In situ modified mesoporous silica nanoparticles: synthesis, properties and theranostic applications

Over the last 20 years, mesoporous silica nanoparticles (MSNs) have drawn considerable attention in the biomedical field due to their large surface area, porous network, biocompatibility, and abundant modification possibilities. In situ MSN modification refers to the incorporation of materials such as alkoxysilanes, ions and nanoparticles (NPs) in the silica matrix during synthesis. Matrix modification is a popular approach for endowing MSNs with additional functionalities such as imaging properties, bioactivity, and degradability, while leaving the mesopores free for drug loading. As such, in situ modified MSNs are considered promising theranostic agents. This review provides an extensive overview of different materials and modification strategies that have been used and their effect on MSN properties. We also highlight how in situ modified MSNs have been applied in theranostic applications, oncology and regenerative medicine. We conclude with perspectives on the future outlooks and current challenges for the widespread clinical use of in situ modified MSNs.

Mesoporous silica coated SPIONs containing curcumin and silymarin intended for breast cancer therapy

INTRODUCTION

Super-paramagnetic iron oxide nanoparticles (SPIONs) are known as promising theranostic nano-drug carriers with magnetic resonance imaging (MRI) properties. Applying the herbaceous components with cytotoxic effects as cargos can suggest a new approach in the field of cancer-therapy. In this study mesoporous silica coated SPIONs (mSiO2@SPIONs) containing curcumin (CUR) and silymarin (SIL) were prepared and evaluated on breast cancer cell line, MCF-7.

METHODS

Nanoparticles (NPs) were formulated by reverse microemulsion method and characterized by DLS, SEM and VSM. The in vitro drug release, cellular cytotoxicity, and MRI properties of NPs were determined as well. The cellular uptake of NPs by MCF-7 cells was investigated through LysoTracker Red staining using confocal microscopy.

RESULTS

The MTT results showed that the IC50 of CUR + SIL loaded mSiO2@SPIONs was reduced about 50% in comparison with that of the free drug mixture. The NPs indicated proper MRI features and cellular uptake through endocytosis.

CONCLUSION

In conclusion the prepared formulation may offer a novel theranostic system for breast cancer researches.

Comparative heating efficiency and cytotoxicity of magnetic silica nanoparticles for magnetic hyperthermia treatment on human breast cancer cells

Magnetic hyperthermia (MHT) is a promising treatment for a variety of cancers due to its ability to increase the sensitivity of cells to other treatments, such as chemotherapy. Superparamagnetic nanoparticles (MNPs) were used for MHT treatment due to their heat generation ability under an AC magnetic field (AMF). In this study, iron oxide and zinc-doped iron oxide MNPs were produced and modified with silica to obtain eleven different types (MSNP-I to -XI) of magnetic silica nanoparticles (MSNPs). The MSNPs which show the highest heating capacity were selected to investigate their MHT ability on non-tumourigenic MCF-10A and tumourigenic MCF-7 cell lines. The cytotoxicity results indicated that the size, the content of the magnetic core and silica coating thickness were important in the heating capacity of MSNPs under AMF. After MHT treatment, selected MSNPs showed limited cytotoxicity on MCF-10A, but significant cell death on MCF-7.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03377-y.

NIR-Absorbing Mesoporous Silica-Coated Copper Sulphide Nanostructures for Light-to-Thermal Energy Conversion

Plasmonic nanostructures, featuring near infrared (NIR)-absorption, are rising as efficient nanosystems for in vitro photothermal (PT) studies and in vivo PT treatment of cancer diseases. Among the different materials, new plasmonic nanostructures based on Cu_2−xS nanocrystals (NCs) are emerging as valuable alternatives to Au nanorods, nanostars and nanoshells, largely exploited as NIR absorbing nanoheaters. Even though Cu_2−xS plasmonic properties are not linked to geometry, the role played by their size, shape and surface chemistry is expected to be fundamental for an efficient PT process. Here, Cu_2−xS NCs coated with a hydrophilic mesoporous silica shell (MSS) are synthesized by solution-phase strategies, tuning the core geometry, MSS thickness and texture. Besides their loading capability, the silica shell has been widely reported to provide a more robust plasmonic core protection than organic molecular/polymeric coatings, and improved heat flow from the NC to the environment due to a reduced interfacial thermal resistance and direct electron–phonon coupling through the interface. Systematic structural and morphological analysis of the core-shell nanoparticles and an in-depth thermoplasmonic characterization by using a pump beam 808 nm laser, are carried out. The results suggest that large triangular nanoplates (NPLs) coated by a few tens of nanometers thick MSS, show good photostability under laser light irradiation and provide a temperature increase above 38 °C and a 20% PT efficiency upon short irradiation time (60 s) at 6 W/cm² power density.

