Current Nanoscience - Volume 13, Issue 2, 2017

Background: The worldwide medicine research is dedicated towards improvement of patients’ health and diseased state. The use of nanotechnology is an upcoming area which is at present, is highly focused in the filed of medicine. Continuous studies in the area have given rise to the development of a novel field called “nanomedicine” which mainly aims to open new perspective of treatments and increasing therapeutic efficacy of existing therapies. Methods: We searched Google, PubMed portals for the literature survey of the following subjects so as to get latest updated information pertaining to latest developments in the field of polymerosomes in nanomedicine. Results: In most of the recent past studies, nanomedicine has gain attention all over the world and has lead to development of new approaches for medical treatments. Some of these approaches involved solubilization, targeting of cancer medicine or application as a diagnostic tool. Polymersomes, which are artificial amphiphilic vesicles, made up of different chemical polymers, are currently being investigated for delivering various probes for imaging target tissues/ organs and cytotoxic drugs to tumor cells and also for gene therapy. In the present review, we discuss the current views on polymerosomes and their medical applications, a prominent emerging area in the field of nanomedicine. Conclusions: Advances in nanomedicine have led to the development of nano-sized polymersomes as vehicles for different medical applications.

Background: Recently it was for the first time found by us, that completely insulating Halloysite nanotubes significantly enhance electrical conductivity of PEDOT/PSS films by simply mixing. Based on this interesting finding highly porous and conductive PEDOT/PSS films hybridized with the Halloysite nanotubes (HNTs) were prepared. The highly porous morphology of the hybrid films would hinder thermal conduction, resulting in lower thermal conductivity which is an advantage for thermoelectric materials. Herein thermoelectric properties of the hybrid films are reported. Methods: The PEDOT/PSS-HNTs film was prepared using PEDOT/PSS dispersion containing 4wt% HNTs and 7wt% ethylene glycol (EG). The PEDOT/PSS-HNTs hybrid films were further treated with ammonium formate (AF) or poly(ethylene glycol) (PEG). The hybrid films were used for measurements of the thermoelectric performance. The electrical conductivity and Seebeck coefficient were measured by using a Ulvac ZEM-3 instrument while the thermal conductivity was measured with a Netzsch LFA 447/2-4/InSb NanoFlash TH Xe flash analyzer and with a Netzsch DSC 204F1 Phoenix differential analyzer, respectively. Results: The PEDOT/PSS-HNTs film, prepared using PEDOT/PSS dispersion containing 4wt% HNTs and 7wt% EG, had moderately high electrical conductivity and Seebeck coefficient, i.e., 46 S cm-1 and 19 μV K-1 at 300 K, respectively, coupled with a quite low thermal conductivity, i.e., 0.16 W m-1 K-1 at 300 K. On the other hand, the PEDOT/PSS-HNTs hybrid films treated with AF or PEG, also showed similar thermoelectric performance. Conclusion: All figure of merit (ZT) values of the hybrid films, which were calculated using corresponding electrical conductivity, Seebeck coefficient and thermal conductivity, were in the range of 1.3-5.5 x 10-3 at 300 K, comparable with those of conventional conducting polymers although the hybrid films composed of insulating HNTs in 75.5 wt%.

Background: Fuel cells have a very low emission of greenhouse gases such as CO2, SOx etc with high efficiencies and are non-polluting energy sources. One of the current challenges is to develop inexpensive and efficient oxygen reduction reaction (ORR) materials. Extensive research has been conducted to develop platinum (Pt) loaded carbon nanomaterials for ORR applications. However, the literature is rife with inconsistencies owing to varying synthesis conditions of Pt nanoparticles, variation of carbon supports materials and indeed the ORR experiments. Method: A comparative electrochemical analysis of various carbon supports, including commercial PtCB, pristine and Pt loaded carbon nanotubes (MWCNTs), graphene oxide (GO) and graphene nano platelets (GNP) has been conducted, to ascertain their electrochemical response towards oxygen reduction reactions under identical experimental conditions. Results: The reduction potential (least negative) and the peak current densities for the materials follow the order of MWCNTs>GNP>GO, with the performance of pristine MWCNTs (3 mA/cm2) comparable to that of N- and B-doped MWCNTs. Furthermore, low-loading of platinum nanoparticles on the carbon supports, carried out via microwave-assisted polyol synthesis, lead to an increase in the peak reduction current density significantly at lower reduction potentials. Although the same synthesis process is used; the MWCNTs, GO and GNP support samples have different metallic Pt loadings. A comparison of ORR current densities mass normalized to Pt loading shows that Pt/MWCNTs have the highest linear sweep voltammetry (LSV) reduction current density of 900 A/g, much higher than 510 A/g of the commercial Pt-carbon black supports, and is followed by Pt/GNP and Pt/GO which have the LSV value of 500 A/g and 200 A/g LSV, respectively. Conclusion: The results showed that the Pt/MWCNTs should be given a favourable consideration in ORR for the future development of fuel cell technologies.

