Reactant enrichment in hollow void of Pt NPs@MnOx nanoreactors for boosting hydrogenation performance.

In confined mesoscopic spaces, the unraveling of a catalytic mechanism with complex mass transfer and adsorption processes such as reactant enrichment is a great challenge. In this study, a hollow nanoarchitecture of MnOx-encapsulated Pt nanoparticles was designed as a nanoreactor to investigate the reactant enrichment in a mesoscopic hollow void. By employing advanced characterization techniques, we found that the reactant-enrichment behavior is derived from directional diffusion of the reactant driven through the local concentration gradient and this increased the amount of reactant. Combining experimental results with density functional theory calculations, the superior cinnamyl alcohol (COL) selectivity originates from the selective adsorption of cinnamaldehyde (CAL) and the rapid formation and desorption of COL in the MnOx shell. The superb performance of 95% CAL conversion and 95% COL selectivity is obtained at only 0.5 MPa H2 and 40 min. Our findings showcase that a rationally designed nanoreactor could boost catalytic performance in chemoselective hydrogenation, which can be of great aid and potential in various application scenarios.

Construction of hollow mesoporous silica nanoreactors for enhanced photo-oxidations over Au-Pt catalysts.

It is highly desirable to design hollow structures with multi-scale functions by mimicking cells for the construction of micro/nanoreactors. Herein, we report the construction of hollow-structured submicrometer-photoreactors with bimetallic catalysts loaded within mesoporous silicas. The synthesis parameters are optimized to study the evolution of hollow structure through hydrothermal treatment and an 'adhesive-contraction' formation mechanism is proposed. AuPt@HMZS catalysts exhibited a broader absorbance region under visible light and the adsorption edge displayed a red-shift, indicating the strong metal-metal interactions at the alloy interface. The reaction performance of the coupled Au-Pt catalysts can be tuned to achieve excellent catalytic activity in cinnamyl alcohol oxidation to cinnamic acid for 3.1 mmol g-1 with 99% selectivity. The proposed strategy to build hollow structures as multifunctional micro/nanoreactors is promising for the design of high-performance and sustainable catalysts for chemical synthesis.

Advances in Multicompartment Mesoporous Silica Micro/Nanoparticles for Theranostic Applications.

Mesoporous silica nanoparticles (MSNs) are promising functional nanomaterials for a variety of biomedical applications, such as bioimaging, drug/gene delivery, and cancer therapy. This is due to their low density, low toxicity, high biocompatibility, large specific surface areas, and excellent thermal and mechanical stability. The past decade has seen rapid advances in the development of MSNs with multiple compartments. These include hierarchical porous structures and core-shell, yolk-shell, and Janus structured particles for efficient diagnosis and therapeutic applications. We review advances in this area, covering the categories of multicompartment MSNs and their synthesis methods, with an emphasis on hierarchical structures and the incorporation of multiple functions. We classify multicompartment mesoporous silica micro/nanostructures, ranging from core-shell and yolk-shell structures to Janus and raspberry-like nanoparticles, and discuss their synthesis methods. We review applications of these multicompartment MSNs, including bioimaging, targeted drug/gene delivery, chemotherapy, phototherapy, and in vitro diagnostics. We also highlight the latest trends and new opportunities.

Dumbbell-Shaped Bi-component Mesoporous Janus Solid Nanoparticles for Biphasic Interface Catalysis.

There is a strong desire to design and synthesize catalysts that assemble at the oil-water interface to improve the efficiency of biphasic reactions. Anisotropic dumbbell-shaped bi-component mesoporous carbon-organosilica Janus particles with asymmetric wettability are synthesized through a one-step compartmentalized growth of a mesoporous organosilica sphere attached to a mesoporous resorcinol-formaldehyde (RF) sphere. A library was prepared of tunable Janus particles possessing diverse hollow structures with various functionalities. As a proof of concept, the Janus particle-derived catalyst can assemble at the oil-water interface to stabilize Pickering emulsions. Owing to the increased reaction interface area, the Janus catalyst exhibits a more than three-fold increase in catalytic efficiency compared to the Pt loaded carbon sphere catalyst in aqueous hydrogenation reactions.

Clay nanosheets for topical delivery of RNAi for sustained protection against plant viruses.

