Current Nanoscience - Volume 8, Issue 4, 2012

The past years have witnessed a persistent deterioration of sexual health, especially among young adults. The most concerning problems are sexually transmitted diseases and non-planned pregnancies that cost millions of dollars in healthcare. Sexually transmitted diseases are usually represented by cutaneous signs which may provide a portal of entry for the transmission of other infections, such as HIV. Skin is a widely used route of delivery of drugs locally, and also potentially promising pathway for systemic targeting. Skin contributes to the physical and chemical protection of the body, providing an important barrier against topical drug administration. However, it may be overcome by nanotechnology-based systems, especially in skin diseases, reducing the side effects. Different approaches have been focused on nanotechnology, not only in the treatment of sexually transmitted diseases, but also in diagnostics and prevention of these infections. The present paper highlights recent advances in the nanotechnology-based systems for the diagnostic, prevention and topical treatment of sexually transmitted diseases.

Skin infection is a major cause of hospital admissions as well as causes significant morbidity. Normal human skin is fortunately endowed with its own arsenal of defence strategies to preclude the ingress of pathogenic microbes. However, certain conditions compromise the barrier integrity of skin and permit pathogens to invade the skin. Skin infections may be caused by bacteria, viruses, fungi, and parasites. Topical delivery is advantageous to treat skin infections as opposed to systemic delivery owing to the direct delivery of drug to site of action, thereby reducing the doses and unwanted effects at other non-target sites. The poor penetration of anti-infective agents into skin layers makes topical therapy of skin infections formidable. Nanocarriers such as liposomes, microemulsions, and lipidic nanoparticles, have the potential to deliver drugs to the skin more efficiently than conventional topical carriers such as creams, ointments, etc. These systems have been explored by various researchers for topical delivery of antifungals, antivirals, and antibacterials. The increasing emergence of antibiotic resistant bacterial strains such as Methicillin resistant Staphylococcus aureus (MRSA) and Vancomycin resistant Enterococcus faecalis (VREF) undermine the need for new antimicrobials and new delivery systems to enhance the therapeutic efficacy of existing anti-infectives. Silver nanoparticles (SNP) have as a result made a comeback into the arsenal of antimicrobials. Also, nitric oxide (NO) releasing nanoparticles have been recently explored for their antimicrobial activity. The article showcases the immense potential of an array of nanocarriers in the treatment of cutaneous infections.

Microemulsions are nanosized thermodynamically stable transparent, single optically isotropic liquid systems of water, oil and surfactants. The thermodynamic stability, ease of production, high solubilization capacity and small droplet size made them ideal for transdermal drug delivery. Microemulsions can be prepared using various oils, surfactants and cosurfactants. This diversity in composition will affect the type of microemulsion and influence the transdermal drug delivery potential. The use of microemulsions in skin drug delivery has been reviewed previously but a lack of consecutive studies hampered drawing general conclusions on the effect of components and properties on the drug delivery rate. In addition, alternative mechanisms were reported for transdermal delivery from microemulsion. The first is related to the high drug loading capacity. The second is the penetration enhancing effect of the microemulsion components. The third depends on possible entrance of microemulsion components into the skin as monomers, increasing the solubility of the drug in the skin. The fourth depends on the microstructure of the system which provides large surface area of drug transfer. The last mechanism relies on the phase transition of microemulsions which provides a possibility for producing supersaturated system with high thermodynamic activity. Safety is another important factor which can influence the formulation development. This manuscript will critically evaluate skin drug delivery potential of microemulsions. The assessment will also highlight possible mechanisms of action before finally reporting on the safety and the feasibility of microemulsions for scaling up.