Background: The separation of enzymes from the bio-product medium constitutes a significant part of total process cost. Therefore, it is of crucial importance that the separation processes for enzymes be specially developed. In this study, the advantages of cross-linked enzyme aggregates (CLEAs) and magnetic iron oxide nanoparticles (MIONPs) have been combined in magnetic CLEAs matrix. Methods: MIONPs were produced by co-precipitation methods. The synthesized MIONPs and CLEAs were characterized by scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), dynamic light scattering (DLS), phase analysis light scattering (PALS), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) analyses. Results: Optimal pH and temperature values of magnetic and non-magnetic CLEAs have been determined to be pH=7.5 and T=45oC. It has been observed that there are differences in apparent KM and Vmax values of magnetic and non-magnetic biocatalysts. Moreover, the high activity of nonmagnetic CLEAs is a result of low α -helix and β -sheet contents. Compared with non-magnetic CLEAs, magnetic CLEAs showed high storage stability and good reusability. Due to the different the protein content, the weight loss of the non-magnetic and magnetic CLEAs determined by TGA was about 65% and 53%, respectively. From DSC analysis, the denaturation temperatures of nonmagnetic and magnetic CLEAs were 97±0.8oC and 108±0.8oC, respectively. Conclusion: The present work provided important information on production, comparison and characterization of non-magnetic and magnetic CLEAs from Candida rugosa lipase (CRL) enzyme. The magnetic CLEAs had significant enhancement on the storage stability, thermal stability, reusability comparing with that of non-magnetic CLEAs. These improved properties of magnetic CLEAs could be an attractive feature towards more stable CLEAs preparation. The high cost of complex separation processes could be eliminated with magnetic CLEAs.

Background: Recently, hydrophilic carbon-coated magnetite (Fe3O4/C) has been prepared and applied in adsorption and separation sciences. Although there have been some works on preparation and application of Fe3O4/C in adsorption and separation sciences, little work has been carried out on protein adsorption and desorption on Fe3O4/C. Herein, the present work investigated the equilibrium and kinetics of protein (lysozyme) adsorption on Fe3O4/C NPs. Methods: Fe3O4/C NPs were prepared by hydrothermal method. Effects of pH, initial lysozyme concentrations, and ionic strength on adsorption performance of Fe3O4/C NPs were investigated. Desorption of lysozyme from the Fe3O4/C was examined using 0.5M NaH2PO4, 0.5M NaCl and 1.5M NaSCN, respectively. Results: Fe3O4 and Fe3O4/C NPs with uniform particle size were of quasi-spherical shapes and the dominant diameters of them were about 300 nm and 330 nm, respectively. A coating thickness of carbon on surface of the Fe3O4/C NPs was about 15 nm. Fe3O4/C NPs exhibited typical superparamagnetic characteristics with the maximal saturation magnetization of 73.8 emu/g. Fe3O4/C NPs had a maximum adsorption of lysozyme at pH 9. The adsorption kinetics data fitted well into the pseudo-second-order model while the adsorption equilibrium results were best described by the Langmuir model. Conclusion: Fe3O4/C NPs were prepared by hydrothermal reaction and applied to adsorb lysozyme. The maximum adsorption of lysozyme on Fe3O4/C NPs arose at pH 9. Adsorption equilibria could be reached within 40 min. Adsorption kinetics of lysozyme on Fe3O4/C NPs could be expressed by pseudo-second order model. Langmuir isotherm fitted with experimental data best. The theoretical maximum adsorption capacity of Fe3O4/C NPs for lysozyme was 76.34 mg/g. The best desorption rate was about 32.7%.