Amino Surface Modification and Fluorescent Labelling of Porous Hollow Organosilica Particles: Optimization and Characterization

Surface modification of silica nanoparticles with organic functional groups while maintaining colloidal stability remains a synthetic challenge. This work aimed to prepare highly dispersed porous hollow organosilica particles (pHOPs) with amino surface modification. The amino-surface modification of pHOPs was carried out with 3-aminopropyl(diethoxy)methylsilane (APDEMS) under various reaction parameters, and the optimal pHOP-NH₂ sample was selected and labelled with fluorescein isothiocyanate (FITC) to achieve fluorescent pHOPs (F-HOPs). The prepared pHOPs were thoroughly characterized by transmission electron microscopy, dynamic light scattering, FT-IR, UV-Vis and fluorescence spectroscopies, and microfluidic resistive pulse sensing. The optimal amino surface modification of pHOPs with APDEMS was at pH 10.2, at 60 °C temperature with 10 min reaction time. The positive Zeta potential of pHOP-NH₂ in an acidic environment and the appearance of vibrations characteristic to the surface amino groups on the FT-IR spectra prove the successful surface modification. A red-shift in the absorbance spectrum and the appearance of bands characteristic to secondary amines in the FTIR spectrum of F-HOP confirmed the covalent attachment of FITC to pHOP-NH₂. This study provides a step-by-step synthetic optimization and characterization of fluorescently labelled organosilica particles to enhance their optical properties and extend their applications.

Synthesis of Porous Hollow Organosilica Particles with Tunable Shell Thickness

Porous hollow silica particles possess promising applications in many fields, ranging from drug delivery to catalysis. From the synthesis perspective, the most challenging parameters are the monodispersity of the size distribution and the thickness and porosity of the shell of the particles. This paper demonstrates a facile two-pot approach to prepare monodisperse porous-hollow silica particles with uniform spherical shape and well-tuned shell thickness. In this method, a series of porous-hollow inorganic and organic-inorganic core-shell silica particles were synthesized via hydrolysis and condensation of 1,2-bis(triethoxysilyl) ethane (BTEE) and tetraethyl orthosilicate (TEOS) in the presence of hexadecyltrimethylammonium bromide (CTAB) as a structure-directing agent on solid silica spheres as core templates. Finally, the core templates were removed via hydrothermal treatment under alkaline conditions. Transmission electron microscopy (TEM) was used to characterize the particles′ morphology and size distribution, while the changes in the chemical composition during synthesis were followed by Fourier-transform infrared spectroscopy. Single-particle inductively coupled plasma mass spectrometry (spICP-MS) was applied to assess the monodispersity of the hollow particles prepared with different reaction parameters. We found that the presence of BTEE is key to obtaining a well-defined shell structure, and the increase in the concentration of the precursor and the surfactant increases the thickness of the shell. TEM and spICP-MS measurements revealed that fused particles are also formed under suboptimal reaction parameters, causing the broadening of the size distribution, which can be preceded by using appropriate concentrations of BTEE, CTAB, and ammonia.

Breaking the fibrinolytic speed limit with microwheel co-delivery of tissue plasminogen activator and plasminogen

BACKGROUND

To reestablish blood flow in vessels occluded by clots, tissue plasminogen activator (tPA) can be used; however, its efficacy is limited by transport to and into a clot and by the depletion of its substrate, plasminogen.

OBJECTIVES

To overcome these rate limitations, a platform was designed to co-deliver tPA and plasminogen based on microwheels (µwheels), wheel-like assemblies of superparamagnetic colloidal beads that roll along surfaces at high speeds.

