosilicate (TEOS) was used as a silica precursor. Hollow mesoporous silica nanoparticles were prepared at room temperature without any additive salts, which is the main key issue compared with the other reports. The hollow structure was found when pentablock copolymer with longer chain length was used, while a bimodal pore structure was obtained using shorter copolymer templates. Moreover, hydrothermal stability for the hollow mesoporous silica samples was investigated inside distilled water at 100 °C for 28 d. It is noteworthy that pore structure and morphology were varied depending on the length scale of pentablock copolymer templates and the hollow mesopore structure was obtained from single- and partially bridged micelle templates at room temperature.

Polyimide composite separator containing surface-modified hollow mesoporous silica nanospheres for lithium-ion battery application

Polyimide (PI) hybrids of biphenyl tetracarboxylic dianhydride (BPDA) and 4,4′-oxydianiline (ODA), containing surface-treated hollow mesoporous silica (AHMS) nanospheres, are synthesized by chemical imidization and freeze-drying. The resulting xerogels exhibit high ionic conductivity and heat resistance. The volume shrinkage of the wet gels, which occurs during the drying process, is avoided by adding AHMS nanoparticles, resulting in the formation of a robust network structure of PI hybrid xerogels as a crosslinker. The cross-sectional structure of the xerogels containing AHMS nanospheres exhibits a network of interconnected polyimide microfibers. Lithium ion batteries are fabricated by inserting the PI hybrid xerogel separator between electrodes. In the repeated charge/discharge experiment, the electrolyte uptake and interfacial compatibility of the PI hybrid xerogel separator are improved significantly compared to those measured from the PI separator.

The improved anticancer effects of Bortezomib-loaded hollow mesoporous silica nanospheres on lymphoma development

As the first clinical proteasome inhibitor, Bortezomib (BTZ) has been reported to improve the outcome of lymphoma. However, due to the unstable property, low bioavailability, and hydrophobic properties of BTZ, it is needed to develop effective drug delivery systems to deliver BTZ into targeted cells or organs. Here we developed a bortezomib (BTZ)-loaded HMSNs (BTZ@HMSNs) system, which can sustain the release of BTZ in targeted tissues. In vitro assays showed that BTZ@HMSNs limited cell proliferation and augmented apoptosis of lymphoma SNK-1 cells. Moreover, BTZ@HMSNs significantly diminished migration and invasion of SNK-1 cells as compared with BTZ. In contrast to the upregulation of SHP-1, BTZ@HMSNs decreased the mRNA levels of c-Kit, NF-κB, and JAK1, which elicit oncogenic role in lymphoma development. Importantly, lymphoma mice model showed that BTZ@HMSNs significantly activated p53 signaling and reduced tumor volume and weight compared with free BTZ. Our data thus demonstrate that BTZ@HMSNs manifests improved tumor-suppressing effect in vitro and in vivo compared to free BTZ. We believe that HMSNs is a promising strategy for delivering therapeutic agents for cancer treatment.

Structure-dependent adsorptive or photocatalytic performances of solid and hollow dendritic mesoporous silica & titania nanospheres

