Current Nanoscience - Volume 10, Issue 2, 2014

Understanding the phenomena for habitat isolation of a heterogeneous cell population in a three-dimensional constructs will be useful for developing biomimetic and functional engineered tissues. To examine the habitation of co-cultured cells, a five-layered human skeletal muscle myoblast (HSMM) sheet, regarded as a plate-shaped aggregate, was overlaid onto target cells, namely human skeletal muscle fibroblasts (HSMFs) and human umbilical vein endothelial cells (HUVECs), with different initial densities on the bottom surface to investigate the behaviors of target cells in the plate-shaped aggregate. Under low-density conditions, HSMFs rapidly and linearly migrated in the vertical direction after detaching from the bottom surface; cells reached the upper layers, resulting in habitation of both the top and bottom of the plate-shaped aggregate. HSMFs under high-density conditions maintained a horizontally spread aggregation, and remained in the lower layers of the five-layered sheet. HUVECs show a horizontally elongated shape to maintain their horizontal connections with neighboring cells; this led to slow migration in the vertical direction through the formation of net-shaped aggregates in the middle of the five-layered sheet, regardless of initial density. In addition, measurement of local fluidity in the plate-shaped aggregate by evaluating target cell migration revealed the highest fluidity on the top layer, suggesting that fast-moving co-cultured cells migrate towards the top of the plate-shaped aggregate. Thus, the heterogeneous cell population made habitation inside a plate-shaped aggregate due to differences in their behaviors of migration and cell-cell connection, as well as their environment of sheet fluidity.

Ultra-high molecular weight polyethylene (UHMWPE) wear debris induces osteolysis and leads to the loosening or failure of artificial joint. The lifetime of artificial joint is mainly determined by its tribological behaviors in synovial fluid. Various synovial fluid compositions such as albumin, globulin, hyaluronic acid (HA) and phospholipid might influence the tribological performance. Therefore, we investigated the nano-tribological behaviors of different biomolecules in synovial fluid for improving the lubrication of artificial joint. In this study, a biomimetic synovial fluid was used as baseline to examine the tribological effects of adding various biomolecules to synovial fluid. The results indicated that adding HA molecules to synovial fluid reduced the friction coefficient and increased the viscosity. Moreover, HA had the potential to decrease the friction caused by accumulative albumin and γ-globulin in synovial fluid. In summary, the findings demonstrated that HA was a critical synovial fluid molecule in dominating the lubricating properties of artificial joint. The efficient concentration of HA in synovial fluid could be adjusted to 4.5 mg/ml. The role of biomolecules in dominating the nanotribological process of artificial joint materials was investigated in this study. It was thought the nano-scaled interactions between the biomolecules may construct the major mechanisms.

The interaction of a single molecule of DNA with cationic comb-type copolymers has been observed using a flow-stretch assay. We have shown that interaction with a copolymer with a high degree of grafting did not cause a coil-to-globule transition but resulted in shrinkage of the DNA by 20%. In this study, a flow-stretch assay was employed in which changes in length and fluorescence intensity of DNA were simultaneously observed. Upon binding of fluorescent intercalator dyes, the DNA length was extended. In the presence of copolymer, dye binding was inhibited and DNA length was not significantly different than that in the absence of dye and copolymer. Our data suggest that the copolymer does not influence DNA length. Our observation implies that use of the fluorescence dye exclusion assay to estimate DNA condensing activity of polycations must be carefully carried out.