Topical application of pathogen-specific double-stranded RNA (dsRNA) for virus resistance in plants represents an attractive alternative to transgenic RNA interference (RNAi). However, the instability of naked dsRNA sprayed on plants has been a major challenge towards its practical application. We demonstrate that dsRNA can be loaded on designer, non-toxic, degradable, layered double hydroxide (LDH) clay nanosheets. Once loaded on LDH, the dsRNA does not wash off, shows sustained release and can be detected on sprayed leaves even 30 days after application. We provide evidence for the degradation of LDH, dsRNA uptake in plant cells and silencing of homologous RNA on topical application. Significantly, a single spray of dsRNA loaded on LDH (BioClay) afforded virus protection for at least 20 days when challenged on sprayed and newly emerged unsprayed leaves. This innovation translates nanotechnology developed for delivery of RNAi for human therapeutics to use in crop protection as an environmentally sustainable and easy to adopt topical spray.

Controllable synthesis of concave cubic gold core-shell nanoparticles for plasmon-enhanced photon harvesting.

Well-defined core-shell nanoparticles (NPs) containing concave cubic Au cores and TiO2 shells (CA@T) were synthesized in colloidal suspension. These CA@T NPs exhibit Localized Surface Plasmon Resonance (LSPR) absorption in the NIR region, which provides a unique property for utilizing the low energy range of the solar spectrum. In order to evaluate the plasmonic enhancement effect, a variety of CA@T NPs were incorporated into working electrodes of dye-sensitized solar cells (DSSCs). By adjusting the shell thickness of CA@T NPs, the plasmonic property can be tuned to achieve maximum photovoltaic improvement. Furthermore, the DSSC cells fabricated with the CA@T NPs exhibit a remarkably plasmonic assisted conversion efficiency enhancement (23.3%), compared to that (14.8%) of the reference cells assembled with spherical Au@TiO2 core-shell (SA@T) NPs under similar conditions. Various characterizations reveal that this performance improvement is attributed to the much stronger electromagnetic field generated at the hot spots of CA@T NPs, resulting in significantly higher light harvesting and more efficient charge separation. This study also provides new insights into maximizing the plasmonic enhancement, offering great potential in other applications including light-matter interaction, photocatalytic energy conversion and new-generation solar cells.

Enhanced transcription and translation in clay hydrogel and implications for early life evolution.

In most contemporary life forms, the confinement of cell membranes provides localized concentration and protection for biomolecules, leading to efficient biochemical reactions. Similarly, confinement may have also played an important role for prebiotic compartmentalization in early life evolution when the cell membrane had not yet formed. It remains an open question how biochemical reactions developed without the confinement of cell membranes. Here we mimic the confinement function of cells by creating a hydrogel made from geological clay minerals, which provides an efficient confinement environment for biomolecules. We also show that nucleic acids were concentrated in the clay hydrogel and were protected against nuclease, and that transcription and translation reactions were consistently enhanced. Taken together, our results support the importance of localized concentration and protection of biomolecules in early life evolution, and also implicate a clay hydrogel environment for biochemical reactions during early life evolution.

Antibody-targeted drug delivery to injured arteries using layered double hydroxide nanoparticles.

Targeted local delivery of a nanoparticle-based, antibody-targeted, and low molecular weight heparin (LMWH) delivery system successfully reduces restenosis and thrombus formation in an animal model. An antibody recognizing cross-linked fibrin (XLF) D-dimer is successfully conjugated to layered double hydroxide nanoparticles. Use of the anti-XLF-conjugated LMWH-carrying layered double hydroxide nanoparticles shows successful targeting of the nanoparticles (red) to the injured artery wall (green), resulting in decreased neointimal thickening and thrombus formation.

Cubic CeO2 nanoparticles as mirror-like scattering layers for efficient light harvesting in dye-sensitized solar cells.

A new type of bilayered photoanodes with cubic CeO(2) nanoparticles as mirror-like scattering thin layers was prepared via a screen-printing technique for dye-sensitized solar cells (DSSCs). The light harvesting efficiency was significantly enhanced due to the mirror-like light scattering effect, resulting in noticeable ∼17.8% improvement of light-to-electric conversion efficiency.

The effects of aspect ratio of inorganic fillers on the structure and property of composite ion-exchange membranes.

