Hierarchically mesoporous silica nanoparticles: extraction, amino-functionalization, and their multipurpose potentials

Encapsulation of ZnO and Ho:ZnO Nanoparticles in the Core of Wrinkled Mesoporous Silica

Wrinkled mesoporous silica (WMS) has a flower- or dendritic-like morphology, tunable pore size, and highly ordered and accessible three-dimensional (3D) pore structures. In this research, a method to encapsulate semiconductor nanoparticles in the core of the wrinkled mesoporous silica during synthesis is described. Highly uniform zinc oxide and holmium-doped zinc oxide nanoparticles have been synthesized by a sonochemical method. Zinc oxide and holmium-doped zinc oxide nanoparticles have been encapsulated in wrinkled mesoporous silica during synthesis. The ZnO@WMS and Ho:ZnO@WMS particles have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-vis spectroscopy, fluorescence, dynamic light scattering (DLS), confocal microscopy, and X-ray diffraction (XRD).

A Multifunctional Nanocarrier System for Highly Efficient and Targeted Delivery of Ketamine to NMDAR Sites for Improved Treatment of Depression

Ketamine (KA), commonly used as an anesthetic, is now widely studied as an antidepressant for the treatment of depression. However, due to its side effects, such as addiction and cognitive impairment, the dosage and frequency of (S)-ketamine approved by the FDA for the treatment of refractory depression is very low, which limits its efficacy. Here, a new multifunctional nanocarrier system (AC-RM@HA-MS) with specific targeting capabilities is developed to improve the efficacy of KA treatment. KA-loaded NPs (AC-RM@HA-MS-KA) are constructed with a multilayer core-shell structure. KA-loaded mesoporous silica NPs are prepared, conjugated with hyaluronic acid (HA) as pore gatekeepers, and sheathed with an RBC-membrane (RM) for camouflage. Finally, the surface is tagged with bifunctional peptides (Ang-2-Con-G, AC) to achieve specific targeting. One peptide (Ang-2) is acted as a guide to facilitate the crossing of the blood-brain barrier (BBB), while the other (Con-G) is functioned as a ligand for the targeted delivery of KA to the N-methyl-D-aspartate receptor sites. Animal experiments reveal that AC-RM@HA-MS-KA NPs effectively cross the BBB and directionally accumulate in the curing areas, thereby alleviating the depressive symptoms and improving the cognitive functions of depressed mice. After treatment, the depressed mice almost completely return to normal without obvious symptoms of addiction.

A dummy molecularly imprinted ratiometric fluorescence nanosensor for the sensitive detection of guanidyl-microcystins in environmental water

An effective strategy is proposed to construct a highly sensitive ratiometric fluorescence sensing platform for microcystins (MCs) based on a dummy molecularly imprinted polymer using metformin as a template. The imprinted nanohybrids of carbon dots (CDs) combined with fluorescein isothiocyanate (FITC) are synthesized (CDs-FITC-SiO₂@MIP), in which the CDs and FITC serve as assisted response signals and reference enhancement signals, respectively. Metformin can be used as a dummy template for MCs due to its partially similar molecular fragments to MCs that can form a specific recognition site cavity. MCs can simultaneously induce an obvious fluorescence quenching effect for the CDs and a reference fluorescence enhancement for FITC-SiO₂, enabling ratiometric fluorescence detection of MCs. Thus, CDs-FITC-SiO₂@MIP used as a signal probe has favorable sensitivity, stability, and selectivity. More importantly, a good linear relationship between the fluorescence intensity ratio (I_620/450) and the concentration of MCs in the range of 0.5-500 μg L^-1 is obtained with a LOD of 0.013 μg L^-1 and 0.022 μg L^-1 for MC-RR and MC-LR, respectively, under the optimum conditions. This method has great application potential in water quality monitoring by using CDs-FITC-SiO₂@MIP as a promising candidate for monitoring MCs in complex systems.

