Camouflaged Virus-Like-Nanocarrier with a Transformable Rough Surface for Boosting Drug Delivery.

Due to non-specific strong nano-bio interactions, it is difficult for nanocarriers with permanent rough surface to cross multiple biological barriers to realize efficient drug delivery. Herein, a camouflaged virus-like-nanocarrier with a transformable rough surface is reported, which is composed by an interior virus-like mesoporous SiO2 nanoparticle with a rough surface (vSiO2 ) and an exterior acid-responsive polymer. Under normal physiological pH condition, the spikes on vSiO2 are hidden by the polymer shell, and the non-specific strong nano-bio interactions are effectively inhibited. While in the acidic tumor microenvironment, the nanocarrier sheds the polymer camouflage to re-expose its rough surface. So, the retention ability and endocytosis efficiency of the nanocarrier are great improved. Owing to it's the dynamically variable rough surface, the rationally designed nanocarrier exhibits extended blood-circulation-time and enhanced tumor accumulation.

Enzyme-Based Mesoporous Nanomotors with Near-Infrared Optical Brakes.

As one of the most important parameters of the nanomotors' motion, precise speed control of enzyme-based nanomotors is highly desirable in many bioapplications. However, owing to the stable physiological environment, it is still very difficult to in situ manipulate the motion of the enzyme-based nanomotors. Herein, inspired by the brakes on vehicles, the near-infrared (NIR) "optical brakes" are introduced in the glucose-driven enzyme-based mesoporous nanomotors to realize remote speed regulation for the first time. The novel nanomotors are rationally designed and fabricated based on the Janus mesoporous nanostructure, which consists of the SiO2@Au core@shell nanospheres and the enzymes-modified periodic mesoporous organosilicas (PMOs). The nanomotor can be driven by the biofuel of glucose under the catalysis of enzymes (glucose oxidase/catalase) on the PMO domain. Meanwhile, the Au nanoshell at the SiO2@Au domain enables the generation of the local thermal gradient under the NIR light irradiation, driving the nanomotor by thermophoresis. Taking advantage of the unique Janus nanostructure, the directions of the driving force induced by enzyme catalysis and the thermophoretic force induced by NIR photothermal effect are opposite. Therefore, with the NIR optical speed regulators, the glucose-driven nanomotors can achieve remote speed manipulation from 3.46 to 6.49 µm/s (9.9-18.5 body-length/s) at the fixed glucose concentration, even after covering with a biological tissue. As a proof of concept, the cellar uptake of the such mesoporous nanomotors can be remotely regulated (57.5-109 µg/mg), which offers great potential for designing smart active drug delivery systems based on the mesoporous frameworks of this novel nanomotor.

Streamlined Mesoporous Silica Nanoparticles with Tunable Curvature from Interfacial Dynamic-Migration Strategy for Nanomotors.

Streamlined architectures with a low fluid-resistance coefficient have been receiving great attention in various fields. However, it is still a great challenge to synthesize streamlined architecture with tunable surface curvature at the nanoscale. Herein, we report a facile interfacial dynamic migration strategy for the synthesis of streamlined mesoporous nanotadpoles with varied architectures. These tadpole-like nanoparticles possess a big streamlined head and a slender tail, which exhibit large inner cavities (75-170 nm), high surface areas (424-488 m2 g-1), and uniform mesopore sizes (2.4-3.2 nm). The head curvature of the streamlined mesoporous nanoparticles can be well-tuned from ∼2.96 × 10-2 to ∼5.56 × 10-2 nm-1, and the tail length can also be regulated from ∼30 to ∼650 nm. By selectively loading the Fe3O4 catalyst in the cavity of the streamlined silica nanotadpoles, the H2O2-driven mesoporous nanomotors were designed. The mesoporous nanomotors with optimized structural parameters exhibit outstanding directionality and a diffusion coefficient of 8.15 µm2 s-1.

Sequential Chemistry Toward Core-Shell Structured Metal Sulfides as Stable and Highly Efficient Visible-Light Photocatalysts.