Background: In the last decade, Fe3O4 nanoparticles have been intensively investigated for medical applications. Up now, various chemical methods have been applied for their preparation. Although, these methods have been improved in the recent years, however, higher temperature (100-300 oC), toxic and expensive precursors and limited controllability of particle morphology and size still the challenges. As an alternative method, cathodic electrochemical deposition can be effectively applied for the preparation of metal oxides and hydroxides nanoparticles. However, this electrochemical route has been rarely applied into the synthesis of iron oxide nanoparticles, and surface coating of these NPs has not been reported through this method. Methods: A two- electrode electrochemical set up was used in all the electrodeposition experiments, which includes a cathodic stainless-steel substrate centered between two parallel graphite anodes. Naked Fe3O4NPs were prepared by galvanostatic electrodeposition from both electrolytes with applying the current density of 5 mAcm-2 for 1h. For preparation of PEI coated NPs, composition of electrolyte was just changed, and PEI polymer with value of 1 g L-1 was added to the electrolyte solution. The prepared NPs were characterized through FE-SEM, TEM, XRD, DLS and VSM techniques. Results: The XRD patterns have the well-defined and relative broad diffraction peaks which is indexed as spinal structure of magnetite. The Scherrer calculations revealed that the naked and PEI coated samples have sizes of 9.2 and 8.7 nm, respectively. FE-SEM images clearly revealed that both samples have well-defined particle shape and no obvious aggregation is observed for polymer coated NPs. The sizes of 10 nm and 15 nm were measured for the naked and PEI coated Fe3O4 nanoparticles, respectively. This size increase proves the possibility of adlayer formation on the Fe3O4 particles during their formation on the cathode surface. The IR vibrations qualitatively confirmed the successful coating of PEI on the surface of Fe3O4 NPs. DSC curve of coated NPs exhibits two main endothermic peaks at 250 and 285 ºC, and TG curves showed two regions of maximum rate of mass loss located at these temperatures with total weight loss of 29.3%. This weight loss in the TG profile proofed the presence of PEI onto the surface of NPs. For the naked NPs, the mean hydrodynamic diameter was measured to be 16 nm. For the PEI coated NPs, DLS profile exhibits mean size of 50 nm. This size is some larger than that of observed for the naked particles (i.e. 16 nm) and completely implicates the presence of polymer layer on the surface of deposited Fe3O4 NPs. The VSM data confirmed the proper superparamagnetic behavior of the prepared magnetite NPs. Conclusion: An efficient and simple platform was proposed to fabricate naked and polyethyleneimine coated Fe3O4 nanoparticles. The FE-SEM and TEM observations indicated that the deposited coated NPs have spherical shape with size about 10nm. confirmed that the pure magnetite crystal phase of the obtained nanoparticles. VSM analysis of the prepared Fe3O4 NPs showed their superparamagnetic characters. The XRD and IR data specified that the prepared nanoparticles have favorable size and suitable magnetic properties for biomedical applications. It was stated that our applied method is efficient platform for in situ preparation of PEI coated Fe3O4NPs from ethanol medium.

Background: ZnO-based varistors are used as surge protectors in electrical circuits. Nonlinear polymer composites are attractive because of their potential applications in low voltage varistors. The aim of this research is to study nonlinear behavior in a new composite containing ZnO, polythiophene and polyethylene. Methods: Sample disks consist of 70 wt% ZnO and 30 wt% polymer matrixes were prepared using the hot press method under 20 MPa at 120 ºC. I-V characteristics of the disks were studied by applying DC voltage. The structure of the products was examined by FESEM and X-ray diffraction. Results: I-V characteristics of the disks show that their resistivity varies nonlinearly under different voltage. By increasing polythiophene content in sample disks, their breakdown voltage decreases whereas nonlinear coefficient increases. On the other hand increasing press temperature has the same effect on the breakdown voltage and nonlinear coefficient. In addition, each increase in working temperature leads to lower breakdown voltage and nonlinear coefficient. Conclusion: Polymer composite containing 70% ZnO-6% polyethylene-24% polythiophene has an appropriate nonlinear behavior. An increase in press temperature enhances nonlinear coefficient and reduces breakdown voltage. FESEM images of the samples show pressing samples at 120 ºC does not affect composite structure.