METHODS

The biochemical speed limit was determined by measuring fibrinolysis of plasma clots at varying concentrations of tPA (10-800 nM) and plasminogen (1-6 µM). Biotinylated magnetic mesoporous silica nanoparticles were synthesized and bound to streptavidin-coated superparamagnetic beads to make studded beads. Studded beads were loaded with plasminogen and tPA was immobilized on their surface. Plasminogen release and tPA activity were measured on the studded beads. Studded beads were assembled into µwheels with rotating magnetic fields and fibrinolysis of plasma clots was measured in a microfluidic device.

RESULTS

The biochemical speed limit for plasma clots was ~15 µm/min. Plasminogen-loaded, tPA-immobilized µwheels lyse plasma clots at rates comparableto the biochemical speed limit. With the addition of a corkscrew motion, µwheels penetrate clots, thereby exceeding the biochemical speed limit (~20 µm/min) and achieving lysis rates 40-fold higher than 50 nM tPA.

CONCLUSIONS

Co-delivery of an immobilized enzyme and its substrate via a microbot capable of mechanical work has the potential to target and rapidly lyse clots that are inaccessible by mechanical thrombectomy devices or recalcitrant to systemic tPA delivery.

Impact of mesoporous SiO2 support for Ni/polypyrrole nanocomposite particles on their capacitive performance

The inclusion of mesoporous H2N-SiO2 support in H2N-SiO2/Ni/PPy nanocomposite particles improved their electrochemical performance, suitable for energy storage devices.

Pomegranate-like Core-Shell Ni-NSs@MSNSs as a High Activity, Good Stability, Rapid Magnetic Separation, and Multiple Recyclability Nanocatalyst for DCPD Hydrogenation

A novel pomegranate-like Ni-NSs@MSNSs nanocatalyst was successfully synthesized via a modified Stöber method, and its application in the hydrogenation of dicyclopentadiene (DCPD) was firstly reported. The Ni-NSs@MSNSs possessed a high specific area (658 m²/g) and mesoporous structure (1.7-3.3 nm). The reaction of hydrogenation of DCPD to endo-tetrahydrodicyclopentadiene (endo-THDCPD) was used to evaluate the catalytic performance of the prepared materials. The distinctive pomegranate-like Ni-NSs@MSNSs core-shell nanocomposite exhibited superior catalytic activity (TOF = 106.0 h^-1 and STY = 112.7 g·L^-1·h^-1) and selectivity (98.9%) than conventional Ni-based catalysts (experimental conditions: Ni/DCPD/cyclohexane = 1/100/1000 (w/w), 150 °C, and 2.5 MPa). Moreover, the Ni-NSs@MSNSs nanocatalyst could be rapidly and conveniently recycled by magnetic separation without appreciable loss. The Ni-NSs@MSNSs also exhibited excellent thermal stability (≥750 °C) and good recycling performance (without an activity and selectivity decrease in four runs). The superior application performance of the Ni-NSs@MSNSs nanocatalyst was mainly owing to its unique pomegranate-like structure and core-shell synergistic confinement effect.

Iron Oxide Mesoporous Magnetic Nanostructures with High Surface Area for Enhanced and Selective Drug Delivery to Metastatic Cancer Cells

This work reports the fabrication of iron oxide mesoporous magnetic nanostructures (IO-MMNs) via the nano-replication method using acid-prepared mesoporous spheres (APMS) as the rigid silica host and iron (III) nitrate as the iron precursor. The obtained nanosized mesostructures were fully characterized by SEM, TEM, DLS, FTIR, XRD, VSM, and nitrogen physisorption. IO-MMNs exhibited relatively high surface areas and large pore volumes (S_BET = 70–120 m²/g and V_pore = 0.25–0.45 cm³/g), small sizes (~300 nm), good crystallinity and magnetization, and excellent biocompatibility. With their intrinsic porosities, high drug loading efficiencies (up to 70%) were achieved and the drug release rates were found to be pH-dependent. Cytotoxicity, confocal microscopy, and flow cytometry experiments against different types of cancerous cells indicated that Dox-loaded IO-MMNs reduced the viability of metastatic MCF-7 and KAIMRC-1 breast as well as HT-29 colon cancer cells, with the least uptake and toxicity towards normal primary cells (up to 4-fold enhancement). These results strongly suggest the potential use of IO-MMNs as promising agents for enhanced and effective drug delivery in cancer theranostics.