A universal sequential synthesis strategy in aqueous solution is presented for highly uniform core-shell structured photocatalysts, which consist of a metal sulfide light absorber core and a metal sulfide co-catalyst shell. We show that the sequential chemistry can drive the formation of unique core-shell structures controlled by the constant of solubility product of metal sulfides. A variety of metal sulfide core-shell structures have been demonstrated, including CdS@CoSx , CdS@MnSx , CdS@NiSx , CdS@ZnSx , CuS@CdS, and more complexed CdS@ZnSx @CoSx . The obtained strawberry-like CdS@CoSx core-shell structures exhibit a high photocatalytic H2 production activity of 3.92 mmol h-1 and an impressive apparent quantum efficiency of 67.3 % at 420 nm, which is much better than that of pure CdS nanoballs (0.28 mmol h-1 ), CdS/CoSx composites (0.57 mmol h-1 ), and 5 %wt Pt-loaded CdS photocatalysts (1.84 mmol h-1 ).

Melt Electrospinning Designs for Nanofiber Fabrication for Different Applications.

Nanofibers have been attracting growing attention owing to their outstanding physicochemical and structural properties as well as diverse and intriguing applications. Electrospinning has been known as a simple, flexible, and multipurpose technique for the fabrication of submicro scale fibers. Throughout the last two decades, numerous investigations have focused on the employment of electrospinning techniques to improve the characteristics of fabricated fibers. This review highlights the state of the art of melt electrospinning and clarifies the major categories based on multitemperature control, gas assist, laser melt, coaxial, and needleless designs. In addition, we represent the effect of melt electrospinning process parameters on the properties of produced fibers. Finally, this review summarizes the challenges and obstacles connected to the melt electrospinning technique.

Molecular Design Strategy for Ordered Mesoporous Stoichiometric Metal Oxide.

A molecular design strategy is used to construct ordered mesoporous Ti3+ -doped Li4 Ti5 O12 nanocrystal frameworks (OM-Ti3+ -Li4 Ti5 O12 ) by the stoichiometric cationic coordination assembly process. Ti4+ /Li+ -citrate chelate is designed as a new molecular precursor, in which the citrate can not only stoichiometrically coordinate Ti4+ with Li+ homogeneously at the atomic scale, but also interact strongly with the PEO segments in the Pluronic F127. These features make the co-assembly and crystallization process more controllable, thus benefiting for the formation of the ordered mesostructures. The resultant OM-Ti3+ -Li4 Ti5 O12 shows excellent rate (143 mAh g-1 at 30 C) and cycling performances (<0.005 % fading per cycle). This work could open a facile avenue to constructing stoichiometric ordered mesoporous oxides or minerals with highly crystalline frameworks.

New Insight into the Synthesis of Large-Pore Ordered Mesoporous Materials.

Ordered mesoporous materials (OMMs) have received increasing interest due to their uniform pore size, high surface area, various compositions and wide applications in energy conversion and storage, biomedicine and environmental remediation, etc. The soft templating synthesis using surfactants or amphiphilic block copolymers is the most efficient method to produce OMMs with tailorable pore structure and surface property. However, due to the limited choice of commercially available soft templates, the common OMMs usually show small pore size and amorphous (or semicrystalline) frameworks. Tailor-made amphiphilic block copolymers with controllable molecular weights and compositions have recently emerged as alternative soft templates for synthesis of new OMMs with many unique features including adjustable mesostructures and framework compositions, ultralarge pores, thick pore walls, high thermal stability and crystalline frameworks. In this Perspective, recent progresses and some new insights into the coassembly process about the synthesis of OMMs based on these tailor-made copolymers as templates are summarized, and typical newly developed synthesis methods and strategies are discussed in depth, including solvent evaporation induced aggregation, ligand-assisted coassembly, solvent evaporation induced micelle fusion-aggregation assembly, homopolymer assisted pore expanding and carbon-supported crystallization strategy. Then, the applications of the obtained large-pore OMMs in catalysis, sensor, energy conversion and storage, and biomedicine by loading large-size guest molecules (e.g., protein and RNA), precious metal nanoparticles and quantum dots, are discussed. At last, the outlook on the prospects and challenges of future research about the synthesis of large-pore OMMs by using tailor-made amphiphilic block copolymers are included.

Nanoengineering of Core-Shell Magnetic Mesoporous Microspheres with Tunable Surface Roughness.

