Nanoscience & Nanotechnology-Asia - Volume 9, Issue 3, 2019

Introduction: Nanocrystals constitutes of 100% drug and considered as a “new drug” by Food and Drug Administration. It is proven to be an effective alternative for topical delivery of drug with increased bioavailability. Recently formulation of the drug as nanocrystals has been accomplished for many drugs exhibiting low aqueous solubility, ineffective permeability or both in order to increase the dermal bioavailability. Conclusion: In this review article, an effort was made to explain the role of nanocrystals in the dermal delivery of the drug which results in increased bioavailability and efficacy through enhancement of solubility, dissolution velocity, permeation and penetration. Recently dermal delivery of the drug as nanocrystals is a challenging method but explained by many researchers through their work. Preparation of drugs as nanocrystals might be a promising method of drug delivery to Class II and Class IV drugs of Biopharmaceutical Classification System. Drug nanocrystals can also be applied in cosmetics for effective results.

Background: Owing to the importance of metallic nanoparticles, different researches and studies have been induced to synthesize them in many ways. One of the ways that paid attention last years is the green synthesis methods of nanoparticles or the so-called ''eco-friendly methods''. The most common sources that has been used for green synthesis of nanoparticles are plants, leaves, fungi and microorganisms. The green synthesis methods are widely used because they are inexpensive, usable, and nontoxic. Moreover, plant extracts are rich in reducing and capping agents. Methods: In the present review, green synthesis methods of gold nanoparticles (AuNps) using Chitosan, Klebsiella pneumoniae, Magnolia Kobus, Elettaria cardamomum (Elaichi) aqueous extract and other agents as a reducing/capping agents will be discussed in details. Moreover, we will make a comparison between different green routes of synthesis and the characterization of the obtained nanoparticles from each route. Results: The characterization and applications of the prepared GNPs from different routes are reviewed. Conclusion: The utilization of gold nanoparticles has been advocated because of their high biocomptability, administration in clinical applicability and in diverse aspects of life. It seems that plants are good candidates for nanoparticles production because they are inexpensive, available and renewable sources in addition, it is too simple to prepare extracts from them. Moreover, the great diversity in the types and amounts of reducing agents from plant extracts is responsible for the effortless generation of metallic nanoparticles of various shapes and morphologies.

Background: Delivery of drugs through the skin has been an attractive as well as a challenging area for research. Topical drug delivery has provided enormous advantages over the systemic route for various drugs and one of the important amongst them is reduced toxicity due to a minimum or zero exposure to non-target organs. Methods: Various nanocarrier loaded topical preparations including organogels, emulgels, niosomal gel, lyotropic liquid crystal based gels, etc have been investigated for their topical application. Nanocarriers loaded topical preparation have been proven for improved permeation through the cutaneous barrier and delivering the drug at the target site. The objective of this review is to study the recent updates regarding newer topical gel formulations and highlighting their current potential and future scope of the same. Results: The present work has summarized different studies related to nanotechnology derived topical gel formulations and also enlisted few drugs which have been successfully formulated as novel topical gels. Advancement in nanocarriers loaded topical preparations have also been reviewed with their permeation and efficacy compared to conventional formulations. Conclusion: The present review will provide an overview of nanotechnology based topical preparation to the readers and will create curiosity for further development.

Background: In photocatalysis and surface chemistry, charge trapping extends the lifetime of photogenerated electrons and holes and decreases their recombination rate. The stable surface of crystals with lowest energy is (110) for rutile and (101), (010) or (100) for anatase. When these surfaces are exposed to simple molecules such as water, oxygen or methane, different reactions can occur. In this paper, the activity and mechanism of dye adsorption were studied and demonstrated significant increase in the resulting photo-catalysis with optimizing surface properties for the first time. Methods: Degussa P25 (Aldrich) was used a based materials. The mixtures of ethanol (C2H5OH) and triethanolamine (TEA, C6H15NO3) and 1 M HNO3 solution were prepared and applied to chemical etching of anatase/rutile mixture. The nano composites with (0.5 % Pt) prepared by wet impregnation methods used as photo catalysts in water splitting reaction. The metallurgical and photo catalytical properties were characterized with standard methods. Results: The X-ray diffraction (XRD) Results of the samples were shown that the chemical process affected the phases and molar ratios. The photo-catalytic properties of these powders were measured with phase ratios, crystalline size, and reaction time as parameters. TEM images of powders chemically etched at different conditions are shown that the average surface area increased. The TiO2powders consist of spherical particles, that modified to cubic like structure with etching but core of the powders seems to have similar microstructures and shapes. The photo reactivity clearly shows that with adjusting phase ratios, the microstructure, surface and photo-catalytic activity of powders are adjusted. Conclusion: In this study, new method to preparation of core shell structure of anatase and rutile with using of etching developed and photo-catalytic activity of anatase and rutile hetro structure has been investigated using two systems. The reaction rate was related to the surface area, phase's ratio, particle and pore size, adsorption mechanism of reactants, concentration of dye and catalyst. The surface reaction sites and photo reactivity are higher in composite powders with similar particle size and band gap. The concentration of reactants (dye or water, H2, O2) is important because they react in suitable surface sites. The suitable sites are determined by size of compounds and surface charges. Additional to the surface properties, effectively charge separation was increasing the photo reactivity of composites.

