Current Nanoscience - Volume 8, Issue 2, 2012

Aiming at the development of a stable drug carrier for bicalutamide (BT), we prepared various lipid nano-emulsions (LNEs) from a lipid mixture of soybean oil, phosphatidylcholine, sodium palmitate and sucrose palmitate (SP). These LNEs had mean particle size of approximately 50 nm and zeta potential (ζ) of -40 to -30 mV and were investigated their stability in saline solution and in bovine serum by using the dynamic light scattering method. In saline solution, while the droplet size of LNEs without and with BT reached more than 150 nm, that of the BT-encapsulated LNEs with SP could be maintained within 100 nm even after 24 h. In contrast, the droplet size of LNEs hardly increased even over 72 h placed in bovine serum, suggesting that bovine serum albumin (BSA) suppressed their coalescence. The intrinsic fluorescence of BSA was quenched and blue-shifted in the presence of LNE. In addition, the ζ values of all LNEs increased to around -20 mV according to the increase of BSA concentration. These results demonstrated that BSA interacted with LNE particles. Furthermore, the fluorescence resonance energy transfer using a fluorescence probe revealed that not only BT encapsulated in LNE particles but also SP strongly interacted with BSA.

The gastrin-releasing peptide receptor (GRP-r) is overexpressed in breast and prostate cancer, and Lys3-bombesin is a peptide that binds with high affinity to the GRP-r. HIV Tat(49-57) is a cell-penetrating peptide that reaches the DNA. In cancer cells,177Lu shows efficient cross-fire effect, while 99mTc that is internalised to cancer cell nuclei acts as an effective system of targeted radiotherapy because of the Auger and IC electron emissions near the DNA. The aim of this research was to prepare a multifunctional system of 177Lu-and 99mTc-labelled gold nanoparticles (AuNPs) that were conjugated to Tat(49-57)-Lys3-bombesin (Tat-BN) and to evaluate the radiation absorbed dose to GRP receptor-positive PC3 tumours that were induced in mice. Cys-Gly-Cys-Tat-BN (CGC-Tat-BN), 1,4,7,10- tetraazacyclododecane-N,N',N'',N'''-tetraacetic-Gly-Gly-Cys (DOTA-GGC) and hydrazinonicotinyl-Phe-Cys-Phe-Trp-Lys-Thr-Cys- Thr-(ol) (HYNIC-TOC) peptides were conjugated to AuNPs to prepare a multifunctional system by means of a spontaneous reaction of the thiol groups of cysteine. TEM, UV-Vis, XPS and Far-IR spectroscopy techniques demonstrated that AuNPs were functionalised with peptides through interactions with the -SH groups. The99mTc labelling was performed via the HYNIC-TOC ligand, and the 177Lu labelling was performed through DOTA-GGC. The radiochemical purity was 96 ± 2%. The 177Lu-absorbed dose per injected activity that was delivered to the PC3 tumours was 7.9 Gy/MBq, and the 99mTc-absorbed dose that was delivered to the nuclei was 0.53 Gy/MBq. The 177Lu/99mTc-AuNP-Tat-BN system showed properties suitable for a targeted radionuclide therapy of tumours expressing GRP receptors due to the energy deposition from β-emissions and the Auger and IC electron emissions near the DNA.

Quantum Dots (QDs) for bio-imaging applications need to be water-stable, exhibit high brightness and physico-chemical stability in order to prevent the leakage of toxic ions. In the present work, the direct synthesis of water-soluble CdSe quantum dots and their surface functionalization were achieved through a micro-wave assisted approach in aqueous phase. Glutathione, an essential tri-peptide, was used to functionalize the QDs as an attempt to develop a non-toxic and biocompatible surface. X-ray diffraction analyses suggested that as-synthesized QDs exhibited an alloy arrangement with an average crystallite size of 3.2 nm. HRTEM measurements suggested a size of around 4 nm for glutathione-functionalized QDs. Stable aqueous suspensions of QDs showed strong visible emission (551nm and 561 nm for bare and glutathione-functionalized QDs) under 460nm excitation. The presence of glutathione in the QDs’s surface was confirmed by FT-IR and NRM spectroscopy measurements. Surface characterization of QDs by using FT-IR indicated that glutathione was chemisorbed onto the surface of the CdSe QDs as carboxylate (vas COO at 1630 cm-1 and vs COO at 1390 cm-1). These water-stable glutathione- functionalized QDs can be considered a very promising nanomaterial for bio-labeling and imaging.