Abstract Two types of titania-containing dendritic mesoporous silica nanospheres (DMSNs) have been successfully fabricated for organic dyes removal, water splitting, and carbon dioxide reduction by their adsorptive or photocatalytic performances. Hybrid dendritic mesoporous silica&titania nanospheres (DMSTNs) were initially prepared by grafting tetrabutyl orthotitanate (TBOT) onto DMSNs. Then, hollow dendritic mesoporous silica&titania nanospheres (HDMSTNs) were realized merely by etching the solid DMSTNs with alkaline solution. The surprising structural evolution from the solid state to the hollow was thoroughly revealed by scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM) for the first time. DMSTNs maintain the dendritic morphology with spherical TiO2 nanoparticles uniformly dispersed. HDMSTNs not only keep the dendritic topology, but also possess the hollow texture with TiO2 nanoparticles unevenly dispersed and aggregated. DMSTNs and HDMSTNs exhibit excellent adsorption capacities for methylene blue, while the latter shows improved adsorption capacity. DMSTNs and HDMSTNs can hardly adsorb methyl orange (MO), nevertheless, the two materials can photodegrade MO with outstanding abilities. Amazingly, the latter exhibits decreased degradation capacity despite of its hollow architecture and higher content of titanium oxide. Furthermore, DMSTNs and HDMSTNs display higher photocatalytic activities over hydrogen generation than that of carbon dioxide reduction under visible light. However, DMSTNs and HDMSTNs show various photocatalytic selectivities and activities for the production of carbon monoxide (CO) and methane (CH4). In short, DMSTNs and HDMSTNs have distinct structural superiorities as adsorbents or photocatalysts for different photocatalytic reactions, respectively.

Thioether-bridged mesoporous organosilica nanocapsules with weak acid-triggered charge reversal for drug delivery

The drug delivery nanosystems with weak acid-triggered surface charge reversal function should be promising for efficient chemotherapy due to the prolonged blood circulation and enhanced the cellular uptake. However, there are only limited reports up to now. In this study, we fabricated a hybrid nanocapsule with a negative-to-positive charge-reversal outer layer triggered by the weak acidity in tumor microenvironment. The short branched polyethylenimine (PEI) with positive charge and weak acid-sensitive hexahydrophthalic anhydride with negative charge were successively modified on the surface of small uniform thioether-bridged hollow mesoporous silica nanospheres with multiple cavities. The modification of PEI as a linker was more favorable for charge reversal than that of aminopropyl group. The constructed hybrid nanocapsules exhibited weak acid (pH 6.0)-triggered charge reversal and drug release behaviors, thus effectively inhibiting the growth of A549 cancer cells. The surface functionalization of hybrid nanocapsules opens new opportunities for the development of silica-based hybrid nanosystems for promising drug delivery. Thioether-bridged hollow mesoporous silica nanocapsules with weak acid-triggered charge reverse and drug release are designed and constructed for efficient tumor drug delivery. • Branched PEI and hexahydrophthalic anhydride were modified on thioether-bridged mesoporous organosilica nanocapsules. • The constructed hybrid nanocapsules exhibited weak acid (pH 6.0)-triggered charged reversal and DOX release behaviors.

Preparation and tribological behaviors of porous oil-containing polyimide/hollow mesoporous silica nanospheres composite films

Porous oil-containing polyimide (PI)/hollow mesoporous silica nanospheres (HMSNs) composite films of PI/HMSNs were fabricated by infusing liquid paraffin into the pores under vacuum. The microstructure, oil storage capability and tribological behaviors of porous oil-containing PI/HMSNs composite films were evaluated using the porous oil-containing PI film as comparisons. As a result, the addition of HMSNs could greatly improve the oil content and oil retention, realizing the intended goals that the prepared oil-containing composites could effectively reduce the friction coefficient and extend the wear life. Besides, liquid paraffin in the porous PI/HMSNs composite films released stably under the actions of the applied load and the friction heat, which can be used in high temperature and load conditions.

Core-Shell Structure Design of Hollow Mesoporous Silica Nanospheres Based on Thermo-Sensitive PNIPAM and pH-Responsive Catechol-Fe3+ Complex.