Introduction: Within the framework of the phenomenological theory of phase transitions of the second kind of Ginzburg-Landau, the kinetics of ordering of a rapidly quenched highly nonequilibrium domain structure is considered using the lithium tantalate and lithium niobate crystals as an example. Experimental: Using the statistical approach, evolution equations describing the formation of the domain structure under the influence of a high-frequency alternating electric field in the form of a standing wave were obtained. Numerical analysis has shown the possibility of forming thermodynamically stable mono- and polydomain structures. It turned out that the process of relaxation of the system to the state of thermodynamic equilibrium can proceed directly or with the formation of intermediate quasi-stationary polydomain asymmetric phases. Results: It is shown that the formation of Regular Domain Structures (RDS) is of a threshold character and occurs under the influence of an alternating electric field with an amplitude less than the critical value, whose value depends on the field frequency. The conditions for the formation of RDSs with a micrometer spatial scale were determined. Conclusion: As shown by numerical studies, the RDSs obtained retain their stability, i.e. do not disappear even after turning off the external electric field. Qualitative analysis using lithium niobate crystals as an example has shown the possibility of RDSs formation in high-frequency fields with small amplitude under resonance conditions.

Background: The characteristic visible emission from ZnO being attributed to the defect energy states can be tailored by doping as well as by synthesis techniques. Rare-earth elements, among various dopants, are interesting because of their unique emission properties in the visible region. Terbium (Tb), in particular, is reported to contribute significantly to the creation of the defect energy states when doped in ZnO. This study investigated the Tb concentration dependent modifications in the structural and optical properties of ZnO nanophosphor. Methods: Tb (0.1, 0.5, 01.0 mol%) doped nanophosphor powder samples prepared by low temperature precipitation method, were sintered in air at 700oC using a home-built temperature controlled (±1oC) muffle furnace. Powder XRD and EDX spectra at room temperature were recorded using Philips X perts x-ray spectrometer while Jeol JSM-7600F was used to record SEM images. Photoluminescence spectra excited by the 280, 300, 380 and 460nm radiation from a Xe lamp were recorded using Carry 8000 spectrophotometer. Raman spectra excited by 514.5nm radiation from an Ar-ion laser, was investigated using Morrison microscope Olympus Bx 41 while UV-VIS absorption spectra were recorded on UV- 1800 UV-VIS Spectrophotometer. Results: FTIR and XRD spectra showed that the basic ZnO wurtzite crystal structure remained unchanged on doping. However, XRD data analysis indicated that the 0.1 mol% Tb might be incorporated in ZnO unit cell at an interstitial and / or substitutional site(s) while at 0.5 and 1.0 mol% doping levels migration of Tb to the surface could be the dominant process. This was further confirmed by Raman and photoluminescence studies. Broad emission (122nm FWHM) peaking around 510nm was observed when the doped samples were excited with 280 and 300nm radiation while characteristic ZnO emission was observed with 380 and 460nm radiation. The calculated chromaticity color coordinates (x,y) of the emission excited by 280nm in 0.5 mol% doped ZnO were: x=0.29 and y=0.31, which are very close to those of the daylight at noon. Conclusion: Concentration dependent lattice distortions were observed; it was concluded that at 0.1mol% concentration level Tb was incorporated in ZnO lattice resulting in interstitial or substitutional defects. On the other hand, at 0.5 and 1.0 mol% doping levels diffusion of Tb to the surface producing strain due to "hydrostatic like pressure" seemed to be the dominating process; maximum strain was observed at 0.5mol% doping. The calculated chromaticity color coordinates of the 280nm excited emission from ZnO:Tb (0.5mol%) were found to be very close to those of the "day light at noon" indicating the suitability of the material for the realization of white light sources.

