Efficient tailoring of platinum nanoparticles supported on multiwalled carbon nanotubes for cancer therapy.

Aim: Therapeutically targeting cancer stem cells (CSCs), which play a role in tumor initiation and relapse, remains challenging. Materials & methods: Novel-formulated platinum nanoparticles (Pt-NPs) supported on polybenzimidazole (PBI)-functionalized polymers and multiwalled carbon nanotubes (MWCNT) were prepared and their effect on CSCs was evaluated. Results: Pt-NPs showed homogenous distribution on the surface of MWCNT/PBI composites, with very narrow particle size. MWCNT/PBI/Pt-NPs resulted in a dramatic decrease in the proliferation rate of CSCs but not bone marrow mesenchymal stem cells (BM-MSCs). Quantitative gene expression analysis revealed that MWCNT/PBI/Pt had a significant inhibitory effect on the epithelial-mesenchymal transition and cell cycle markers of CSCs. Conclusion: MWCNT/PBI/Pt exhibited a specific cytotoxic effect on breast CSCs but not on adult stem cells.

Synthesis of a New Nitrate-Fertilizer Form with a Controlled Release Behavior via an Incorporation Technique into a Clay Material.

The current study shows an advanced synesthetic technique of a nitrate-fertilizer with a controlled release behavior into different soils (normal and acidic agriculture soils solutions) at different climate temperatures. The environmentally friendly and the biocompatible layered double hydroxide (LDH) clay material was used as a host to accommodate the nitrate anion into its interlayer gallery by applying a reconstruction-incorporation technique (the memory effect property of LDH that allows calcined LDH to memorize its original structure). The prepared materials were characterized by different spectroscopic techniques including; X-ray powder spectroscopy, IR, SEM, TEM, and TGA analyses. A remarkable loading ratio of the nitrate anion fertilizer was recorded into the LDH structure. Around 90 wt% of the intercalated nitrate anion was released in a sustained controlled behavior over around 24 days, while the same amount of nitrate was released over 10 days in the acidic soil. Accordingly, the present study offers a new passway for the formulation of controlled release fertilizers by using the hosting anionic clay LDH materials.

Tailoring of a Potential Nanoformulated Form of Gibberellic Acid: Synthesis, Characterization, and Field Applications on Vegetation and Flowering.

Nanoformulation of agrochemicals has become a potential choice to improve the physicochemical properties, enhance the utilization efficiency, and reduce the side effects and ecotoxicity of many hazardous chemicals. Here, we tailored a new formulation platform for gibberellic acid (GA) using the layered double hydroxides (LDH) as a potential carrier. Typically, we synthesized, characterized, and potentially applied the newly nanoformulated form of GA on the quantity and quality properties of Dendranthema grandiflorum cultivar. We also evaluated the synergetic effect of the carrier LDH on the release behavior of GA, showing a remarkable impact on the utilization efficiency of GA. The nanohybrid structure of GA also showed an enhanced thermal stability and safe preservation for the incorporated moieties. Taking into account the hazardous effect of free GA on the environment and human health, the hybrid technique of GA is one of the best choices among all of the studied protocols.

A highly durable fuel cell electrocatalyst based on double-polymer-coated carbon nanotubes.

Driven by the demand for the commercialization of fuel cell (FC) technology, we describe the design and fabrication of a highly durable FC electrocatalyst based on double-polymer-coated carbon nanotubes for use in polymer electrolyte membrane fuel cells. The fabricated electrocatalyst is composed of Pt-deposited polybenzimidazole-coated carbon nanotubes, which are further coated with Nafion. By using this electrocatalyst, a high FC performance with a power density of 375 mW/cm(2) (at 70 ˚C, 50% relative humidity using air (cathode)/H2(anode)) was obtained, and a remarkable durability of 500,000 accelerated potential cycles was recorded with only a 5% loss of the initial FC potential and 20% loss of the maximum power density, which were far superior properties compared to those of the membrane electrode assembly prepared using carbon black in place of the carbon nanotubes. The present study indicates that the prepared highly durable fuel cell electrocatalyst is a promising material for the next generation of PEMFCs.

Enhancement of platinum mass activity on the surface of polymer-wrapped carbon nanotube-based fuel cell electrocatalysts.

Cost reduction and improved durability are the two major targets for accelerating the commercialization of polymer electrolyte membrane fuel cells (PEFCs). To achieve these goals, the development of a novel method to fabricate platinum (Pt)-based electrocatalysts with a high mass activity, deposited on durable conductive support materials, is necessary. In this study, we describe a facile approach to grow homogeneously dispersed Pt nanoparticles (Pt) with a narrow diameter distribution in a highly controllable fashion on polymer-wrapped carbon nanotubes (CNTs). A PEFC cell employing a composite with the smallest Pt nanoparticle size (2.3 nm diameter) exhibited a ~8 times higher mass activity compared to a cell containing Pt with a 3.7 nm diameter. This is the first example of the diamter control of Pt on polymer-wrapped carbon supporting materials, and the study opens the door for the development of a future-generation of PEFCs using a minimal amount of Pt.