A kind of core-shell hybrid nanoparticle comprised of a hollow mesoporous silica nanoparticles (HMS) core and a copolymer shell bearing N-(3,4-dihydroxyphenethyl) methacrylamide (DMA) and N-isopropylacrylamide (NIPAM) as responsive moieties was prepared. Moreover, the factors that could impact the surface morphology and hierarchical porous structure were discussed. In the presence of Fe3+, catechol-Fe3+ complexes were formed to achieve pH-responsive polymer shell, combining with thermal-sensitiveness of poly(N-isopropylacrylamide). Doxorubicin (DOX) was applied as a model drug and the behaviors of its loading/release behaviors were investigated to prove the idea. The results exhibited a significant drug loading capacity of 8.6% and embed efficiency of 94.6% under 1 mg ml–1 DOX/PBS solution. In fact, the loading capacity of drug can be easily improved to as high as 28.0% by increasing the DOX concentration. The vitro cytotoxicity assay also indicated that the as-prepared nanoparticles have no significant cytotoxicity on RAW 264.7 cells. The in vitro experiment showed that the cumulative release of DOX was obviously dependent on the temperature and pH values. This pH/temperature-sensitive hollow mesoporous silica nanosphere is expected to have potential applications in controlled drug release.

Amino Acid-functionalized hollow mesoporous silica nanospheres as efficient biocompatible drug carriers for anticancer applications.

Herein, a series of new amino acid-functionalized hollow mesoporous silica nanospheres (HMSNs) by post-grafting methods were prepared. These new materials were characterized by different techniques and were studied as matrices for the antineoplastic drug (cisplatin) transport and delivery. The results demonstrate that the surface functionalization of the carriers has a remarkable positive influence on the loading efficiency and release rate of cisplatin. The highest drug entrapment efficiency and the most optimal release properties were observed when the (2-(butylamino) ethyl) glycine groups are grafted on the HMSNs surface (AFS-2-HMSNs sample). Moreover, the in vitro cytotoxic effect of both empty and cisplatin-loaded AFS-2-HMSNs sample (CDDP@AFS-2-HMSNs) on MCF-7 cells (human breast adenocarcinoma cell line) and HepG2 cells (human liver carcinoma cell line) were evaluated by MTT assay. The most important outcome is that the empty carrier revealed no cytotoxicity to cancer cells. However, CDDP@AFS-2-HMSNs caused a notable inhibition of cell viability which was affected from the dose and time. Our results demonstrate that the synthesized materials could be used as carriers for drug delivery with controlled release applications.

A facile solvent-free and one-step route to prepare amino-phosphonic acid functionalized hollow mesoporous silica nanospheres for efficient Gd(III) removal

Abstract Gadolinium is known to be a most widely used but toxic rare-earth element, and Gd(III) ions exist in aqueous media will bring about serious damage to the ecosystem. However, few work on the application of adsorption strategy with enough high Gd(III) uptake is reported. Since the hollow mesoporous silica nanospheres (HMSNs) and amino-phosphonic acid (APA) compounds have shown inherent advantage for being used as effective adsorbent and chelating ligand in toxic metals adsorption due to their remarkable properties. Herein, we follow the cleaner production philosophy, proposing for the first time to modify the HMSNs nanomaterial with APA group by reacting phosphorous acid with cyano-functionalized hollow mesoporous SiO2 (CFHMSNs) via one-step reaction under solvent-free conditions, and apply to remove Gd(III) form wastewater. The obtained materials are characterized by a variety of techniques. Characterization results show that the APA-functionalized material (AFHMSNs) has ordered mesoporous structure, high stability and large surface area (825.3 m2/g). The maximum uptake of Gd(III) for AFHMSNs (387.3 mg/g) is much higher than those of the reported adsorbents because of the high surface area, and multifunctional chelating interactions of the adsorbent with Gd(III) ions. Gd(III) adsorption onto AFHMSNs can be well described by the Langmuir isotherm and pseudo second order kinetics model. The adsorption is chemical complexation mechanism which is proposed based on FTIR and XPS analysis. It is found for the first time that the adsorption of Gd(III) onto AFHMSNs slightly enhanced with the coexistence of Al3+ in the relatively lower concentrations, which may be due to the synergistic effect of pseudo-boehmite. This work provides a favorable strategy to design and synthesis of hollow mesoporous nanomaterial with superior adsorption performances and potential for the cleanup of toxic metals from wastewater.