Functional core-shell mesoporous microspheres with integrated functions, controlled structure, and surface properties and morphologies have received increasing attention due to their excellent physicochemical properties. Herein, core-shell magnetic mesoporous materials with cauliflower-like morphology and tunable surface roughness have been synthesized through a kinetics-controlled interface co-assembly and deposition of mesostructured nanocomposites on Fe3O4@RF microspheres (RF refers to resorcinol formaldehyde resin). The obtained microspheres, synthesized via this interface nanoengineering method, possess well-defined sandwich structure with a tunable rough morphology, uniform size (560-1000 nm), perpendicularly aligned mesopores (∼5.7 nm) in the outer shell, RF-protected magnetic responsive core, high surface area up to 382 m2/g, and large pore volume of 0.66 cm3/g. As a result of the unique surface features and magnetic properties, these microspheres exhibit excellent performance in stabilizing and oxygen-free manipulating aqueous solutions in petroleum ether by a magnetic field. They also exhibit superior cell uptake properties compared with traditional smooth core-shell magnetic mesoporous silica microspheres, opening up the possible applications in fast drug delivery in cancer therapy.

Plasmolysis-Inspired Nanoengineering of Functional Yolk-Shell Microspheres with Magnetic Core and Mesoporous Silica Shell.

Yolk-shell nanomaterials with a rattle-like structure have been considered ideal carriers and nanoreactors. Traditional methods to constructing yolk-shell nanostructures mainly rely on multistep sacrificial template strategy. In this study, a facile and effective plasmolysis-inspired nanoengineering strategy is developed to controllably fabricate yolk-shell magnetic mesoporous silica microspheres via the swelling-shrinkage of resorcinol-formaldehyde (RF) upon soaking in or removal of n-hexane. Using Fe3O4@RF microspheres as seeds, surfactant-silica mesostructured composite is deposited on the swelled seeds through the multicomponent interface coassembly, followed by solvent extraction to remove surfactant and simultaneously induce shrinkage of RF shell. The obtained yolk-shell microspheres (Fe3O4@RF@void@mSiO2) possess a high magnetization of 40.3 emu/g, high surface area (439 m2/g), radially aligned mesopores (5.4 nm) in the outer shell, tunable middle hollow space (472-638 nm in diameter), and a superparamagnetic core. This simple method allows a simultaneous encapsulation of Au nanoparticles into the hollow space during synthesis, and it leads to spherical Fe3O4@RF@void-Au@mSiO2 magnetic nanocatalysts, which show excellent catalysis efficiency for hydrogenation of 4-nitrophenol by NaBH4 with a high conversion rate (98%) and magnetic recycling stability.

Constructing Three-Dimensional Mesoporous Bouquet-Posy-like TiO2 Superstructures with Radially Oriented Mesochannels and Single-Crystal Walls.

Constructing three-dimensional (3-D) hierarchical mesostructures with unique morphology, pore orientation, single-crystal nature, and functionality remains a great challenge in materials science. Here, we report a confined microemulsion self-assembly approach to synthesize an unprecedented type of 3-D highly ordered mesoporous TiO2 superstructure (Level-1), which consists of 1 spherical core and 12 symmetric satellite hemispheres epitaxially growing out of the core vertices. A more complex and asymmetric TiO2 superstructure (Level-2) with 13 spherical cores and up to 44 symmetric satellite hemispheres can also be well manipulated by increasing the size or content of impregnated TiO2 precursor emulsion droplets. The obtained 3-D mesoporous TiO2 superstructures have well-defined bouquet-posy-like topologies, oriented hexagonal mesochannels, high accessible surface area (134-148 m2/g), large pore volume (0.48-0.51 cm3/g), and well single-crystalline anatase walls with dominant (001) active facets. More interestingly, all cylindrical mesopore channels are highly interconnected and radially distributed within the whole superstructures, and all TiO2 nanocrystal building blocks are oriented grown into a single-crystal anatase wall, making them ideal candidates for various applications ranging from catalysis to optoelectronics. As expected, the bouquet-posy-like mesoporous TiO2 superstructure supported catalysts show excellent catalytic activity (≥99.7%) and selectivity (≥96%) in cis-semihydrogenation of various alkynes, exceeding that of commercial TiO2 (P25) supported catalyst by a factor of 10. No decay in the activity was observed for 25 cycles, revealing a high stability of the mesoporous TiO2 superstructure supported catalyst.