Strong and Elastic Hydrogels from Dual-Crosslinked Composites Composed of Glycol Chitosan and Amino-Functionalized Bioactive Glass Nanoparticles

Mesoporous bioactive glass (BG) nanoparticles (NPs) with a high specific surface area were prepared. The surfaces of BG NPs were further modified using an amino-containing compound or synthesized precursors to produce three kinds of amino-functionalized bioactive glass (ABG) NPs via devised synthetic routes. The achieved ABG NPs possessed various spacer lengths with free amino groups anchored at the end of the spacer. These ABG NPs were then combined with glycol chitosan (GCH) to construct single- or dual-crosslinked ABG/GCH composite hydrogels using genipin (GN) alone as a single crosslinker or a combination of GN and poly(ethylene glycol) diglycidyl ether (PEGDE) as dual crosslinkers. The spacer length of ABG NPs was found to impose significant effects on the strength and elasticity of GN-crosslinked ABG/GCH hydrogels. After being dually crosslinked with GN and PEGDE, the elastic modulus of some dual-crosslinked ABG/GCH hydrogels reached around 6.9 kPa or higher with their yielding strains larger than 60%, indicative of their strong and elastic features. The optimally achieved ABG/GCH hydrogels were injectable with tunable gelation time, and also able to support the growth of seeded MC3T3-E1 cells and specific matrix deposition. These results suggest that the dual-crosslinked ABG/GCH hydrogels have the potential for some applications in tissue engineering.

Interfacial Assembly and Applications of Functional Mesoporous Materials

Functional mesoporous materials have gained tremendous attention due to their distinctive properties and potential applications. In recent decades, the self-assembly of micelles and framework precursors into mesostructures on the liquid-solid, liquid-liquid, and gas-liquid interface has been explored in the construction of functional mesoporous materials with diverse compositions, morphologies, mesostructures, and pore sizes. Compared with the one-phase solution synthetic approach, the introduction of a two-phase interface in the synthetic system changes self-assembly behaviors between micelles and framework species, leading to the possibility for the on-demand fabrication of unique mesoporous architectures. In addition, controlling the interfacial tension is critical to manipulate the self-assembly process for precise synthesis. In particular, recent breakthroughs based on the concept of the "monomicelles" assembly mechanism are very promising and interesting for the synthesis of functional mesoporous materials with the precise control. In this review, we highlight the synthetic strategies, principles, and interface engineering at the macroscale, microscale, and nanoscale for oriented interfacial assembly of functional mesoporous materials over the past 10 years. The potential applications in various fields, including adsorption, separation, sensors, catalysis, energy storage, solar cells, and biomedicine, are discussed. Finally, we also propose the remaining challenges, possible directions, and opportunities in this field for the future outlook.

Dendritic Mesoporous Nanoparticles: Structure, Synthesis and Properties

Recently, a new family of "dendritic" mesoporous silica nanoparticles has attracted great interest with widespread applications. Despite a large number of publications (>800), the terminology of "dendritic" is ambiguous. Understanding what possible "dendritic structures" are, their formation mechanisms and the underlying structure-property relationship is fundamentally important. With the advance of characterization techniques such as electron tomography, two types of tree branch-like and flower-like structures can be distinguished, both described as "dendritic" in literature. In this review, we start with the definition of "dendritic", then provide critical analysis of reported dendritic silica nanoparticles according to their structural classification. We also update the understandings of the formation mechanisms of two types of "dendritic" nanoparticles, with a focus on how to control different structural parameters. Various applications of dendritic mesoporous nanoparticles are also reviewed with a focus in biomedical field, providing new insights into the structure-property relationship in this family of nanomaterials.

Micro-mesoporous submicron silica particles with pore size tunable in a wide range: synthesis, properties and prospects for LED manufacturing

