Hybrid Mesoporous Silica Nanoparticles Research Articles

Multifunctional Nanoparticles with Superparamagnetic Mn(II) Ferrite and Luminescent Gold Nanoclusters for Multimodal Imaging.

Gold nanoclusters (AuNCs) with fluorescence in the Near Infrared (NIR) by both one- and two-photon electronic excitation were incorporated in mesoporous silica nanoparticles (MSNs) using a novel one-pot synthesis procedure where the condensation polymerization of alkoxysilane monomers in the presence of the AuNCs and a surfactant produced hybrid MSNs of 49 nm diameter. This method was further developed to prepare 30 nm diameter nanocomposite particles with simultaneous NIR fluorescence and superparamagnetic properties, with a core composed of superparamagnetic manganese (II) ferrite nanoparticles (MnFe2O4) coated with a thin silica layer, and a shell of mesoporous silica decorated with AuNCs. The nanocomposite particles feature NIR-photoluminescence with 0.6% quantum yield and large Stokes shift (290 nm), and superparamagnetic response at 300 K, with a saturation magnetization of 13.4 emu g-1. The conjugation of NIR photoluminescence and superparamagnetic properties in the biocompatible nanocomposite has high potential for application in multimodal bioimaging.

Enhanced adsorption-catalysis combination for the removal of sulphur from fuels using polyoxometalates supported on amphipathic hybrid mesoporous silica nanoparticles.

Polyoxometalate (POM) mesoporous silica-based materials with a low POM loading have been designed with hydrophilic and hydrophobic properties. These materials act as powerful heterogeneous catalysts in oxidative desulfurization (ODS), owing to their ability to adsorb both H2O2 and sulphur-containing compounds from the model oil simultaneously. The formation of charge transfer salts through ion pair interaction with a choline functionality, available on the hybrid silica support, affords robust and recyclable heterogeneous catalysts for the ODS process under mild conditions (45 min and 40 °C). Besides, the nature of the polyoxometalate anions is highly dependent on the characteristics of the silica surface. The masking of silanol groups present on the silica surface using silylating agents, with diverse reactivity and steric hindrance, influences the silica surface-heteropolyanion interactions, as well as heteropolyanion-heteropolyanion interactions. In addition, it modifies the hydrophobic properties of the surface, which is a determining factor in the adsorption properties of non-polar dibenzothiophene (DBT) by the catalysts. Adsorption, an anterior step to the oxidation reaction, has been demonstrated to be key to the superior activity of POM-SiMe3-Chol-MSN, where the silanol groups have been capped by trimethylsilyl groups. For the first time, and to better understand POM-surface and POM-POM anion interactions, an extensive characterization of the materials has been performed using 13C, 31P, and 95Mo MAS NMR spectroscopy and solid-state electrochemical techniques, among others.

PH-Responsive Drug Delivery and Imaging Study of Hybrid Mesoporous Silica Nanoparticles.

A system of pH-responsive and imaging nanocarriers was developed using mesoporous silica nanoparticles (MSNs), in which gadolinium (Gd) was doped through in situ doping (Gd2O3@MSN). Sodium alginate (SA) was attached to the surfaces of the amino groups of MSNs (NH2-Gd2O3@MSN) through the electrostatic adsorption between the amino groups and the carboxyl groups with the formation of hybrid SA-Gd2O3@MSN nanoparticles (NPs). The SA-coated NPs were spherical or near-spherical in shape with an average size of nearly 83.2 ± 8.7 nm. The in vitro drug release experiments of a model rhodamine B (RhB) cargo were performed at different pH values. The result confirmed the pH-responsiveness of the nanocarriers. The results of the cytotoxicity studies indicated that the SA-Gd2O3@MSN NPs were not cytotoxic by themselves. The results of the in vivo safety evaluation and the hemolysis assay confirmed that the system is highly biocompatible. It is noteworthy that the T1 contrast of the system was significantly enhanced by the Gd, as indicated by the result of the MR imaging. This study confirms that the synthesized hybrid nanosystem is promising for pH-responsive drug delivery and MR imaging for cancer diagnosis and treatment.