Dermatomycosis are fungal infections that involve the stratum corneum of the skin and the nails, hair, and surfaces of mucous membranes. Mycological infections represent important public health disorders, and their incidence has increased in recent years. This increase may result from a number of causes, such as an increase in the susceptible population, including the elderly and immunodeficient, and social and cultural exchanges associated with sports and the use of swimming pools. In immunodeficient individuals, the lesions associated with dermatomycosis are more intense, and what are initially superficial lesions can result in disseminated and fatal forms. The primary reasons for this include antifungal resistance, toxicity, lack of rapid and specific diagnoses and the poor penetration of drugs. The currently available antifungal agents for the treatment of dermatomycosis include azole and the allylamine group of drugs. The problems related to dermatomycosis therapy are the low residence times of the dosage forms in the site of action, side effects and variable drug permeability. Thus, novel topical drug delivery systems for antifungal therapy have been developed, including liposomes, niosomes, solid lipid nanoparticles, nanostructured lipid carriers, silver nanoparticles, microemulsion and liquid crystals. The objective of this study is to present a systematic review of nanotechnology-based drug delivery systems for dermatomycosis treatment.

It is known that nitric oxide (NO) exerts numerous physiological activities in mammals and it is considered a key mediator in many skin disorders. NO is synthesized in human skin cells where it regulates diverse physiological mechanisms such as dermal blood flow, wound healing, skin pigmentation, and aging. The great challenge of NO-based therapies is to preserve the biological activity of this ephemeral free radical. To this end, new biomaterials have been emerging as platforms for NO release for diverse biomedical applications. This review will discuss the new strategies for releasing/generating controlled amounts of NO for several dermatological applications through the use of nanotechnology.

Despite the efficacy of topical retinoic acid, skin reactions have limited its acceptance by patients. Other retinoids, like Retinyl Palmitate (RP), are considerably less irritating, but they are also less effective. In order to enhance the performance of retinoids, in this work RP has been added to cosmetic formulations such as nanoemulsions, which can provide better penetration of this active substance. Because the vehicle can directly influence the skin penetration and the effectiveness of RP, two skin care products containing 5000 UI RP have been developed and investigated, namely a nanoemulsifying system and a classic gel cream. In vitro penetration tests were conducted by using Franz diffusion cells and placing porcine ear skin and iso-propanol in the receptor compartment. The RP concentration in the skin layers was analyzed by high performance liquid chromatography, and a Zeta-Sizer system was employed for measurement of the the particle size distribution. The penetration tests revealed a large difference between the vehicles in terms of the RP concentrations in each skin layer. The classic gel cream furnished better RP penetration in both the stratum corneum and the epidermis without stratum corneum + dermis, as compared to the self-nanoemulsifying system. The two vehicles displayed the same particle size (between 100 and 200 nm). Better understanding of RP skin delivery using different vehicles has been acquired, and the importance of evaluating the efficacy of nanocosmetics. Results from the present study should also contribute to the assessment of commercial self-nanoemulsifying systems with potential application in the facile production of nanoemulsions.

Topical photodynamic therapy (PDT) has been applied to almost all types of nonmelanoma skin cancer and numerous superficial benign skin disorders. Strategies to improve the accumulation of photosensitizer in the skin have been studied in recent years. Although the hydrophilic phthalocyanine zinc compound, zinc phthalocyanine tetrasulfonate (ZnPcSO4) has shown high photodynamic efficiency and reduced phototoxic side effects in the treatment of brain tumors and eye conditions, its use in topical skin treatment is currently limited by its poor skin penetration. In this study, nanodispersions of monoolein (MO)-based liquid crystalline phases were studied for their ability to increase ZnPcSO4 uptake by the skin. Lamellar, hexagonal and cubic crystalline phases were prepared and identified by polarizing light microscopy, and the nanodispersions were analyzed by dynamic light scattering. In vitro skin penetration studies were performed using a Franz's cell apparatus, and the skin uptake was evaluated in vivo in hairless mice. Aqueous dispersions of cubic and hexagonal phases showed particles of nanometer size, approximately 224 ±10 nm and 188 ± 10 nm, respectively. In vitro skin retention experiments revealed higher fluorescence from the ZnPcSO4 in deeper skin layers when this photosensitizer was loaded in the hexagonal nanodispersion system when compared to both the cubic phase nanoparticles and the bulk crystalline phases (lamellar, cubic and hexagonal). The hexagonal nanodispersion showed a similar penetration behavior in animal tests. These results are important findings, suggesting the development of MO liquid crystal nanodispersions as potential delivery systems to enhance the efficacy of topical PDT.

