Current Nanoscience - Volume 13, Issue 5, 2017

Background: Al-doped ZnO (AZO) films were successfully deposited on the glass substrates at temperature 400 by aerosol-assisted chemical vapour deposition method. Zinc acetate dihydrate, aluminum nitrate nonahydrate, methanol were used as a starting material and solvent, respectively. The influences of carrier gas (N2) flow rate on the structural, optical and electrical properties of grown AZO films were full investigated. The research results indicated that the growth orientation between polar and nonpolar faces in ZnO crystal exhibited obvious difference with increasing carrier gas flow rate. Additionally, carrier gas transport also had a great effect on crystal quality, surface structure and electrical properties of the sample. The uniform AZO film with the resistivity value of 6.7×10-3 Ω·cm and optical transmittance of 80% in the visible range was obtained at a suitable carrier gas flow rate of 30 L/h. Methods: AZO films were deposited on glass substrates in air at temperature 400 by the cold-wall AACVD technique. 0.1 M (mol/L) starting solution was prepared from zinc acetate [Zn(CH3COO)2·2H2O] and aluminum nitrate [Al(NO3)3·9H2O] dissolved in methanol, with a constant Al/Zn atomic ratio of 4 at.%. The reagents used in the experiments were analytical grade and utilized without further purification. The glass substrates were previously cleaned by appropriate solvents (detergent, water, methanol or acetone) and dried in air. Then they were placed into a cold-wall reaction chamber, where two clean parallel plates, 8 mm apart, were heated using a graphite block controlled by a thermostat monitored by a Pt–Rh thermocouple. The precursor solution of 35 ml was nebulized by an ultrasonic humidifier with a wave frequency of 1.7 MHz to form an aerosol mist within a glass bottle. The aerosol mist was transported by an inert gas (N2) to reaction chamber, where it evaporated and then the films deposited on the glass substrate. Carrier gas flow rate ranged from 20 L/h to 40 L/h. The substrates and films were allowed to cool to room temperature in situ and were stored in air. The film uniformity on the substrate at each end of carrier gas flow was different from the central area. Residual part of 70 mm was used for testing after cutting out 40 mm from two ends of the sample, respectively. Results: These researches mostly focused on the doping element, solvent, raw materials, concentrate, and temperature, etcetera. Carrier gas (N2) transport is also an important experimental parameter. The present work, therefore, reveals the mechanism of preferred growth orientation for faces was discussed by Fujihara theory and Boundary layer model in CVD system. In addition, the relationship between carrier gas transport and structure, optical and electrical characteristics of the AZO films were also discussed systematacially in the cold-wall AACVD system. Conclusion: In summary, the mass transport process of inert gas (N2) acted as a carrier in AACVD system has obvious effects on preferred growth orientation, crystal quality, surface structure and electrical properties of deposited films. The AZO films with different growth orientation can be obtained by only adjusting carrier gas flow rate. It has a great significance for preparing ZnO films application to different field. Based on boundary layer model, the appropriate carrier gas flow rate is beneficial to achieve high deposition rate and uniform coating film with excellent electrical properties together with light trapping structure. In this work, we fabricate the AZO film with (110) preferred growth orientation on the soda-lime glass substrates at a suitable carrier gas flow rate of 30 L/h. Meanwhile, deposited films have the resistivity value of 6.7×10-3 Ω·cm and optical transmittance of 80% in the visible range. It is a low cost and simple art, we believe the AACVD technique can potentially be used to fabricate a wider range of zinc oxide films with controlled growth orientation and morphology.