An approach has been developed that allows the synthesis of submicron spherical silica particles with a controlled micro-mesoporous structure possessing a large specific surface area (up to 1300 m²g^-1). Particle synthesis is carried out by the hydrolysis of a mixture of various organosilanes mostly associated either with CTAB or with each other. A change in the concentration of CTAB in the reaction mixture apparently leads to a change in the formation mechanism of nuclei for the silica particle growth, which allows for varying the diameter of the synthesized particles in the range from 40-450 nm. The effect of the composition of the silica precursor ([3-(methacryloyloxy)propyl]trimethoxysilane, (3-aminopropyl)triethoxysilane and tetraethoxysilane) on the formation process and porosity of the resulting particles is studied. It was shown that by simply varying the ratio of organosilanes in the composition of the precursor, one can control the pore diameter of the particles in a wide range from 0.6-15 nm. The large-pore (up to 15 nm) silica particles are used as a matrix for the spatial distribution of luminescent carbon dots. The incorporation of carbon dots into SiO₂particles prevents their aggregation leading to emission quenching after drying, thus allowing us to obtain highly luminescent composite particles. LEDs based on the obtained composite material show bright visible luminescence with spectral characteristics similar to that of a commercial cold white LED.

Biomedical applications of dendritic fibrous nanosilica (DFNS): recent progress and challenges

Dendritic fibrous nanosilica (DFNS), with multi-component and hierarchically complex structures, has recently been receiving significant attention in various fields of nano-biomedicine. DFNS is an emerging class of mesoporous nanoparticles that has attracted great interest due to unique structures such as open three-dimensional dendritic superstructures with large pore channels and highly accessible internal surface areas. This overview aims to study the application of DFNS towards biomedical investigations. This review is divided into four main sections. Sections 1–3 are related to the synthesis and characterization of DFNS. The biomedical potential of DFNS, such as cell therapy, gene therapy, immune therapy, drug delivery, imaging, photothermal therapy, bioanalysis, biocatalysis, and tissue engineering, is discussed based on advantages and limitations. Finally, the perspectives and challenges in terms of controlled synthesis and potential nano-biomedical applications towards future studies are discussed.

Dendritic fibrous nanosilica (DFNS) , with multi-component and hierarchically complex structures, has recently been receiving significant attention in various fields of nano-biomedicine.

pH- and temperature-responsive radially porous silica nanoparticles with high-capacity drug loading for controlled drug delivery

The design of smart and functional nanocarriers for drug delivery systems that use a variety of organic and inorganic materials has led to the development of nanomedicines with improved therapeutic efficiency and reduced side effects. In this study, a pH- and temperature-responsive, controlled-release system with a high capacity for drug loading was developed based on radially porous silica nanoparticles composed of functionalized ligands and polymer encapsulation. This drug delivery system uses radially oriented mesoporous silica nanoparticles as the drug carrier, and control of the surface chemistry of those nanocarriers allows high-capacity loading efficiency of target drugs and stimuli-responsive release kinetics governed by pH and temperature. The delivery of ibuprofen was chosen to test this system, and a maximum loading efficiency of ca. 270 wt% was established, which was 3 times greater than that in previous studies for silica nanoparticles such as SBA-15, MCA-41, and MCM-48. In addition, the pH- and temperature-responsive release of ibuprofen was achieved when the surface of the nanocarriers was treated by pH-responsive amine functionalization and a temperature-responsive surface coating of agarose gel. Finally, cytotoxicity testing using the fibroblast cells showed that the developed silica nanocarriers have no toxicity on the cells, which should allow these nanocarriers to be applied as a nanomedicine in drug delivery systems.

Immobilization of β-Glucosidase over Structured Cordierite Monoliths Washcoated with Wrinkled Silica Nanoparticles

The enzymatic conversion of biomass-derived compounds represents a key step in the biorefinery flowsheet, allowing low-temperature high-efficiency reactions. β-Glucosidases are able to hydrolyze cellobiose into glucose. Wrinkled silica nanoparticles (WSNs) were demonstrated to be a good support for the immobilization of β-glucosidases, showing better performance than free enzymes in batch reaction; on the other hand, immobilized enzyme microreactors (IEMs) are receiving significant attention, because small quantities of reagents can be used, and favorable heat and mass transfer can be achieved with respect to conventional batch systems. In this work, we prepared, characterized, and tested structured enzymatic reactor compounds by a honeycomb monolith, a WSN washcoat, and β-glucosidases as the active phase. Powder and structured materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 physisorption, thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FT-IR). Structured catalysts were tested under both batch and continuous flow reaction conditions and compared to powder catalysts (batch reaction). The WSN washcoat was attached well onto the monolith walls, as suggested by the negligible weight loss after ultrasound treatment; the WSNs preserved their shape, porosity, and individual nature when deposited onto the monolith walls. The immobilized enzyme microreactors proved to be very efficient in hydrolysis of cellobiose to glucose, showing a complete conversion under continuous flow reaction at a batch-equivalent contact time equal to 120 min vs. 24 h obtained in the batch experiments. The apparent KM value showed a 20-fold decrease with respect to the batch process, due to the absence of external diffusive transport limitations.