Chitosan based novel occlusive bioadhesive system for prophylaxis and/or treatment of oral mucositis based on chitosan, suitable surfactants (Cetyl trimethylammonium bromide and Polyquaternium-1 (Polyquad®)) and Propolis ethanolic extract were developed and evaluated in this investigation. The positive synergy was observed combined the antifungal and antioxidant capacity of synthetic and natural biomaterials into functional biocompatible gel. The in vitro antioxidant capacity (free radical scavenging by ORAC and intrinsic reducing capacity by Folin-Ciocalteu Method) was quantified and the influence of antioxidant capacity of Propolis extract on the rate of release of nystatin, from chitosan based material was investigated. These copolymer systems are able to release the drug over several weeks and therefore may be useful as a drug carrier in the treatment of oral mucosatis.

β-Galactosyl residues were covalently attached to modified 10 kDa polyethylenimine (PEI) derivatives and the conjugates were evaluated for cell type-specific effects on transfection efficiency and cytotoxicity. The PEI derivatives consisted of 10 kDa branched PEI, which has lower molecular weight and less cytotoxicity than the more widely used 25 kDa PEI, which was initially carboxyalkylated with three different alkyl chain lengths (C-6, C-10, C-16) and then the primary amine content that was lost in the alkylation process was replaced by attaching the oligoamines, spermidine or diethylentriamine by an amide linkage. β-Galactosyl residues were attached to PEI derivatives by a reductive amination with lactose. β-Galactosylated alkyl-oligoamine derivatives of PEI were able to condense plasmid DNA optimally at a carrier to plasmid DNA (C/P) weight ratio ≥2:1. All β-galactosylated constructs examined yielded complexes significantly larger than those formed with alkyl-oligoamine derivatives of PEI. The measured particle size was in the range of 101–147 nm. β-Galactosylated PEI derivatives containing a C-10 linker and complexed with a luciferase reporter gene (pCMV-luc) gave transfection efficiencies in HepG2 human liver carcinoma cells, which express asialoglycoprotein receptors, up to 2.1 fold higher than for 25 kDa PEI polyplexes prepared in the same manner, whereas in Neuro2A cells there was no significant β-galactosylation-associated differences in transfection efficiencies. β-Galactosylated PEI derivatives exhibited significantly reduced cytotoxicity with both HepG2 and Neuro2A cells at all C/P ratios tested. These results support the use of β-galactosylated derivatives of PEI in any attempt to develop a hepatocytetargeting gene carrier.

In this paper we have implemented the semi-empirical compact model for CNTFETs already proposed by us both in SPICE, using ABM library, and in Verilog-A in order to compare them. Typical analogue circuits and logic blocks have been simulated and results have been presented to validate the implementation of the proposed CNTFET model both in Verilog-A and in SPICE. The obtained results have been the same in static simulations and comparable in dynamic simulations, in which the differences are due to the better implementation of the capacitance model in Verilog-A. We have found many advantages using Verilog-A: the development time in writing the model is shorter, the simulation run time much shorter and the software is much more concise and clear than schemes using ABM blocks in SPICE.

By a method that already has been introduced by Eliasi and Taeri, we computed the diameter of zigzag polyhex nanotubes. As a consequence of calculating, the reverse Wiener index and reciprocal complementary Wiener index of zigzag polyhex nanotorus were computed. We expressed the results in terms of Gamma function, to help us use the software to speed up calculations. Finally, we obtain these indices for some numerical values.