Combination of biomaterials with nanotechnology has been applied to the immobilization of chitosan on nano-gold particles by plasma and grafting treatments. In this study, gold (Au) nanoparticles were first synthesized by chemical reduction method using mixing solution of HAuCl4.4H2O and sodium citrate or NaBH4. The synthesized gold nanoparticles were then reacted with 11- mercaptoundecanoic acid (MUA) containing thiol group to modify the surface of gold nanoparticle. The MUA-modified Au nanoparticles were subjected to O2 plasma pretreatment before the UV light grafting polymerization with N-Isopropylacrylamide (NIPAAm) on the plasma-treated Au nanoparticles to form a thermosensitive polymer on the surface. The functional groups on the grafted Au nanoparticles surface were combined with glutaraldehyde to immobilize biological molecules of chitosan. The results show that preparation of nano-Au particles using NaBH4 solution as reductant is better than using the sodium citrate solution. The preferable reaction temperature for the preparation using NaBH4 solution to produce nano-Au particles is 100°C. From the TEM observation the prepared Au nanoparticle was spherical-like and about 10~20 nm in size. The zeta potential measurement on the immobilized Au nanoparticles proves that chitosan was indeed immobilized on the Au nanoparticles surface.

The goal of this research is to improve the mechanical and biological properties of widely used polylactic acid (PLA) in order to enhance the mechanical processability and bioactivity performance of the PLA-based medical implants. A polypropylene carbonate (PPC) polymer was utilized to control the bending strength of the PLA composites, leading to elastic PLA composites without any nontoxicity to osteoblast-like cells. Furthermore, a bioceramic material, tricalcium phosphate (β-TCP), was also introduced to further finetune the mechanical properties of the PLA composites. Experimental data revealed that the resulting elastic β-TCP/PPC/PLA nanocomposites exhibited elongation at break (%) of 1100% with tensile strength close to 1 MPa. The method developed in this study provides a simple strategy for fabricating biodegradable PLA based-materials with desired mechanical processability and malleability at room temperature.

One of the major challenges in the development of biomaterials is the adaptation of the complex elastic nature and elongation of human tissues during biomechanical functional loading. Composite materials present the most appropriate means of attempting to match the mechanical and biocompatibility requirements. Composite films from polylactic acid (PLA) and sol-gel derived bioglass (BG) powders with particle size ranging from 50-100 nm were produced by solution casting method. Three different bioglass mixtures of 0.1, 0.5 and 1% bioglass were prepared. Physico-chemical and morphological properties of bioglass, pure PLA and PLA composites were investigated using XRD, SEM and FTIR. Bioglass particles were further treated by nanolayer coating of 3-aminopropyltriethoxysilane (APTES) to improve its mechanical properties. The effects of surface treated bioglass on the fracture of the PLA/bioglass composites were investigated under tensile loading conditions. The results suggest by nano-surface treating the bioglass with 1% APTES significantly influences the percentage elongation of the PLA/bioglass composite at fracture. SEM shows more agglomeration of untreated bioglass within the composite. In the treated samples, a better distribution of nanosized bioglass within PLA matrix was observed. Nanolayer modified bioglass /PLA thin film composites may have a wide range of biomedical applications in tissue engineering with improved elastic properties.

Stents are miniature medical devices that can be inserted into arteries and expanded during angioplasty to restore blood flow and prevent arterial collapse. They have been the primary treatment for cardiovascular diseases since the 1990s. However, after stenting, potential risks associated with restenosis may occur, and several studies have shown that stent design could be one of the critical factors in this process. Computational modeling has been widely used as an important tool to predict the clinical performance of stents and hemodynamic behavior in stented arteries. In this study, computational fluid dynamics models were developed to investigate the effects of cardiovascular stent design on the wall shear stress distribution in straight and curved coronary arteries. Results showed that the stent design pattern alone did not have a significant impact on stent hemodynamics; however, stenting in curved arteries increased the low shear stress area, the region where wall shear stress is less than 5 dynes/cm2, which may lead to a higher restenosis rate. The total surface area of low wall shear stress almost doubled when the angle of artery curvature increased from 0o to 90o. The implication is that stent implantation in a tortuous artery greatly increases the risk of restenosis. The proposed methodology and findings show that the presence of a stent in straight or curved arteries alters the flow field and wall shear stress distribution within arteries, providing great insight for the future design optimization and physician practice to help achieve the best possible clinical outcomes.