Background: In this study, nanoemulsion based gel formulation of acyclovir was prepared in order to increase its topical effectiveness and target the disease site, which is the foremost limitation associated with the topical marketed formulations of acyclovir. Methods: In this study, nanoemulsion based gel formulation of acyclovir was prepared in order to increase its topical effectiveness and target the disease site, which is the foremost limitation associated with the topical marketed formulations of acyclovir. A w/o nanoemulsion in the strength of 5%w/w was prepared using probe sonication method and was characterized extensively in vitro, ex vivo and in vivo to determine the quantity of drug that reached into skin to effectively treat the disease. Results: Skin deposition across the rat skin was found to be 6.6 fold higher with developed nanoemulsion based gel formulation in comparison to the marketed cream. The results of enhanced skin permeation and deposition were deep-rooted by carrying out different mechanistic studies like FTIR and CLSM of skin treated with prepared formulation. The rheological characterization study depicted the shear thinning property and better structural recovery of nanoemulsion based gel (99.17±1.1%) as compared to marketed cream (95.03±0.8%). Further in-vivo localization index, which was found to be 60.33±0.9% and 19.21±0.6% for prepared gel and marketed cream, respectively, assured high skin deposition and adequate penetration of the prepared gel to the different layers of skin with no significant absorption into the systemic circulation. Conclusion: Higher drug solubility, lower particle size, higher surface area and enhanced skin permeation and deposition associated with prepared formulation seems to be responsible for its elevated skin penetration which makes developed w/o nanoemulsion based gel as effective carrier for increasing the local bioavailability of acyclovir.

Background: Different methods of fertilization including chemical (chemical fertilizer such as urea), biological (microbial inoculums) and nano (nutritional elements at the nano level) fertilization are used for providing plants with their essential nutrients under different conditions including stress. With respect to the properties of nutrients at the nano level, the method of nano fertilization, which is a new era in the research, can be used as an efficient method of fertilization for plant growth and yield production. Methods: Accordingly, we have suggested a new type of fertilization in this research work by using a mixture of useful soil microbes with nano nutrients, namely nano biologic. The use of biological and chemical nano fertilization on the yield of pinto bean (Phaseolus vulgaris L.) was investigated under drought stress (water deficit) conditions. The experiment was a split plot in which the drought treatments (different levels of irrigation, according to the water loss from the evaporation pan, class A), at control (60 mm), medium (90 mm) and high (120 mm) level of stress were used as the main plots and fertilization treatments including: 1) control (0), 2) Nano Biologic, 3) Nano Biologic with 75 kg pure N (urea, surface braodcast), 4) 150 kg pure N (urea), 5) 75 kg pure N with nano ZnFeMn (foliarly applied), and 6) 75 kg pure N with ZnFeMn (foliarly applied) were used as the subplots. Yield and yield components of pinto beans were determined. Results: The results indicated that although drought adversely affected bean growth and yield production, nano fertilization types including 3 and 5 resulted in the highest rate of yield and yield components under water sufficient and deficient conditions. Conclusion: Accordingly, the importance of this research work is by introducing and selecting the most appropriate type of fertilization (Nano Biologic and nano ZnFeMn) for bean growth and yield production under drought stress. Such type of fertilizations can gradually provide the plant with its essential nutrients and can be of environmental and economical significance compared with the chemical type of fertilization.

Background: Materials with features such as high transparency and nonlinearity in a wide range of infrared wavelengths can be used in the manufacture of optical fibers. Amongst the materials that are used in the manufacture of optical fibers, chalcogenide compounds are the key materials in the infrared wavelength range. This paper presents a new hexagonal nanostructured photonic crystal fiber based on chalcogenide glass. Methods: In this paper, the parameters like chromatic dispersion, confinement loss, effective area of the propagating mode, and the nonlinear coefficient are examined and simulated. Each concept is explained and the relations among them are explicated. The core is made up of As2Se3 chalcogenide glass and the cladding network consists of 6 air hole rings embedded in the As2Se3 chalcogenide glass. The most important factors in controlling dispersion in the structure are its geometrical parameters. Results: Simulations are carried out using FDTD method. In this structure, parameters such as dispersion, confinement loss, effective mode area, and nonlinear coefficient are examined and the results are presented. It can be concluded that there are four zero dispersion points at 1.03, 2.27, 9.75 and 14.77 μm. The amount of loss from 1 μm to about 10 μm is almost negligible. Considering that within this range, there are also three zero dispersion points, hence, this makes our proposed N-PCF ideal for supercontinuum generation. Conclusion: By adjusting the structural parameters of the N-PCF, the confinement loss is almost zero over the wavelength range of 1 μm to about 10 μm, 4 zero dispersion points are obtained in the mid-infrared region and the nonlinear coefficient is calculated to be about 35 w-1m-1 at 1.55 μm. It is also concluded that the dispersion is almost flat in the infrared wavelength range. The proposed NPCF with the above characteristics is suitable for supercontinuum generation.