Microspherical and uniform LiFePO4/C was successfully prepared by a spray drying method assisted with template. The materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The as-synthesized LiFePO4/C was used as cathode materials for battery evaluation. The material prepared with PVA as template possess perfect olivine structure of lithium ion battery with uniform size distribution. A sample prepared with optimum conditions achieved a capacity of 156.7 mAh g–1 at a rate of 0.1 C, and no obvious degradation can be observed after 15 cycles at various rates. It was found that the template affected the structure and performance of the material significantly, the addition of polyvinyl alcohol (PVA) as template resulted in uniform microsphere morphology and high performance.

In this work, Polyaniline (PANI) microtubes and magnetite (Fe3O4) nanoparticles have been synthesized by using ammonium persulphate as oxidant via in-situ chemical oxidative polymerization in the presence of organic sulfonic acid. The resulting PANI / Fe3O4 nanocomposite materials have been characterized by X-ray diffraction, UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sampling magnetometer, and thermogravimetric analysis. Spectroscopic results indicated formation of Fe3O4 nanoparticles on PANI micro tubes. Morphologies of PANI / Fe3O4 nanocomposites were found to be dependent on the molar ratios of aniline to organic acid. As obtained PANI / Fe3O4 nanocomposites contained Fe3O4 particles in the range of 3-7 nm in size which showed superparamagnetism. Nanocomposites exhibited higher thermal stability compared to pure PANI.

The direct mix of aqueous FeCl3 and o-phenylenediamine (OPD) solutions at room temperature leads to supramolecular microfibrils of OPD dimers generated by the oxidation of OPD monomers by FeCl3. In this paper, we demonstrate that the subsequent treatment of such microfibrils with a HAuCl4 aqueous solution leads to Au nanoparticle (AuNP)-decorated nanoplates. The possible formation mechanism involved is also discussed. It is found that such nanocomposites can effectively catalyze both oxidization and reduction of H2O2. The sensor constructed with these nanocomposites exhibits a fast amperometric response time of less than 4 s. The linear detection range is estimated to be from 100 μM to 170 mM (r=0.997), and the detection limit is estimated to be 8 μM at a signal-to-noise ratio of 3.

Hierarchical single-crystalline β-SiC nanowires were synthesized by simply heating carbonaceous silica xerogel. A fairly high density of stacking faults was observed perpendicular to [111] growth direction of the hierarchical nanowires. A possible vapor-solid growth mechanism for the hierarchical nanowires was discussed. The photoluminescence spectrum of hierarchical SiC nanowires at room temperature shows two emission peaks at 406 nm and 432 nm. The blue emission at 432 nm may be related to 3C-SiC, while the emission peak at 406 nm may be attributed to 6H-SiC segments formed by stacking faults in 3C-SiC nanowire matrix.

This paper describes a nano-heat transfer fluid (NHTF) consisting of a novel mixture of alkali metal nitrate salt eutectic doped with silica nanoparticles at 0.5% mass concentration with a low melting point, high thermal stability and high specific heat capacity. These properties produce a wide operating range Heat Transfer Fluid and enable effective thermal storage for parabolic trough concentrating solar power plants as compared to present molten salt heat transfer fluids that usually has a high melting point, typically 220°C or higher. This limits its use due to the risk of freezing. The advanced NHTF exploits eutectic behavior with a novel composition of materials and nanoparticles, resulting in a low melting point of 120 °C, a thermal stability limit over 500 °C and an increase in specific heat capacity owing to the presence of suspended silica nanoparticles.