Composite bone cement composed of tricalcium silicate (Ca3SiO5, C3S), hydroxyapatite particle (nano-HAp) and collagen was prepared and investigated in this study. We synthesized C3S through a solid-state reaction and modified it by adding zinc oxide (ZnO) in order to stabilize the C3S phase during preparation. In order to achieve proper setting time and better powder characteristics, a series of different molar ratio of ZnO to CaCO3 precursors were tested. An optimized composition, Zn02.5C2.75SiO5, was chosen for further studies. Zn02.5C2.75SiO5 powder was mixed with 10 wt% NaH2PO4 solution with the liquid to powder (L/P) ratio of 2:5. The setting time was measured to be within one hour, and the pH value maintained between 8 and 10. Furthermore, 5 wt% nano-HAp particle and 2 wt% type I collagen were mixed to comprise the composite bone cement. The set product had a compressive strength up to 85 MPa. The set materials were further tested in vitro by culturing the mouse fibroblast cell line L929. Through the cytotoxicity tests (MTT) of the extracts in medium, the results revealed that the set matter had a good biocompatibility. When the cells were directly seeded onto the material, the cells attached well and would out-stretch their pseudopodia through SEM observation. The results of in vivo test through subcutaneous implantation in rat showed that the material was well biocompatible with neovessel formation. The results indicate that this novel composite bone cement exhibits good properties and biocompatibility as well as a desirable biomaterial.

This objective of this study is to investigate the antibacterial properties and biocompatibility of Portland cement/bismuth oxide/ zinc oxide (PC/Bi2O3/ZnO) composites hydrated by a novel calcium lactate gluconate (CLG) accelerant. The 23.1 wt% CLG aqueous solution and deionized water (DDW) were used to set PC/Bi2O3/ZnO, MTA (mineral trioxide aggregate)-like cements, and commercial ProRoot®WMTA. Changes in setting time, pH values, antibacterial properties, and cell viability were assessed by Vicat needle measurement, pH meter, agar diffusion, and MTT assay, respectively. Unlike set by DDW, the PC/Bi2O3/ZnO, MTA-like cements, and ProRoot® WMTA revealed short setting times and low pH values when set by CLG solution. The agar diffusion test showed a significant decrease in inhibition zone diameter against Streptococcus mutans (p < 0.05) in the ProRoot®WMTA and MTA-like groups when set by 23.1 wt% CLG solution but not in the PC/Bi2O3/ZnO group. The MC3T3-E1 cell-based MTT assay revealed that ProRoot®WMTA set using CLG had significantly higher cell viability than the other groups (p < 0.05). The PC/Bi2O3/ZnO cement hydrated with the CLG solution revealed improved antibacterial properties and biocompatibility over ProRoot®WMTA.

Stem cell therapy and research have been a debated topicin recent years. Regardless of the usefulness and great potential of stem cells in the fields of tissue engineering and regenerative medicine, preservation techniques suitable for stem cells have not yet been established. We attempted to develop a preservation solution that can enhance the viability of stem cells after preservation. Cryopreservation is a standard technique for long-term cell storage, but the toxicity of conventional cryoprotective agents (CPAs) such as dimethylsulfoxide(DMSO) make it difficult to recover cells after thawing. ε-poly-L-lysine (PLL), in which the amino groups were converted to carboxyl groups at an appropriate ratio (more than 50mol % to 80mol %), was shown to have higher cryopreservation efficiency and lower cytotoxicity than current cryoprotective agents (CPAs). Using PLL with 65 mol% [PLL(0.65)] carboxylation, the protective effect on mouse induced pluripotent stem (iPS) cells under hypothermic preservation (4°C and -196°C) was investigated. After preservation, iPS cells retained their proliferation capacity and expressed markers of undifferentiated cells. Thus, we concluded that an effective and safe CPA was developed. PLL(0.65) can therefore be a valuable component of a DMSO-free, xeno-free, and chemically defined preservation solution for stem cells that also can be utilized at 4°C.

