Ultra-large Surface Area Research Articles

Role of Graphene Nano-Composites in Cancer Therapy: Theranostic Applications, Metabolic Fate and Toxicity Issues.

Graphene and its modified nano-composites have gained much attention in recent times in cancer therapy as nanotheranostics due to low production cost, ease in synthesis and physicochemical properties (ultra-large surface area with planar structure and π-π conjugation with the unsaturated and aromatic drugs/biomolecules) being favorable for multiple payloads and drug targeting. Yet, graphene nano-composites are a relatively new and rapid development. The adoption of graphene nano-composites in cancer nanobiomedicine research raises questions about in vivo metabolism and disposition as well as biological interaction and safety profile of these nano-particles. Limited in-vitro and in-vivo findings are available in literature, indicating the inconsistencies about the factors affecting in-vivo bio-interaction and toxicity. Presently, there is a lack of anticipated biodistribution and toxicity pattern of graphene. It appears that surface functionalization, biocompatible coating, and size are the key factors in determining the metabolic fate of graphene nano-composites. In-vitro and in-vivo toxicity data suggests that graphene nano-composites exhibit dose and size dependent toxicity. This review summarizes up-to-date research outcome of this promising inorganic nanomaterial for cancer therapy. Moreover, the metabolic fate and toxicity issues of graphene and its nano-composites shall also be discussed in detail.

Facile Preparation of Core-Shell Magnetic Metal-Organic Framework Nanoparticles for the Selective Capture of Phosphopeptides.

In regard to the phosphoproteome, highly specific and efficient capture of heteroideous kinds of phosphopeptides from intricate biological sample attaches great significance to comprehensive and in-depth phosphorylated proteomics research. However, until now, it has been a challenge. In this study, a new-fashioned porous immobilized metal ion affinity chromatography (IMAC) material was designed and fabricated to promote the selectivity and detection limit for phosphopeptides by covering a metal-organic frameworks (MOFs) shell onto Fe3O4 nanoparticles, taking advantage of layer-by-layer method (the synthesized nanoparticle denoted as Fe3O4@MIL-100 (Fe)). The thick layer renders the nanoparticles with perfect hydrophilic character, super large surface area, large immobilization of the Fe(3+) ions and the special porous structure. Specifically, the as-synthesized MOF-decorated magnetic nanoparticles own an ultra large surface area which is up to 168.66 m(2) g(-1) as well as two appropriate pore sizes of 1.93 and 3.91 nm with a narrow grain-size distribution and rapid separation under the magnetic circumstance. The unique features vested the synthesized nanoparticles an excellent ability for phosphopeptides enrichment with high selectivity for β-casein (molar ratio of β-casein/BSA, 1:500), large enrichment capacity (60 mg g(-1)), low detection limit (0.5 fmol), excellent phosphopeptides recovery (above 84.47%), fine size-exclusion of high molecular weight proteins, good reusability, and desirable batch-to-batch repeatability. Furthermore, encouraged by the experimental results, we successfully performed the as-prepared porous IMAC nanoparticle in the specific capture of phosphopeptides from the human serum (both the healthy and unhealthy) and nonfat milk, which proves itself to be a good candidate for the enrichment and detection of the low-abundant phosphopeptides from complicated biological samples.

Scalable synthesis of three-dimensional interconnected mesoporous TiO2 nanotubes with ultra-large surface area

Mesoporous nanotubes represent a unique class of nanostructures with numerous applications including biomaterials, lithium ion battery anodes, and photocatalysts. Herein we describe for the first time a general, scalable, and reproducible approach for the production of 3D interconnected mesoporous TiO2 nanotubes with ultrahigh specific surface area and large pore volume by using a nanofibrous template of bacterial cellulose (BC). The obtained samples were characterized by Brunauer–Emmett–Teller (BET) surface area measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results demonstrated that TiO2 nanotubes sustained the 3D interconnected structure of pristine BC and exhibited an average diameter of 36nm and a mesoporous wall with a mean mesopore size of 3.2nm. The particular structure endows TiO2 nanotubes with ultra-large surface area (1629m2g−1) and high photocatalytic activity.

