Effects of temperature and clay content on water absorption characteristics of modified MMT clay/cyclic olefin copolymer nanocomposite films: Permeability, dynamic mechanical properties and the encapsulated organic device performance

In the present study, amino-silane modified layered organosilicates were used to reinforce cyclic olefin copolymer to enhance the thermal, mechanical and moisture impermeable barrier properties. The optimum clay loading (4%) in the nanocomposite increases the thermal stability of the film while further loading decreases film stability. Water absorption behavior at 62 degrees C was carried out and compared with the behavior at room temperature and 48 degrees C. The stiffness of the matrix increases with clay content and the recorded strain to failure for the composite films was lower than the neat film. Dynamic mechanical analysis show higher storage modulus and low loss modulus for 2.5-4 wt% clay loading. Calcium degradation test and device encapsulation also show the evidence of optimum clay loading of 4 wt% for improved low water vapor transmission rates compared to other nanocomposite films. (C) 2014 Elsevier Ltd. All rights reserved.

Mesoporous silica-chondroitin sulphate hybrid nanoparticles for targeted and bio-responsive drug delivery

This work proposes the fabrication of a novel targeted drug delivery system based on mesoporous silica-biopolymer hybrids that can release drugs in response to biological stimuli present in cancer cells. The proposed system utilizes mesoporous silica nanoparticles as a carrier to host the drug molecules. A bio-polymer cap is attached onto these particles which serves the multiple functions of drug retention, targeting and bio-responsive drug release. The biopolymer chondroitin sulphate used here is a glycosaminoglycan that can specifically bind to receptors over-expressed in cancer cells. This molecule also possesses the property of disintegrating upon exposure to enzymes over-expressed in cancer cells. When these particles interact with cancer cells, the chondroitin sulphate present on the surface recognizes and attaches onto the CD44 receptors facilitating the uptake of these particles. The phagocytised particles are then exposed to the degradative enzymes, such as hyaluronidase present inside the cancer cells, which degrade the cap resulting in drug release. By utilizing a cervical cancer cell line we have demonstrated the targetability and intracellular delivery of hydrophobic drugs encapsulated in these particles. It was observed that the system was capable of enhancing the anticancer activity of the hydrophobic drug curcumin. Overall, we believe that this system might prove to be a valuable candidate for targeted and bioresponsive drug delivery.

Nanocomposite Made of an Oligo(p-phenylenevinylene)-Based Trihybrid Thixotropic Metallo(organo)gel Comprising Nanoscale Metal-Organic Particles, Carbon Nanohorns, and Silver Nanoparticles

A silver ion (Ag+)-triggered thixotropic metallo(organo)gel of p-pyridyl-appended oligo(p-phenylenevinylene) derivatives (OPVs) is reported for the first time. Solubilization of single-walled carbon nanohorns (SWCNHs) in solutions of the pure OPVs as well as in the metallogels mediated by pi-pi interactions has also been achieved. In situ fabrication of silver nanoparticles (AgNPs) in the SWCNH-doped dihybrid gel leads to the formation of a trihybrid metallogel. The mechanical strength of the metallogels could be increased step- wise in the order: freshly prepared gel

A Surlyn/magnesium oxide nanocomposite as an effective water vapor barrier for organic device encapsulation

A reactive polymer nanocomposite system was proposed as an effective water vapor barrier material for organic device encapsulation. Nanosized magnesium oxide (MgO) was synthesized by the solution combustion technique using two different fuels, lactose and alanine. The purity and crystallite size of MgO were determined from X-ray diffraction studies. The surface areas and porosity measurements were used to determine the water adsorption capacities of MgO. Nanocomposites with various concentrations (wt% = 0.25, 0.5, 1 and 2.5) of MgO were prepared using Surlyn as the base polymer. The permeation rate of moisture through the fabricated films was calculated using calcium degradation test and these rates were further used to calculate the diffusivities. Accelerated aging experiments were conducted to study the performance of organic photovoltaic devices encapsulated with synthesized films under accelerated weathering conditions. The performance of the barrier materials with synthesized MgO was also compared to that obtained with commercial MgO. The films containing MgO obtained from lactose exhibited better barrier properties compared to other films made with commercial MgO and MgO synthesized using alanine as well as other nanocomposites reported in the literature.

Mechanical properties of CNT-Bisphenol E cyanate ester-based CFRP nanocomposite developed through VARTM process

This paper reports on the effect of multiwall carbon nanotubes (CNTs) without and with chemical functionalization on the mechanical properties of Bisphenol E cyanate ester resin (BECy) based carbon fibre reinforced plastic (CFRP) laminated composites. BECy with its low viscosity, low moisture uptake and superior mechanical properties is selected for its application in CFRP laminates through the cost-effective Vacuum Assisted Resin Transfer Moulding (VARTM) process. However, unlike CNT-epoxy-CFRP composites, processing and performance issues such as dispersion of CNTs, chemical bonding with resin, functionalization effects, effects on mechanical properties, etc. for BECy-CNT-CFRP composite system are not well reported. The objective of this study is to improve the mechanical properties of BECy resin with small additions of CNTs and functionalized CNTs in CFRP laminates. CNTs and fCNTs are infused into BECy using ultrasonication and standard mixing methods. Improvements in Young's modulus and strength in tension, compression, shear, flexure and interlaminar shear strength are analysed. It is observed that addition of 0.5wt% CNTs effected for maximum mechanical properties of the resin and 1wt% CNTs for the mechanical properties of CNT-CFRP nanocomposite. Further, improvements obtained with fCNTs are marginal. Dispersion behaviour and effect of CNTs/fCNTs in load transfer corroborated with SEM pictures are presented. The enhanced mechanical properties realized in VARTM processing of BECy-CFRP laminate indicate clear advantage of CNT based modification of the process.