Novel poly-L-lactic acid (PLLA) microtube array membranes (MTAMs) with a porous wall structure were prepared by electrospinning. Porogen of polyethylene glycol (PEG) was mixed with PLLA and dissolved in a dichloromethane/dimethylformamide solvent. The solution dope was delivered to the outer layer of coaxial spinneret, while the PEG/polyethylene oxide (50/50 wt. %) aqueous solution was delivered to the core layer, to form arrays of core-shell fibers through an electrospinning process. Porogen was then washed off to produce array of microtubes with a porous wall structure. The morphology and physical properties of the MTAMs were characterized by scanning electron microscopy (SEM), a texture analyzer (TA), and a thermogravimetric analysis (TGA). With porogen content of 0~50 wt.%, pores, ranging from a few tens of nanometers to a few microns, were clearly seen in SEM micrographs for the surface of PLLA/PEG30-50 MTAMs after the washing process. However, porogen was effectively washed off only from PLLA/PEG30-50 MTAMs, thus their wall structure was transformed from a dense to porous one. PLLA/PEG MTAMs remained relatively hydrophobic. Young’s modulus of PLLA/PEG MTAMs decreased from 850 to 400 kPa, while the fracture work increased from 854 g.mm to a maximum value of 4478 g.mm for PLLA/PEG10. Permeation through MTAMs was conducted, and results revealed that only pores in the walls of PLLA/PEG30-50 MTAMs were well interconnected. Cumulative permeation increased with the PEG content. These results suggest that multifunctional porous PLLA MTAMs can potentially be used in medical applications, such as nerve regeneration conduits.

The aliphatic polyesters PLLA (poly L-lactic acid) and PBSA (poly (butylene succinate)-co-(butylene adipate)) were used to fabricate nonwoven-type scaffolds with sub-micrometer fiber diameters via an electrospinning method. The electrospun membrane surfaces were further coated with either γ-PGA (poly-γ-glutamic acid) or collagen through physical bonding. These specialized surfaces were employed as peripheral nerve conduits to regulate cell adhesion and cell proliferation in vitro of the neuron cell line PC12. Furthermore, the expression of neuron growth-related (GAP-43, MAP-2) and apoptosis-related genes (Bcl-xL, Bcl-2, Bax, Fas) was evaluated for PC12 cells cultured on the electrospun membranes in response to NGF (nerve growth factor) treatment. No significant differences in apoptosis-related gene expression were observed as a function of membrane type. The GAP-43 and MAP-2 genes were highly expressed on the PLLA samples with NGF but performed variably on the PBSA samples depending on the type of coating material. Our results suggest that electrospun PLLA membranes can serve as proper matrices for neuron outgrowth and that electrospun PBSA membranes are suitable surfaces for PC12 cell attachment and proliferation.

Anticancerous activity of silver nanoparticles, synthesized by Streptomyces olivaceus was evaluated against Non-small cell lung carcinoma cell line (NCI-H460). The optimum concentration of 1mM silver nitrate required for biological synthesis was identified by inoculating the pellet and supernatant obtained from Streptomyces olivaceus-1392 in various concentrations of Silver nitrate solution. The nanoparticles were synthesized intracellularly by inoculating the culture in 1mM silver nitrate under standard conditions and the production was determined by UV Spectrophotometer analysis. Fourier Transform Infrared Spectroscopy confirmed the presence of proteins as the stabilizing agent surrounding the Silver nanoparticles. The anticancerous activity against Non-small cell lung carcinoma cell line (NCI-H460) by MTT assay reveals that 12.52μg(IC50) inhibits the NCI-H460 growth. The effect of nanoparticles on cell morphology was studied by Hoechst staining to confirm the cell death. The DNA damage in the treated cells was evaluated using single-cell gel electrophoresis (comet) assay. DNA was observed in cells treated with nanoparticles after 24h incubation whereas the percentage of damaged cells increased on treatment with this compound for 48h, which was shown by the appearance of prominent comets with tail. The study demonstrated the possible use of biologically synthesized silver nanoparticles as an effective drug against cancer. ROS generation shows the nanoparticle treatment which was measured spectrofluorimetrically through DCFH-DA staining.