Combination wound healing using polymer entangled porous nanoadhesive hybrids with robust ROS scavenging and angiogenesis properties

Nanoadhesives can achieve tight wound closure by connecting biomacromolecules from both sides. However, previously developed adhesive systems suffered from suboptimal wound healing efficiency due to the lack of interparticle cohesion, sufficient reactive oxygen species (ROS)-scavenging sites, and angiogenesis consideration. Herein, we developed a polymer entangled porous nanoadhesive system to address the above challenge by synergy of three functional components. Firstly, hybrid mesoporous silica nanoparticles with highly integrated polydopamine (MS-PDA) were prepared by templated synthesis. The entangling between PVA polymer and MS-PDA contributed to much stronger cohesion between nanoparticles, which led to 75% larger adhesion strength. As confirmed by in vitro and in vivo evaluations, the highly exposed catechol groups boosted the scavenging activity of ROS (1.8–4.1 fold enhancement as compared with nonporous counterpart). Consequently, more macrophages exhibited anti-inflammatory phenotype, leading to 2–2.6 fold lower pro-inflammatory cytokine levels. Moreover, the sustained release of bioactive SiO44− by the disintegration of nanoparticles contributed to ∼3-fold higher expression of VEGF and enhanced new blood vessel formation, as well as better wound repair. This platform can provide a new paradigm for developing multifunctional nanoadhesive systems in treating skin wounds. Statement of significancePVA polymer entangled mesoporous nanoadhesives of polydopamine (PDA)/silica hybrids with the combination of excellent wound closure effect, boosted ROS-scavenging activity, and significant angiogenesis ability were developed for improving the suboptimal skin wound healing efficiency. This strategy not only greatly advances our ability to rationally integrate repairing elements in nanoadhesives for manipulating combined processes of interfacial events during wound healing, but also offers general implications toward application of polymers to reinforce the adhesion strength in nanoadhesive systems. In addition, our findings on the impacts of pore effects mediated ROS species conversion and polymer entanglement may also trigger great interests and facilitate the development/broad application of therapeutic adhesives.

New biocides based on imidazolinium-functionalised hybrid mesoporous silica nanoparticles

Here, we report the development of a new biocide based on hybrid mesoporous silica nanoparticles (MSN). The MSN was synthesized by condensation method in emulsion followed by grafting with two different silylated ionic liquid moieties, namely butyl imidazolinium bromide and imidazolinium propansulfonate betaine. Features of nanoparticles were characterized by Thermogravimetry, Infrared and ss-NMR Spectroscopy, and Transmission Electron Microscopy. The antibacterial properties were tested against a Gram-positive bacterial strain previously isolated from artefacts of interest in the field of Cultural Heritage. Interestingly, the hybrid material presents an antibacterial activity higher than its single constituents, showing a synergic effect probably due to the high local concentration of the ionic liquid anchored to nanoparticles. The more promising material was applied to fragments of stones retrieved from the Santa Margherita cave (Italy) and affected by bio-deterioration, comparing its antibacterial action with a commercial biocide.

Smart pH responsive system based on hybrid mesoporous silica nanoparticles for delivery of fungicide to control Fusarium crown and root rot in tomato

Mesoporous silica nanoparticles (MSNs) can promote the solubility and absorption of pesticides by plants and are widely used as a delivery system to improve the efficacy of pesticide applications. In this study, MSNs with 20 nm particle size were produced. Additionally, a water-soluble chitosan (CS) derivative, here called N-(2-Hydroxyl) propyl-3- tri-methyl-ammonium CS chloride (HTCC) was produced and used to cap the outer surface of the MSNs preloaded with the pesticide fludioxonil (Flu). The HTCC coating layers resulted in a pesticide loading efficiency of 84% on the MSNs in comparison to a loading efficiency of 20% of uncoated particles. A comparative in vitro analysis indicated that Flu@MSNs20nm-HTCC loaded with a 0.05 mg/L dose of fungicide had significant higher fungicidal activity than the same fungicide at 1 mg/L dose against F. oxysporum f. sp. radicis-lycopersici (FORL). Moreover, after an initial burst, MSNs20nm-HTCC kept releasing Flu for 21 d, compared to an activity of 7 d associated with the direct release of Flu. Greenhouse data showed that 0.1 mg/L Flu applied through MSNs20nm-HTCC is sufficient to reduce Fusarium crown and root rot disease severity to a value of less than 6% in tomato plants, without any noticeable phytotoxicity after 70 d. In comparison, 1.56 mL/L of the fungicide are required to reach a 27% disease severity level. Thus, we suggest that HTCC-decorated MSNs20nm has a great potential as a nanodelivery systems for agrochemical applications. We also suggest that this work contributes to the notion that agro-nanotechnology is a powerful, environmentally-safe and cost-effective approach for a sustainable and long term protection of plants from disease.