Highly ordered functionalized mesoporous silicate nanoparticles reinforced poly (lactic acid) gatekeeper surface for infection treatment

The controlled release of a drug considers the key feature of the delivery carrier that enhances therapeutic efficacy. This study was aimed at design, synthesis of nano valve and capping systems onto caged functionalized mesoporous silica nanoparticles (SBA15) with nanoflowers polylactic acid (PLA-NF). Levofloxacin (LVX) as a specific model drug was encapsulated onto series; SBA15, SBA15@NH2, and SBA15@NH2/PLA. The examined nanocarriers released in a controlled fashion by external stimuli. The delivery vehicle based on PLA-NF coated SBA15@NH2, potent conjugated with LVX with experienced a high extent of trapping content with fast releasing by pH regulating mechanism. In vial LVX released profile and in vitro antifungal forceful of the selected microbes were detected. However, SBA15@NH2/PLA exhibited pore size, surface area and pore volume 5.4 nm, 163 and 0.011 respectively, but the significantly clear zone was obtained with Staphylococcus aureus ATCC 6538 (G+ve), Escherichia coli ATCC 25922 (G-ve), Candida albicans ATCC 10231 (yeast) and Aspergillus niger NRRL A-326 (fungus). Viability test avouch that rising functionality enhanced cytocompatibility and non-toxicity profile. Based on the aforementioned promising data, this type of nanocarriers offers when functionalized with targeting cells, the accessibility to deliver antibiotics onto nanosystem for increased potency against microbes and reduce side effects.

Improving Interaction at Polymer-Filler Interface: The Efficacy of Wrinkle Texture

One of the main issues in preparing polymer-based nanocomposites with effective properties is to achieve a good dispersion of the nanoparticles into the matrix. Chemical interfacial modifications by specific coupling agents represents a good way to reach this objective. Actually, time consuming compatibilization procedures strongly compromise the sustainability of these strategies. In this study, the role of particles' architectures in their dispersion into a poly-lactic acid matrix and their subsequent influences on physical-chemical properties of the obtained nanocomposites were investigated. Two kinds of silica nanoparticles, "smooth" and "wrinkled," with different surface areas (≈30 and ≈600 m2/g respectively) were synthesized through a modified Stöber method and used, without any chemical surface pre-treatments, as fillers to produce poly-lactic acid based nanocomposites. The key role played by wrinkled texture in modifying the physical interaction at the polymer-filler interface and in driving composite properties, was investigated and reflected in the final bulk properties. Detailed investigations revealed the presence of wrinkled nanoparticles, leading to (i) an enormous increase of the chain relaxation time, by almost 30 times compared to the neat PLA matrix; (ii) intensification of the shear-thinning behavior at low shear-rates; and (iii) slightly slower thermal degradation of polylactic acid.

Dual-Porosity Hollow Carbon Spheres with Tunable Through-Holes for Multi-Guest Delivery

Dual-porosity hollow carbon spheres (DPHCs) with small mesopores (2-4 nm) and large through-holes (20-30 nm) in shells were successfully synthesized using colloidal silica as the template, small silica nanoparticles as nanomasks, and nontoxic dopamine as the carbon precursor followed by post-carbonization and etching. The synthesized DPHCs were further oxidized to be hydrophilic and then used to simultaneously deliver the protein bovine serum albumin (21 × 4 × 14 nm³) and the small molecule doxorubicin (<1 nm), which exhibited a high loading capacity of 689.4 and 1421.2 mg/g, respectively. The release of these two guest molecules can be controlled independently under the stimuli of heat and acidity. In vitro and in vivo experiments also proved that the DPHCs are promising for the co-delivery of multiple cargoes of different sizes.