Carbon nanotubes (CNTs) have emerged as a new option for possible use in methodologies of cancer treatment, bioengineering and gene therapy. In this study, multi-walled carbon nanotubes (MWCNTs) were functionalized by dapsone in dimethylformamide (DMF) to form MWCNT-Dapsone, then the modification of multi-walled carbon nanotubes was investigated by benzaldehyde, isatin and phenylisocyanate. All products were characterized by Fourier transform infrared (FTIR), Raman spectroscopy (RS) and transmission electron microscopy (TEM). We investigated the effect of functionalized MWNTs on toxicity of cancer cells, in addition to developing the amidation of MWNTs with aromatic amines. Biological activity with human gastric cancer cells (MKN-45) and MTT test for measurement of viable cell numbers were performed. The used biological data in this study had anti-cancer activity against MKN-45.

Poly(D,L-lactide-co-glycolide) nanoparticles (PLGA NPs) modified with chitosan (CS) have been used as carriers for epirubicin (EPB) to overcome multidrug resistance in an adriamycin-resistant human breast cancer cell line (MCF-7/ADM). EPB-loaded PLGA NPs were prepared using the solvent evaporation technique and then surface modified with CS according to the adsorption (ADCS NPs) and chemical binding methods (CBCS NPs). The EPB-loaded PLGA NPs were observed to be spherical in shape by scanning electron microscopy and their mean size was determined to be 214.4 ± 21.0 by laser light scattering. The size of the EPB-loaded PLGA NPs increased following the CS-surface modification, but the drug encapsulation efficiency was reduced from 84.1 ± 3.4 to 72.0 ± 3.5% for the ADCS NPs and to 70.1 ± 3.6% for the CBCS NPs. The rates of in vitro drug release from the CS-modified NP formulations were determined by dialysis with both systems showing a biphasic release pattern involving an initial rapid release followed by a very slow release after 24 h. Moreover, the results of cell experiments showed that the cellular uptake of the CS-modified NPs into the MCF-7/ADM cells had increased compared with the free EPB and EPB-loaded PLGA NP, whereas their inhibitory effects on cell viability were reduced. Taken together, these results demonstrate that CS-modified EPB-loaded PLGA NPs exhibit several advantages for sustained drug release and the enhancement of drug toxicity in drug-resistant tumor cells, indicating that NPs of this type could potentially be used as carriers for anticancer drugs.

Valsartan is an effective, highly selective and orally active antihypertensive exhibiting low aqueous solubility and poor dissolution that limit its absorption resulting in low bioavailability. The objective of the present study was to prepare and characterize selfnanoemulsifying drug delivery system (SNEDDS) of Valsartan and evaluate their performance in animal models. SNEDDS was prepared by the spontaneous emulsification method. Saturation solubility of the drug was studied in various oils, surfactants and co-surfactants. The formulations were characterized for droplet size, shape, DSC, FTIR, in vitro drug release and for pharmacokinetic studies in Wistar rats. SNEDDS were prepared using triacetin and castor oil as oil phase, Tween 80 as surfactant and PEG 600 as co-surfactant. The globule size was 139.29 ± 10.5 nm for triacetin SNEDDS and 142.6 ± 18.6 nm for castor oil SNEDDS when diluted with 500-fold volume of the Milli-Q water. TEM images confirmed the uniform shape and nano size of the system. The formulations were stable on storage at accelerated conditions. The SNEDDS significantly increased the Cmax and area under the curve (AUC) compared to that of the pure Valsartan. Thus SNEDDS can be effectively used to improve the oral bioavailability of Valsartan.