Enteric-coated guar gum microspheres of ornidazole aimed for colon drug delivery have been developed. The influence of core to coat ratio was investigated upon the encapsulation efficiency, swelling, weight loss and drug release behavior. The SEM was used to characterize the surface of these microspheres. Drug–polymer interactions were studied by differential scanning calorimetry and X-ray diffractometry. Enteric coating with Eudragit® S100 enabled maintenance of microspheres integrity until its expected arrival to colon. The in vitro drug release was investigated using USP dissolution rate test paddle type apparatus in different simulated mediums. Only 10 % of drug was release after 5 h while after 8 h (in PBS pH 7.5) a significant increase in percent cumulative drug release (85 %) was observed. In medium containing rat cecal content (pH 7.0) i.e. the amount of the drug released from the formulation was found to be 68 % and ˜ 78.3 % with 2 % and 4% w/v cecal matter. Drug release in presence of culture of Bacteriodes ovatus was found to be 77 %. Ornidazole release kinetics corresponds best to zero order model and drug release mechanism was diffusion and swelling controlled. The significance of differences was evaluated by analysis of variance (ANOVA). Differences were considered statistically significant at P < 0.05.

Nanosized Cr doped ZnO particles were synthesized by facile sol-gel method. The structural, optical and photocatalytic properties of the particles have been investigated by XRD, UV-Vis and FTIR spectroscopy at room temperature for 0%, 0.5%, 1%, 3% and 5% doping concentrations of Cr. X-ray diffraction analysis reveals that the Cr doped ZnO occurs in a single phase polycrystalline nature with wurtzite lattice. The average crystallite size decreases with increase in Cr concentration. The UV-Vis spectra of the nanoparticles indicate decrease in band gap energy upto 3.47 eV for 5% Cr substituion. FTIR results also show the correlation between structural and optical properties of the nanoparticles. The photocatalytic activity of the nanoparticles was investigated by studying the degradation of a dye derivative, Acid Red 17 under UV light source as a function of irradiation time. An increase in the degradtion of the dye was observed from 24.86% to 66.47 % from pure nanosized ZnO to Cr doped ZnO during 70 min of illumination.

The physical properties and performance of polymer matrix composites can be significantly improved by the addition of carbon nanotubes (CNTs) as reinforcements. Nanocomposites formed from poly(lactic-co-glycolic acid) (PLGA) and carboxylated multiwall CNTs (MWCNTs) have been recently fabricated in order to generate suitable implant materials for bone tissue engineering. Here, we reported the cellular reactions of osteoblasts grown on PLGA-MWCNTs nanocomposite films, and investigated the molecular mechanisms responsible for the artificial surface of the films-induced modulation of cellular functions. The results showed that interaction with the PLGA-MWCNTs films induced an increased cell proliferation, DNA synthesis and S phase accumulation, and modulated osteogenic differentiation in osteoblasts. The well-defined stress fibers and enhanced phosphorylation of focal adhesion kinase (FAK) were also observed in osteoblasts cultured on PLGA-MWCNTs films. Assessment of signaling molecules suggested that extracellularsignal- regulated kinases (ERK1/2), but not p38 mitogen-activated protein kinases (p38MAPK) or c-Jun-N-terminal kinases (JNK), were selectively phosphorylated in osteoblasts grown on PLGA-MWCNTs film. Pre-treatment of osteoblasts with PD98059, a specific inhibitor of ERK 1/2, resulted in a significant reduction in cell viability and stress fibers formation of osteoblasts cultured on PLGA-MWCNTs film, suggesting the involvement of ERK1/2 in cell viability and stress fibers formation. These results provided the molecular basis for enhanced biocompatibility of osteoblasts response to the surfaces of PLGA-MWCNTs nanocompostie films, which may account for the potential use of PLGA-MWCNTs composites as promising substrates for bone regenerative applications.

In the present research, the effect of citric acid amounts on the structural and magnetic properties of ferrite particles with a chemical composition of Ni0.4Cu0.2Zn0.4Fe2O4 has been evaluated. Molar ratios of metal nitrates to citric acid (MN: CA) were selected as 1:1 and 1:2. X-ray diffraction pattern confirmed the formation of the spinel phase. Thermal gravimetric analysis, differential thermal analysis, field emission scanning electron microscopy, transmission electron microscopy and vibrating samples magnetometer were used to evaluate the thermal behavior, structural and magnetic properties of the synthesized powders. It was observed that magnetization of nanoparticles decrease by an increase in the amount of citric acid. The results confirmed that with an increase in copper content for the Ni0.6-xCuxZn0.4Fe2O4 ferrite the particle size and blocking temperature increases.