Background: An innovative technique to improve the heat transfer involves dispersing the nanoscale particles in a base fluid, known as nanofluid. In earlier studies, to determine the nanofluid properties, especially the effective viscosity and thermal conductivity, basic models, namely the Brinkman model and Maxwell model have been employed. Yet these models do not take into account the dependency of the viscosity and thermal conductivity on the parameters, say, the mean diameter of the nanoparticles and the temperature. Considering this, recently, some researchers have studied nanofluid with variable properties and proposed new correlations, based on the experimental and theoretical data available in the literature, for calculating the nanofluid properties. The present paper aims to study the effects of uncertainties of different viscosity models of Al2O3–water nanofluid, namely the Brinkman, Abu-Nada, Khanafer and Vafai, and Corcione models on natural convection flow and heat transfer within a differentially heated square enclosure. Employing these models, effects of volume fraction and the mean diameter of nanoparticles, as well as the Rayleigh number, on the characteristics of flow and heat transfer are examined. Methods: The finite volume method was used in order to solve the governing equations as well as the associated boundary conditions. Also, using a second-order central difference scheme, the diffusion terms in the equations were discretized, while, to approximate the convection terms, an upwind scheme was employed. In addition, the SIMPLER algorithm was adopted to solve the coupled system of governing equations. Results: At a Rayleigh number of 105, as the volume fraction of nanoparticles increased, the average Nusselt number increased for the Brinkman model and decreased for the Khanafer and Vafai model and Corcione model, whereas an increase (at high nanoparticle volume fractions) and decrease (at low nanoparticle volume fractions) was seen for the Abu-Nada model. Also, at Ra = 106, as the volume fraction of nanoparticles increased, the average Nusselt number at first decreased and then increased for both the Khanafer and Vafai model and the Corcione model, while for the Abu-Nada model, at first it increased (at low nanoparticle volume fractions), and after that, it decreased and then increased (at high nanoparticle volume fractions). Furthermore, for all volume fractions of nanoparticles and both Rayleigh numbers of Ra = 105 and 106, the Brinkman model predicted a maximum value for the average Nusselt number. As is clear in obtained results, at both Ra = 105 and 106, as the mean diameter of the nanoparticles increased, the average Nusselt number increased for the Khanafer and Vafai model and Corcione model. However, it decreased for the Brinkman model at all volume fractions of nanoparticles. Conclusion: The maximum and minimum average Nusselt number could be obtained using the Brinkman model for Ra = 105 and 106. For Ra = 105, as the volume fraction of nanoparticles increased, the average Nusselt number decreased for the Khanafer and Vafai model and Corcione model and increased for the Brinkman model, while increasing and decreasing behavior was observed for the Abu-Nada model. For Ra = 106, as the volume fraction of nanoparticles increased, the average Nusselt number increased for the Brinkman model; however, increasing and decreasing behavior was observed for the 3 other models. For both Ra = 105 and 106, the maximum absolute value of the stream function increased for the Brinkman model, whereas increasing and decreasing behavior was noticed for the 3 other models. All 4 viscosity models employed did not significantly affect the isotherm contours.

Background: Photodynamic therapy (PDT) which has been approved by FDA is a noninvasive clinical method for the treatment of various cancer and non-cancer diseases. In this work, we herein develop a dual-modality chemo-photodynamic therapy in the G3-PHSNPs drug delivery system, in which rose bengal (RB), an anionic water soluble xanthene dye capable of photocatalytic conversion of oxygen molecule to 1O2 upon irradiation, was used as a photodynamic sensitizer and then anchored to G3-PHSNPs via electrostatic interaction, and subsequently doxorubicin (DOX) as a chemo-therapeutic agent was also loaded onto the same silica cargo via a simple immersion process. Methods: The experiment includes loading of RB onto G3-PHSNPs, chemical method-based detection of 1O2, cell culture and assessment of particle endocytosis, loading and release of DOX onto RBG3- PHSNPs, and cell phototoxicity assay. Results: In vitro studies have demonstrated the active uptake of the RB loaded G3-PHSNPs into the cytosol of tumor cells. Irradiation of the RB-entrapped G3-PHSNPs with light results in efficient generation of highly active 1O2 species. A considerable high loading efficacy and sustained release of DOX may be obtained on account of the inherent structural features of the self-made silica material. In vitro cytotoxicity assays showed that DOX-RB-PHSNPs photoinduced higher cell death compared to the combination of free DOX and RB. These results demonstrate that functionalized therapeutic complexes are potential dual carriers for the combination of photodynamic therapy and chemotherapy in future treatment of cancer. Conclusion: G3-PHSNPs have been successfully fabricated as drug vehicles for dual-modality chemo-photodynamic therapy by assembling RB to amino groups of PAMAM dendrimers located at the external region of silica carriers and subsequently loading DOX in the inner voids/wall pore channels of silica material. The final cell viability of DOX-RB-G3-PHSNPs is lower than that of the combination of free DOX and RB, and the dual-modality DOX-RB-G3-PHSNPs drug-carrier vehicles boosts the combined cell-killing efficacy of DOX and RB.