In this paper, Ag/α-Al2O3 composites were fabricated from biosynthesized AgNPs, and their antibacterial performance against S. aureus and E. coli was investigated. Ag NPs with sizes 18.0±5.6 nm were produced through the rapid reduction of [Ag(NH3)2]+with dried Corynebacterium sp. SH09 assisted by [OH-]. The AgNPs were completely immobilized onto α-Al2O3 after calcination at 200 oC without aggregation. Both the biosynthesized AgNPs and Ag/α-Al2O3 composites exhibited good and rapid antibacterial abilities on S. aureus and E. coli. The Ag/α-Al2O3 composites loaded 1 wt.% Ag killed 100% of E. coli and S. aureus after contact time of 30 s and 5 min, respectively.

There is a need to find an effective and durable method for disinfecting historical objects made from natural fibres, paper, leather, and wood that does not cause these materials to degrade. The aim of this study was to examine the influence of nanosilver misting disinfection of above–mentioned materials on the reduction of the number of microorganisms: A. niger, B. subtilis, E. coli and S. aureus. In addition, the objective was to examine the changes in mechanical and optical properties of tested materials occurring during the disinfection and accelerated ageing process. The results show that nanosilver misting — provided silver content in materials were equal to 1.2–7.0 ppm is an effective method for protecting all tested materials against A. niger, B. subtilis, E. coli and S. aureus. The highest reduction of microorganisms was obtained in the case of paper and textile disinfection. The established sensitivity of microorganisms was as follows: A. niger >E. coli >S. aureus >B. subtilis. The presence of nanosilver in the materials does not result in a significant deterioration of their mechanical and optical properties during an accelerated light ageing process (equivalent to about 24 years of museum exposure). Based on the results obtained in this study, it can be stated that the nanosilver misting method may have potential beneficial use in the preservation of historical objects.

The aim of present investigation was to develop and evaluate cholesterol-rich nanoemulsions (LDE) of cholesteryl-succinyl-5- fluorouracil (CS-5-FU conjugate) in order to improve therapeutic efficacy and to reduce adverse effects of the treatment. LDE formulations of CS-5-FU conjugate were developed by high energy emulsification technique and developed formulations were physicochemically characterized for droplet size, polydispersity index, zeta potential, surface morphology and refractive index. In vitro drug release studies of CS-5FU conjugate from LDE nanoemulsions were performed using dialysis membrane. The droplet size (42.2 nm), polydispersity index (0.119), zeta potential (-29.65 mV), viscosity (35.22 cp) and refractive index (1.337) were found to be lowest for optimized formulation LDE5 (containing CS-5-FU-6 mg/cholesterol-0.5 mg/Triolein-1 mg/phosphatidylcholine-20 mg/cholesteryloleate-40 mg/Tween-80-0.3 ml/Labrasol-0.3 ml). Optimized formulation LDE5 also showed best drug release profile (98.4%) through dialysis membrane after 24 h of study. These preliminary studies indicated that developed LDE nanoemulsions could be applied for targeting of CS-5-FU conjugate to cancer cells.

Coenzyme Q10 (CoQ10) has been reported as a powerful antioxidant in plasma. Recent in vivo investigations showed that cosmetically applied CoQ10 can reduce photo-aging. However, CoQ10 was barely satisfactory in topical drug delivery because of its poor solubility and high molecular weight. To improve the anti-oxidative efficiency of CoQ10 in skin photo-aging, a novel water-soluble nanoscale solid dispersion of CoQ10 (CoQ10-SD) was prepared by heat melt and high-pressure homogenization method in the present study. Three sizes of CoQ10-SDs were obtained and characterized. The spectral investigations showed that the smaller particle size solution of CoQ10-SD was more effective against ultraviolet (UV) radiation. The UVB radiation absorption and reflection of the CoQ10-SD solution increased with increasing concentration and decreasing particle size. The in vitro antioxidants of CoQ10-SD were also assessed. The results showed that, smaller particle size results in higher antioxidant effect. A lower level of intracellular reactive oxygen species was found when the myocardial cells were treated with CoQ10-SD of smaller size. These findings indicated that CoQ10-SD can be an effective cosmetic delivery system to protect the skin from early aging induced by UV.