Bio-inspired route for the synthesis of spherical shaped MgO:Fe3+ nanoparticles: Structural, photoluminescence and photocatalytic investigation

MgO:Fe3+ (0.1-5 mol%) nanoparticles (NPs) were synthesized via eco-friendly, inexpensive and simple low temperature solution combustion route using Aloe vera gel as fuel. The final products were characterized by SEM, TEM and HRTEM. PXRD data and Rietveld analysis revealed the formation of cubic system. The influence of Fe3+ ion concentration on the structure morphology, UV absorption, PL emission and photocatalytic activity of MgO:Fe3+ NPs were investigated. The yellow emission with CIE chromaticity coordinates (0.44, 0.52) and average correlated color temperature value was found to be 3540 K which corresponds to warm light of NPs. The control of Fe3+. on MgO matrix influences the photocatalytic decolorization of methylene blue (MB) under UV light. The enhanced photocatalytic activity of MgO:Fe3+ (4 mol%) was attributed to dopant concentration, effective crystallite size, textural properties, decreased band gap and capability for reducing the electron hole pair recombination. Further, the trends of inhibitory effect in the presence of different radical scavengers were explored. These findings open up new avenues for the exploration of Fe-doped MgO in eco-friendly water applications and in the process of display devices. (C) 2015 Elsevier B.V. All rights reserved.

Dispersible crystalline nanobundles of YPO4 and Ln (Eu, Tb)-doped YPO4: rapid synthesis, optical properties and bio-probe applications

Undoped and Ln(3+) (Eu and Tb)-doped crystalline nanobundles of YPO4 were prepared by a facile microwave-assisted route with water as a solvent and without using any surfactant. TEM investigations reveal that the as-prepared powder consists of lenticular-shaped nanobundles (similar to 100 nm in diameter) made of very small nanorods with diameter less than 10 nm and length varying from 20 to 50 nm. Each nanorod in turn is single crystalline, as revealed by HRTEM imaging. The as-prepared nanobundles are easily dispersible in various solvents, especially water, without any surface functionalization, which is critical for various bio-probe applications like cell and tissue imaging. The Eu- and Tb-doped YPO4 nanobundles show good photoluminescence properties and were further evaluated for their use as fluorescent biolabels. Our results show that HeLa cells labelled with Eu- and Tb-doped YPO4 nanobundles show bright red (Eu) and green (Tb) intracellular luminescence under a confocal microscope. Concentration-and time-dependent MTT cell viability assays show that the nanobundles show low toxicity towards cells which makes them promising in bioimaging field.

The Holy Grail of Polymer Therapeutics for Cancer Therapy: An Overview on the Pharmacokinetics and Bio Distribution

In recent years, multifaceted clinical benefits of polymeric therapeutics have been reported. Over the past decades, cancer has been one of the leading causes of mortality in the world. Many clinically approved chemotherapeutics encounter potential challenges against deadly cancer. Moreover, safety and efficacy of anticancer agents have been limited by undesirable pharmacokinetics and biodistribution. To address these limitations, various polymer drug conjugates are being studied and developed to improve the antitumor efficacy. Among other therapeutics, polymer therapeutics are well established platforms that circumvent anticancer therapeutics from enzymatic metabolism via direct conjugation to therapeutic molecules. Interestingly, polymer therapeutics meets an unmet need of small molecules. Further clinical study showed that polymer-drug conjugation can achieve desired pharmacokinetics and biodistribution properties of several anticancer drugs. The present retrospective review mainly enlightens the most recent preclinical and clinical studies include safety, stability, pharmacokinetic behavior and distribution of polymer therapeutics.

Photoelectrochemical degradation of eosin yellowish dye on exfoliated graphite-ZnO nanocomposite electrode

In the quest for harnessing more power from the sun for water treatment by photoelectrochemical degradation, we prepared a novel photoanode of exfoliated graphite (EG)-ZnO nanocomposite. The nanocomposite was characterised by X-ray diffractometry, energy dispersive spectroscopy, Brunauer-Emmett-Teller surface area analyser, thermal gravimetric analyser, and X-ray photoelectron spectroscopy. The EG-ZnO nanocomposite was fabricated into a photoanode and applied for the photoelectrochemical degradation of 0.1 x 10(-4) M eosin yellowish dye in 0.1 M Na2SO4 under visible light irradiation. The degradation was monitored with a visible spectrophotometer. The photoelectrochemical degradation process resulted in enhanced degradation efficiency of ca. 93 % with kinetic rate of 11.0 x 10(-3) min(-1) over photolysis and electrochemical oxidation processes which exhibited lower degradation efficiencies of 35 and 40 % respectively.