The current study was designed to find out the cancer cell killing efficacy of as-synthesized dumbbell-shaped Fe3O4 and γ-Fe2O3 magnetic nanoparticles under AC (alternating current) magnetic-fields induction condition. Dumbbell-shaped Fe3O4 and γ-Fe2O3magnetic nanoparticles were successfully prepared by a modified hydrothermal method. Ferrous chloride tetrahydrate was solely used asa precursor for the nanomaterials. The as-synthesized nanomaterials were characterized by using XRD, FE-SEM and TEM. Dumbbellshapedparticle morphology was observed for the first time in all of iron oxides with magnetic properties. The particle size observed was50-60 nm. The synthesized nanomaterials showed acceptable magnetization values when magnetic hysteresis loops were measured usinga superconducting quantum interference device (SQUID) as well as colloidal stability. Moreover, the as-prepared magnetic nanoparticlessuspensions showed significant temperature increments and cancer (HeLa) cell destroying potentiality (91% and 95% for Fe3O4 and γ-Fe2O3, respectively) under an AC magnetic-field induction condition at room temperature using the concentration of 150 ?g/mL.
Aim of this work was to study the technological parameters influencing the adsorption process of Bovine Serum Albumin(used as model protein) on the surface of PLGA (polylactic co-glycolic acid) based nanoparticles. Several factors as adsorption mediums,concentration ratio between proteins and nanoparticles, temperature, time of incubation were evaluated and main importance was done tothe chemical characteristics of polymers and surfactants used for nanoparticles obtainment. Afterward adsorption studies, further tests ofpermeation through cellular monolayers and synthetic membranes were done in order to study the desorption process of BSA fromnanoparticles surface. The mediums influence on the desorption rate of the protein from the nanoparticles and the influence of polymericexcipients on the permeation profile of the protein were evaluated.
Data showed demonstrated that the adsorption process as well as the desorption capability and the permeation rate of BSA are strictly influencedby the nanoparticles composition and several kind of interactions between polymers and protein.
The interaction between human serum albumin and cholesterol-modified pullulan (CHP) nanoparticles with different degreesof substitution (DS) of cholesterol moiety was investigated using spectroscopic and thermodynamic methods. Albumin fluorescence intensitywas quenched by nanoparticles with maximum emission intensity decreasing at the initial reaction and increasing at the last reactedperiod. Binding constants (Kb) were 1.12 x 105 M-1, 4.12 x 105 M-1 and 7.44 x 105 M-1 to CHP-3.11, CHP-6.03 and CHP-6.91, respectively,as determined by Stern-Volmer analysis. Adsorption of albumin to nanoparticles was an exothermic reaction process and revealed ahigher DS of cholesterol moiety with higher enthalpy and entropy changes. Upon interaction with nanoparticles, albumin conformationchanged with a reduction of α-helix, suggesting a partial protein unfolding. Furthermore, albumin could gradually change its helicalstructure due to the structural change of the complexed nanoparticle. Particle hydrophobicity and shell-core structure play a main role inthe alteration of albumin conformation in the nanoparticle-protein interaction process.
Stable silver nanoparticles (AgNPs) with narrow size distribution were non-enzymatically synthesized through hydroxyl ions(OH-) assisted bioreduction of diamine silver complex with dry Aeromonas sp. SH10 cells. The effects of reaction temperature, concentrationsof OH-, silver and the dry cells on the reduction of Ag ions as well as on the properties of the AgNPs were investigated. Resultsshow that the introduction of appropriate quantity of OH- ions considerably accelerates the process. In fact, higher yields of AgNPs (>95%) could be obtained at relatively higher initial silver concentration (1 g·L-1) with more than 1 g(Ag)·g(bio)-1 productivity of AgNPs. Plausiblebioreductive mechanism is therefore proposed; wherein [Ag(NH3)2]+ ions initially reacted with OH- to form an unstable AgOH. Thisis then transformed into Ag2O spontaneously, and finally non-enzymatically reduced into AgNPs by the cells.