Chromium oxide nanoparticles (NPs) were rapidly synthesized by reduction of potassium dichromate solution with a Tridax procumbens leaf extract containing carbohydrates as a major component which act as reducing agent. The results indicated that watersoluble carbohydrates which have aldehyde group may cause the formation of Cr2O3 nanoparticles. The purification process of the Cr2O3 product does not require expensive methods, since a solid product is obtained from a reaction in liquid phase. The antibacterial effect of Cr2O3 nanoparticles against Escherichia coli was investigated as a model for Gram-negative bacteria. Bacteriological tests were performed in Luria–Bertani (LB) medium on solid agar plates and in liquid systems supplemented with different concentrations of nanosized Cr2O3 particles. These particles were shown to be an effective bactericide. The resulting Cr2O3 nanoparticles were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), UV-VIS absorption and Fourier-transform infrared (FTIR) spectroscopy.

The Ag nanorods were prepared by a simple hydrothermal process, and no any harmful chemicals, templates or surfactants were used. The products were characterized in detail by multiform techniques: scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray analysis. The results show that the products are Ag nanorods with diameters about 40-50 nm and lengths ranging between 400 and 600 nm. Electrocatalytic property of the prepared Ag nanorods was characterized by cyclic voltammetry. CV results indicate that Ag nanorods exhibit a remarkable electrocatalytic activity for the H2O2 reduction. Furthermore, the obtained Ag nanorods have been employed as electrode materials for electrochemical sensing H2O2.

In this study, different amounts of sol-gel derived strontium-containing bioactive glass nano-powders were added to hydroxyapatite to improve its mechanical properties. The bodies were sintered at 1000-1200 °C. Strontium was used in the bioglass composition for its stimulating effects on bone formation. XRD, SEM and microindentation methods were employed for phase analysis, microstructure observation and microhardness/toughness measurements, respectively. Proliferation and activity of rat-derived osteoblastic cells on samples were also determined using MTT and alkaline phosphatase assays. The results showed that the phase composition of pure hydroxyapatite was not affected by elevating temperature; however, the addition of 1-10% of bioactive glass nano-powder to hydroxyapatite led to the formation of β -TCP phase in which its content increased with bioglass concentration and temperature. In addition to β- TCP, α-TCP and calcium phosphate silicate were also found in the composition of hydroxyapatite sintered with 10% bioglass. Bending strength, microhardness and fracture toughness were improved by adding 1-5% bioglass to hydroxyapatite, whereas a decrease in these mechanical properties was observed by adding 10% bioglass. According to the results, the addition of nano-sized bioglass did not change the rate of cell proliferation, but increased the level of alkaline phosphatase produced.

Fe3O4 nanoparticles were successfully synthesized using electrooxidation of iron by a chronoamperometric technique in the presence of tetramethylammoniumchloride surfactant in an aqueous medium. The effect of surfactant concentration and ultrasonic excitation on the structural properties of the nanoparticles we studied using XRD, AES, FT-IR, TEM, and UV-visible spectroscopy. XRD results clearly showed the formation of the spinel phase of Fe3O4. The purity of the nanoparticles was confirmed by AES. FT-IR spectroscopy results confirmed that the surface of the Fe3O4 nanoparticles was covered by surfactant molecules due to electrostatic attraction. The resultant TEM images showed that the particle size and their size dispersion can be controlled by surfactant concentration and ultrasonic treatment. According to these images, an increase in surfactant concentration leads to a reduction in the particle size, a narrower size distribution, and also the particle shape changing from cubic, tetragonal, hexagonal, and triangular to quasi-spherical. Electron diffraction results show that the particles have polycrystalline structure. UV-vis spectroscopy, indicating that their maximum absorption wavelength and peak width decrease with increasing surfactant concentration and ultrasonic treatment.

