Current Nanoscience - Volume 9, Issue 6, 2013

The application of bio-active noble-metal-based nano-particles (NPs) with unique physico-chemical properties is multifaceted. Among other roles, they can be used as anti-viral agents, and at the same time might serve as matrix to facilitate the transport of various molecules for therapeutic purposes directly or via genetically modified microbes. For this reason, the influence of nano-materials on viral infection in living cells is described in this study utilizing pseudo-typed lenti-viral particles based on human immuno-deficiency virus 1 (HIV-1). Cells were exposed to various NPs and subsequently infected with lenti-virus. Transfection efficiency was quantified by flow-cytometry analysis. Gold-based NPs increased, silver-containing NPs decreased, while other NPs had little or no effect on viral infection rate. The opposing effect of NPs is determined by the size, chemical nature and surface chemistry of the nano-materials, which govern their interactions with molecular species present in their environment. These characteristics enable the distinct use of different NPs in various fields of bio-medicine.

In an attempt to develop caffeic acid for drug delivery, caffeic acid-loaded solid lipid nanoparticles (CA-SLNs) were constructed, and were characterized to determine their properties followed by their evaluation for in vitro cytotoxic properties. The SLNs were prepared by using hot homogenization method. The treatment of H-Ras 5RP7 and NIH/3T3 cell lines with CA and CA-SLNs suggested that CA-SLNs are less toxic to NIH/3T3 normal cells but have more cytotoxic effects on H-Ras 5RP7 as compared with free CA by using MTT assay. In addition, CA-SLNs can increase the cytotoxic effect and accelerate cellular uptake of CA on H-Ras 5RP7 cells. Finally, we observed the structural and ultrastructural changes in both H-Ras 5RP7 and NIH/3T3 cells by using transmission electron and confocal microscopy, respectively. We observed both structure and ultrastructural changes in H-Ras 5RP7 cells without causing any damage to NIH/3T3 cells. These results showed that the SLNs formulation may be promising as a substitute nanosize based drug delivery system for cancer treatment.

Although Camptothecin (CPT) has significant antitumor activity to lung, ovarian, breast, pancreas, and stomach cancers; lactone ring opening causes a reduction in cytotoxic activity and severe side effects in physiological conditions (pH: 7.4, 37°C) due to decreased cell membrane binding, membrane diffusibility, and intrinsic potency against the topoisomerase target. Taken into consideration the targeted delivery advantage of biocompatible magnetic particles, in order to contribute to the removal of the handicap (lactone ring opening), the current study investigated stability, release, and in vitro bioactivity of CPT in oleic acid (OA)-pluronic F127 (PL) coated iron oxide micro and nanoparticles. CPT encapsulated magnetite micro (~10 μm) and nano (~30 nm) formulations were synthesized without changing their magnetic properties. Analysis of encapsulated CPT illustrated that over 99% of the lactone form was protected in the magnetic particle formulations and release of CPT from the magnetic micro and nanoparticles lasted for 9 and 4 days respectively. In addition, in a representative in vitro cytotoxicity study, CPT encapsulated OA-PL stabilized magnetite microparticles were approximately 65% more effective than free CPT to inhibit 100% cell growth on three different human liver carcinoma cell lines. Therefore, the OA-PL stabilized iron oxide formulation is ideal for achieving targeted and sustained CPT delivery in bioactive lactone form to overcome its handicaps in clinical conditions.

An industrial pre-reduced iron catalyst for ammonia synthesis was reduced at 773 K and heated in the hydrogen atmosphere at temperatures in the range of 773 K – 973 K. Samples of different mean sizes of nanocrystallites depending on heating temperature were obtained (773 K 20 nm, 823 K 30 nm, 873 K 35 nm, 923 K 38 nm and 973 K 40 nm). The mean sizes of crystallites were determined by XRD method. The chemical method was applied to determine the size distributions of nanocrystallites, using the results of measuring the rate of nanocrystalline iron nitriding reaction with simultaneous measurement of catalytic ammonia decomposition reaction rate. Samples were nitrided with ammonia under atmospheric pressure at 748 K in a tubular reactor equipped with systems enabling simultaneous conducting of continuous thermogravimetric measurements together with analysis of gas phase composition. Along with an increase of mean crystallites sizes both the values of the minimum nitriding potential, at which the nanocrystalline iron nitriding reaction begins, and the nitriding degree increase, but the rate of surface reaction of catalytic ammonia decomposition decreases. Changes in shapes of nanocrystallites size distributions depending on the heating temperature were observed. With the increase of the heating temperature bimodal distribution becomes unimodal.