Highly efficient and fast removal of colored pollutants from single and binary systems, using magnetic mesoporous silica

Magnetic mesoporous silica material was tested as adsorbent for removal of two usual colored compounds present in industrial wastewater. The magnetic mesoporous silica was synthesized by modified sol-gel method and characterized from the morpho-textural, structural and magnetic point of view. The specific surface area and the total pore volume indicate a good adsorption capacity of the material, and the obtained saturation magnetization strength value denotes a good magnetic separation from solution. The adsorption capacity of magnetic mesoporous silica increases with the increase of the initial dye concentration, and the removal efficiency of the dyes was dependent on the pH of the solution and decreased with increasing temperature. The pseudo-second-order kinetic model described best the adsorption mechanism, and the maximum adsorption capacities were determined from the Sips isotherm model, being 88.29 mg/g for Congo Red and 208.31 mg/g for Methylene Blue. A complete thermodynamic evaluation was performed, by determining the free energy, enthalpy and entropy, and the result showed a spontaneous and exothermic adsorption process. The recovery and reutilization of the adsorbent were estimated in five cycles of adsorption-desorption, and the results indicated a good stability and reusability of magnetic mesoporous silica. The new magnetic mesoporous silica can be easily separated from solution, via an external magnetic field, and may be effectively applied as adsorbent for elimination of dyes from colored polluted waters.

Polymer-modified mesoporous silica microcubes (P@MSMCs) for the synergistic oxidative entrapment of Ag(i), Ti(iv), and Zn(ii) from natural river water

Herein, we demonstrate a hydrothermal route to the one-pot synthesis of polymeric mesoporous silica microcubes (P@MSMCs) for the adsorption of heavy metal ions. During the synthesis of P@MSMCs from column silica gel, the roles and combination of the polymer and an etchant were characterized. Moreover, the porosity of P@MSMCs was tailored by adjusting the reaction temperature between 75 °C and 200 °C. The characterization through UV, FTIR, FESEM, XRD, BET, and EDX techniques exhibited that P@MSMCs have a well-ordered mesoporous structure with cubic morphology. The P@MSMCs had a diameter of 2 μm, with an average pore volume and pore size of 0.69 cm3 g-1 and 10.08 nm, respectively. The results indicated that the P@MSMCs have excellent adsorption capacity for Ag(i), Ti(iv), and Zn(ii) due to the formation of an aggregated complex. These aggregations led to affordable density difference-based separation of these metal ions through centrifugation, filtration or simple decantation. The removal efficiencies for Ag(i), Ti(iv), and Zn(ii) were observed to be 520, 720, and 850 mg g-1, respectively. The kinetic studies demonstrated that the adsorption performance fitted well to the pseudo-second-order kinetic model. The as-synthesized P@MSMCs were stable in the wide pH range of 4-8. Significantly, the recycling or reuse results displayed effective adsorption performance of these P@MSMCs for up to 5 cycles. The adsorption results obtained herein will promote the development of similar strategies for the removal of heavy metal ions from natural water.

Preparation of iron oxide mesoporous magnetic microparticles as novel multidrug carriers for synergistic anticancer therapy and deep tumor penetration

The preparation of mesoporous iron oxides with controllable physiochemical properties for effective therapeutic drug delivery remains a formidable challenge. Herein, iron oxide mesoporous magnetic microparticles (IO-MMMs) were prepared by a modified reverse hard-templating approach using, for the first time, acid-prepared mesoporous spheres (APMS) as the hard silica template. The obtained mesostructures exhibited remarkably high surface area and large pore volumes (S_BET = 240 m²/g and V_pore = 0.55 cm³/g), controllable average sizes, generally uniform morphologies, and excellent biocompatibilities, allowing them to achieve optimal drug release in cancer cells and tumor tissues. IO-MMM carriers were able to co-load high amounts of hydrophilic chemotherapeutic drugs (Dox or Daun) and/or hydrophobic hormonal anticancer drugs (Tam), and release them sustainably in a pH-dependent manner, utilizing the fluorescence of Daun to real-time trace the intracellular drug distribution, and employing Daun/Tam to treat cancer by combined chemo/hormonal therapy. Cytotoxicity assays against different types of cancerous cells showed that the combinatory Daun/Tam@IO-MMM formulation significantly reduced the viability of metastatic MCF7 and KAIMRC1 breast as well as HCT8 colorectal cancer cells, with the least potency towards non-cancerous normal primary cells (up to 10-fold). Electron, flow, and live confocal microscopy imaging confirmed that the loaded vehicles were successfully and differentially uptaken by the different tested cells, gradually releasing their payloads, and causing apoptotic cell death. Importantly, compared to free drugs, Daun/Tam@IO-MMMs displayed enhanced drug accumulation in patient breast primary tumor tissues, deeply penetrating into the tumor region and killing the tumor cells inside. The designed carriers described here, thus, constitute a novel promising magnetic mesoporous smart system that entraps different kinds of drugs and release them in a controlled manner for combinatorial chemo/hormonal cancer theranostics. This multifactorial platform may open new avenues in cancer therapy as efficient synergistic antitumor system through overcoming limitations of conventional cancer therapy.