Substituted strontium ferrites SrFe12-xCrx/2Alx/2O19 (x=0–2.5) / multi-walled carbon nanotubes (MWCNTs) nanocomposites were prepared by a sol- gel method. The XRD patterns show a relatively weak peak at around 26º, corresponding to the graphite (002) lattice plane of the MWCNTs. The peak of Fourier transform infrared spectroscopy (FTIR) at about 1730 cm-1 could be assigned to the stretching mode of carbonyl groups (C=O), indicating the presence of PAA chains in PAA-carbon nanotubes. Field emission scanning electron microscopy (FE-SEM) micrographs revealed that dot array of ferrites on the surface of carbon nanotubes were formed. The magnetic properties confirmed that the values of saturation magnetization for nanocomposites are considerably lower than that of SrFe12-xCrx/2Alx/2O19 nanoparticles. The reflection loss of pure MWCNTs is rather low as compared to the nanocomposites for whole frequencies in the range of 12–18 GHz. It was found that MWCNTs could enhance reflection loss value of ferrites.

We illustrate that the redistribution of a compatible homopolymer blended in a certain block copolymer results in a shift of phase boundaries and in the stabilization of well-ordered structures by using polystyrene (PS) homopolymer blended in polystyrenepolybutadiene- polystyrene triblock copolymer (SBS1102) as a model system. The addition of the homopolymer into the asymmetric triblock copolymer increases the periodic orientation normal to the substrate, enabling directed self-assembly of the block copolymers into arrays of highly oriented, high-aspect-ratio cylindrical nanostructures over large areas. Thus, we show that blending a homopolymer with well controlled molecular weight provides an effective ordering process for self-assembly of block copolymers.

Statins can inhibit growth of malignant cells. Aims: The aim of the present work was to increase efficacy of simvastatin on chronic meyloid leukemia K562 cells by folate targeted solid lipid nanoparticles (SLN). Methodology: Folate targeting agent was prepared by chemical reaction between folic acid and dodecylamine. Folate targeted SLNs of simvastatin were prepared by an emulsification- solvent evaporation method. Then cytotoxicity of SLNs was studied on K562 cell line by Trypan blue and cellular uptake by flow cytometry method. Different concentrations of doxorubicin were used in combination to SLNs of simvastatin to study their possible synergistic effect in reducing the required cytotoxic dose of doxorubicin. Results: Simvastatin loaded SLNs were more cytotoxic than free simvastatin. The targeting property of glyceryl monostearate (GMS) SLNs was more efficient than other studied lipids. SLNs of simvastatin could reduce the cytotoxic dose of doxorubicin particularly when the dose of doxorubicin was low. Conclusion: Folate targeted SLNs can significantly enhance cytotoxic effect of simvastatin on K562 cell line and show synergistic effect with doxorubicin in reducing its dose. This may be of great value from clinical point of view in reduction of the cardiac toxicity of doxorubicin.

An aqueous suspension containing magnetic nanoparticles is not stable because the nanoparticles aggregate. As the aggregates size increases and the number of particles in suspension decreases, the rheological properties of the nanofluid, which are important for biomedical applications, change tremendously. Modified versions of the SLS and DLS experiments were used to monitor the nanoparticle aggregation and the results are presented in detail.