Chitosan as a copious natural polysaccharide has been proposed for a wide range of biomedical applications such as non-viral gene delivery due to its biodegradable and non-toxic nature. The presence of primary amines in the chitosan structure enables derivatization with different functional moieties to improve its properties such as solubility and transfection efficiency. In the current study, we prepared a series of hydrophobic chitosan-based constructs which was decorated with alkylcarboxylate polyethylenimine as an approach to overcome the drawbacks of chitosan in gene transfer while developing a potential safe vector. Physicochemical and biological characteristics of the synthesized vectors were investigated in terms of condensation ability, buffering capacity, size and zeta potential measurements, cytotoxicity and efficiency of the transgene expression in Neuro-2a cells. Modified chitosans led to nanocarriers with suitable mean diameter and slightly positive surface charge which showed significantly higher transfection efficiencies than that of unmodified chitosan. The most probable reasons for the higher efficacy of the synthesized vectors could be their optimal buffering capacity and hydrophobicity by incorporating PEI and alkanoate segments, respectively. Moreover, the new derivatives showed favorable solubility at physiological pH which may help their in vivo application to be more feasible.

The aim of present study was to evaluate the impact of various combinations of nonionic surfactants on selfnanoemulsification efficiency of Sefsol-218 in glibenclamide nanoemulsion. Surfactants Labrasol, HCO-60, Tween-80, Cremophor-EL and Gelucire-44/14 along with cosurfactants Transcutol-HP, isopropyl alcohol and ethanol were investigated for this purpose. Formulations were prepared by spontaneous emulsification method and subjected for thermodynamic stability and self-nanoemulsification test. Only those formulations which were found to be stable at various stress conditions of thermodynamic stability and selfnanoemulsification tests were further characterized in terms of droplet size, viscosity, refractive index and % transmittance. Formulations prepared with Labrasol or Gelucire-44/14 were found to be suitable for self-emulsifying drug delivery system only whereas those prepared using HCO-60, Tween-80 and Cremophor-EL were found to be suitable for self-nanoemulsifying drug delivery system or selfmicroemulsifying drug delivery system. Based on lowest droplet size (39.1 nm), optimal values of polydispersity index (0.292) & refractive index (1.332), lowest viscosity (34.3 cp) and highest % transmittance (99.6), formulation S23 (Sefsol-218/Cremophor- EL/ethanol/water) was optimized as best formulation for self-nanoemulsifying drug delivery system of glibenclamide. These results indicated that Cremophor-EL could be the best surfactant in terms of self-nanoemulsification.

The performance of photoelectrochemical cell (PEC) depends on the morphology of quasi zinc oxide nanorods (NRs) that were influenced by the concentration of ammonia and zinc acetate precursors in growth reaction. The quasi-NRs shape becomes more rounded, fatter and highly compact film with the increase in the ammonia concentration. Meanwhile, the diameter and thickness of the quasi-NRs decrease with ammonia concentration in the range 36 mM to 360 mM, corresponding to the diameter in the range 30 to 18 nm and the thickness in the range 97 to 87 nm, respectively. The PEC utilizing ZnO nanorod produced from these various ammonia concentrations reveals that the photovoltaic parameters increase with ammonia concentration. The best Jsc was 0.2mA cm-2 obtained at 360mM ammonia. The morphology in terms of diameter and length of ZnO nanorod also changes with zinc acetate concentration. The diameter and thickness of the quasi-NRs decrease with zinc acetate concentration in the range 10 to 30 mM corresponding to the diameter in the range 18 to 40 nm and the thickness in the range 87 to 110 nm, respectively. The PEC utilizing ZnO nanorod prepared from these various zinc acetate concentrations reveals that the best Jsc of 0.2 mA cm-2 was obtained at 20 mM zinc salt corresponding to the diameter of 27 nm and thickness of 110 nm, respectively.