Background: Among some of the widely adopted modification methods, metal ion doping in TiO2 based materials is believed to be helpful to retard recombination of photogenerated electronhole pairs. The combination of indium and gadolinium in synthesizing In-Gd co-doped TiO2 is a new approach. The effects of calcination temperature on characterizations and photocatalytic activity of 3%In-0.1%Gd-TiO2 photocatalyst were investigated. Methods: The In-Gd co-doped 3%In-0.1%Gd-TiO2 were synthesized through a sol-gel process. XRD, SEM, FT-IR/FIR, UV-Vis diffuse reflectance, and N2 adsorption-desorption analyses were measured to the materials. Decoloration of methyl orange was conducted to evaluate the activity of the materials. Results: All the samples are composed of anatase phase TiO2 in tetragonal system despite the difference in calcination temperature, while the crystal cell expands at high temperature. The band gap of the co-doped 3%In-0.1%Gd-TiO2 is lower than the normal band gap of pure TiO2. The average pore size increases and the BET surface area decreases with rising calcination temperature, although the total pore volume is unchanged. The sample calcinated at 400 oC has the strongest activity on photocatalytic degradation of methyl orange. Methyl orange molecules are broken up during photocatalytic degradation process. Conclusion: The rising of calcination temperature leads to enlarging crystallite size and cell expansion of TiO2. A continuous decrease of the adsorbed methyl orange amount can be seen with increasing calcination temperature, while the sample calcinated at 400 oC has the strongest activity on photocatalytic degradation of methyl orange.

Background: Amorphous NiAl alloys, whose atomic arrangement is disordered, have attracted a lot of attention due to their unique physical properties, such as high mechanical strength and hardness, high toughness, low friction, good corrosion resistance, and minimal shrinkage. The alloys have excellent corrosion resistance at high temperature and thus are often used in blade coatings. Nanoimprinting lithography (NIL) is an accessible and low-cost technique for fabricating various components on micro- and nanometer scales. Methods: The purpose of this work is to quantitatively study the forming and mechanics properties of the amorphous NiAl films during the NIL process utilizing the molecular dynamics (MD) simulations. The effects of taper angle of mold cavities, interval between mold cavities, and annealing temperature on amorphous NiAl films are studied. Results: The results are discussed in terms of atomic trajectories, shear strain, imprinting force, and elastic recovery of imprinted films. The study contributes to a better understanding of the amorphous material forming mechanisms and mechanics at the nanoscale. MD simulations were used to investigate the effect of taper angle of mold cavities, mold cavity interval, and annealing temperature on amorphous NiAl films. The required imprinting force and adhesion force between the mold and imprinted films increase with decreasing mold cavity interval. Conclusion: Undesired elastic recovery of patterns can be reduced by using molds with smaller taper angles and cavity intervals. During imprinting, film atoms with high shear strain values are mainly distributed in areas with a geometric discontinuity of mold, forming significant defects. Thermal annealing effectively decreases the shear strain of imprinted films; however, it increases the elastic recovery of patterns, especially in the area at the top of a pattern.

Background: Microfluidic chip, also known as lab-on-chip, is recognized as one of the most important advanced science and technology in twenty-first Century. Due to high chemical specificity and high information content, SERS can be used in a microfluidic channel to achieve simultaneous monitoring of composition of multiple analytes. In this paper, we present a simple method to prepare SERS substrate inside a microfluidic chip to detect SYBR Green I. Methods: A microfluidic chip was prepared by a 248 nm excimer laser. A particle-free and lowviscosity precursor solution synthesized by silver acetate, formic acid, and aqueous ammonium hydroxide was dropped in the microfluidic channel. After fifteen minutes of heating on a heating platform, Ag nanoparticles were generated in the channel of microfluidic chip. Then the SERS-based microfluidic systems was used to detect the SYBR Green I dye molecules. Results: Raman signal of SYBR Green I dye can be significantly enhanced in this system. Moreover, SYBR Green I could be quantitatively detected using this system by measuring the SERS signal. Conclusion: In this paper, a method for rapid and in situ fabrication of Ag nano materials in microfluidic chip was presented to detect SYBR Green I by SERS. This method is simple and fast. It has good research and application prospects in polymerase chain reaction (PCR) detection or biological and pharmaceutical testing.Keywords: microfluidic chip, Surface enhanced Raman, SYBR Green I, polymerase chain reaction, excimer laser, PMMA.