The least efficacy of most of the active pharmaceutical ingredients in the brain is attributed to the blood-brain barrier (BBB),which represents insurmountable obstacle for the effective management of majority of CNS disorders. The present research was plannedwith the objective to design novel poly (d, l) lactide (PLA) nanoparticles coupled with natural tripeptide i.e. glutathione to enhance drugdelivery to brain. To evaluate the brain targeting efficiency of the glutathione conjugated nanoparticles, fluorescein sodium was exploredas a model compound due to its polar nature and least possibility to cross BBB. The entrapment efficiency of fluorescein sodium was improvedby screening several formulation variables like drug: polymer ratio, solvent selection, electrolyte addition and pH alteration.Scanning Electron Micrograph (SEM) and dynamic light scattering results of optimized formulation showed that prepared nanoparticleshave a round and regular shape with a mean diameter of 257.8 ± 3.78 nm with narrow size distribution. Biodistribution pattern and braintargeting potential of optimized glutathione conjugated PLA nanocarriers was determined using wistar rat as an animal model in comparisonto non-conjugated PLA nanoparticles and fluorescein sodium solution. The results showed significant increase in fluorescein sodiumuptake in brain with glutathione conjugated PLA nanoparticles as compared to fluorescein sodium solution. The present investigationsdemonstrated that glutathione can serve as a potential ligand for brain drug delivery, which was observed with glutathione coupledPLA nanoparticles resulting into enhanced delivery of drug to nearly 5 folds in the brain.
Nanosized Nd-doped strontium ferrites, SrNdxFe12-xO19, with x=0.3, were successfully prepared through a chemical coprecipitationprocess. The samples were characterized by TG-DSC, XRD, FT-IR. The results of TG-DSC and XRD showed that the single phaseof Nd-doped strontium ferrite formed directly through the reaction of SrCO3, amorphous Fe2O3 and Nd2O3, without other intermediatephases. The crystallite size was around 35 nm.
The core-shell structure SiO2@Ag nanoparticles were synthesized by a facile chemical reduction method. Firstly, the mercapto-silica spheres had been prepared by the stober method, in which 3-mercaptopropyltrimethoxysilane (MPS) was used as a sole silicasource. The reaction involves mixing the MPS precursor, ammonia in aqueous solvent at room temperature. Secondly, the core-shellstructure SiO2@Ag nanoparticles were synthesized by reducing AgNO3 on the surface of mercapto-silica spheres in the presence of thereducing agent. The core-shell structure SiO2@Ag nanoparticles were investigated by means of ultraviolet-visible absorption spectroscopy(UV-vis), high resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD) and X-ray photoelectronspectroscopy (XPS). Antibacterial properties of the as-synthesized SiO2@Ag nanoparticles were investigated using both Gram negativeof Escherichia coli (E. coli) and Gram positive of Staphylococcus aureus (S. aureus) as bacterial strains. The results show that the coreshellstructure SiO2@Ag nanoparticles exhibit excellent antibacterial properties against E. coli and S. aureus bacteria.
Synthesis, Characterization and Anti-Listeria monocytogenes Effect of Amino Acid Coated Magnetite Nanoparticles by Alireza Ebrahiminezhad, Soodabeh Davaran, Sara Rasoul-Amini, Jaleh Barar, Mehdi Moghadam, Younes Ghasemi (868-874).
Nanoparticles as antimicrobial agents are a novel field in nanomedicine and nanobiotechnology. Unlike many investigationsabout antimicrobial effects of silver nanoparticles, few experiments have been conducted about the impact of iron-oxide nanoparticles onmicroorganisms. In the current paper, we have synthesized and characterized amino acid (L-arginine and L-lysine)-coated magnetitenanoparticles and evaluated the effects of these particles on a pathogen strain of Listeria monocytogenes. Primary antibacterial tests weredone by the microdilution method and for more investigation the effects of nanoparticles on the growth curve of L. monocytogenes wereanalyzed by a microbiological analyzer. We found that, in low concentrations (below 20 μg/ mL), L. monocytogenes can benefit frommagnetite nanoparticles for more growth, probably as an iron source, but as concentration increases gradual bacteriostatic effects wouldappear and at 40 μg/mL magnetite nanoparticles have a significant bacteriostatic effect.
Synthesis and Characterization of Mesoporous Magnetite Based Nanoparticles by Denisa Ficai, Ecaterina Andronescu, Anton Ficai, Georgeta Voicu, Bogdan Vasile, Valentin IONITA, Cornelia Guran (875-879).
Mesoporous, magnetite based nanoparticles (MNPs) were successfully synthesized by a modified precipitation method. Forthis purpose, the precursors' solution was sprayed into a sodium hydroxide or sodium hydroxide/citrate precipitation bath. In order to determinatethe structure and morphology of the as-synthesized mesoporous MNPs the following methods were used: X-ray diffraction(XRD), Brunauer-Emmett-Teller (BET), infrared spectra (IR), high-resolution transmission electron microscopy (HRTEM) coupled withselected area electron diffraction (SAED) and energy dispersive spectrometry (EDS). The Brunauer-Emmett-Teller (BET) analysis revealeda mesoporous structure of the samples which has a specific surface area of about 160m2/g (unstabilized Fe3O4 nanoparticles) and247 - 257 m2/g (for the stabilized Fe3O4 nanoparticles). The average pore size of the MNPs is 2 - 5nm which means that mesoporous materialswere obtained.
