Synthesis and characterization of carbon coated nanoparticles produced by a continuous low-pressure plasma process

Core–shell nanoparticles coated with carbon have been synthesized in a single chamber using a continuous and entirely low-pressure plasma-based process. Nanoparticles are formed in an argon plasma using iron pentacarbonyl Fe(CO)₅ as a precursor. These particles are trapped in a pure argon plasma by shutting off the precursor and then coated with carbon by passing acetylene along with argon as the main background gas. Characterization of the particles was carried out using TEM for morphology, XPS for elemental composition and PPMS for magnetic properties. Iron nanoparticles obtained were a mixture of FeO and Fe₃O₄. TEM analysis shows an average size of 7–14 nm for uncoated particles and 15–24 nm for coated particles. The effect of the carbon coating on magnetic properties of the nanoparticles is studied in detail.     

Fibrinolytic activity of kaempferol isolated from the fruits of Lagenaria siceraria (Molina) Standley

This study was undertaken to isolate a flavonol, kaempferol, from the fruits of Lagenaria siceraria (bottle gourd) as a sole compound and to explore the fibrinolytic potential of the methanolic extract of the fruits of L. siceraria and the isolated compound using their in vitro activity. The fibrinolytic activity in terms of percentage of plasma clot liquefaction was determined by plasma clot lysis at 37°C in 24?h. The fibrinolytic activity of both substances was compared to the well-known thrombolytic agent streptokinase (30,000?IU). The percentage of fibrinolytic activity of the extract and isolated compound were found to be 54.72?±?0.7210 and 77.37?±?1.3010, respectively. Streptokinase was considered as the standard fibrinolytic enzyme for comparative purposes and had 91.46?±?0.7625% fibrinolytic activity. The conclusion drawn in our study after testing the hypothesis by experimental procedures is that in vitro fibrinolytic activity on plasma clots is an inherent property of kaempferol isolated from the fruits of L. siceraria, and its comparison with streptokinase is a new aspect for further study.     

2.45 GHz Microwave Irradiation-Induced Oxidative Stress Affects Implantation or Pregnancy in Mice, Mus musculus

The present experiment was designed to study the 2.45 GHz low-level microwave (MW) irradiation-induced stress response and its effect on implantation or pregnancy in female mice. Twelve-week-old mice were exposed to MW radiation (continuous wave for 2 h/day for 45 days, frequency 2.45 GHz, power density?=?0.033549 mW/cm², and specific absorption rate?=?0.023023 W/kg). At the end of a total of 45 days of exposure, mice were sacrificed, implantation sites were monitored, blood was processed to study stress parameters (hemoglobin, RBC and WBC count, and neutrophil/lymphocyte (N/L) ratio), the brain was processed for comet assay, and plasma was used for nitric oxide (NO), progesterone and estradiol estimation. Reactive oxygen species (ROS) and the activities of ROS-scavenging enzymes— superoxide dismutase, catalase, and glutathione peroxidase—were determined in the liver, kidney and ovary. We observed that implantation sites were affected significantly in MW-irradiated mice as compared to control. Further, in addition to a significant increase in ROS, hemoglobin (p?<?0.001), RBC and WBC counts (p?<?0.001), N/L ratio (p?<?0.01), DNA damage (p?<?0.001) in brain cells, and plasma estradiol concentration (p?<?0.05), a significant decrease was observed in NO level (p?<?0.05) and antioxidant enzyme activities of MW-exposed mice. Our findings led us to conclude that a low level of MW irradiation-induced oxidative stress not only suppresses implantation, but it may also lead to deformity of the embryo in case pregnancy continues. We also suggest that MW radiation-induced oxidative stress by increasing ROS production in the body may lead to DNA strand breakage in the brain cells and implantation failure/resorption or abnormal pregnancy in mice.     