Background: To succeed in biomedical implant surgery, materials must be biocompatible. Willemite nanoparticles can be used in biomedical applications. MTT assay shows that willemite nanoparticles have non-toxic interaction between Hela (Cervical cancer) cell lines and the willemite found to be biocompatible for further applications in-vivo systems. In depth cell particle interaction was carried out, by using staining technique coupled with inverted microscopy. The antibacterial test was performed against Gram-negative Escherichia coli (E. coli, ATCC 8739) and Gram-positive Staphylococcus aureus (S. aureus, ATCC 6538). The optimal properties with excellent antibacterial ability can be achieved when willemite nanoparticles concentration is between 0.30 ppm and 2.3 ppm. According to the obtained results, the synthesized nano composite powder confirms biocompatibility of willemite, which could be an attractive candidate for biomedical applications. Methods: Pure willemite nanoparticles were synthesized via the modified sol-gel method. Synthesized powder was studied by thermo gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) with SAED techniques. The in vitro biocompatibility of willemite was studied. The biocompatibility of the willemite nanoparticles was studied using Hela (Cervical cancer) cell lines with MTT assays up to 24 h. Results: Willemite nanoparticles were synthesized by facile sol-gel method. The synthesis method is cost-effective and easy to scale up. The results of this work demonstrate the applicability of willemite nanoparticles in the biomedical field. The antibacterial rate increased from 65% to 99% while the cell viability decreased from 98% to 70 % when the willemite nanoparticles concentration varied from 0.05 to 190 ppm. Furthermore, the cytotoxicity studies show that the willemite has lower cytotoxicity. Hence, it is revealed that willemite nano crystals are potentially applicable as bone substitution materials in tissue engineering. Conclusion: Willemite nanoparticles possess effective in vitro noncytotoxicity and antibacterial activity. The favourable properties with excellent cytocompatibility and antibacterial ability can be achieved when willemite concentration is between 0.30 ppm and 2.3 ppm. The antibacterial willemite is non-toxic to the living cells and tissues even if the particles are internalized by cells. Willemite is an excellent candidate in the biomedical field. Novel willemite nano crystals may provide new opportunities for a non-cytotoxic implant with antibacterial ability in bone tissue engineering.

Background: There are enormous methods for modifying electrodes by Prussian blue analogues. We present here rather a very straight forward method of modification by noval nonelectrical deposition of PY nano thin film as a modifier ITO substrate. Methods: PY film was deposited on ITO substrate by simply dipping it in liquid mixture solution of Fe+3 and Fe(CN)6-3 in water at (30C0) the resultant film was washed dried and characterized by XRD,AFM,UV and FTIR. Results: Prepared PY films showed remarkable properties especially electro catalytic activity towards oxidation of AA, so the PY modified electrode was used as a sensor for AA with satisfactory sensitivity and practical linear range. Conclusion: A new type of a nano PY film modified ITO electrode by very versatile and direct method by dip dry method, such PY film shows remarkable electrochemical properties and stability. PY film as a sensor offered a linear response to AA.