Nanoscale Fluid Mechanics and Energy Conversion

Under nanoconfinement, fluid molecules and ions exhibit radically different configurations, properties, and energetics from those of their bulk counterparts. These unique characteristics of nanoconfined fluids, along with the unconventional interactions with solids at the nanoscale, have provided many opportunities for engineering innovation. With properly designed nanoconfinement, several nanofluidic systems have been devised in our group in the past several years to achieve energy conversion functions with high efficiencies. This review is dedicated to elucidating the unique characteristics of nanofluidics, introducing several novel nanofluidic systems combining nanoporous materials with functional fluids, and to unveiling their working mechanisms. In all these systems, the ultra-large surface area available in nanoporous materials provides an ideal platform for seamlessly interfacing with nanoconfined fluids, and efficiently converting energy between the mechanical, thermal, and electrical forms. These systems have been demonstrated to have great potentials for applications including energy dissipation/absorption, energy trapping, actuation, and energy harvesting. Their efficiencies can be further enhanced by designing efforts based upon improved understanding of nanofluidics, which represents an important addition to classical fluid mechanics. Through the few systems exemplified in this review, the emerging research field of nanoscale fluid mechanics may promote more exciting nanofluidic phenomena and mechanisms, with increasing applications by encompassing aspects of mechanics, materials, physics, chemistry, biology, etc.

Precise extension-mode resonant sensor with uniform and repeatable sensitivity for detection of ppm-level ammonia

This paper presents a micromechanical resonant gas sensor, which is operated in extensional bulk mode, for high-accuracy sensing of ultra-low concentration chemical vapors. The designed and fabricated gravimetric resonant microsensor has exhibited both high Q-factor of 11157 in air and high mass sensitivity of 10.16 Hz pg−1. Much more importantly, both theoretical analysis and sensing experiment have verified that such an extensional resonance mode is technically advantageous in sensing accuracy (e.g., output signal linearity in terms of gas concentration and reproducibility of sensitivity), which can be attributed to the uniform vibration amplitude at each point of the gas-adsorbing area. Loaded with –COOH functionalized mesoporous-silica nanopaticles as sensing material, which features an ultra-large surface area, the chemical sensing micro-resonator experimentally performs precise detection performance to ppm-level ammonia vapor. The limit of detection is as low as 1 ppm and the response time of the sensor is as short as 10 s.

Novel graphene oxide sponge synthesized by freeze-drying process for the removal of 2,4,6-trichlorophenol

Graphene oxide (GO) spongy materials as environmental pollutant scavengers have drawn great attention owing to their ultralarge surface area, unique spongy structure and hydrogen-bonding interactions.

Facile preparation of mesocellular graphene foam for direct glucose oxidase electrochemistry and sensitive glucose sensing

Biocompatible mesocellular graphene foam (MGF) was easily synthesized and conveniently used for the immobilization, direct electrochemistry, and biosensing of glucose oxidase (GOD). Detailed characterization revealed that the as-prepared MGF has high conductivity, ultra-large surface area (2581m2g−1) and pore volume (5.53cm3g−1) as well as high loading of GOD. When the pristine MGF served as a glucose biosensor, the direct and fast electron transfer with rate constant of 4.8s−1 was observed by cyclic voltammetry measurements. Based on the decrease of electrocatalytic currents, the prepared biosensor exhibited a wide linear range from 1.0 to 12mM with a detection limit of 0.25mM and a sensitivity of 2.87μAmM−1cm−2. Furthermore, the repeated and long-run test showed that the glucose biosensor was stable in both direct electrochemistry and sensitive glucose sensing. All these features besides the facile preparation, suggested that MGF would be a potential matrix for novel biosensor preparation.

Three-Dimensional Graphene Oxide Nanostructure for Fast and Efficient Water-Soluble Dye Removal

In this study, we demonstrated the potential of graphene nanomaterials as environmental pollutant adsorbents by utilizing the characteristics of ultralarge surface area and strong π-π interaction on the surface. We generated a three-dimensional (3D) graphene oxide sponge (GO sponge) from a GO suspension through a simple centrifugal vacuum evaporation method, and used them to remove both the methylene blue (MB) and methyl violet (MV) dyes which are main contaminants from the dye manufacturing and textile finishing. The efficiency and speed of dye adsorption on a GO sponge was investigated under various parameters such as contact time, stirring speed, temperature, and pH. The adsorption process shows that 99.1% of MB and 98.8% of MV have been removed and the equilibrium status has been reached in 2 min. The 3D GO sponge displays adsorption capacity as high as 397 and 467 mg g(-1) for MB and MV dye, respectively, and the kinetic data reveal that the adsorption process of MB and MV dyes is well-matched with the pseudo second-order model. The MB and MV adsorption on the 3D GO sponge involved in endothermic chemical adsorption through the strong π-π stacking and anion-cation interaction with the activation energy of 50.3 and 70.9 kJ mol(-1), respectively. The 3D GO sponge has demonstrated its high capability as an organic dye scavenger with high speed and efficiency.