(3-Chloro-7-methoxyfuro[2,3-b]-quinolin-4-yl)-(4-methoxyphenyl)amine (CYL), a chemotherapeutic agent, is an analogue of amsacrine. The water insolubility of CYL limits its delivery and thus its application. The aim of the study was to utilize solid lipid nanoparticles (SLNs) to improve the delivery of CYL, and investigate its biodistribution behavior in an animal model. Characterizations of SLNs were evaluated including the particle size, zeta potential and entrapment efficiency. An in vivo study was used to investigate the pharmacokinetics and biodistribution behaviors. We established a rapid and sensitive high-performance liquid chromatographic (HPLC) technique with electrochemical detection to determine CYL, and the limit of detection was 40 ng/ml. We found that particle sizes of CYL-loaded SLNs were about 25%∼33% larger then empty SLNs. The entrapment efficiency (E%) of CYL embedded in the SLN matrix was about 80%∼98%. Moreover, the E% of SLNs incorporating glyceryl monostearate (GMS) significantly increased by about 11%∼17% and the polydispersity index dropped 0.3∼0.39. An in vivo pharmacokinetics study of intravenous CYL displayed linear plasma pharmacokinetics and fit a two-compartment model. The biodistribution behavior demonstrated that CYL-loaded tristearin(TS)- GMS SLNs mainly accumulated in the heart, lungs, liver, pancreas, and kidneys.

This paper reports the fabrication of a carbon nanotubes based carbon mono-oxide gas sensor. Initially, iron catalyzed carbon nanotubes were grown on silicon oxide grown silicon substrate using low pressure chemical vapor deposition. Morphology and microstructure of these CNTs were studied by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Morphological analysis shows the formation of multi-walled carbon nanotubes (MWCTs) with an average diameter of 30 nm. Typical response of MWCNTs gas sensor in the presence of CO gas has been studied. It was observed that this MWNTs gas sensor gives a quick response to CO gas and the recovery time of this sensor is also fast. The sensitivity of this sensor was found to decrease with an increase in the CO gas concentration. At a particular gas concentration, the responsiveness of this sensor increases with the increase in temperature. Electrical transport properties of this MWNTs film sensor have also been explained on the basis of temperature dependence of conductivity. On the basis these properties, it is suggested that this MWNTs-based gas sensor has potential to be used as a novel CO gas sensor.

Green synthesis of metal nano particles is an emerging branch of nanotechnology, very cost effective, eco-friendly, thus, can be an economic and efficient alternative for the large-scale synthesis of nano particles. This study focuses on the bio synthesis property of Peanut (Arachis hypogaea L.) leaf extract in the synthesis of silver nano particles at room temperature without using any harmful reducing agents and its antibacterial activity. Characterization of synthesized silver nano particles was made using UV-Vis, SEM, XRD and FT-IR studies. The average particle sizes ranged from 7 - 8nm. Synthesised silver nano particles made a coating on glass substrates and morphological properties were characterized by SEM. Antibacterial activity of silver nano particles was analysed with various pathogens like Klebsiella pneumoniae, Pseudomonas sp, proteus sp and Escherichia coli. Agriculture wastes of its leaves were utilised in the synthesis of silver nano particles. Our results suggest that Arachis hypogaea L. mediated silver nano particles that could act as an effective antibacterial agent in development of antibacterial control systems in water treatment, medicine and industries in future. Silver nano coating on the different glass substrate possesses different colour & morphological property that could support the modern coating techniques in the industries.

Magnetic iron oxide nanoparticles (MION) with unique surface properties have been widely used in various fields of sciences such as biomedicine. In addition to complicated chemical methods of iron oxide nanoparticles synthesis, there are great concerns regarding their application in vivo. The aims of this study were to investigate both the biologic synthesis of iron nanoparticles and toxic effects of MIONs on red blood cells from healthy and thalassemic blood donors. A Gram negative bacterium was isolated from iron enriched media and was identified as an Acinetobacter radioresistens strain by 16s RNA sequencing. The FTIR, SEM-EDX and XRD analysis results showed that the isolate could synthesize MIONs (≤ 104 nm) in filter sterilized iron enriched media (media with high iron ions) under strict aerobic condition. Further, our results indicated that although none of bacterial or artificial nanoparticles are toxic to Gram positive or negative bacteria but depending of their size and concentration could cause lysis in red blood cells (RBC) and as well as white blood cells (WBC). Toxicity of commercial and bacterial MIONs on peripheral blood cells was evaluated by monitoring hemagglutination, hemolysis and morphological changes. Our data also indicated while lysis occurs in low concentration of nanoparticles but severe hemagglutination is seen in samples treated with commercial nanoparticles (8 nm) beginning at 50μg/mL. The rate of hemolysis and morphological changes was intensified by increasing the concentrations of MIONs. In contrast, the bacterial MIONs did not induce any morphological changes on peripheral blood cells. To our knowledge, this is the first report about construction of nontoxic MIONs by Acinetobacter radioresistens.