Green, Rapid and Facile HPMo-Assisted Synthesis of Silver Nanoparticles by Ali Ahmadpour, Bahareh Tanhaei, Fatemeh F. Bamoharram, Ali Ayati, Mika Sillanpaa (880-884).
In the present paper, we have described the interesting behavior of molybdophosphoric acid (H3[PMo12O40], HPMo) in thesize-controlled synthesis of silver nanoparticles under UV-irradiation. In this process which is based on the reduction of Ag+ (AgNO3),HPMo plays the role of photocatalyst, reducing agent as well as stabilizer, and propan-2-ol acts as a sacrificial agent. The method allowsthe rapid synthesis of uniform spherical nanoparticles with an average size that varies between 2.2 and 35.2 nm by altering the silver ionconcentration, molar ratio of silver ion to HPMo (or dose of HPMo) and Propan-2-ol amount. It is found that there is a critical ratio for[Ag+]/[HPMo] (i.e. 3.8 in the present case), in which two opposing trends in the size of silver nanoparticles take place.
Vinorelbine tartrate is a semi-synthetic drug with a broad-spectrum anti-tumor activity. An injectable formulation ofvinorelbine (Navelbine® IV) has been widely used in the world, despite existing some disadvantages. In this study, in order to improvethe efficacy of vinorelbine injection metabolism with minimal side effects, rHSA nanoparticles entrapping VLBT were prepared by adesolvation procedure, and subsequently decorated by folic acid. A central composite design was applied for modeling the process. Tosome extent, the drug release rate could be adjusted by cross-linking with different amount of glutaraldehyde. In this paper, FarHSANPs-VLBT with three degrees (25%, 50% and 75%) of cross-linking were obtained under the optimum conditions for preparing thenanoparticles. Then we carried out a further study to compare the characteristics of the nanoparticles, such as drug entrapment efficiency(DEE), drug-loading efficiency (DLE), surface morphology, surface chemistry, physical status of VLBT in Fa-rHSANPs-VLBT, amountof folate conjugation, and release kinetics in vitro. The experiment results displayed that as the degree of cross-linking increased, both thezeta potential (ZP) and folate content associated with the VLBT-rHSANPs showing a reduced tend. Moreover, the increasing glutaraldehydeconcentration made the rate of release of the VLBT from these nanoparticles decrease.
Self-decoration of silver (Ag) nanoparticles on the surface of titanium dioxide (TiO2, Degussa P25) photocatalyst are preparedvia simple solution chemistry in absence of specific organic ligands for metal reduction, with an available natural light source. An in-situmethod is carried out for the self-induced decoration of Ag nanoparticles onto the TiO2 surfaces and the properties of the metal nanoparticlehave been revealed based on the photocatalytic activity. The average particle size of the self-decorated Ag nanoparticle on the TiO2surface was ~2 nm. The photocatalytic degradations of fluorescein dye in aqueous suspensions of pure TiO2 and Ag/TiO2 photocatalystswere studied under Xenon light irradiation. We found that the photocatalytic degradation rate was largely influenced by the particle sizeof the self-decorated Ag nanoparticles on the TiO2 surface. The proposed photodegradation mechanism proved the possibility visible lightexcitation due to localized surface plasmon resonance and the electron transfer from the plasmonically excited Ag nanoparticles to theconduction band of TiO2 in addition to the usual ultra-violet excitation. The combined UV and visible light excitation improve the photodegradationbehavior on fluorescein dye molecules effectively over the 83% of dye degradation.
Silica Nanoparticles for Increased Silica Availability in Maize (Zea mays. L) Seeds Under Hydroponic Conditions by Rangaraj Suriyaprabha, Gopalu Karunakaran, Rathinam Yuvakkumar, Venkatachalam Rajendran, Narayanasamy Kannan (902-908).