In this paper, the influence of nickel silicide thin film on series resistance of silicon solar cells is investigated. The frontside two-layer electrodes are fabricated by the light induced electroless plating of nickel and light-induced plating of silver. The nickel films are deposited onto the silicon wafers surface by light induced electroless plating in the nickel-plating bath containing main nickel source. The nickel film thicknesses of 200 nm, 400 nm and 600 nm are identified by the SEM observations. The formation of nickel silicide thin films are obtained after the thermal annealing process for 1 min, 3 min and 5 min. The nickel silicide thin film reduces the series resistance mainly due to the decrease of contact resistance between metal electrode and silicon substrate. The reduction in contact resistance and series resistance are confirmed by using transmission line model analysis and dark current-voltage characteristics in experiment. The improvement of series resistance extracted from the dark current-voltage curve in the upper voltage range is observed. The minimum series resistances of silicon solar cells with different nickel film thicknesses are obtained after different thermal annealing periods, respectively. The silicon solar cell with nickel film of 400 nm thick after thermal annealing process of 3 min possesses the minimum series resistance of 0.66 Ω cm2.

Size-selected palladium nanoclusters have been produced by dc sputtering and inert gas condensation technique using mixtures of argon and helium gases. By controlling the source parameters, it was possible to produce Pd nanoclusters with size in the range of 2-10 nm. Transmission electron microscopy (TEM) images were used to confirm the produced sizes of nanocluster. It was found that increasing the percentage of helium to argon have two main effects: i) decreases the nanocluster size as a result of the high drift velocity of helium, and ii) decreases the number of measured nanoclusters due to the low sputtering yield of helium. Since He gas is primarily responsible for the cluster-condensation process, its partial pressure can be used to control the nanoclusters growth. The source parameters and their effects on the size and number of nanoclusters are of great importance in understanding the Pd nanoclusters growth mechanism.

The present study is aimed at the effect of heat treatment on nanosilver-impregnated Populus nigra, Fagus orientalis, and Abies alba to find out nail and screw withdrawal resistance. Treatments included control, heat-treated, and nano-silver-impregnated heattreated specimens. Empty-cell process was used for impregnation with a 200 ppm aqueous dispersion of silver nanoparticles with the size range from 10 to 80 nm under 3 bars in a pressure vessel for 20 minutes. For heat treatment, both seasoned nano-silver-impregnated and heat-treatment specimens were kept for 24 hours at 135°C. The nails and screws were installed according to ASTM D 1761-88 specifications. Results showed that the maximum nail and screw withdrawal resistance was closely related to the density. The difference between longitudinal and radial withdrawal resistance in both nail and screw was significantly influenced by the species as a softwood or hardwood. Regardless of the species, heat treatment was more influenced by the density rather than species. However, nano-silverimpregnation of the specimens aggravated the effects of heat treatment in hardwoods (more increasing in poplar and more decreasing in beech), but it decreased the withdrawal resistance in fir.

ZnFe2O4 and CdS nanoparticles were loaded onto TiO2 nanotubes (NTs) formed on Ti-5Zr alloy. The ZnFe2O4 and CdS nanoparticles were obtained by electrodeposition and chemistry bath deposition (CBD) methods, respectively. For the electrodeposition of Fe-Zn alloys, transitional steady current density decreased while the concentration of Zn ion in the electrolyte increased. Meanwhile, Fe/Zn ion ratio in the electrolyte determined the composition of Fe-Zn alloys; optimum electrodeposited Fe-Zn alloys for ZnFe2O4 formation were obtained by tuning the deposition variables. The mean diameters of ZnFe2O4 and CdS were about 160 nm and 25 nm, respectively. Study on scanning electron microscopy (SEM), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) indicated that the prepared samples were highly ordered TiO2 NTs composite with ZnFe2O4 and CdS nanoparticles loading on.