Highly compressive and stretchable poly(ethylene glycol) based hydrogels synthesised using pH-responsive nanogels without free-radical chemistry

Poly(ethylene glycol) (PEG) based hydrogels are amongst the most studied synthetic hydrogels. However, reports on PEG-based hydrogels with high mechanical strength are limited. Herein, a class of novel, well-defined PEG-based nanocomposite hydrogels with tunable mechanical strength are synthesised via ring-opening reactions of diglycidyl ethers with carboxylate ions. The pH responsive crosslinked polyacid nanogels (NG) in the dispersed phase act as high functionality crosslinkers which covalently bond to the poly(ethylene glycol) diglycidyl ethers (PEGDGE) as the continuous matrix. A series of NG-x-PEG-y-z gels are prepared where x, y and z are concentrations of NGs, PEGDGE and the PEGDGE molecular weight, respectively. The hydrogel compositions and nano-structural homogeneity of the NGs have strong impact on the enhancement of mechanical properties which enables property tuning. Based on this design, a highly compressive PEG-based nanocomposite hydrogel (NG-13-PEG-20-6000) exhibits a compressive stress of 24.2 MPa, compressive fracture strain greater than 98% and a fracture energy density as high as 1.88 MJ m-3. The tensile fracture strain is 230%. This is amongst one of the most compressive PEG-based hydrogels reported to-date. Our chemically crosslinked gels are resilient and show highly recoverable dissipative energy. The cytotoxicity test shows that human nucleus pulposus (NP) cells remained viable after 8 days of culture time. The overall results highlight their potential for applications as replacements for intervertebral discs or articular cartilages.

Tailoring cubic and dodecagonal quasicrystalline mesophases of mesoporous organosilica nanoparticles and core/shell structure

Herein, the synthesis of mesoporous organosilica nanoparticles with cubic and dodecagonal quasicrystalline mesophases is reported. Mesoporous nanoparticles are synthesized by base-catalyzed hydrolysis and condensation reactions of silane-based monomers in the presence of hexadecyltrimethylammonium bromide (CTAB), which is used as a structure-directing agent to form the mesostructures. Cubic orders in the mesophases are formed using tetraethoxysilane monomers, and the mesophase is tuned to the dodecagonal quasicrystalline order by using binary monomers including tetraethoxysilane and dimethyldiethoxysilane. The size of the quasicrystalline-phase organosilica is tailored by changing the amount of base catalyst used. Additionally, we obtained well-defined core/shell structures with quasicrystalline ordered mesoporous organosilica. Furthermore, we investigate the cytotoxicity of mesoporous organisilica nanoparticles using a CCK-8 assay to demonstrate that our NPs have a potential for the utilization as biomedical applications. These novel findings could guide the formation of mesophase structures with quasicrystalline order in silica-based mesoporous nanoparticles.

The Anionic Surfactant/Ionic Liquids Intercalated Reduced Graphene Oxide for High-performance Supercapacitors

The thermally reduced graphene oxide (TRG) composites with various interlayer distances were synthesized. These TRG sheets are intercalated with anionic surfactant sodium dodecyl sulfate (SDS) to prevent the restacking between TRG sheets. A facile approach is employed to enlarge the interlayer distance between the TRG sheets by the Coulomb force interaction between the intercalated surfactants and the ionic liquids. A systematic investigation of the morphology and the electrical performances of these EDLC cells was carried out. It was found that the energy density of the cells is improved from 34.9 to 61.8 Wh/kg at 1 A/g suggesting that the increased interlayer distance could enlarge the accessible surface area for the ionic liquid electrolyte.

