Current Nanoscience - Volume 10, Issue 6, 2014

Understanding how the substrate topography acts on human bone marrow-derived mesenchymal stromal cells (MSCs) can help the rational design of scaffolds for improving bone regeneration protocols. MSCs are highly sensitive to the extracellular physical properties and can be successfully manipulated by simple contact interaction with supporting substrates. To this end, some polymeric materials were introduced, but polyethylene terephthalate (PET), a thermoplastic polymer approved by the US Food and Drug Administration for clinical use and very attractive in terms of biocompatibility and mechanical properties, has not been tested yet in terms of cell mechanotransduction. Here, we propose PET nanogratings (alternating lines of submicron ridges and grooves) as scaffolds for stimulating mechanotransduction mechanisms. Low-temperature hot embossing is exploited as fabrication method, and standard oxygen plasma activation as functionalization to improve cell adhesion and spreading. We show that the substrate directionality stimulus is optimally delivered to the MSCs, which in turn elongate and align to the nanograting lines. Finally, we verify that this polarization occurs also at level of cytoskeleton fibers and, though to a lesser extent, of nuclei.

The use of heparin or low molecular weight heparin (LMWH) is calling attention as an alternative for treating of skin ulcers. However, clinical topical application heparin has challenges such as stability, permeation and number of administrations. Thus, the encapsulation of heparin in nanoparticles may enable the clinical application of this molecule for the treatment of lesions. Therefore, the goal of this study was evaluated the use of free and encapsulated LMWH in mucoadhesive nanoparticles on acute skin lesions in an in vivo rat model. The polymeric nanoparticles was prepared using poly(ε-caprolactone) and chitosan in order to obtain a particle with mucoadhesive properties. Spherical nanoparticles with an average diameter of 511 nm and with positive superficial charge (+ 20 mV) were produced. In vivo experiments with free or encapsulated enoxaparin showed no beneficial effect upon the size of the skin lesions in comparison to controls. Furthermore, no renal, hepatic or hematological toxicity was detected in all groups analyzed. In conclusion, mucoadhesive particles with high encapsulation efficiency (98%) were produced, however with no favorable effect for the treatment of acute skin wounds.

This study investigates new lipidic nanocarrier preparations for production of babassu oil formulations, which are indicated as less radical herbal therapeutic alternatives for the prevention of benign prostatic hyperplasia. The babassu oil was obtained in high yield using the previously studied, reproducible soxlhet extraction process. We investigated the preparation of nanostructured babassu oil lipid carriers and babassu oil nanoemulsions, to determine conditions that yield a high percentage of babassu oil encapsulation, have appropriate size distribution and zeta potential for vectorization of babassu oil to the prostate. Cytotoxicity tests were performed using intestinal epithelial Caco-2 cells and J-774 macrophages, which indicated that nanostructured lipid carriers for babassu oil are not toxic to front Caco-2 cells and are able to reduce J774 cell viability. This indicates their potential use for treatment against inflammatory processes such as prostatitis and for administration through the oral route. Whereas, in previous studies conducted by our research group, other babassu oil nanosystems showed activity when tested in cell strains of human benign prostatic hyperplasia lineage. The new babassu oil nanostructured lipid carriers prepared in this study can be used as a new prototype for phytotherapic nanoformulations for the prophylaxis of prostate pathologies, since they are highly lipophilic, have narrow size distribution and have low toxicity.

ZnS (Zinc Sulfide) nanoparticles (2-4 nm) were synthesized by chemical precipitation method. Their characteristics and physical properties were evaluated by scanning tunneling microscopy, ultraviolet-visible spectrophotometry and X-ray diffraction. It was found that the synthesized ZnS nanoparticles are cubic of high-quality. Moreover, it was realized that ZnS optical properties are related to the environment temperature. Antibacterial effects of ZnS nanoparticles against some pathogen bacteria were studied. Pseudomonas aeruginosa, Actinomycete and Salmonella typhi were used as test microorganisms. Disc bacteriological tests were performed in order to assess the effects of ZnS concentration (0.3 to 50 mg/mL) as antibacterial agent. The inhibition zone diameter was directly and strongly related to the nanoparticle concentration and Actinomycete was the most affected bacteria.