Mesoporous Tungsten Oxides with Crystalline Framework for Highly Sensitive and Selective Detection of Foodborne Pathogens.

Foodborne pathogens like Listeria monocytogenes can cause various illnesses and pose a serious threat to public health. They produce species-specific microbial volatile organic compounds, i.e., the biomarkers, making it possible to indirectly measure microbial contamination in foodstuff. Herein, highly ordered mesoporous tungsten oxides with high surface areas and tunable pores have been synthesized and used as sensing materials to achieve an exceptionally sensitive and selective detection of trace Listeria monocytogenes. The mesoporous WO3-based chemiresistive sensors exhibit a rapid response, superior sensitivity, and highly selective detection of 3-hydroxy-2-butanone. The chemical mechanism study reveals that acetic acid is the main product generated by the surface catalytic reaction of the biomarker molecule over mesoporous WO3. Furthermore, by using the mesoporous WO3-based sensors, a rapid bacteria detection was achieved, with a high sensitivity, a linear relationship in a broad range, and a high specificity for Listeria monocytogenes. Such a good gas sensing performance foresees the great potential application of mesoporous WO3-based sensors for fast and effective detection of microbial contamination for the safety of food, water safety and public health.

A Micelle Fusion-Aggregation Assembly Approach to Mesoporous Carbon Materials with Rich Active Sites for Ultrasensitive Ammonia Sensing.

Nanostructured carbon materials have received considerable attention due to their special physicochemical properties. Herein, ordered mesoporous carbons (OMCs) with two-dimension (2D) hexagonal mesostructure and unique buckled large mesopores have successfully been synthesized via a micelle fusion-aggregation assembly method by using poly(ethylene oxide)-block-polystyrene (PEO-b-PS) diblock copolymers as a template and resorcinol-based phenolic resin as a carbon precursor. The obtained ordered mesoporous carbons possess unique fiber-like morphology, specific surface area of 571-880 m(2)/g, pore volume of 0.54 cm(3)/g and large mesopores (up to 36.3 nm) and high density of active sites (i.e., carboxylic groups) of 0.188/nm(2). Gas sensor based on the ordered mesoporous carbons exhibits an excellent performance in sensing NH3 at a low temperature with fast response (<2 min), ultralow limit of detection (<1 ppm), and good selectivity, due to the large pore sizes, high surface area and rich active sites in the carbon pore walls.

Epitaxial Growth of Lattice-Mismatched Core-Shell TiO2 @MoS2 for Enhanced Lithium-Ion Storage.

Core-shell structured nanohybrids are currently of significant interest due to their synergetic properties and enhanced performances. However, the restriction of lattice mismatch remains a severe obstacle for heterogrowth of various core-shells with two distinct crystal structures. Herein, a controlled synthesis of lattice-mismatched core-shell TiO2 @MoS2 nano-onion heterostructures is successfully developed, using unilamellar Ti0.87 O2 nanosheets as the starting material and the subsequent epitaxial growth of MoS2 on TiO2 . The formation of these core-shell nano-onions is attributed to an amorphous layer-induced heterogrowth mechanism. The number of MoS2 layers can be well tuned from few to over ten layers, enabling layer-dependent synergistic effects. The core-shell TiO2 @MoS2 nano-onion heterostructures exhibit significantly enhanced energy storage performance as lithium-ion battery anodes. The approach has also been extended to other lattice-mismatched systems such as TiO2 @MoSe2 , thus suggesting a new strategy for the growth of well-designed lattice-mismatched core-shell structures.

Ordered Macro/Mesoporous TiO2 Hollow Microspheres with Highly Crystalline Thin Shells for High-Efficiency Photoconversion.

Well ordered, uniform 3D open macro/mesoporous TiO2 hollow microspheres with highly crystalline anatase thin shells have been successfully synthesized by a simple solvent evaporation-driven confined self-assembly method. The 3D open macro/mesoporous TiO2 hollow microspheres show high energy-conversion efficiency (up to 9.5%) and remarkable photocatalytic activity (with photodegradation of 100% for methylene blue in 12 min under UV light irradiation).