High-Performance Asymmetric Supercapacitors Based on the Surfactant/Ionic Liquid Complex Intercalated Reduced Graphene Oxide Composites

In this paper, ionic surfactants are employed to intercalate thermally-reduced graphene oxide (TRG). The ionic interaction between the intercalated surfactant and the ionic liquid could lead to the formation of large-sized ionic aggregates and, hence, enlarge the interlayer distance between the TRG sheets. The morphology and vibration modes of these composites were systematically characterized using XRD (X-ray diffraction), SAXS (small-angle X-ray scattering), and FTIR (Fourier transform infrared spectroscopy). An asymmetric supercapacitor, which consisted of a cationic surfactant-intercalated electrode on one side and an anionic surfactant-intercalated electrode on the other, was examined. It was found that, with the increased interlayer distance, the energy density and capacitance of the cells were improved. It seems that the cell with a cationic surfactant as the cathode had the best energy density of 67.8 Wh/kg, which is 4.4-fold higher than that of the TRG cell.

The Influence of the Interlayer Distance on the Performance of Thermally Reduced Graphene Oxide Supercapacitors

In this paper, cationic surfactant cetyltrimethylammonium bromide (CTAB) was employed to prevent the restack of the thermally reduce graphene oxide (TRG) sheets. A facile approach was demonstrated to effectively enlarge the interlayer distance of the TRG sheets through the ionic interaction between the intercalated CTAB and ionic liquids (ILs). The morphology of the composites and the interaction between the intercalated ionic species were systematically characterized by SEM, SAXS, XRD, TGA, and FTIR. In addition, the performance of the EDLC cells based on these TRG composites was evaluated. It was found that due to the increased interlayer distance (0.41 nm to 2.51 nm) that enlarges the accessible surface area for the IL electrolyte, the energy density of the cell can be significantly improved (23.1 Wh/kg to 62.5 Wh/kg).

Preparation of amino-functionalized Fe3O4@mSiO2 core-shell magnetic nanoparticles and their application for aqueous Fe3+ removal

Fe₃O₄ nanoparticle with magnetic properties and nanoscale features has provoked wide research interest and great potential application. Herein, a modified Stober and template-removing method was adopted to prepare magnetic mesoporous silica nanoparticles (MSNs), comprising a Fe₃O₄ core and a mesoporous silica shell. The shell was functionalized by amino-groups with tunable removal efficiency for aqueous heavy metals ions. Structural and magnetic properties were characterized by XRD, SEM, FT-IR, vibrating sample magnetometer (VSM) and BET (Brunauer-Emmertt-Teller) techniques. Also, the adsorbing efficiency for heavy metal ions was measured by UV-vis spectrometry. Results revealed that the pure magnetite is cubic with a side length of 40 - 70nm, while the silica-coated magnetite is spherical with a diameter of 220-260nm. The mesoporous silica shell has an average pore size of 2.6nm and a high surface area of 675m²·g^-1, which lead to a large adsorption capacity for Fe³⁺ (up to 20.66mg of Fe per g of adsorbent). Moreover, rapid magnetic separation and regeneration of as-prepared adsorbent were achieved conveniently. The distinctive structure and the heavy metal ions removal property of magnetic nanocomposites reflect their prospective application in water treatment.

Fe3O4@Au@mSiO2 as an enhancing nanoplatform for Rose Bengal photodynamic activity

A novel nanoplatform composed of three types of materials with different functionalities, specifically core-shell Fe₃O₄@Au nanoparticles encapsulated near the outer surface of mesoporous silica (mSiO₂) nanoparticles, has been successfully synthesised and used to enhance the efficiency of a photosensitiser, namely Rose Bengal, in singlet oxygen generation. Fe₃O₄ is responsible for the unusual location of the Fe₃O₄@Au nanoparticle, while the plasmonic shell acts as an optical antenna. In addition, the mesoporous silica matrix firmly encapsulates Rose Bengal by chemical bonding inside the pores, thus guaranteeing its photostability, and in turn making the nanosystem biocompatible. Moreover, the silica surface of the nanoplatform ensures further functionalisation on demand.