Folate receptor-targeting semiconducting polymer dots hybrid mesoporous silica nanoparticles against rheumatoid arthritis through synergistic photothermal therapy, photodynamic therapy, and chemotherapy

With ideal optical properties, semiconducting polymer quantum dots (SPs) have become a research focus in recent years; a considerable number of studies have been devoted to the application of SPs in non-invasive and biosafety phototherapy with near-infrared (NIR) lasers. Nevertheless, the relatively poor stability of SPs in vitro and in vivo remains problematic. PCPDTBT was chosen to synthesize photothermal therapy (PTT) and photodynamic therapy (PDT) dual-model SPs, considering its low band gap and desirable absorption in the NIR window. For the first time, cetrimonium bromide was used as a stabilizer to guarantee the in vitro stability of SPs, and as a template to prepare SP hybrid mesoporous silica nanoparticles (SMs) to achieve long-term stability in vivo. The mesoporous structure of SMs was used as a reservoir for the hypoxia-activated prodrug Tirapazamine (TPZ). SMs were decorated with polyethylene glycol-folic acid (SMPFs) to specifically target activated macrophages in rheumatoid arthritis (RA). Upon an 808 nm NIR irradiation, the SMPFs generate intracellular hyperthermia and excessive singlet oxygen. Local hypoxia caused by molecular oxygen consumption simultaneously activates the cytotoxicity of TPZ, which effectively kills activated macrophages and inhibits the progression of arthritis. This triple PTT-PDT-chemo synergistic treatment suggests that SMPFs realize the in vivo application of SPs and may be a potential nano-vehicle for RA therapy with negligible side-toxicity.

Pd(II)/Pd(0) Anchored on Magnetic Organic–Inorganic Hybrid Mesoporous Silica Nanoparticles: A Nanocatalyst for Suzuki–Miyaura and Heck–Mizoroki Coupling Reactions

Pd(II)/Pd(0) Anchored on Magnetic Organic–Inorganic Hybrid Mesoporous Silica Nanoparticles: A Nanocatalyst for Suzuki–Miyaura and Heck–Mizoroki Coupling Reactions

Structure, stability, electrochemical and catalytic properties of polyoxometalates immobilized on choline-based hybrid mesoporous silica

Polyoxometalate-based heterogeneous catalysts have been prepared by immobilization of Keggin-type heteropolyacid on hybrid mesoporous silica nanoparticles with choline hydroxide based ionic liquid. The immobilization process has been accomplished by a simple acid-base reaction with phosphomolybdic acid. For comparison purposes, additional supports (hybrid-SBA-15 and TiO2) have been also used in order to establish the nature of the interactions between the heteropolyacid and the surface's groups of the support. To do this, electrochemical and 31P MAS-NMR studies have been carried out finding the formation of moieties like (Chol)2[HPMo12O40] and/or (Chol)3[PMo12O40] on the silica materials. Polyoxometalate-based heterogeneous catalysts have been effectively tested for the oxidative desulfurization of DBT in model oil. Thus, complete removal of sulfur (99.7%) was achieved with polyoxometalate supported on the silica after 2 h and using H2O2 as a green oxidant. Additionally, reusability and stability studies of the most active catalyst have been performed.