Background: Two-component gels are a class of gel system which have different functionalized chemical groups and nanoparticles. The aim of this paper is to introduce readers to the new two-component gels system composed of N-(4-aminobenzoyl)-L-glutamic acid diethyl ester with polyacrylic acid by the self-assembly in different solvents. The obtained morphological and spectral data demonstrate that the single or mixed solvents make a great difference on the gelation abilities of these studied supramolecular gels. Methods: All the two-component mixed gels were prepared in an ordinary way. We put the weighted binary mixtures and selected single or mixed solvents measured volume before put these into a sealed glass bottle. Then in order to get a better dispersion we put them all in a sonic bath for 15 min. Later, the solutions were heated at the temperature of 80°C for 20 min in a water bath. Results: Under the SEM technique which can give the typical nanostructures of these gels, the obtained morphologies show many belt-like structures appeared in the xerogels from solvents of benzene and toluene. In addition, the xerogels from ethanol/water mixed solvents with different volume ratios were also characterized by SEM. IR spectra of the obtained gels are demonstrated main peaks, which can be assigned to the carboxyl and N-H stretching, C=O stretching of ester, amide I band, and benzene ring stretching, respectively. Furthermore, the hydrogel exhibits a continuous adsorption process as well as the equilibrium times are approximately 400 min for MB and CR, respectively. It is acceptable that it takes 400 min to reach equilibrium for high-efficiency adsorption illustration. Conclusion: We have achieved the gelation behaviors and adsorption capacities investigation of new two-component supramolecular gels based on glutamic acid diethyl ester derivatives and polyacrylic acid in different solvents. The solvents and molecular skeletons in two-component gelators make a great difference on the gelation abilities of these studied supramolecular gels. Suitable single solvents or proper volume ra> tios of mixed solvents had an obvious influence on regulating the stacking units as well as assembly modes in the present obtained self-assembly gel systems.

Background: New generation hybrid solar cell has the promising potential in the energy industry due to the most economics energy device, abundant and flexible design for thin film photovoltaic device. The aim of the paper to increase the performance of DSSC by loading optimum amount of titanium dioxide (TiO2) and reduced graphene oxide (rGO) to maximize the textural and electronic properties of photoanode film. The nanocrystal growth on rGO is an important approach to produce nanocomposite film for DSSCs system, since controlled nucleation and growth affords optimal chemical interactions and bonding between TiO2 and rGO, since the rGO is an electron rich material which attract very strong electrical and mechanical coupling within the hybrid nanocomposite film. Methods: By using a facile and cost effective TiO2-rGO nanocomposite film was successfully formed via sol gel method and using titanium (IV) isopropoxide (TTIP) and rGO as our starting material. The nanocomposite was turns into paste and applied to FTO glass using Doctor Blade Method. The current-voltage characteristics and electron impedance was analyzed to obtained the overall performance of the device. Results: The enhancement performance of photoanode and DSSC can be observed by the HRTEM, FESEM, reduction of band gap, photocurrent density-voltage and electron impedance. From the tauc plot relation, band gap energy of TiO2 shows Eg of 3.20 eV and the TiO2-rGO band gap energy, Eg of 2.64 eV shows that rGO nanocomposite was slightly red shifted towards a higher wavelength of about 500 nm, assignable to a narrowing band gap energy effect. From the FESEM and HRTEM results there are reduction of size in the TiO2-rGO film where the reduction in size for TiO2 attribute from the rGO that as it is an electron rich material/ surface where the electron attraction between Ti4+ and the rGO surface contributes to reduction in size of TiO2. The photovoltaic performance of TiO2-rGO nanocomposite (η = 4.18%) was higher than that of pure TiO2 sample (η = 2.21%) due to the high photocatalytic activity during the irradiation. From the EIS results, TiO2-rGO DSSCs semicircle was decreased from the TiO2 semicircle arc reflecting lower charge recombination and faster charge transfer in the interface. The effective path due to 2D graphene bridge that contributes to effective photogenerated electron separation and transport across the photoanode. Conclusion: As for conclusion, TiO2-rGO nanocomposite sample significantly improved the overall conversion efficiency of DSSCs by approximately two times higher than that of the pure TiO2 sample. The improvements in device properties contributed by the homogeneously dispersed of small TiO2 particles on rGO sheet and the pluronic template helps in increasing the active area as it promotes more porosity on the TiO2-rGO nanocomposite to enhance the dye attachments, thus contribute to the better photocurrent efficiency, and improve electron transfer in the material interface during illumination.