A nonenzymatic biosensor for hydrogen peroxide (H2O2) is developed based on a glassy carbon electrode loaded with layered nano-structured perovskite-type oxide LaNiTiO3 by sol-gel method. Characterizations of as-synthesized LaNiTiO3 are conducted using powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy and low temperature N2 adsorption and desorption isotherms techniques. Electrochemical properties of the fabricated biosensor are studied by cyclic voltammetry and currenttime curves. Experimental results show the electrochemical biosensor has high activity to the oxidation of H2O2 with a fast response time of ~ 2 s in 0.1 M NaOH solution. A wide linearity is obtained from 0.05 μM to 10.0 m with a low detection limit of 0.01 μM (S/N = 3) and a high sensitivity of 854 μA mM-1 cm-2 under optimal conditions: the content of LaNiTiO3 modifier (5.0 μL, 0.5 mg/mL) and applied potential (0.55 V). The biosensor also exhibits good stability, reproducibility and anti-interference ability, suggesting potential practical application of LaNiTiO3 in biological analysis and environmental detection.

This study reported the preparation and properties of quaternized carboxymethyl chitosan (QCMC)/sodium alginate (SA) composite sponge with Ag NP-loaded quaternized carboxymethyl chitosan/organic rectorite (QCORAg) nanocomposite. The structures of QCMC/SA/QCORAg composite sponges were characterized by FT-IR, SEM, TEM and EDS. The results showed that the polyelectrolyte with a highly cross-linked structure can be obtained by mixing QCMC and SA. The composite sponges had good water-absorption capacity, which could absorb 21 times of water of its original weight. Compared to commercially available gelfoam, due to the addition of silver nanoparticles and organic rectorite, the QCMC/SA/QCORAg composite sponges showed excellent antibacterial and hemostatic properties. The composite sponges also performed well on healing the wounds. This study indicated that the composite sponges had the potential to be a new wound dressing.

The thermal performance of Cu/Al interface structure is studied based on the investigation of the diffusion interfacial thickness, phonon scattering and phonon coincidence degree by using the NEMD (non-equilibrium molecular dynamics) method under different temperatures. There is an interesting phenomenon that the thermal conductivity increases with the increasing temperature although the phonon scattering becomes more seriously which would reduce the thermal conductivity of Cu/Al interface. It implies that the phonon is not the only factor affecting the thermal conductivity. Then, the MD-TTM (molecular dynamics-two temperature model) mixed model is used to describe the interfacial heat transfer considering the coupling of phonon and electron. The results show that the electron affects the thermal performance of the Cu/Al interface and it becomes more and more intense with the increase of temperature, which proves that the phonon is not the only thermal transfer carrier in the metallic interface. The investigation is helpful for understanding the heat transfer mechanism in the metallic matching interface, which implies a potential method for the analysis of the interface performance and the design of the interface in micro/nano manufacturing.

Silver nanocrystals with different particle sizes were prepared by chemical reduction of silver nitrate with sodium borohydride in the presence of citrate. The formation and ripening mechanisms of silver nanocrystals were also proposed. TEM images show that the mean diameter of silver nanocrystals is about 2 nm by addition of NaBH4 all at once and 10 nm by addition of NaBH4 drop by drop. UVVis spectra show that the mean diameter of the nanocrystals prepared at 0°C is smallest and then increases with the temperature. The aging time has obvious influence on the small nanocrystals and little influence on the big nanoparticles. Only the crystal planes of small nanocrystals have a high possibility of selective adsorption of citrate at the early stage of aging process. However, the smaller nanocrystals in the colloidal solution have aggregated into larger nanoparticles after 8 h of aging.