Localized electric field induced transition and miniaturization of two‐phase flow patterns inside microchannels

Strategic application of external electrostatic field on a pressure‐driven two‐phase flow inside a microchannel can transform the stratified or slug flow patterns into droplets. The localized electrohydrodynamic stress at the interface of the immiscible liquids can engender a liquid‐dielectrophoretic deformation, which disrupts the balance of the viscous, capillary, and inertial forces of a pressure‐driven flow to engender such flow morphologies. Interestingly, the size, shape, and frequency of the droplets can be tuned by varying the field intensity, location of the electric field, surface properties of the channel or fluids, viscosity ratio of the fluids, and the flow ratio of the phases. Higher field intensity with lower interfacial tension is found to facilitate the oil droplet formation with a higher throughput inside the hydrophilic microchannels. The method is successful in breaking down the regular pressure‐driven flow patterns even when the fluid inlets are exchanged in the microchannel. The simulations identify the conditions to develop interesting flow morphologies, such as (i) an array of miniaturized spherical or hemispherical or elongated oil drops in continuous water phase, (ii) “oil‐in‐water” microemulsion with varying size and shape of oil droplets. The results reported can be of significance in improving the efficiency of multiphase microreactors where the flow patterns composed of droplets are preferred because of the availability of higher interfacial area for reactions or heat and mass exchange.     

Poly(γ‐glutamic acid)/Silica Hybrids with Calcium Incorporated in the Silica Network by Use of a Calcium Alkoxide Precursor

Current materials used for bone regeneration are usually bioactive ceramics or glasses. Although they bond to bone, they are brittle. There is a need for new materials that can combine bioactivity with toughness and controlled biodegradation. Sol‐gel hybrids have the potential to do this through their nanoscale interpenetrating networks (IPN) of inorganic and organic components. Poly(γ‐glutamic acid) (γ‐PGA) was introduced into the sol‐gel process to produce a hybrid of γ‐PGA and bioactive silica. Calcium is an important element for bone regeneration but calcium sources that are used traditionally in the sol‐gel process, such as Ca salts, do not allow Ca incorporation into the silicate network during low‐temperature processing. The hypothesis for this study was that using calcium methoxyethoxide (CME) as the Ca source would allow Ca incorporation into the silicate component of the hybrid at room temperature. The produced hybrids would have improved mechanical properties and controlled degradation compared with hybrids of calcium chloride (CaCl₂), in which the Ca is not incorporated into the silicate network. Class II hybrids, with covalent bonds between the inorganic and organic species, were synthesised by using organosilane. Calcium incorporation in both the organic and inorganic IPNs of the hybrid was improved when CME was used. This was clearly observed by using FTIR and solid‐state NMR spectroscopy, which showed ionic cross‐linking of γ‐PGA by Ca and a lower degree of condensation of the Si species compared with the hybrids made with CaCl₂ as the Ca source. The ionic cross‐linking of γ‐PGA by Ca resulted in excellent compressive strength and reduced elastic modulus as measured by compressive testing and nanoindentation, respectively. All hybrids showed bioactivity as hydroxyapatite (HA) was formed after immersion in simulated body fluid (SBF).     

Convenient photooxidation of alcohols using dye sensitised zinc oxide in combination with silver nitrate and TEMPO

A novel photooxidative system using dye sensitised zinc oxide in combination with silver nitrate and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) in an aqueous solution is described. Under visible light irradiation the selective oxidation of alcohols to their corresponding aldehydes and ketones was effected in good to excellent yields.     

Nanoencapsulation and characterization of Albizia chinensis isolated antioxidant quercitrin on PLA nanoparticles

The plant isolated antioxidant quercitrin has been encapsulated on poly-d,l-lactide (PLA) nanoparticles by solvent evaporation method to improve the solubility, permeability and stability of this molecule. The size of quercitrin-PLA nanoparticles is 250 ± 68 nm whereas that PLA nanoparticles is 195 ± 55 nm. The encapsulation efficiency of nanoencapsulated quercitrin evaluated by HPLC and antioxidant assay is 40%. The in vitro release kinetics of quercitrin under physiological condition reveals initial burst release followed by sustained release. Less fluorescence quenching is observed with equimolar concentration of PLA encapsulated quercitrin than free quercitrin. The presence of quercitrin specific peaks on FTIR of five times washed quercitrin loaded PLA nanoparticles provides an extra evidence for the encapsulation of quercitrin into PLA nanoparticles. These properties of quercitrin nanomedicine provide a new potential for the use of such less useful highly active antioxidant molecule towards the development of better therapeutic for intestinal anti-inflammatory effect and nutraceutical compounds.