Effect of a Swelling Agent on the Performance of Ni/Porous Silica Catalyst for CH4-CO2 Reforming

Hierarchical porous materials are of great interest in various industrial applications because of their potential to overcome the mass transport limitations typically encountered for single-mode porous materials. This report describes the synthesis of a hierarchical trimodal porous silica-based material using a 7.5 molar ratio of a relatively inexpensive nonionic surfactant template, triblock copolymer P123, EO₂₀PO₇₀EO₂₀. The pore size distribution curve shows the presence of three types of pores with average diameters of ∼8, 25, and 89 nm. Electron microscope images confirm the existence of smaller ordered mesopores (first mode), larger ordered mesopores (second mode), and macropores (third mode). Ni nanoparticles dispersed on this trimodal porous silica produce a material that exhibited excellent catalytic performance for the CO₂ reforming of CH₄. This research provides new insights that will facilitate the development of trimodal porous silica (TMS) materials for a variety of applications. The results demonstrated that the presence of large pores (second and third mode pores) in TMS material increased the number of accessible active Ni sites, which led to the high activity observed for Ni/TMS catalyst.

Dendrimer-like amino-functionalized hierarchical porous silica nanoparticle: A host material for 2,4-dichlorophenoxyacetic acid imprinting and sensing

In this work, a novel molecularly imprinted electrochemical sensor based on the amino-functionalized silica nanoparticles was built for the sensitive and selective detection of 2,4-dichlorophenoxyacetic acid (2,4-D). The hierarchical porous dendrimer-like silica nanoparticles (HPSNs-NH₂) were synthesized by an ethyl ether emulsion method. The selective molecularly imprinted polymers (MIP) was prepared on the HPSNs-NH₂ modified electrode via electropolymerization by using 2,4-D as the template and o-phenylenediamine (OPD) as the monomer. The porous structure of HPSNs-NH₂ reduced the diffusion limitations of the analytes, enhanced the accessibility and increased the surface area of the sensor, while the MIP layer offered the ability to recognize and quantify target 2,4-D by using ferro/ferricyanide as probes. Several significant experimental parameters on the analytical performance of the MIP/HPSNs-NH₂ sensor were explored and optimized. Under the optimized condition, the sensor displayed an appreciable selectivity over structurally related compounds and good sensitivity toward 2,4-D. The linear range of 2,4-D detection was from 1.00 × 10^-10 to 2.50 × 10^-8M and the detection limit was down to 1.17 × 10^-11M according to the 3S_a/b criteria. This method has been applied to detect 2,4-D in bean sprout samples with satisfying results.

One-Step Synthesis of Hydrophobic Multicompartment Organosilica Microspheres with Highly Interconnected Macro-mesopores for the Stabilization of Liquid Marbles with Excellent Catalysis

The combination of an emulsion template with polymerization is a very convenient approach to the one-step realization of both simple control porous structures via a change in emulsion formulation and easy functionalization via the concomitant choice of an on-demand monomer. A major challenge of this approach is the inherent instability of the oil/water interface in emulsions, especially the occurrence of chemical reactions in oil or aqueous phases. This study reports the pioneering preparation of highly interconnected macro-mesopores and multicompartment (HIMC) vinyl organosilica microspheres with hydrophobicity by the one-step formation of W/O/W emulsions acting as a template. The emulsion system consists of acidified deionized water, a stabilizer, and vinyltriethoxysilane (VTEO) in which VTEO can be used to produce an organosilica skeleton of the resultant microsphere by a sol-gel process. The study demonstrated that the marvelous stability of W/O/W emulsions aids the formation of multicompartment organosilica microspheres with highly interconnected macro-mesopores by emulsion droplets rather than single-compartment (SC) microspheres. Meanwhile, the internal porous structure and surface morphology of as-prepared organosilica microspheres could be largely tuned by a simple variation of the pH value, the volume fraction of the water phase, and the stabilizer concentration in the initiating multiemulsions. Benefiting from such a well-orchestrated structure and the existence of numerous vinyl groups on the surface, HIMC organosilica microspheres exhibit very high hydrophobicity (with a water contact angle larger than 160°), which allows them to stabilize liquid marbles with excellent stability and high mechanical robustness. Because of its strong catalyst, Ag nanoparticles within HIMC organosilica microspheres enable Ag/HIMC-vinyl organosilica microsphere-based liquid marbles to be an efficient catalytic microreactor, realizing the complete degradation of MB to leuco methylene blue by NaBH₄ in 10 min. The result of this work could provide some guidance for the easy, low-cost, benign preparation of HIMC microspheres having the potential to be excellent supporter of metal nanoparticles or other functionalized compounds for applications in sensing, optoelectronics, and catalysis.