Hybrid mesoporous nanoparticles with highly integrated polydopamine for pH-responsive membrane permeation and drug delivery

By the synergy of surface amines/catechols, polydopamine (PDA)-based nanomaterials are appealing in inducing wet-adhesion and membrane permeabilization for efficient intracellular delivery of drugs, especially those with low membrane permeability. Herein, hybrid mesoporous silica nanoparticles with highly integrated PDA on the pore walls were developed using ionic liquid as an organic template. Small particle diameters (~30–50 nm), high surface area (549 m2 g−1), and abundant mesopores (~ 5 nm), were achieved. Modification of arginine and pH-sensitive sheddable PEG was realized to construct a membrane-lytic surface and a protective coating, respectively. The nanocarriers can mediate efficient drug loading, sustained release, and cytosolic delivery of a model BCS Class III drug (cytarabine) after efficient lysosomal escape. Moreover, the intrinsic photothermal conversion property of PDA can enhance the cancer cell inhibition. The results show the potential of highly integrated PDA in porous nanocarriers for overcoming intracellular obstacles of drug delivery.

The thermal/pH-sensitive drug delivery system encapsulated by PAA based on hollow hybrid nanospheres with two silicon source

The synthesis of drug delivery systems based on hollow mesoporous silica nanoparticles (MSNs) is still a major challenge. In this work, the hollow hybrid MSNs were successfully prepared by cetyltrimethylammonium bromide-directed sol-gel process and one-step hydrothermal treatment process. The hollow hybrid MSNs had hybrid ethane-bridged frameworks with the uniform particle size (250 nm) and mesoporous pore diameter (3.7 nm). The polyacrylic acid (PAA) encapsulated drug delivery system based on hollow hybrid MSNs was prepared by using silanization, surface modification, doxorubicin hydrochloride (DOX) loading, and PAA coating. Drug encapsulation and release behavior at different temperatures and pH were studied by using DOX as a model guest molecule. The results displayed that the modified hollow ethane-bridged MSNs possessed good biocompatibility and excellent thermal/pH-dual-sensitive drug release property. This novel thermal/pH-sensitive drug delivery system based on hollow ethane-bridged MSNs has the advantages of feasible synthesis, no cytotoxicity, and good drug loading capacity, which may have potential applications in the anticancer therapy.

Preparation and Applications of Organo-Silica Hybrid Mesoporous Silica Nanoparticles for the Co-Delivery of Drugs and Nucleic Acids.

Combination therapies rely on the administration of more than one drug, with independent mechanisms of action, aiming to enhance the efficiency of the treatment. For an optimal performance, the implementation of such therapies requires the delivery of the correct combination of drugs to a specific cellular target. In this context, the use of nanoparticles (NP) as platforms for the co-delivery of multiple drugs is considered a highly promising strategy. In particular, mesoporous silica nanoparticles (MSN) have emerged as versatile building blocks to devise complex drug delivery systems (DDS). This review describes the design, synthesis, and application of MSNs to the delivery of multiple drugs including nucleic acids for combination therapies.

Catcher in the rel: Nanoparticles-antibody conjugate as NF-κB nuclear translocation blocker

Transcription factor complex NF-κB (p65/p50) is localized to the cytoplasm by its inhibitor IκBα. Upon activation, the Rel proteins p65/p50 are released from IκBα and transported through nuclear pore to affect many gene expressions. While inhibitions of up or down stream signal pathways are often ineffective due to crosstalks and compensations, direct blocking of the Rel proteins p65/p50 has long been proposed as a potential target for cancer therapy. In this work, a nanoparticle/antibody complex targeting NF-κB is employed to catch the Rel protein p65 in perinuclear region and thus blocking the translocation near the nuclear pore gate. TAT peptide conjugated on mesoporous silica nanoparticles (MSN) help non-endocytosis cell-membrane transducing and converge toward perinuclear region, where the p65 specific antibody performed the targeting and catching against active NF-κB p65 effectively. The size of the p65 bound nanoparticle becomes too big to enter nucleus. Simultaneous treatment of mice with the hybrid MSN and doxorubicin conferred a significant therapeutic effect against 4T1 tumor-bearing mice. The new approach of anti-body therapy targeting on transcription factor with “nucleus focusing” and “size exclusion blocking” effects of the antibody-conjugated nanoparticle is general and may be applicable to modulating other transcription factors.