Self-assembled monolayer (SAM) as a unique type of nanomaterials has played important roles in modern nanotechnology. In this study, we described a novel method to fabricate SAM with a surfactant-like peptide A6K, which has been known to self-assemble into micellar nanofibers in aqueous solution. Firstly a simple filtration method was used to remove self-assembling nanofibers and retain peptide monomers in solution. Pyrene-fluorescence, dynamic light scattering (DLS) and atomic force microscopy (AFM) were used to confirm that nanofibers were effectively removed and filtered solution contained only peptide monomers. Then by incubating the filtered peptide solution on mica surface, the peptide monomers could self-assemble into a flat and continuous peptide SAM, which was further proved to be a suitable substrate for creating nanopatterns by AFM nanolithography.

A rapid synthesis route for the preparation of spherical cadmium sulfide (CdS) nanoparticles (NPs) was demonstrated by thermal decomposition of cadmium diethyldithiocarbamate(Cd[Ddtc]2) metal complex in the presence of a catalytic amount of hexadecylamine (HDA) using olive oil as the reaction medium. CdS nanoparticles were isolated and characterized by using HRTEM, FESEM, TGA, XRD, EDAX, PL, and Raman studies. The photocatalytic behaviour of the CdS nanoparticles was analyzed against the textile dye Congo red (CR). The degradation process follows the pseudo first order kinetics and the proposed method can be utilized for the efficient degradation of Congo red textile dye using UV light irradiation.

In this work, we have developed a facile but efficient method to prepare mushroom-like Zinc oxide (ZnO) nanostructures with a flat cap in the diameter of around 1μm, by thermal evaporation of the mixture of ZnS and carbon powder on a tungsten substrate. The mushroom-like nanostructures were characterized by using advanced techniques such as scanning electron microscope (SEM), X ray diffraction (XRD) and Raman spectroscopy. The optical properties of such product were also investigated by photoluminescence spectroscopy, revealing a strong green emission band emerged, which may be attributed to the oxygen vacancies and various surface states. Finally the formation and growth mechanisms for the mushroom-like ZnO nanostructures were proposed and discussed.

Barium doped ZnO nano-particles have been prepared via homogeneous precipitation method under ambient conditions using zinc chloride and barium chloride as starting materials and were found to be effective catalysts for the three-component condensation reaction of 2-aminobenzoic acid, triethyl orthoformate and aromatic amines. The structural features of the samples were assessed by X-ray diffraction (XRD), BET, field emission scanning electron microscopy (FE-SEM) and Energy-dispersive X-ray spectroscopy (EDAX). The average crystalline size estimated by using the Scherrer formula from the highest peak of the XRD was 85-86 nm for all samples. The results of BET are comparable with those obtained from XRD patterns. The change in the morphology and particle size of the as prepared composites was investigated. The particles are irregular in shape, mostly are spherical and some of them have hexagonal structure. The prepared nano-particles have been applied to the synthesis of a variety of quinazolin-4(3H)-ones. The products were isolated in high yields. In addition, the catalyst could be reused without any significant loss of its catalytic activity.

Dy+3 doped strontium ferrites Sr1-Dyx (ZnZr)0.5 Fe11O19 (x=0, 0.01, 0.02 and 0.03) were prepared by the citrate sol-gel method. The X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry, and vector network analyzer were used for phase characterization and microwave absorption properties of obtained powders. X-ray diffraction identified that all samples were single phase with the M-type hexagonal-ferrite structure. The average crystallite size was about 48-62 nm. The microwave electromagnetic properties of the samples were studied at the frequency range from 12 GHz to 20 GHz. It was shown that small amounts of Dy+3 substitution could magically adjust to microwave electromagnetic parameters. The reflection loss indicates a minimum peak when ‘‘x=0.01’’, and the peak value was 41.0 dB. Also results indicate that a wide bandwidth of microwave absorption is obtained in the composite samples containing ferrite powders with composition ‘‘x=0.02’’ and ‘‘x=0.03’’ in Ku-band frequencies. It should be noted that thicknesses of the absorbers are only 1.7 mm.