A new type of nanocomposite ion-exchange membranes containing sulfonated polyethersulfone (sPES) polymer matrix and sulfonated surface-functionalized mesoporous silica (SS) inorganic fillers was prepared. Various characterizations revealed that the addition of inorganic fillers with different shapes had a significant influence on the membrane structure. The mesoporous inorganic fillers not only created extra pore and water channels, assisting the ionic migration and improving conductivity of the composites, but also provided additional fixed charge groups upon surface modification. This allows the Donnan exclusion to work effectively and thus improve the selectivity of membranes. It was proved that the incorporation of appropriate amount of SS additive could significantly improve the conductivity (up to 20 folds) and permselectivity (about 14%) of the sPES membranes. The performance of these newly developed membranes in desalination by electrodialysis was comparable with that of a commercial membrane (FKE).

Cellular trafficking of low molecular weight heparin incorporated in layered double hydroxide nanoparticles in rat vascular smooth muscle cells.

This paper reports a clear elucidation of the pathway for the cellular delivery of layered double hydroxide (LDH) nanoparticles intercalated with anti-restenotic low molecular weight heparin (LMWH). Cellular uptake of LMWH-LDH conjugates into cultured rat vascular smooth muscle cells (SMCs) measured via flow cytometry was more than ten times greater than that of LMWH alone. Confocal and transmission electron microscopy showed LMWH-LDH conjugates taken up by endosomes, then released into the cytoplasm. We propose that LMWH-LDH is taken up via a unique 'modified endocytic' pathway, whereby the conjugate is internalized by SMCs in early endosomes, sorted in late endosomes, and quickly released from late endosomes/lysosomes, avoiding degradation. Treatment of cells with LMWH-LDH conjugates suppressed the activation of ERK1/2 in response to foetal calf serum (FCS) for up to 24h, unlike unconjugated LMWH which had no significant effect at 24h. Improved understanding of the intracellular pathway of LMWH-LDH nanohybrids in SMC will allow for refinement of design for LDH nanomedicine applications.

Dipolar molecules as impellers achieving electric-field-stimulated release.

Here we report the design of a new external electric field-controlled release system using functional dipolar molecules as nanoimpellers. The dipolar molecule 4-(3-cyanophenyl)butylene, which can reorient in response to external electric fields with different frequencies because of its strong inherent dipole moment, was synthesized and grafted onto the inner surfaces of mesopores. Under an alternating electric field, the swinging flexible molecular chains consequently push guest molecules out of the pore voids. This innovative approach to controlled release may provide important application opportunities in tumor treatment with a number of advantages in terms of local release with targetability, external remote control, and the nonelectrochemical nature of the process.

Transforming triglycerides and fatty acids into biofuels.

Fuels derived from biobased materials are attracting attention for their potential in securing the energy supply and protecting the environment. In this Minireview, we evaluate the use of biobased sources, particularly fatty acids and triglycerides from seed oils and animal fats, as fuels. The physical and chemical properties of these fatty acids and triglycerides are discussed, including the link to their sources and current availability to meet fuel demands. The current technologies, also known as the first-generation ones, for converting triglycerides into fuels are covered, including conventional methods such as transesterification, pyrolysis, cracking, and emulsions. Recent, second-generation technological developments that lead to more commercially viable biofuels based on diesel-like hydrocarbons are also discussed.

Micro-Raman spectroscopic observation of water expulsion induced destruction of hydrophobic clusters in crystalline lysozyme.

In this paper, three kinds of solid lysozyme samples with different water contents were investigated by confocal Raman spectroscopy. For the rod-like lysozyme crystal with highest water content, a sudden decrease of the intensity ratio of the doublet at 1338 and 1360 cm(-1) was observed when the ambient relative humidity (RH) was lower than 86%, indicating the destruction of hydrophobic clusters of lysozyme induced by the expulsion of the hydration water from the crystal. In contrast to the rod-like crystal, tetragonal crystal and floor-like precipitate with a smaller amount of water showed no change of the structures of the hydrophobic clusters when the relative humidity was decreasing. The presence of bulk water in the rod-like crystal is believed a necessary factor for the function of the hydration water which promotes the hydrophobicity of hydrophobic clusters.

Facile synthesis and characterization of potassium-doped MnO2 nanowires.