Stimuli-Responsive Shapeshifting Mesoporous Silica Nanoparticles

Stimuli-responsive materials have attracted great interest in catalysis, sensing, and drug delivery applications and are typically constituted by soft components. We present a one-pot synthetic method for a type of inorganic silica-based shape change material that is responsive to water vapor exposure. After the wetting treatment, the cross-sectional shape of aminated mesoporous silica nanoparticles (MSNs) with hexagonal pore lattice changed from hexagonal to six-angle-star, accompanied by the loss of periodic mesostructural order. Nitrogen sorption measurements suggested that the wetting treatment induced a shrinkage of mesopores resulting in a broad size distribution and decreased mesopore volume. Solid-state (29)Si nuclear magnetic resonance (NMR) spectroscopy of samples after wetting treatment displayed a higher degree of silica condensation, indicating that the shape change was associated with the formation of more siloxane bonds within the silica matrix. On the basis of material characterization results, a mechanism for the observed anisotropic shrinkage is suggested based on a buckling deformation induced by capillary forces in the presence of a threshold amount of water vapor available beyond a humidity of about 50%. The work presented here may open a path toward novel stimuli-responsive materials based on inorganic components.

Silica-assisted incorporation of polydopamine into the framework of porous nanocarriers by a facile one-pot synthesis

Mussel-inspired polydopamine (PDA), with its advanced bio-adhesive properties, has shown great potential in drug delivery based on host–guest interaction.

One-step synthesis of magnetic hollow mesoporous silica (MHMS) nanospheres for drug delivery nanosystems via electrostatic self-assembly templated approach

Yolk–shell magnetic hollow mesoporous silica nanospheres were synthesized in one-step via electrostatic self-assembly for controlled release in diagnosis and therapy.

Size-controlled synthesis of mesoporous palladium nanoparticles as highly active and stable electrocatalysts

We report a solution phase synthesis of monodispersed mesoporous Pd nanoparticles (MPNs) with narrow particle size distributions.

Regulation of multifunctional mesoporous core–shell nanoparticles with luminescence and magnetic properties for biomedical applications

A new kind of Gd³⁺-based/mesoporous silica-coated multifunctional nanomedical platform is developed for potential use as optical-MR dual-modal imaging agent.

Multicompartment mesoporous silica nanoparticles with branched shapes: an epitaxial growth mechanism

Mesoporous nanomaterials have attracted widespread interest because of their structural versatility for applications including catalysis, separation, and nanomedicine. We report a one-pot synthesis method for a class of mesoporous silica nanoparticles (MSNs) containing both cubic and hexagonally structured compartments within one particle. These multicompartment MSNs (mc-MSNs) consist of a core with cage-like cubic mesoporous morphology and up to four branches with hexagonally packed cylindrical mesopores epitaxially growing out of the cubic core vertices. The extent of cylindrical mesostructure growth can be controlled via a single additive in the synthesis. Results suggest a path toward high levels of architectural complexity in locally amorphous, mesostructured nanoparticles, which could enable tuning of different pore environments of the same particle for specific chemistries in catalysis or drug delivery.

Silica-iron oxide magnetic nanoparticles modified for gene delivery: a search for optimum and quantitative criteria

PURPOSE

To optimize silica-iron oxide magnetic nanoparticles with surface phosphonate groups decorated with 25-kD branched polyethylenimine (PEI) for gene delivery.

METHODS

Surface composition, charge, colloidal stabilities, associations with adenovirus, magneto-tranduction efficiencies, cell internalizations, in vitro toxicities and MRI relaxivities were tested for the particles decorated with varying amounts of PEI.

RESULTS

Moderate PEI-decoration of MNPs results in charge reversal and destabilization. Analysis of space and time resolved concentration changes during centrifugation clearly revealed that at >5% PEI loading flocculation gradually decreases and sufficient stabilization is achieved at >10%. The association with adenovirus occurred efficiently at levels over 5% PEI, resulting in the complexes stable in 50% FCS at a PEI-to-iron w/w ratio of ≥7%; the maximum magneto-transduction efficiency was achieved at 9-12% PEI. Primary silica iron oxide nanoparticles and those with 11.5% PEI demonstrated excellent r(2)* relaxivity values (>600 s(-1)(mM Fe)(-1)) for the free and cell-internalized particles.

CONCLUSIONS

Surface decoration of the silica-iron oxide nanoparticles with a PEI-to-iron w/w ratio of 10-12% yields stable aqueous suspensions, allows for efficient viral gene delivery and labeled cell detection by MRI.