Hypoxia-responsive, organic-inorganic hybrid mesoporous silica nanoparticles for triggered drug release

Hypoxia is a manifestation of various diseases with an ischemic component, including cancer. Tumor hypoxia is a hallmark of cancer, creating an opportunity to exploit hypoxia to ensure delivery of anticancer drugs to cancer cells. Here, we describe the development of nanoparticles that specifically release drugs under hypoxic conditions. To this end, we prepared a hybrid mesoporous silica nanoparticle, modified to contain 4-(phenylazo)benzoic acid (4-PA, SNA) and β-cyclodextrin (β-CD, SNAC) on the external surface. 4-PA and β-CD act through host-guest interactions to serve as gatekeepers to block the pores of mesoporous sililica nanoparticles (SN), and subsequent selective cleavage of the azo group of 4-PA by intracellular nitroreductases under hypoxic conditions allows the release of entrapped drugs. Under normoxic conditions, doxorubicin (DOX)-loaded SNAC (DOX@SNAC) showed low cytotoxicity, reflecting inhibition of premature release of DOX from SNAC by 4-PA and β-CD. In contrast, under hypoxic conditions, DOX@SNAC showed significant cytotoxicity, similar to that of free DOX. Collectively, these results show that SNAC can function as effective drug-delivery systems in hypoxic conditions. Moreover, these SNACs, hypoxia-responsive hybrid mesoporous silica nanoparticles, could be effective not only in cancer, but also other diseases characterized by ischemic conditions.

Hybrid Mesoporous Silica Nanoparticles Grafted with 2-(tert-butylamino)ethyl Methacrylate-b-poly(ethylene Glycol) Methyl Ether Methacrylate Diblock Brushes as Drug Nanocarrier.

This paper introduces the synthesis of well-defined 2-(tert-butylamino)ethyl methacrylate-b-poly(ethylene glycol) methyl ether methacrylate diblock copolymer, which has been grafted onto mesoporous silica nanoparticles (PTBAEMA-b-PEGMEMA-MSNs) via atom transfer radical polymerization (ATRP). The ATRP initiators were first attached to the MSN surfaces, followed by the ATRP of 2-(tert-butylamino)ethyl methacrylate (PTBAEMA). CuBr2/bipy and ascorbic acid were employed as the catalyst and reducing agent, respectively, to grow a second polymer, poly(ethylene glycol) methyl ether methacrylate (PEGMEMA). The surface structures of these fabricated nanomaterials were then analyzed using Fourier Transform Infrared (FTIR) spectroscopy. The results of Thermogravimetric Analysis (TGA) show that ATRP could provide a high surface grafting density for polymers. Dynamic Light Scattering (DLS) was conducted to investigate the pH-responsive behavior of the diblock copolymer chains on the nanoparticle surface. In addition, multifunctional pH-sensitive PTBAEMA-b-PEGMEMA-MSNs were loaded with doxycycline (Doxy) to study their capacities and long-circulation time.

Heterogeneous oxidative desulfurization catalysed by titanium grafted mesoporous silica nanoparticles containing tethered hydrophobic ionic liquid: A dual activation mechanism

In this study, heterogeneous catalysts containing ionic liquid and/or titanium have been prepared and used for oxidative desulfurization. For the synthesis of hybrid mesoporous silica nanoparticles (ILBF4-MSN), a grafting method has been employed with the ionic liquid 1-octyl-3-(3-(triethoxysilyl)propyl)-4,5-dihydro-1H-imidazol-3-ium tetrafluoroborate (ILBF4) which contains a long alkyl chain. Titanium hybrid mesoporous silica nanoparticles (ILBF4-x%TiCp2-MSN) and mesoporous silica nanoparticles containing titanium (TiCp2-MSN) have also been prepared using titanocene dichloride. The catalyst containing ionic liquid and titanium, ILBF4-3%TiCp2-MSN exhibited the highest desulfurization efficiency (99.1%) in model oil with high concentration of DBT and using H2O2 as oxidant. In addition, the effect of immobilization of the ionic liquid on titanium materials has been investigated by solid-state 13C, 47/49Ti and 19F NMR spectroscopy and solid state electrochemical techniques. The titanium species and ionic liquid play an important role in the oxidative desulfurization reaction since they might activate synergistically sulfur derivatives and enhance the process.