In this work, we have studied the interaction between graphene oxide (GO) and the biomolecules immobilized on an electrode surface, which has been further employed to develop new kind of biosensors by fabricating gammaglutamyltransferase (γ-GGT) sensor as an example. Specifically, glutathione (GSH) is firstly immobilized on the surface of a gold electrode, and GO nanosheet is introduced to recognize the charge change of GSH caused by the catalysis of γ-GGT. Then, the introduction of reductant and Ag+ induces silver deposition and partial reduction of GO, forming GOAgNPs complex for electrochemical readout. Since this complex may have excellent electric conductivity and the solidstate voltammetry of Ag/AgCl can provide a well-defined symmetrically sharp silver stripping peak, a sensitive electrochemical biosensor for the detection of γ-GGT is thus developed. Moreover, the experimental results obtained in this work indicate that GO itself can serve as a general recognition element for biosensor fabrication and GO-AgNPs can be a promising material in a general sensing platform, so such kind of more biosensors can be developed in the future.

The purpose of present investigation is to describe ciliary motion of the transport of fluids in human body based on the mathematical model of the copper nanofluid with pure water as the base fluid. We considered that the group of cilia operate together and produce metachronal waves to transport the fluid at the walls of a tube of finite length. The expressions for exact solutions of the aforementioned problem have been obtained and the results have been discussed graphically for velocity, temperature and pressure gradient for different physical quantities.

Background: The present study was planned to formulate, characterize and evaluate the pharmacokinetics of a novel “nanopolypill” comprising four commonly prescribed cardiovascular drugs, atorvastatin, aspirin, atenolol and candesartan. Methods: The candidate drugs were loaded in Poly (DL-lactide-co-gycolide) (PLGA) by emulsion- diffusion-evaporation method. The formulations were evaluated for their size, morphology, drug loading and in vitro release individually. Single dose pharmacokinetic profiles of the nanoformulations alone and in combination, as a nanopolypill, were evaluated in Wistar rats. Results: The candidate drugs were encapsulated inside PLGA with entrapment efficiencies ranging from 27.8%, 33.5%, 47.5% and 62.9% for aspirin, candesartan, atenolol and atorvastatin respectively. The nanoparticles ranged in size from 50 to 169 nm. In vitro release profile of the nanoformulation showed 100% release by day 6 in the physiological pH 7.4 set up with PBS (phosphate buffer saline) and by day 4-5 in the intestinal pH 1.2 and 8.0 set up SGF (simulated gastric fluid) and SIF (simulated intestinal fluid) respectively. In pharmacokinetic analysis a sustained-release for 6 days and significant increase in the mean residence time (MRT), as compared to the respective free drugs was noted [MRT of atorvastatin, atenolol, aspirin and candesartan changed from 12.9 to 75.75 hours, 8.5 to 74.19 hours, 15.8 to 53.06 hours, and 12.6 to 94.92 hours respectively]. Conclusions: We have shown for the first time that encapsulating atorvastatin, aspirin, atenolol and candesartan into a single nanoformulation, to get the “nanopolypill” is a feasible strategy which has a potential of decreasing pill burden.

Zinc Oxide (ZnO) nanowires were produced by using the seed layer deposition, RF cylindrical magnetron sputtering and sol-gel spin coating techniques. The ZnO seed layer films were characterized by atomic force microscopy (AFM) and ellipsometry. The ZnO nanowires were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Deposition of ZnO seed layer films using the RF cylindrical magnetron sputtering technique produced the best aligned c-axis orientated nanowires with uniform dimensions. An increase in the gold (Au) film layer thickness produced nanowires of smaller diameter and less orientation in the c-axis. Polycrystalline Au film layer increased the mean diameter of the ZnO nanowires without effecting the c-axis orientation. This study provided valuable information in controlling the dimensions and alignment of ZnO nanowires.

TiO2 photocatalysts doped with three transition metal ions of varying concentration were prepared by adsorption phase synthesis. The influence of different metal ion species and contents on the morphology and crystallization of TiO2 sintered under various temperatures was explored by transmission electron microscopy, X-ray diffractometry, UVvis spectroscopy, and X-ray photoelectron spectroscopy. Photodegradation experiments on methyl-orange were employed to evaluate photocatalytic activity. Results indicated that 0.05 at.% Fe3+ and Cd2+ doping introduces lattice distortions as shallow trapping sites; moreover, doping improved the activity of adsorption phase synthesis (APS) catalysts. TiO2 crystallization was restricted when the doping content was greater than 0.05 at.% because other metal ions destroy the TiO2 lattice structure. Restriction also increased with doping content. An optimum doping content was observed during the preparation of TiO2 doped with Cd2+ and Fe3+. As the Fe3+ radius is close to the Ti4+ radius, the influence of Fe3+ doping content on TiO2 crystallization and activity was more apparent than that of Cd2+ doping content. Increases in sintering temperature resulted in fewer lattice distortions acting as shallow trapping sites and decreases in APS catalyst activities.