C-S-H is the most important component of hardened cement paste accounting for 60%-70% in hydrating products of OPC and is the most complex material system in material science. Based on the AFM observation of the surface of cement paste with low water/ cement ratio around 0.29~0.35, it has been found that C-S-H has three types of fundamental structure units in nano scale namely granular, platy and cellular, and six types of patterns namely amorphous, granular, platy, agglomerated granular, layer and bulk. These six types of patterns are formed by the three types of structure units. In micro scale, the amorphous type is amorphous matrix composed of cellular nano scale structure unit; the platy structure unit forms the platy to brick like type of C-S-H; the nano particle can be found in granular, agglomerated granular, layer and bulk type of C-S-H. In the nano granular type, the nano particle packs without orientation; the agglomerated granular has obvious tendency to connect with each other; while the layer type is formed by nano granular with notable orientation; there are some granular types that remain on the surface of the bulk and some notable fiber (the diameter in nano size) bundle can be found in the crack of bulk type, thus the bulk forming also from closely packed nano granular types.

The dry sliding wear and friction behavior of epoxy reinforced with Multi-walled Carbon Nanotubes (MWCNTs) were investigated using pin on disc machine. The MWCNTs with the weight fraction of 0.1wt.%, 0.5wt.%, 1.25wt.%, 2.5wt.% and 5wt.% in the epoxy/MWCNTs were used in this study. A pin of 6mm diameter as epoxy/MWCNTs nanocomposites was slide against steel disc at a speed of 200rpm under the load of 60N. Wear performance was observed with the sliding distance of 942m in 30min.The experimental investigation showed that the addition of MWCNTs in considerable amount can improve the wear performance of epoxy/MWCNTs nanocomposites. The specific wear rate and friction co-efficient of the nanocomposites decrease with the increase of MWCNTs content until the weight fraction of 1.25wt.% is achieved. However, the weight fraction of 1.25wt.% of MWCNTs nanocomposites shows superior wear resistance than pure epoxy. Furthermore, addition of MWCNTs forms localized bundle and does not exhibit significant improvement of wear performance due to non homogeneous dispersion in the epoxy matrix. Field Emission Scanning Electron Microscope (FESEM) was utilized to examine localized bundle of MWCNTs, wave formation of the fracture surface, as well as rough and smooth morphology of worn surface in pin material. The typical topographical analysis of pure and functionalized MWCNTs was examined by transmission electron microscopy (TEM).

This work focuses on the identification and optimization of formulation and process variables affecting the characteristics of nanosuspension, using the Esomeprazole magnesium as a drug candidate. Formulation factors evaluated were ratio of stabilizers to drug and ratio of anti-solvent to solvent, whereas process parameters were ultrasonication time, power input, stirring speed and process temperature effect. The test revealed that ratio of the stabilizer to drug and ratio of anti-solvent to solvent has the significant effect on zeta potential and particle size, whereas different process parameters have significant effect on the particle size and their distribution. In this study, nanosuspension having the particles as small as 132 (± 20.2) nm was produced by anti solvent precipitation-ultrasonication method. The zeta potential and PDI (poly dispersity index) of optimized batch were -25.5 (± 2.5) mV and 0.474 (± 0.086), respectively. The formulated nanosuspension has shown a faster dissolution profile (100% in 60 min), relative to that of micronized esomeprazole suspension (23.6% in 60 min), mainly due to presence of nanosized particle. The aged nanosuspension exhibited the increase in particle size from 132 to 187 nm, when it was stored at 25°C/75% relative humidity for six months. Graphically, the aged nanosuspension also showed the lower release rate than the fresh nanosuspension. However, statistically there was no significant difference (P > 0.05) in rate of release of aged nanosuspension compared with the fresh nanosuspension.

Samarium (Sm)-doped CdSe nanoparticles with different Sm contents were synthesized by an easy hydrothermal method using samarium (III) nitrate hexahydrate as the doping material. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis showed that the particles were crystallized to a high degree and corresponded to the cubic CdSe phase. SEM images indicated that the size range of synthesized nanocrystallites was 50–100 nm. The photocatalytic efficiency of pure and Smdoped CdSe samples was evaluated by the degradation of C.I. Acid Orange 7 (AO7) in aqueous solution under visible light irradiation. The results showed that CdSe with Sm doping of 0.06 mole fraction led to enhanced photocatalytic activity. Color removal efficiency of 53.40% for CdSe and 90.08% for Sm0.06Cd0.94Se was achieved at 120 min. The Langmuir–Hinshelwood (L–H) adsorption and rate coefficients for the photocatalytic process were successfully established. Reusability tests were performed to test the stability of the photocatalysts. There was almost no loss of photocatalytic activity after four cycles of repeated use.