Application of graphene for preconcentration and highly sensitive stripping voltammetric analysis of organophosphate pesticide

Electrochemical reduced β-cyclodextrin dispersed graphene (β-CD-graphene) was developed as a sorbent for the preconcentration and electrochemical sensing of methyl parathion (MP), a representative nitroaromatic organophosphate pesticide with good redox activity. Benefited from the ultra-large surface area, large delocalized π-electron system and the superconductivity of β-CD-graphene, large amount of MP could be extracted on β-CD-graphene modified electrode via strong π–π interaction and exhibited fast accumulation and electron transfer rate. Combined with differential pulse voltammetric analysis, the sensor shows ultra-high sensitivity, good selectivity and fast response. The limit of detection of 0.05 ppb is more than 10 times lower than those obtained from other sorbent based sensors. The method may open up a new possibility for the widespread use of electrochemical sensors for monitoring of ultra-trace OPs.

Thinning vertical graphenes, tuning electrical response: from semiconducting to metallic

A simple, uniquely plasma-enabled and environment-friendly process to reduce the thickness of vertically standing graphenes to only 4–5 graphene layers and arranging them in dense, ultra-large surface area, ultra-open-edge-length, self-organized and interconnected networks is demonstrated. The approach for the ultimate thickness reduction to 1–2 graphene layers is also proposed. The vertical graphene networks are optically transparent and show tunable electric properties from semiconducting to semi-metallic and metallic at room and near-room temperature, thus recovering semi-metallic properties of a single-layer graphene.

Controllable Fabrication of Three-Dimensional Radial ZnO Nanowire/Silicon Microrod Hybrid Architectures

A facile method by combining bottom-up and top-down approaches was developed to construct uniform three-dimensional (3D) ZnO nanowires (NWs)/silicon microrod (SiMR) hybrid architectures. Patterned SiMR arrays with controlled geometry and density were structured by photolithography and chemical etching on single-crystal silicon wafers, which subsequently served as 3D scaffolds for the ZnO NW growth. In contrast to the top-down approach to fabricate SiMR scaffolds, the radial ZnO NWs grown conformally on the SiMRs follow a bottom-up method by employing a modified carbon-assisted self-catalytic growth via chemical vapor deposition. The light absorption and the photocatalytic capability of methyl red of ZnO NW arrays were demonstrated to improve significantly by the 3D constructions. The method is expected to be applicable to the synthesis of 3D hybrid structures of other nanomaterials. The heterojunction and ultralarge surface area of the 3D architectures are promising for diverse applications in photovoltaics, catalysts, and sensing.

Review. Processing, Properties and Applications of Reactive Silica from Rice Husk — An Overview

AbstractFor Abstract see ChemInform Abstract in Full Text.

Review Processing, properties and applications of reactive silica from rice husk—an overview

Rice husk is an abundantly available waste material in all rice producing countries. In certain regions, it is sometimes used as a fuel for parboiling paddy in the rice mills. The partially burnt rice husk in turn contributes to more environmental pollution. There have been efforts not only to overcome this but also to find value addition to these wastes using them as secondary source of materials. Rice husk contains nearly 20% silica, which is present in hydrated amorphous form. On thermal treatment, the silica converts to crystobalite, which is a crystalline form of silica. However, under controlled burning conditions, amorphous silica with high reactivity, ultra fine size and large surface area is produced. This micro silica can be a source for preparing advanced materials like SiC, Si3N4, elemental Si and Mg2Si. Due to the high pozzolanic activity, this rice husk silica also finds application in high strength concrete as a substitute for silica fume. Possibility of using this silica as filler in polymers is also studied. The present paper is an attempt to consolidate and critically analyse the research work carried out so far on the processing, properties and application of rice husk silica in various laboratories and also highlighting some results on the processing and characterization of RHA and reactive silica obtained from it in the authors' laboratory.