Background: Gd2O3 in nano-size has been found efficient in electronic and optoelectronic devices. The main aim of the presented work is to exploit the as-prepared Gd2O3 nanorods as a dielectric material. Methods: Nanorods of Gd2O3 have been prepared by hydrothermal method, and next these nanorods are characterized by different techniques showing the absence of impurities. Furthermore, the as prepared nanorods are exploited as a dielectric material to explore the dielectric properties. The observed dielectric properties extend the scope of Gd2O3 nanorods for large scale applications as dielectric material in devices. Results: Powder X-ray diffractometry (PXRD) analysis of as-prepared Gd2O3 nanorods confirms the base-centered cubic crystal structure of as-prepared materials of average crystallite size (54.40±14.45) nm. Field effect scanning electron microscopy (FESEM) reveals the nanorod shapes of average diameter (58.14±10.46) nm. FTIR spectra represent the characteristic peaks of Gd-O-Gd stretching-vibration and Gd–O vibration. In the entire frequency region (100 Hz – 30.0 MHz), the corresponding values of dielectric constants and dielectric losses are (from 64 to 9) and (from 2.2 to 0.05), respectively. Whereas, the consistent value of dielectric constant (~ 10) and low value of dielectric loss (~ 0.75) in the high frequency region advocate the good optical quality and less defect of the material. In the low frequency region, the material shows the dc conductivity, whereas in the mid and high frequency region, the value of ac conductivity has been found to increase according to frequency power law (σ (ω) α ωn). Conclusion: Nanorods of Gd2O3 can be prepared by simple hydrothermal method at low temperature. As prepared nanorods show the potential and smart behaviour as a dielectric material, this indicates that the as-prepared nanorods can be used as an efficient compound semiconductor dielectric material in electronic and optoelectronic devices.

Background: Novel photocatalytic materials with promising activity are always the most important research focus. The preparation of Sm2Ti2O7 by sol-gel method is hardly found in the literature. Modification of Sm2Ti2O7 by PEG template is interesting for the purpose of synthesizing porous Sm2Ti2O7 material. Methods: Sm2Ti2O7 photocatalyst was synthesized by sol-gel method using PEG4000 as a template. The samples were characterized by XRD, SEM, FT-IR/FIR, UV-Vis DRS, N2 desorption-adsorption, TG and PLS methods. Adsorption and photocatalytic decolorization of RBR X-3B were examined. Results: Pyrochlore phase Sm2Ti2O7 in the Fd3m lattice of cubic crystal system begins to form at 800 °C. Crystallite size and cell volume of Sm2Ti2O7 are enlarged with increasing calcination temperature. The bandgap energies of the samples calcined at 800, 900 and 1000 °C are 3.36, 3.41 and 3.48 eV, respectively. The increase in calcination temperature leads to enlarging pore size and reducing surface area and pore volume. The maximum •OH radicals are produced on the Sm2Ti2O7 sample calcined at 900 °C, accompanied with the optimal photocatalytic activity. Conclusion: High temperature thermal treatment is favorable for crystallization and crystal growing of pyrochlore phase Sm2Ti2O7. The bandgap energies of the Sm2Ti2O7 samples are enlarged with rising calcination temperature. The increase in calcination temperature leads to enlarging pore size and reducing surface area and pore volume. The production efficiency of hydroxyl radical is proportional to photocatalytic activity of the materials. The Sm2Ti2O7 calcined at 900 °C has the maximum photocatalytic activity.

Background: Increasing demands in resource consumption cannot be sustained by a reliance on fossil fuels because of limited supply and catastrophic consequences to climate change. Cellulose is being deemed as the most valuable renewable resources and cellulosic biofuels have been regarded as the most promising candidates to substitute current fossil fuels. This review aims to depict the state-of-the-art development of solid acidic nanostructured catalysts employed in the selective conversion of cellulose into glucose, fructose, 5-hydroxymethylfurfural (HMF) and 5-ethoxymethylfurfural (EMF) via hydrolysis, isomerization, dehydration and etherification. Methods: We try to describe multiple catalytic processes in the catalytic transformation of cellulose into glucose, fructose, HMF and EMF promoted by nanoscale catalysts. Emphasis is also paid to discuss plausible reaction pathways mediated by the nanostructured catalysts with different functionalities. Results: With regards to the efficiently catalytic transformations of cellulose, nano-catalysts are showing great potential in greener processing, higher yield and selectivity's and more favorable economics. 5 tables are presented in details in this review in order to describe the different performance of solid acidic nanostructured catalysts regarding the reaction pathways, including hydrolysis of cellulose into glucose, isomerization of glucose into fructose, dehydration of fructose into HMF, and etherification of HMF into EMF. Likewise, 7 schemes are also described to demonstrate the reaction mechanism of the transformation reactions and the structure-property of the catalysts. This review depicted the state-of-the-art development of solid acidic nanostructured catalysts employed in the selective conversion of cellulose chemicals and biofuels regarding the design and optimization of these materials, and green catalysis. Conclusion: The catalytic conversion of cellulose into fuels alternative and value-added chemicals via different types of reactions has attracted considerable concern in both scientific and industrial communities. Nano-catalysts are showing great potential in greener processing, higher yield and selectivity's and more favorable economics. In order to make these processes practical, environmental- friendly, and cost-competitive, the development of solid catalysis especially nanomaterials mediated catalytic systems able to operate in the aqueous phase is hence critical.