A study on the uptake of silica source by maize seeds was conducted under hydroponic conditions and pot experiments supplementedwith nano-SiO2 (20-40 nm) extracted from natural source (rice husk) and their bulk silica counterparts such as micro-SiO2,sodium silicate, and silicic acid. Employing hydroponic incubation experiment to explore the nanosilica absorption is a novel approach inmaize. Seeds after different silica source treatments were analyzed with regard to germination percentage (GP %), elemental analysis, androot growth parameters to investigate the efficiency of nano-SiO2. Hydroponic culture studies revealed an increase in GP (95.5%), dryweight (6.52±0.2), silica accumulation (18.2%), and better nutrient alleviation in seeds exposed to nano-SiO2 than in those exposed tobulk sources. Variations in the pH, conductivity and SiO2 content in the hydroponic solution reflect the utilization of silica by seeds.Maize seeds and roots during pot experiments absorbed nano-SiO2 better when compared with absorption of other micron sources, whichled to the conclusion that nano-SiO2 can be used as an immediately utilizable source for plants.
Critical Size of Temperature-Dependent Band Shift in Colloidal PbSe Quantum Dots by Yu Zhang, Wenchao Cheng, Tieqiang Zhang, Quanqin Dai, Tian Cui, Yiding Wang, William W. Yu (909-913).
The temperature-dependent property of band gap in colloidal PbSe quantum dots has been investigated from both experimentand theory above room temperature. When the particle size increases, the temperature coefficient evolves from negative values to zeroand then to positive value following the trend to its bulk material value. The calculated critical size of 4.88 nm for the temperature coefficientdE / dT = 0 is consistent with the experimental result. When the particle size is smaller than the critical size, the temperature coefficientdE / dT is also dependent on the temperature, which has not been observed before. However, this phenomenon is not obvious atlarge particle sizes. The functions of size- and temperature-depended band gap E and temperature coefficient dE / dT are achievedthrough theoretical calculation and experimental calibration. Temperature-induced variations of quantum confinement energy and exciton-phonon coupling are the key factors for the temperature coefficient. The balance between the variations of confined effect and exciton-phonon coupling causes the critical size of temperature coefficient in colloidal PbSe quantum dots.
We report efficient conversion of any of the primary colors to white light under ambient conditions, by ZnO nanostructures.Not only UV, blue, and NIR LEDs, but also the green and red LEDs can be used for the production of white light. The conversion efficiencyis supposed to be high and it is possible to tune the nature of white light (warm, natural and cool). Correlated color temperaturecan be tailored by changing the excitation source. The white light emission does not depend on vacuum, or doping or any magic size orany specific design of nanocrystal.
High quality 3%Cu-SnO2 nanoparticles have been prepared onto the glass substrate by using novel and economical ultrasonicspray pyrolysis technique. The X-ray diffraction patterns showed that 3% Cu-SnO2 nanoparticles formed in tetragonal rutile structure.The intensities of peaks shown by X-ray pattern were indexed as (110), (101), (200) and (211). The microstructure, surface morphology,particle size and elemental properties of 3%Cu-SnO2 nanoparticles were characterized using, scanning electron microscope (SEM), andTransmission electron microscopy (TEM). These nanoparticles were tested for H2S sensors applications. It was observed that 3%Cu-SnO2 nanoparticles exhibited remarkable sensitivity to H2S (200 ppm) gas at 150°C, more precisely showing good response andrecovery.
Silicon and polysilicon based nanogap electrode devices have been developed. The devices are able to detect lower concentrationsof yeast at various pH values. Nanogap electrodes sense subtle changes due to molecular species perturbing the electrochemical signalsacross the gap. Two different materials and size of the nanogap electrodes were used to detect the biochemical solutions.Silicon and polysilicon nanogaps electrodes were characterized electrically by measuring the current-voltage and by optical imaging usingSEM and FESEM. The capacitance, permittivity and conductivity were measured using a dielectric analyzer to sense and to profilepH under a simple and complex background. Polysilicon based electrode showed slightly higher sensitivity to the permittivity and conductanceas compared to silicon based electrode over the same range of concentration. The data suggest that these electrodes can be usedas low cost electrical devices for biomolecular sensing while consuming very low power (voltage).
Green Photocatalytic Synthesis of Au Nanoparticles/Multi-walled Carbon Nanotubes Nanocomposites and their Application for Glucose Sensing by Qingzhen Li, Juan Du, Xiaoyun Qin, Yonglan Luo, Wenbo Lu, Guohui Chang, Chenjiao Ge, Abdullah M. Asiri, Abdulrahman O. Al-Youbi, Xuping Sun (930-933).