Background: The properties of the material are altered when material size shifted towards nano-regime. This feature could be used for wastewater treatment process using model pollutant such as dyes. Recently, nanoparticles are synthesized by a green chemical route using different capping agents. This is the reason we adopt starch as green capping agent along with sol-gel method. Objective: To synthesize cobalt oxide nanoparticles by green chemical route and utilized it in degradation of dyes. Methods: Synthesis of cobalt oxide nanoparticles by sol-gel method using starch as a capping agent. The characteristics of surface modifications were investigated by UV-VIS, TEM, SEM, XRD and FTIR techniques. Results: Cobalt oxide nanoparticles synthesized and inhibited photocatalytic activity. Conclusion: Deactivation of photocatalytic activity due to complex nature of starch. This property can be used elsewhere as in light shielding applications to coat and protect surfaces in order to keep them cool and safe from damage as in the painting of vehicles, roofs, buildings, water tanks, etc.

Introduction: In this study, Persian gum/poly (vinyl alcohol) nanofiber and whey protein isolate/ poly (vinyl alcohol) nanofiber were fabricated using electrospinning system. Materials & Methods: The effects of supplementation of Oliveria decumbens Vent. essential oil on the physicochemical and biological characteristics of the nanofibers were investigated by applying the techniques including antioxidant activity measurement, scanning electron microscopy, viscosity and conductivity tests, and fourier-transform infrared spectroscopy. Results: The results showed that the incorporation of 1% Oliveria decumbens Vent. essential oil to the polymer dispersions causes the formation of thin nanofibers with the least beads. Both types of nanofibers containing essential oil exhibited significant radical scavenging activities up to 76.82±0.36% and 61.09±0.13% for whey protein isolate/poly (vinyl alcohol) nanofiber and Persian gum/poly (vinyl alcohol) nanofiber, respectively. Conclusion: The results of fourier-transform infrared spectroscopy proposed the structurally incorporation of the essential oil into nanofibers to be considered as novel coating film for active packaging technology.

Introduction: Convective heat and mass transfer in nanofluids is a topic of major contemporary interest in both science and technology. In view of this, an unsteady MHD free convective flow of nanofluids through a porous medium bound by a moving vertical semi-infinite permeable flat plate with a constant heat source and convective boundary condition in a rotating frame of reference is studied theoretically. Experimental: The novelty is the consideration of constant heat source and convective boundary condition in a rotating frame. The velocity along the plate i.e., slip velocity is assumed to oscillate in time with constant frequency so that the solutions of the boundary layer are of the same oscillatory type. The dimensionless governing equations for this investigation are solved analytically using small perturbation approximation. Two types of nanofluids, namely Cu-water and Al2O3-water are used. Results: The effects of various parameters on the flow, heat and mass transfer characteristics are discussed through graphs and tables. Conclusion: An increase in the convective parameter and nanoparticle volume fraction leads to increase the thermal boundary layer thickness but opposite effect occurs for heat generation.

Introduction: An alternative source of synythesis of nanoparticles is plant extract rather than chemical methods. This is because of presence of secondary metabolites or reducing agents in plant extract which are responsible for nanoparticles synthesis. In bioaccumulation, this synthesis depends upon the availability of particular enzymes or protein in plant extract. Materials & Methods: Considering the therapeutic potentials of nanoparticles, this work has been designed to find out antibacterial activity of silver nanoparticles. Objectives of this work are - preparation of silver nanoparticles chemically and biologically, characterisation of nanoparticles and evaluation of their antibacterial activities against E. coli. Comparision of antibacterial properties were made among NaBH4- AgNPs, Azadirachta indica (Neem) extract AgNPs and Brassica oleracea (Cauliflower) extract AgNPs. UV- absorption spectra of chemically and biologically synthesized AgNPs at different time intervals were measured using UV-Visible spectrophotometer. Particle size of AgNPs was measured by dynamic laser scattering technique (DLS) using Malvern Aimil Zetasizer. Results: The obtained silver nanoparticles were of sizes between 10 nm and 100 nm. Conclusion: It was clear from antibacterial activities that biologically synthesized AgNPs were more effective against E. coli than chemically synthesized AgNPs.