Macroporous materials: microfluidic fabrication, functionalization and applications

This article provides an up-to-date highly comprehensive overview (594 references) on the state of the art of the synthesis and design of macroporous materials using microfluidics and their applications in different fields.

Integration of polymers in the pore space of mesoporous nanocarriers for drug delivery

The construction of carrier-polymer–drug hybrids in confined nanopore space is reviewed for advancing related drug delivery systems.

A magnetically recoverable photocatalyst prepared by supporting TiO2nanoparticles on a superparamagnetic iron oxide nanocluster core@fibrous silica shell nanocomposite

A magnetically recoverable photocatalyst was prepared by supporting TiO₂nanoparticles on a superparamagnetic iron oxide nanocluster core@fibrous silica shell nanocomposite.

Functionalized Silica Nanoparticles As an Alternative Platform for Targeted Drug-Delivery of Water Insoluble Drugs

The selective action of drugs in tumor cells is a major problem in cancer therapy. Most chemotherapy drugs act nonspecifically and damage both cancer and healthy cells causing various side effects. In this study, the preparation of a selective drug delivery system, which is able to act as a carrier for hydrophobic and anticancer drugs is reported. Amino-functionalized silica nanoparticles loaded with curcumin were successfully synthesized via sol-gel approach and duly characterized. Thereafter, the targeting ligand, folate, was covalently attached to amino groups of nanoparticle surface through amide bond formation. The cytotoxic effect of nanoparticles on prostate cancer cells line was evaluated and compared to normal cells line (prostate epithelial cell). Cytotoxicity experiments demonstrated that folate-functionalized nanoparticles were significantly cytotoxic to tumor cells, whereas normal cells were much less affected by the presence of these structures.

Formation of mesoporous silica nanoparticles with tunable pore structure as promising nanoreactor and drug delivery vehicle

Mesoporous silica nanoparticles with tunable pore structures have been successfully fabricated by simply tuning the ethanol amounts in the precursor.

Dendritic silica particles with center-radial pore channels: promising platforms for catalysis and biomedical applications

Dendritic silica micro-/nanoparticles with center-radial pore structures, a kind of newly created porous material, have attracted considerable attention owing to their unique open three-dimensional dendritic superstructures with large pore channels and highly accessible internal surface areas compared with conventional mesoporous silica nanoparticles (MSNs). They are very promising platforms for a variety of applications in catalysis and nanomedicine. In this review, their unique structural characteristics and properties are first analyzed, then novel and interesting synthesis methods associated with the possible formation mechanisms are summarized to provide material scientists some inspiration for the preparation of this kind of dendritic particles. Subsequently, a few examples of interesting applications are presented, mainly in catalysis, biomedicine, and other important fields such as for sacrificial templates and functional coatings. The review is concluded with an outlook on the prospects and challenges in terms of their controlled synthesis and potential applications.