Background: Photodynamic therapy is an approach in which a photosensitizer is activated by light for treatment of diseases such as skin cancer and psoriasis. Because photo irradiation is applied only in the disease area, photodynamic therapy offers the possibility of decreased side effects and good cosmetic results, with consequent better patient compliance with the treatment, thus enhancing the therapeutic outcome. For successful topical photodynamic therapy, the photosensitizer must be able to penetrate into the skin and pass through the stratum corneum barrier which controls the entry of molecules. For enhanced transdermal delivery, nanoparticles have been evaluated as carriers of drugs, including photosensitizers. Methods: In this work, we have developed a review article from structured search of bibliographic databases using a focused in vivo and in vitro use of liquid crystalline nanodispersions based on monoolein, an effective penetration enhancer, to improve photodynamic therapy efficacy. Results: Emphasis is given to photodynamic therapy principles and photosensitizers of different classes which have been loaded into liquid crystalline nanodispersions of different structures. A conceptual framework for understanding the improved photosensitizer skin penetration from monoolein is demonstrated. The main components and characterization techniques of the nanodispersions systems containing different photosensitizer and mechanisms of obtaining each system are discussed as well the components that influence the formation of its internal structure. Finally, a summary of major in vitro and in vivo findings on these nanodispersions in the field of topical photodynamic therapy is discussed. Conclusion: This article briefly outlined recent advances in the field of liquid crystallines nanodispersions based on monoolein. The results demonstrate that their applications on photodynamic therapy of skin diseases are highly effective due to their role on increasing photosensitizer skin uptake without causing healthy cells cytotoxicity. These characteristics make them excellent nanostructured systems potentially applicable for non melanoma cancer and recurrent basal cell carcinoma therapy.

Background: In this part of review, a detailed discussion of plasma enhanced chemical vapour deposition (PECVD) has been done specially for the growth of single wall carbon nanotubes (SWCNTs). Many scientific groups are working on this technique and modifying it day by day. This part of discussion generally reviews the emerging status and high modification of nanotechnology in the field of growth techniques specially for the carbon nanotubes (CNTs) which includes the (1) Reaction chamber (2) Role of plasma in CNT growth (3) Mechanism of CNT growth (4) Applications of CNTs. Nanotechnology is the emerging field nowadays. This technology is changing the face and structure of the world. New nanomaterials are being designed and fashioned by advanced techniques like PECVD as per the application point of view. The new properties of the materials are being investigated with the reduced dimension of the materials. Nanoparticles are showing completely different properties as compared to the bulk materials. From these nanomaterials carbon nanotubes (CNTs) are one of them. CNTs are attracting much attention of scientific community due to their excellent properties. Methods: As per the literature survey, there are three main techniques for the growth of CNTs. The main three techniques are as follows: (1) arc discharge technique, (2) Laser ablation technique, (3) Chemical vapour deposition (CVD) technique. Plasma enhanced chemical vapour deposition (PECVD) is the best alternative, excellent and most modified technique of chemical vapour deposition (CVD) for the growth of CNTs. In this technique, the growth of CNTs takes place in the presence of plasma at low temperature. Results: Nanotechnology is making the things cheaper, smaller, durable and faster due to best designed synthesis techniques. Due to the good properties of CNTs, the highly advanced CNT nano technology can be used for a lot of market applications like energy storage, sensors, field emission displays and transistors etc. New applications of CNTs are being explored. Conclusion: High quality SWCNTs with extra ordinary properties can be successfully grown by PECVD technique at low temperature for field emission display devices, sensor, and energy storage application.