Objective: In this research, carboxylated multi-walled carbon nanotubes were used to construct working and counter electrodes of the electrochemical gas sensor. The 1-allyl-3- methylimidazolium bromides which is a hydrophilic room temperature ionic liquid was used as the electrolyte. Finally, the sensor was used to measure hydrogen sulfide and carbon monoxide in the air. Methods: The electrochemical method was used to measure the hydrogen sulfide concentration. To record sensor response, chronoamperometry was performed. Also, impedance spectroscopy of screen printed electrodes modified with MWCNTs-COOH was done. The working electrode was characterized by field emission scanning electron microscopy (FESEM), Energy-Dispersive X-Ray Spectroscopy (EDX) and Fourier-Transform Infrared (FTIR) spectroscopy. Results: In the range of 0.6 ppm to 10 ppm, the sensor had a linear behavior and its sensitivity was 0.3716 μA / ppm. The results of the FESEM, EDX and FTIR analysis confirm the desired structure of the working electrode. Impedance spectroscopy shows that by using ionic liquid electrolyte the impedance is less than the case of the sulfuric acid electrolyte. Conclusion: The use of ionic liquid as an electrolyte can increase the sensor sensitivity about 141% with respect to sulfuric acid as the electrolyte, in 0.6 ppm to 10 ppm concentration range of H2S gas. Also, the sensor response to hydrogen sulfide is more than one thousand times greater than its response to carbon monoxide per 1 ppm of gas.

Background: Escherichia coli (E. coli) bacteria is one of the hazardous human pathogens. Consequently, developing the rapid and effective method for identification and quantization of E. coli is popular in biotechnological researches in recent years. Experimental: In this research, a label-free capacitance E. coli biosensor was fabricated based on immobilizing bacteriophage on the carbon paste electrode (Cp). Reduced graphene (RGr) was synthesized and used as a substrate for immobilization of bacteriophage on the Cp surface. E. coli bacteriophage was trapped in graphene modified carbon paste electrodes. The immobilization accuracy was confirmed via electrochemical techniques. The modified electrodes were applied as indicator electrodes for capacitance measurements of E. coli. Results: Through this method, E. coli was detected in a concentration range of 33x10-3 to 330x10-3 N L-1 (number of E. coli per Liter) with a correlation coefficient of 0.99 and a detection limit of 12x10-3 N L-1. Conclusion: The proposed biosensor has a fast response time of about 5 s and good selectivity over other bacteria.

Background: Diatoms are a large unique group of unicellular microalgae with a significant ornamented cell wall made of hydrated silica, which is called "frustule". Their ornamented siliceous shells are usually composed of multi-layer structures with multi-scale porosity, which can be used as a promising source to obtain hierarchical macro and mesoporous silica microparticles. The present study is one step forward through a long road seeking for green nanofabrication techniques of such porous materials that will be economically more efficient with large design flexibility. Materials and Methods: For seeking different porosity scales, architectures, and distribution patterns, a total of 237 diatom species and varieties belonging to 68 genera were identified from 59 samples, which were collected from different Egyptian habitats and environments. Of these eight species were selected to study their frustules' ultra-structures in details, including; Aulacoseira granulata (Ehrenberg) Simonsen, Actinocyclus octonarius Ehrenberg, Cyclotella meneghiniana Kützing, Pleurosira laevis (Ehrenberg) Compére, Synedra ulna (Nitzsch) Ehrenberg, Achnanthes brevipes Agardh, Nitzschia amphibia Grunow and Nitzschia palea (Kützing) W. Smith. Nitzschia palea (Kützing) W. Smith was also isolated and cultivated. Results: The ultrastructure and porosity of all studied species had been revealed. The porosity scale was ranged from 5 to 500 nm in diameter. Conclusion: The obtained results showed the potential of diatom frustules in nanotechnology as a source of natural silica microparticles with macro and mesoporous structures could be of a large interest for applications including ultra, micro and nanofiltration, drug delivery systems, optoelectronics, or other novel nanotechnology applications.