The conjugation of gold nanoparticles (GNPs) with magnetite nanoparticles is achieved in a two step process in which the initial step is a self-assembled monolayer of mercaptoundecanol on conjugation to GNPs by reducing HAuCl4 to obtain wine color suspension of hydroxyl capped GNPs. The reaction is further proceeded with phosphorus oxychloride, followed by hydrolysis, in which the final step would be anchoring to magnetite nanoparticles by sonication. The nanometer sized core-shell hybrid materials having a GNPs core with a ligand - shell conjugated magnetite nanoparticles in an ambient temperature have been prepared in a facile synthetic manner. The grafting reaction is then confirmed using ultraviolet-visible spectroscopy, X-ray diffraction, transmission electron a microscopy and Infrared spectroscopy. This new approach of conjugating of two metal nanoparticles in a single linkage ligand will have a fascinating approach in biomedical application.

The removal of phenolic solution is of great importance for the treatment of industrial waste water and the purification of drink water. By carbonizing an alumina porous tube and depositing platinum nanoparticles on the ex/interior surface, a novel enforced porous ceramic tubular electrode, Pt/C/Tub-Al2O3, was prepared and used for the removal of phenol contained waste water via enforced electrocatalytic oxidation process. Excellent removal efficiency has been achieved at 2.0V of applied cell voltage, and temperature of 40 ºC. No obvious performance attenuation can be observed after 10 times recycle utilization, which can be attributed to the structure features of porous membrane, high dispersed Pt nanoparticles and good conductivity. N2 sorption, XRD, SEM/TEM and cyclic voltammetry measurements were performed to characterize the structure of Pt/C/Tub-Al2O3 electrode. The enforced oxidation with this tubular porous electrode may provide an effective candidate technique for the removal of phenol from waste water.

In the present article, peristaltic nanofluid flow of an incompressible six constant Jeffrey’s fluid model in an asymmetric channel has been discussed. The flow has been analyzed in a wave frame of reference moving with the wave speed c. The problem formulation has been done for two dimensional and two directional flow under long wave length and low Reynold’s number approximation. The numerical solutions for the velocity, temperature and nanoparticle fraction and pressure rise are calculated using fourth and fifth order Runge-Kutta-Fehlberg method. The graphical results are presented to interpret the behaviour of various flow parameters.

The mechanisms of ultrashort pulsed laser ablation of polycrystalline diamond (PCD) are investigated by means of molecular dynamics simulations. The simulation model provides a detailed atomistic description of the laser energy deposition to the PCD specimen, which is verified by an experiment using 300 fs laser irradiation of a typical PCD sample. It is found that non-homogeneous melting initiates from grain boundaries composed by sp2 hybridized denser diamond-like amorphous carbon atoms of higher potential energies. Furthermore, the interplay of the photomechanical spallation and evaporation is found to be accounted for the material removal in the laser ablation. The laser ablation-induced microstructure changes of the sample are characterized in detail. Simulation results suggest that the sample after laser ablation consists of four zones of different structural lattices. It is found that the top layer of the ablated surface composed by amorphous carbon with abundant vacancies can be wiped off from the surface easily, which agrees well with experimental results.

Electro-spinning of nanofibers can be applied to fabricate artificial scaffolds for tissue engineering. The uniformity of nanofibers distribution in each scaffold mat role plays critically in tissue engineering. Many attempts have been made to improve uniformity of nanofibers scaffolds but none of them could produce uniform distribution of nanofibers in scaffolds, completely. The aim of present research is to produce scaffolds with uniformly distributed nanofibers by using a rotating collector in electro-spinning setup. A novel collector was developed to produce nanofibers in uniform distribution by controlling the collector parameters. The distribution of the nanofibers was precisely controlled by adjusting the velocity of collector rotation and the diameter of collector. Experiments were carried out to investigate capability of presented method in adjusting the formation of distribution for Polycaprolactan (PCL) nanofibers. Significant improvement of the uniformity of the fiber distribution was observed by the image processing method of nanofibers SEM images.