Tunable stellate mesoporous silica nanoparticles for intracellular drug delivery

Stellate mesoporous silica nanoparticles with special radial pore morphology were easily synthesized using triethanolamine as the base catalyst in a wide range of synthesis conditions. By adjusting the surfactant composition, reaction temperature and time, and reagent ratio, the particle size of the material could be tailored continuously ranging from 50 to 140 nm and the pore size from 2 to 20 nm. By analyzing the effects of different synthesis parameters, it is concluded that the particles are formed following a nucleation-growth mechanism and the reaction kinetics play an important role in determining the particle size and pore structure. These stellate MSNs can be conveniently functionalized with a nontoxic low molecular weight poly(ethylene imine) (PEI, 800 Da) by a delayed condensation method. The resulting nanocomposites not only possess auto-fluorescence for suitable particle tracking but also demonstrate good potential for intracellular delivery of the anticancer doxorubicin drug.

Sensing Properties of GO and Amine-Silica Nanoparticles Functionalized QCM Sensors for Detection of Formaldehyde

In the current work, graphene oxides (GO) and Amine-Functionalized Silica Nanoparticles ( NH 2-SNs) were used as sensing layer on quart crystal microbalance (QCM) for detection of HCHO gas. The GO and NH 2-SNs functionalized QCM resonators all had a significant response to HCHO gas. The sensitivity of GO functionalized QCM resonator is 0.04 Hz/(μg⋅ppm), which is four times as high as that of NH 2-SNs functionalized QCM resonator (0.01 Hz/(μg⋅ppm)). The GO functionalized QCM resonators would be of benefit in area of environmental applications.

Fabrication of mesoporous silica nanospheres with radially oriented mesochannels by microemulsion templating for adsorption and controlled release of aspirin

The MSN spheres with narrow size distribution and radially oriented mesoporous channels were prepared using an O/W microemulsion system, consisting of CTAB (or PVP), ethanol, cyclohexane and water as template.

Controlled etching of internal and external structures of SiO2 nanoparticles using hydrogen bond of polyelectrolytes

We have demonstrated a novel strategy for the synthesis of mesoporous silica nanoparticles (MSNPs) using a surfactant-free method under ambient conditions. By the simple addition of an amine-based polymer (polyethylenimine; PEI) with a high molecular weight to a silica nanoparticle (SNP) solution, two types of MSNPs, including rambutan-like MSNPs (R-MSNPs) and hollow MSNPs (H-MSNPs), were produced. The structural changes of the MSNPs were systematically studied using various reaction conditions (reaction time, molar ratio and molecular weight of PEI, etc.) and were observed using electron microscopic techniques. The formation mechanisms of both MSNPs were carefully investigated using XPS, Raman, and IR spectroscopies. Because the synthesized MSNPs are highly porous materials that contain internal organic/inorganic networks, we investigated the removal/adsorption properties of these MSNPs with respect to pollutants toward possible future use in environmental remediation applications. The H-MSNPs exhibited better environmental remediation capabilities relative to the R-MSNPs because PEI is present between the cobweb-like internal structures of the H-MSNPs, thereby providing a significant number of reaction sites for the adsorption of pollutants. The approach presented here can also be used as a direct method for the preparation of intraconnected networks within the substructures.

Mesoporous carbon coated molybdenum oxide nanobelts for improved lithium ion storage

Mesoporous carbon-coated molybdenum oxide nanobelt composites were synthesized hydrothermally with subsequent organic–organic assembly and calcination, and used as Li-ion-battery anodes.

Formation of cagelike sulfonated polystyrene microspheres via swelling-osmosis process and loading of CdS nanoparticles

In this report, we studied the formation mechanism of cagelike polymer microspheres fabricated conveniently and efficiently through a swelling-osmosis process of sulfonated polystyrene (SPS) microspheres in a ternary mixed solvent (water/ethanol/heptane). The scanning electron microscopy and transmission electron microscopy observations indicated that the morphology of the final cagelike SPS microspheres is mainly controlled by the composition of the mixed solvent and the swelling temperature. Considering the solubility parameters of related reagents and the low interface tension of heptane and the aqueous solution of ethanol (only 6.9 mN/m), we confirm that the porogen procedure starts from the swelling of SPS microspheres by heptane, followed by the osmosis process of water molecules into the swollen SPS microspheres forced by the strong hydrophilicity of -SO3H group. The water molecules permeated into SPS microspheres will aggregate into water pools, which form the pores after the microspheres are dried. These prepared cagelike SPS microspheres are further served as the scaffold for the in situ generated CdS nanoparticles under γ-ray radiation. The CdS/SPS composite microspheres show good fluorescence performance. This work shows that the cagelike SPS microspheres have a wide industrial application prospect due to their economical and efficient preparation and loading nanoparticles.