In this communication, we report a new method for effective immobilization of Ag nanoparticles (AgNPs) on thiolated singlestranded DNA (thiol-ssDNA) modified Au electrode (AuE) surface via coordination interactions between the nitrogen atoms of DNA bases and AgNPs. It suggests that the AgNP-immobilized AuE exhibits notable catalytic performance for H2O2 reduction and the loading of AgNPs on the AuE surface and therefore the effective catalytic area can be tuned by the immobilization time of thiol-ssDNA and adsorption time of AgNPs. This H2O2 sensor has a fast amperometric response time of less than 3 s and its linear range and detection limit are estimated to be from 0.1 mM to 160 mM (r = 0.995) and 0.8 μM at a signal-to-noise ratio of 3, respectively.

We, report for the first time, the synthesis and kinetics of Ni and Fe3O4 nanobioconjugates obtained by covalent conjugation of nanoparticles to lactate dehydrogenase (LDH). The conjugation reaction was performed using bis(sulfosuccinimidyl) suberate (BS3) as a cross-linking agent. The kinetics of discrete conjugates was studied through conversion of lactate and pyruvate and subsequent reduction of NAD+ to NADH at 340 nm. The enzyme velocities and the Km values designated that LDH-Ni conjugate developed a higher affinity for substrate. The fabrication of LDH-Ni conjugates makes them promising candidates for biotechnology applications. These novel findings pave way to device a convenient nanoparticle-based LDH assay void of any radioactive isotope or use of complicated dyes for invitro detection and management of malignancies such as leukemia, malaria, to determine cytotoxic potential of compounds in food, cosmetics and pharmaceutical industries. Furthermore, the altered comportment of novel conjugates may serve as a guideline in the development of nanobioconjugates and new advances in nanoparticle based diagnosis and therapeutics.

A careful comparison of the experimental results reported in the literature reveals different variations of the melting temperature even for the same materials. Though there are different theoretical models, thermodynamic model has been extensively used to understand different variations of size-dependent melting of nanoparticles. There are different hypotheses such as homogeneous melting (HMH), liquid nucleation and growth (LNG) and liquid skin melting (LSM) to resolve different variations of melting temperature as reported in the literature. HMH and LNG account for the linear variation where as LSM is applied to understand the nonlinear behaviour in the plot of melting temperature against reciprocal of particle size. However, a bird’s eye view reveals that either HMH or LSM has been extensively used by experimentalists. It has also been observed that not a single hypothesis can explain the size-dependent melting in the complete range. Therefore we describe an approach which can predict the plausible hypothesis for a given data set of the size-dependent melting temperature. A variety of data have been analyzed to ascertain the hypothesis and to test the approach.

Dye-sensitized solar cells are electrochemical devices with very interesting properties that provide an alternative to the conventional semiconductor solar cell technology. However, the details of the charge transport mechanisms, which include both electronic and ionic transport, are not yet fully understood. In this paper, we present a novel approach to dye-sensitized solar cell modeling and simulation which is based on population dynamics models that have recently been extensively used to model reactions between biological molecules. It is shown that the proposed model can be used to simulate the operation of dye-sensitized solar cells and produces I-V characteristics that are in qualitative agreement with the experimental ones. Furthermore, the model presented here can be used to optimize the characteristics and the design of dye-sensitized solar cells.