Hybrid Mesoporous Nanoparticles for pH-Actuated Controlled Release.

Among a variety of inorganic-based nanomaterials, mesoporous silica nanoparticles (MSNs) have several attractive features for application as a delivery system, due to their high surface areas, large pore volumes, uniform and tunable pore sizes, high mechanical stability, and a great diversity of surface functionalization options. We developed novel hybrid MSNs composed of a mesoporous silica nanostructure core and a pH-responsive polymer shell. The polymer shell was prepared by RAFT polymerization of 2-(diisopropylamino)ethyl methacrylate (pKa ~6.5), using a hybrid grafting approach. The hybrid nanoparticles have diameters of ca. 100 nm at pH < 6.5 and ca. 60 nm at pH > 6.5. An excellent control of cargo release is achieved by the combined effect of electrostatic interaction of the cargo with the charged silica and the extended cationic polymer chains at low pH, and the reduction of electrostatic attraction with a simultaneous collapse of the polymer chains to a globular conformation at higher pH. The system presents a very low (almost null) release rate at acidic pH values and a large release rate at basic pH, resulting from the squeezing-out effect of the coil-to-globule transition in the polymer shell.

Ultrasound Reversible Response Nanocarrier Based on Sodium Alginate Modified Mesoporous Silica Nanoparticles.

Mesoporous silica nanoparticles (MSN) covered by polymer coatings, cross-linked by weak coordination bonds were expected to present a reversible responsiveness under on-off ultrasound stimuli. Herein, we prepared a sodium alginate (SA) modified MSN with carboxyl-calcium (COO−-Ca2+) coordination bonds in the modified layer, which could block the mesopores of MSN and effectively prevent the cargo from pre-releasing before stimulation. The coordination bonds would be destroyed under the stimulation of low intensity ultrasound (20 kHz) or high intensity focused ultrasound (HIFU, 1.1 MHz), leading to a rapid and significant cargo release, and then they could be reformed when ultrasound was turned off, resulting in an instant cargo release stopping. The reversible cleavage and reformation of this coordination bonds under on-off ultrasound stimulus were confirmed by the gel-sol transition behaviors of the SA-CaCl2 gels. An excellent real-time control of rhodamine B (RhB) release performance was obtained under the ultrasound stimuli. Obviously, the cargo release ratio could reach to nearly 40% when HIFU (80 W) was turned on for 5 min, and remained basically constant when ultrasound was turned off, which would finally reach to nearly 100% within 30 min under this on-off pulsatile status. These hybrid MSN based nanoparticles with excellent reversible ultrasound on-off responsiveness were of great interest in on-demand drug delivery applications in the future.

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.

Glucose Oxidase-Based Glucose-Sensitive Drug Delivery for Diabetes Treatment.

The glucose-sensitive drug delivery systems based on glucose oxidase (GOD), which exhibit highly promising applications in diabetes therapy, have attracted much more interest in recent years. The self-regulated drug delivery systems regulate drug release by glucose concentration automatically and continuously to control the blood glucose level (BGL) in normoglycemic state. This review covers the recent advances at the developments of GOD-based glucose-sensitive drug delivery systems and their in vivo applications for diabetes treatment. The applications of GOD-immobilized platforms, such as self-assembly layer-by-layer (LbL) films and polymer vesicles, cross-linking hydrogels and microgels, hybrid mesoporous silica nanoparticles, and microdevices fabricated with insulin reservoirs have been surveyed. The glucose-sensitive drug delivery systems based on GOD are expected to be a typical candidate for smart platforms for potential applications in diabetes therapy.