General strategy to synthesize uniform mesoporous TiO2/graphene/mesoporous TiO2 sandwich-like nanosheets for highly reversible lithium storage.

Uniform oxide deposition on graphene to form a sandwich-like configuration is a well-known challenge mainly due to their large lattice mismatches and poor affinities. Herein, we report a general strategy to synthesize uniform mesoporous TiO2/graphene/mesoporous TiO2 sandwich-like nanosheets (denoted as G@mTiO2), which cannot be achieved by conventional one-pot synthetic methods. We show that by rational control of hydrolysis and condensation of Ti precursors in a slow way, GO sheets can be conformably coated by amorphous TiO2 shells, which then can be facilely transformed into the well-defined G@mTiO2 nanosheets by annealing. This amorphous-to-crystalline strategy conveniently allows bypassing strain fields that would inevitably arise if direct growth of mesoporous anatase shells on graphene. As distinct from the most common structures of graphene-based composites (mixed, wrapped, or anchored models), the resultant materials display a uniform sandwich-like configuration: few-layer graphene conformably encapsulated by mesoporous TiO2 shells. This new G@mTiO2 nanosheet exhibits ultrathin nature (∼34 nm), small size and high crystalline nanocrystals (∼6 nm), high surface areas (∼252 m(2)/g) and uniform mesopores (∼3.4 nm). We further show that the thickness of mesoporous TiO2 shells can be facilely adjusted as desired by controlling the ammonia content, and this facile strategy can be easily extended to design other oxide/graphene/oxide sandwich-like materials. More importantly, we showcase the benefits of the resultant G@mTiO2 nanosheets as anodes in lithium ion batteries: they deliver an extra high capacity, an excellent high-rate capability, and long cycle life.

An Interface Coassembly in Biliquid Phase: Toward Core-Shell Magnetic Mesoporous Silica Microspheres with Tunable Pore Size.

Core-shell magnetic mesoporous silica microspheres (Magn-MSMs) with tunable large mesopores in the shell are highly desired in biocatalysis, magnetic bioseparation, and enrichment. In this study, a shearing assisted interface coassembly in n-hexane/water biliquid systems is developed to synthesize uniform Magn-MSMs with magnetic core and mesoporous silica shell for an efficient size-selective biocatalysis. The synthesis features the rational control over the electrostatic interaction among cationic surfactant molecules, silicate oligomers, and Fe3O4@RF microspheres (RF: resorcinol formaldehyde) in the presence of shearing-regulated solubilization of n-hexane in surfactant micelles. Through this multicomponent interface coassembly, surfactant-silica mesostructured composite has been uniformly deposited on the Fe3O4@RF microspheres, and core-shell Magn-MSMs are obtained after removing the surfactant and n-hexane. The obtained Magn-MSMs possess excellent water dispersibility, uniform diameter (600 nm), large and tunable perpendicular mesopores (5.0-9.0 nm), high surface area (498-623 m(2)/g), large pore volume (0.91-0.98 cm(3)/g), and high magnetization (34.5-37.1 emu/g). By utilization of their large and open mesopores, Magn-MSMs with a pore size of about 9.0 nm have been demonstrated to be able to immobilize a large bioenzyme (trypsin with size of 4.0 nm) with a high loading capacity of ∼97 µg/mg via chemically binding. Magn-MSMs with immobilized trypsin exhibit an excellent convenient and size selective enzymolysis of low molecular proteins in the mixture of proteins of different sizes and a good recycling performance by using the magnetic separability of the microspheres.

Solar-driven photoelectrochemical probing of nanodot/nanowire/cell interface.