In this communication, we report on a novel green photocatalytic route to synthesize Au nanoparticles/multi-walled carbonnanotubes (AuNPs/MWCNTs) nanocomposites with the use of Sn-porphyrin (SnP) as a high-efficiency photocatalyst to reduce Au3+ toform AuNPs onto MWCNTs. Such AuNPs/MWCNTs nanocomposites exhibit good catalytic performance toward both oxidation and reductionof H2O2. An electrochemical glucose biosensor was further constructed by dropping glucose oxidase on the surface ofAuNPs/MWCNTs nanocomposites modified glassy carbon electrode. The biosensor shows linear response toward different concentrationsof glucose from 1 to 33 mM (r = 0.998) and the detection limit at 0.5 V is estimated to be 240 ?M at a signal-to-noise ratio of 3.
A One Step Hydrothermal Approach for the Improved Synthesis of Graphene Nanosheets by Karthikeyan Krishnamoorthy, Murugan Veerapandian, Gui-Shik Kim, Sang Jae Kim (934-938).
In this paper, we are reporting a one step hydrothermal approach to the synthesis of graphene nanosheets via reduction of grapheneoxide (GO). The obtained graphene nanosheets are characterized using X-ray diffraction (XRD), UV-vis spectroscopy, Transmissionelectron microscope (TEM), X-ray photoelectron (XPS) and Raman spectroscopic techniques. XRD analysis revealed the regraphitizationprocess occurred in the graphene nanosheets. The UV-vis spectroscopy showed red shift in the absorption band due to theformation of graphene nanosheets. TEM studies revealed the sheet like morphology of the obtained graphene. XPS spectra confirmed theremoval of oxygenated functional groups in graphene due to the hydrothermal reduction reaction. Raman spectra confirmed the restorationof sp2 clusters in graphene sheets after the reduction. The average crystallite size of the sp2 clusters in graphene sheets was calculatedfrom the Raman spectra as 11.76 nm.
Measurement of Specific Heat of Nanofluids by T. Yiamsawasd, A. S. Dalkilic, S. Wongwises (939-944).
This article reports an experiment on specific heat measurement of nanofluids using a calorimeter of the comparison type. Themeasurement is based on a differential thermal analysis technique. The studied TiO2 and Al2O3 nanoparticles are dispersed in base fluidswhich are pure water and a mixture of ethylene glycol/water (20/80 wt.%). Concentrations between 0 and 8 vol.% and temperatures arebetween 15 and 65oC. Results show that the measured specific heat of nanofluids is lower than that of the base liquid decreases as theparticle concentrations increases. Furthermore, the specific heat of nanofluids was found to increase with increasing temperatures. Whencompared with predicted values from existing correlations and data reported by other researchers, measurements are compatible with theprediction from the thermal equilibrium model presented by Xuan and Roetzel. Finally, new correlations are proposed for predicting thespecific heat of Al2O3 and TiO2 nanofluids
The Ag/polyaniline (Ag/PANI) films have been prepared by a two-step electrochemical method. The PANI film was firstlygrown by a potentiodynamic polymerization method in aniline electrolytes, and then Ag nanoparticles were electrodeposited on the PANIfilm through potentiostatic methods in 0.1 M AgNO3 solution. The products were characterized in detail by multiform techniques: X-raydiffraction (XRD), energy-dispersive X-ray analysis (EDS), scanning electron microscopy (SEM). The obtained Ag/PANI electrode wasused as glucose sensor to detect glucose in 0.1 mol/L KOH. The results show excellent electrocatalytic activity for glucose detection onthe present electrochemical sensing platform.
Forced Convective Heat Transfer of Nanofluids - A Review of the Recent Literature by A. S. Dalkilic, N. Kayac?, A. Celen, M. Tabatabaei, O. Y?ld?z, W. Daungthongsuk, S. Wongwises (949-969).
The forced convection of fluids has been investigated by numerous researchers, both experimentally and numerically. A goodunderstanding of characteristics of nanofluid flowhas thoroughly been investigated in these studies. Since the nanoparticles behave morelike a single-phase fluid than a solid-liquid mixture, it is assumed that nanofluids are ideally suited in the applications as their usagecauses little or no penalty in pressure drop. In recent years, many researchers have tried to fill the gaps on this subject in the literature. Tomeet the demand for improving the performance of heat transfer equipment, re-examination of the individual components is consideredto be essential. The addition of the nanoparticles to the base fluid is one of the significant issues for the optimal performance of heattransfer systems. This paper reports on most of the forced convective heat transfer literature occurring both in-tubes and in-channels regardingthe use and preparation of nanofluids. The peer reviewed papers published in citation index journals up to 2012 have been selectedfor review in the paper. Classification of the papers has been performed according to the publication years. The critical informationon the theoretical, experimental and numerical works is presented comprehensively for each paper.