A new type of potassium doped manganese oxide nanowires were synthesized using a simple hydrothermal route. The reduction of MnO4- in the presence of acetate species led to the formation of the Multi-filamentous nanowire structure. Detailed TEM and chemical characterizations indicated that potassium ions were homogeneously distributed in the nanowires. XPS results show a clear binding energy shift (1 eV) for K(2p) peak in nanowires compared with its starting material of KMnO4. Detailed synthetic condition investigation indicated that the presence of acetate ions played an important role in the formation of such a type of nanowires other than layered structures.

Chemoselective catalytic conversion of glycerol as a biorenewable source to valuable commodity chemicals.

New opportunities for the conversion of glycerol into value-added chemicals have emerged in recent years as a result of glycerol's unique structure, properties, bioavailability, and renewability. Glycerol is currently produced in large amounts during the transesterification of fatty acids into biodiesel and as such represents a useful by-product. This paper provides a comprehensive review and critical analysis on the different reaction pathways for catalytic conversion of glycerol into commodity chemicals, including selective oxidation, selective hydrogenolysis, selective dehydration, pyrolysis and gasification, steam reforming, thermal reduction into syngas, selective transesterification, selective etherification, oligomerization and polymerization, and conversion of glycerol into glycerol carbonate.

Co(3)(PO(4))(2)·4H(2)O.

Single crystals of Co(3)(PO(4))(2)·4H(2)O, tricobalt(II) bis-[ortho-phosphate(V)] tetra-hydrate, were obtained under hydro-thermal conditions. The title compound is isotypic with its zinc analogue Zn(3)(PO(4))(2)·4H(2)O (mineral name hopeite) and contains two independent Co(2+) cations. One Co(2+) cation exhibits a slightly distorted tetra-hedral coordination, while the second, located on a mirror plane, has a distorted octa-hedral coordination environment. The tetra-hedrally coordinated Co(2+) is bonded to four O atoms of four PO(4) (3-) anions, whereas the six-coordinate Co(2+) is cis-bonded to two phosphate groups and to four O atoms of four water mol-ecules (two of which are located on mirror planes), forming a framework structure. In addition, hydrogen bonds of the type O-H⋯O are present throughout the crystal structure.

A second polymorph with composition Co(3)(PO(4))(2)·H(2)O.

Single crystals of Co(3)(PO(4))(2)·H(2)O, tricobalt(II) bis-[ortho-phosphate(V)] monohydrate, were obtained under hydro-thermal conditions. The compound is the second polymorph of this composition and is isotypic with its zinc analogue, Zn(3)(PO(4))(2)·H(2)O. Three independent Co(2+) cations are bridged by two independent orthophosphate anions. Two of the metal cations exhibit a distorted tetra-hedral coordination while the third exhibits a considerably distorted [5 + 1] octa-hedral coordination environment with one very long Co-O distance of 2.416 (3) Å. The former cations are bonded to four different phosphate anions, and the latter cation is bonded to four anions (one of which is bidentate) and one water mol-ecule, leading to a framework structure. Additional hydrogen bonds of the type O-H⋯O stabilize this arrangement.

Fe-USY zeolite catalyst for effective decomposition of nitrous oxide.

Zeolite matrix FAU is applied as an effective support that can be readily exchanged with ferric ions simply by wet ion exchange. The high exchange degree in this zeolite (USY) probably benefits from its larger channel dimension, which makes the diffusion of hydrated ferric ions into the channels easier. The as-prepared and subsequently calcined Fe-USY samples contain various kinds of iron species, which enable Fe-USY to efficiently decompose N2O to N2 and O2. The presence of O2 (20%), H2O (2%), or both reduces the N2O conversion only to a small extent at the same temperature. To test the feasibility and the catalytic activity in a practical situation, we prepared a monolithic Fe-USY/cordierite sample and investigated the N2O conversion under similar conditions. Such a cordierite-supported Fe-USY catalyst (approximately 9 wt % USY and 0.5 wt % Fe) shows the catalytic performance in N20 decomposition similar to the pure Fe-USY catalyst. Remarkably, both the pure Fe-USY and Fe-USY/cordierite catalysts demonstrate a very good durability because there is no activity lost after 100 and 144 h tests. Thus, the Fe-USY zeolite shows its potential as a cost-effective catalyst for N2O elimination in future applications.