We report a nitrogen-doped carbon nanodot (N-Cdot)/TiO2 nanowire photoanode for solar-driven, real-time, and sensitive photoelectrochemical probing of the cellular generation of H2S, an important endogenous gasotransmitter based on a tunable interfacial charge carrier transfer mechanism. Synthesized by a microwave-assisted solvothermal method and subsequent surface chemical conjugation, the obtained N-Cdot/TiO2 nanowire photoanode shows much enhanced photoelectrochemical photocurrent compared with pristine TiO2 nanowires. This photocurrent increase is attributed to the injection of photogenerated electrons from N-Cdots to TiO2 nanowires, confirmed by density functional theory simulation. In addition, the charge transfer efficiency is quenched by Cu(2+), whereas the introduction of H2S or S(2-) ions resets the charge transfer and subsequently the photocurrent, thus leading to sensitive photoelectrochemical recording of the H2S level in buffer and cellular environments. Moreover, this N-Cdot-TiO2 nanowire photoanode has been demonstrated for direct growth and interfacing of H9c2 cardiac myoblasts, with the capability of interrogating H2S cellular generation pathways by vascular endothelial growth factor stimulation as well as inhibition.

Fully solar-powered photoelectrochemical conversion for simultaneous energy storage and chemical sensing.

We report the development of a multifunctional, solar-powered photoelectrochemical (PEC)-pseudocapacitive-sensing material system for simultaneous solar energy conversion, electrochemical energy storage, and chemical detection. The TiO2 nanowire/NiO nanoflakes and the Si nanowire/Pt nanoparticle composites are used as photoanodes and photocathodes, respectively. A stable open-circuit voltage of ∼0.45 V and a high pseudocapacitance of up to ∼455 F g(-1) are obtained, which also exhibit a repeating charging-discharging capability. The PEC-pseudocapacitive device is fully solar powered, without the need of any external power supply. Moreover, this TiO2 nanowire/NiO nanoflake composite photoanode exhibits excellent glucose sensitivity and selectivity. Under the sun light illumination, the PEC photocurrent shows a sensitive increase upon different glucose additions. Meanwhile in the dark, the open-circuit voltage of the charged pseudocapacitor also exhibits a corresponding signal over glucose analyte, thus serving as a full solar-powered energy conversion-storage-utilization system.

Biological Screening of Newly Synthesized BIAN N-Heterocyclic Gold Carbene Complexes in Zebrafish Embryos.

N-Heterocyclic carbene (NHC) metal complexes possess diverse biological activities but have yet to be extensively explored as potential chemotherapeutic agents. We have previously reported the synthesis of a new class of NHC metal complexes N-heterocyclic with acetate [IPr(BIAN)AuOAc] and chloride [IPr(BIAN)AuCl] ligands. In the experiments reported herein, the zebrafish embryos were exposed to serial dilutions of each of these complexes for 10-12 h. One hundred percent mortality was observed at concentrations≥50 µM. At sub-lethal concentrations (10-30 µM), both compounds influenced zebrafish embryonic development. However, quite diverse categories of abnormalities were found in exposed embryos with each compound. Severe brain deformation and notochord degeneration were evident in the case of [IPr(BIAN)AuOAc]. The zebrafish embryos treated with [IPr(BIAN)AuCl] exhibited stunted growth and consequently had smaller body sizes. A depletion of 30%-40% glutathione was detected in the treated embryos, which could account for one of the possible mechanism of neurotoxicity. The fact that these compounds are capable of both affecting the growth and also compromising antioxidant systems by elevating intracellular ROS production implies that they could play an important role as a new breed of therapeutic molecules.

Growth of Single-Layered Two-Dimensional Mesoporous Polymer/Carbon Films by Self-Assembly of Monomicelles at the Interfaces of Various Substrates.

Single-layered two-dimensional (2D) ultrathin mesoporous polymer/carbon films are grown by self-assembly of monomicelles at the interfaces of various substrates, which is a general and common modification strategy. These unconventional 2D mesoporous films possess only a single layer of mesopores, while the size of the thin films can grow up to inch size in the plane. Free-standing transparent mesoporous carbon ultrathin films, together with the ordered mesoporous structure on the substrates of different compositions (e.g. metal oxides, carbon) and morphologies (e.g. nanocubes, nanodiscs, flexible and patterned substrates) have been obtained. This strategy not only affords controllable hierarchical porous nanostructures, but also appends the easily modified and multifunctional properties of carbon to the primary substrate. By using this method, we have fabricated Fe2 O3 -mesoporous carbon photoelectrochemical biosensors, which show excellent sensitivity and selectivity for glutathione.