Developing functionalized dendrimer-like silica nanoparticles with hierarchical pores as advanced delivery nanocarriers

Functionalized dendrimer-like hybrid silica nanoparticles with hierarchical pores are designed and synthesized. The unique structure, large surface area, and excellent biocompability render such materials attractive nanocarriers for the advanced delivery of various sized drugs and genes simultaneously.

Cysteine-assisted tailoring of adsorption properties and particle size of polymer and carbon spheres

A series of cysteine-stabilized phenolic resin-based polymer and carbon spheres were prepared by the modified Stöber method. Cysteine plays a very important role in the proposed one-pot synthesis of the aforementioned spheres; namely, it acts as a particle stabilizer and a source of heteroatoms (nitrogen and sulfur) that can be introduced into these spheres. The diameter of these spheres can be tuned in the range of 70-610 nm by adjusting the cysteine amount and reaction temperature. Since polymer spheres obtained in the presence of cysteine contain sulfur and nitrogen heteroatoms, they were tested for adsorption of copper ions. It is shown that adsorption isotherms recorded for copper ions can be well fitted by Langmuir equation, giving unprecedented adsorption capacities up to ~65 mg/g.

Functionalized self-assembled monolayers on mesoporous silica nanoparticles with high surface coverage

Mesoporous silica nanoparticles (MSNs) containing vinyl-, propyl-, isobutyl- and phenyl functionalized monolayers were reported. These functionalized MSNs were prepared via molecular self-assembly of organosilanes on the mesoporous supports. The relative surface coverage of the organic monolayers can reach up to 100% (about 5.06 silanes/nm.

Amino-functionalized silica nanoparticles with center-radially hierarchical mesopores as ideal catalyst carriers

Our previously fabricated amino-functionalized silica nanoparticles (NPs) with center-radially hierarchical mesopores (NH(2)-HMSNs) were purified by a filtration membrane and used as catalyst carriers in the current article. Noble metal NPs (Au, Pd, Pt and Au & Pt) with small sizes (3-8 nm) were successfully immobilized into the NH(2)-HMSNs via the deposition-precipitation method. These noble metal NPs with readily adjusted small sizes have high density and well-dispersed distribution on the surface of large mesopores of NH(2)-HMSNs. Among them, Au-NH(2)-HMSNs were investigated as the composite catalyst in the catalytic reduction of 2-nitroaniline (2-NA) as a model reaction and exhibited excellent catalytic activity and stability. The presence of center-radially large mesopores in the NH(2)-HMSNs may favor the loading of noble metal NPs with high density and well-dispersed distribution on the surface of large mesopores of NH(2)-HMSNs. Metal-NH(2)-HMSNs may be more promising composite catalysts due to their superstructure of center-radially hierarchical mesopores that maybe significantly enhance and harmonize the diffusion of guest molecules of different sizes through the porous matrices.

Spherical silica micro/nanomaterials with hierarchical structures: synthesis and applications

This paper reviews the progress made recently in synthesis and applications of spherical silica micro/nanomaterials with multilevel (hierarchical) structures. The spherical silica micro/nanomaterials with hierarchical structures are classified into four main structural categories that include (1) hollow mesoporous spheres, (2) core-in-(hollow porous shell) spheres, (3) hollow spheres with multiple porous shells and (4) hierarchically porous spheres. Due to the complex structures and being focused on spherical silica micro/nanomaterials, some novel methods based on the combination of two routine methods or two surfactants, and some special synthetic strategies are proposed to produce the spherical silica micro/nanomaterials with hierarchical structures. Compared with the same-sized solid, porous or hollow silica spheres, these fantastic spherical silica micro/nanomaterials with hierarchical structures exhibit enhanced properties which may enable them to be used in broad and promising applications as ideal scaffolds (carriers) for biological, medical, and catalytic applications.