The main objective of the present study is to discuss the slip-flow of a rotating nanofluid over a stretching sheet. The two phase nanofluid model is used for the physical modeling of the system. Using suitable similarity transformations, governing partial differential equations are reduced into three coupled ordinary differential equations. These equations are then solved numerically using mid-point integration scheme along with Richardson extrapolation via Maple [26-28]. Influence of non-dimensional slip parameter K, rotation parameter γ and nanoparticle volume fraction φ on velocity, temperature and skin frictions have been tabularized, demonstrated graphically and discussed. In order to validate our numerical scheme, skin friction coefficients and local heat flux are computed in the absence of slip and rotation and they are found to be in very good agreement with the previously published literature.

Hydroxyapatite nanoparticles (HAP) were surface-grafted with poly(ε-caprolactone) (PCL) using two types of hydroxyl groups: inherent hydroxyl groups within HAP and hydroxyl groups of poly(2-hydroxyethyl methacrylate) (PHEMA) grafted on the HAP surface by atom transfer radical polymerization (ATRP). The grafting efficiency and the amount of grafted polymer were evaluated by thermal gravimetric analysis (TGA). The colloidal stability testing suggested that the surface-grafted HAP retained higher dispersibility in methylene chloride than pure HAP nanoparticles did. Moreover, the dispersity of the modified particles was significantly improved with the increasing amount of PCL grafted. The composite scaffolds of PCL and surface-grafted HAP exhibited enhanced compressive strength and modulus, which was attributed to the increased interfacial interaction between PCL and surface-modified HAP. In particular, it was found that the compressive modulus of the surface-grafted HAP with 47.2 wt% PCL was 91.6% higher than that of pure HAP mixed with PCL scaffold.

The MHD Peristaltic flow and nanofluid with Newtonian heating in asymmetric channel are considered. The governing coupled equations are constructed “under long wavelength and low Reynold’s number approximation”. The Newtonian heating is controlled by a dimensionless conjugate parameter, which varies between walls of channel. HPM solutions are evaluated for nano particle fraction and heat transfer, while exact solutions are computed for stream function and pressure gradient. The important findings in this study are the variation of the “conjugate parameter for Newtonian heating γ Hartman number M, thermophoresis parameter Nt and Brownian motion parameter Nb on pressure rise, nano particle fraction, heat transfer phenomena, pressure gradient and streamlines”. The velocity field rises due to rise in M close the channel ramparts though velocity field declines at the centre of the canal.

This study reports the synthesis of CoFe2O4 nanoparticles by coprecipitation method in the presence of Linseed Oil as surfactant. The capping agent was used to stabilize the particles and prevent their agglomeration. The characterization studies were conducted by in situ X-ray diffraction, transmission electron microscopy, thermal analysis (TG-DTA) and FTIR spectroscopy. The average particle sizes obtained by XRD data were used to obtain a correlation with size of CoFe2O4 nanoparticles determined, using mathematical equations based on different models. The statistical studies show that the cubic model gives a good correlation within the whole temperature range (100 – 850 °C). The result of these investigations was very useful for establishing the optimal calcination temperature. FT-IR spectroscopy and thermogravimetric analysis (TG) showed that the core-shell structure type of CoFe2O4 nanoparticles is stable below this annealing temperature. TEM analysis indicates that the CoFe2O4 samples during the calcinations treatment were spherical in shape and uniform in morphology and particles size.

Production and characterization of multilayered polymer solar cells consisting of P3HT thin films deposited on titanium dioxide nanosponges are reported. The photovoltaic response is remarkable, considering the simplicity of the thin film production method employed here. The nanostructured TiO2 anodic films were grown in buffered aqueous phosphoric acid solutions under potentiostatic regime at room temperature and then characterized using scanning electron microscopy. The P3HT films were prepared by spin coating technique and the samples were annealed at 180°C. Conversion efficiencies around 0.4% were obtained, with open circuit voltages and short circuit current densities as high as 560 mV and 2.7 mA/cm2, respectively.

The planar defects such as basal stacking faults (BSFs) are probed on m-plane ZnO grown on LaAlO3(112) substrate by reflective second harmonic generation (RSHG). The BSFs result in nonvanishing single-direction dipoles that behave similar to a mirror-like symmetrical dipole. The RSHG pattern from m-plane ZnO comprised of not only the bulk dipole contribution of ZnO but also an additional mirror-like symmetrical dipole contribution from BSF defects. Transmission electron microscopy image displays the presence of BSFs that lie in the c-plane of ZnO and agrees well with RSHG results. Planar BSFs are formed due to the anisotropic stress relaxation between m-plane ZnO film and LaAlO3(112) substrate, resulting in higher-quality m-plane ZnO films.