Target delivery and controlled release of the chemopreventive drug sulindac by using an advanced layered double hydroxide nanomatrix formulation system.

Target delivery and controlled release of the chemopreventive drug sulindac that possesses low water solubility present a great challenge for its pharmaceutical industry. Here, we offered an advanced nanomatrix formulation system of sulindac based on layered double hydroxide materials. The X-ray analysis and infrared spectroscopy confirmed the incorporation of sulindac into the gallery of the layered double hydroxides. The incorporation ratios of sulindac were recorded to be 45, 31 and 20 for coprecipitation, anion-exchange and reconstruction techniques, respectively. The scanning electron microscopy showed a nanomatrix-structure of ~50 nm. The release studies of sulindac-nanomatrix showed a 96% controlled release at the small intestine solution during 3 h(s), indicating an enhancement in the dissolution profile of sulindac after the matrix formation. The layered structure of the matrix supplied sulindac with a well-ordered structure and a relatively hydrophobic microenvironment that controlled the guest hydrolysis and reactivity during the release process. The laminar structure of layered double hydroxides offered a safe preservation for sulindac against photodecarboxylation, and enhanced the drug thermal stability from 190 to 230° C. The ionic electrostatic interaction of sulindac through its acidic group with layered double hydroxides demolished the gastrointestinal ulceration.

Design of a multifunctional nanohybrid system of the phytohormone gibberellic acid using an inorganic layered double-hydroxide material.

To offer a multifunctional and applicable system of the high-value biotechnological phytohormone gibberellic acid (GA), a nanohybrid system of GA using the inorganic Mg-Al layered double-hydroxide material (LDH) was formulated. The ion-exchange technique of LDH was applied to synthesize the GA-LDH hybrid. The hybrid structure of GA-LDH was confirmed by different spectroscopic techniques. The nanohybrid size was described by SEM to be ∼0.1 µm. The GA-LDH nanohybrid structure was the key parameter that controlled GA properties. The layered molecular structure of LDH limited the interaction of GA molecules in two-dimensional directions. Accordingly, GA molecules did not crystallize and were released in an amorphous form suitable for dissolution. At various simulated soil solutions, the nanohybrids showed a sustained release process following Higuchi kinetics. The biodegradation process of the intercalated GA showed an extended period of soil preservation as well as a slow rate of degradation.

Nanocomposite formulation system of lipid-regulating drugs based on layered double hydroxide: synthesis, characterization and drug release properties.

PURPOSE: To design a nanocomposite formulation system of lipid-regulating drugs with versatile approaches using layered double hydroxide (LDH) material. METHODS: The co-precipitation technique has been used to prepare the selected drugs [bezafibrate (BZF) and clofibric acid (CF)]-LDH nanocomposites. The nanocomposite materials (BZF-LDH and CF-LDH) were characterized by X-ray powder diffraction, infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The in vitro study was investigated in simulated gastrointestinal solutions at 36.8°C. RESULTS: X-ray measurement and spectroscopic analysis indicated the formation of fully monophase drug-nanocomposites. The nanocomposites' gallery heights were calculated to be 23.5 and 16.3 Å for BZF and CF, respectively. The new gallery heights indicated that BZF and CF drugs have been stacked into LDH as a monolayer with a staggered inter-digitated arrangement. The size of the nanocomposites described by SEM microscopy was ∼ 0.1 µm. The nanocomposite formulation has improved the drugs properties (thermal stability, dissolution, and controlled release) beside the achievement of drug target delivery. CONCLUSIONS: Nanocomposites composed of lipid-regulating drugs (BZF and CF) with LDH were successfully synthesized as a new formulation system of this drug category. The LDH nanocomposite formulation system has improved the drugs release properties.

Unusually large hysteresis of temperature-responsive poly(N-ethyl-2-propionamidoacrylamide) studied by microcalorimetry and FT-IR.

We reported here the full characterization of the hysteresis of the phase transition behavior of an aqueous solution of poly(N-ethyl-2-propionamidoacrylamide) (PNEPA), which has a unique alpha,alpha-disubstituted structure, by using microcalorimetry and FT-IR. Phase transition temperatures near the thermodynamic equilibrium were determined by extrapolating the scanning rate of the microcalorimetry to zero. The calculated hysteresis from the phase transition temperature was unusually very large (approximately 8 degrees C). FT-IR analysis indicated that the large hysteresis of PNEPA resulted from a coupling of intra-/intermonomeric unit hydrogen bonds, which is known to occur in a beta-sheet of proteins but has never been reported in temperature-responsive polymers. The effects of the molecular weight and polymer concentration on the hysteresis were studied by using fractionated PNEPAs and it was found that a low molecular weight and a low concentration enhanced the hysteresis.