Nanoscale Particle Size Research Articles

Turning an antiviral into an anticancer drug: Nanoparticle delivery of acyclovir monophosphate

Anti-herpes simplex virus (HSV) drug acyclovir (ACV) is phosphorylated by the viral thymidine kinase (TK), but not the cellular TK. Phosphorylated ACV inhibits cellular DNA synthesis and kills the infected cells. We hypothesize that ACV monophosphate (ACVP), which is an activated metabolite of ACV, should be efficient in killing cells independent of HSV-TK. If so, ACVP should be a cytotoxic agent if properly delivered to the cancer cells. The Lipid/Calcium/Phosphate (LCP) nanoparticles (NPs) with a membrane/core structure were used to encapsulate ACVP to facilitate the targeted delivery of ACVP to the tumor. The LCP NPs showed entrapment efficiency of ~70%, the nano-scaled particle size and positive zeta potential. Moreover, ACVP-loaded LCP NPs (A-LCP NPs) exhibited concentration-dependent cytotoxicity against H460 cells and increased S-phase arrest. More importantly, a significant reduction of the tumor volume over 4days following administration (p<0.05–0.005) of A-LCP NPs, suggests excellent in vivo efficacy. Whereas, two free drugs (ACV and ACVP) and blank LCP NPs showed little or no therapeutic effect. It was also found that the high efficacy of A-LCP NPs was associated with the ability to induce dramatic apoptosis of the tumor cells, as well as significantly inhibit tumor cell proliferation and cell cycle progression. In conclusion, with the help of LCP NPs, monophosphorylation modification of ACV can successfully modify an HSV-TK-dependent antiviral drug into an anti-tumor drug.

Effect of calcium phosphate particle shape and size on their antibacterial and osteogenic activity in the delivery of antibiotics in vitro.

Powders composed of four morphologically different calcium phosphate particles were prepared by precipitation from aqueous solutions: flaky, brick-like, elongated orthogonal, and spherical. The particles were then loaded with either clindamycin phosphate as the antibiotic of choice or fluorescein, a model molecule used to assess the drug release properties. A comparison was carried out of the effect of such antibiotic-releasing materials on: sustained drug release profiles; Staphylococcus aureus growth inhibition; and osteogenic propensities in vitro. Raman spectroscopic analysis indicated the presence of various calcium phosphate phases, including monetite (flaky and elongated orthogonal particles), octacalcium phosphate (brick-shaped particles), and hydroxyapatite (spherical particles). Testing the antibiotic-loaded calcium phosphate powders for bacterial growth inhibition demonstrated satisfying antibacterial properties both in broths and on agar plates. All four calcium-phosphate-fluorescein powders exhibited sustained drug release over 21 days. The calcium phosphate sample with the highest specific surface area and the smallest, spherical particle size was the most effective in both drug loading and release, consequently having the highest antibacterial efficiency. Moreover, the highest cell viability, the largest gene expression upregulation of three different osteogenic markers--osteocalcin, osteopontin, and Runx2--as well as the least disrupted cell cytoskeleton and cell morphologies were also noticed for the calcium phosphate powder composed of the smallest, spherical nanosized particles. Still, all four powders exerted a viable effect on osteoblastic MC3T3-E1 cells in vitro, as evidenced by both morphological assessments on fluorescently stained cells and measurements of their mitochondrial activity. The obtained results suggest that the nanoscale particle size and the corresponding coarseness of the surface of particle conglomerates as the cell attachment points may present a favorable starting point for the development of calcium-phosphate-based osteogenic drug delivery devices.

Síntese e estudo microestrutural de perovskita do tipo La0,8Ca0,2MO3 (M = Co ou Mn) com gelatina como precursor orgânico para aplicação em catálise automotiva

Materiais com estrutura perovskita são potenciais catalisadores para prevenir a emissão de componentes poluentes no meio ambiente. Vários métodos têm sido propostos para a síntese desses materiais visando produzir materiais homogêneos com tamanho de partícula nanométrico. Neste trabalho os compostos manganato de lantânio e cobaltato de lantânio com substituição parcial de cálcio foram sintetizados com gelatina como agente de polimerização, visando sua utilização como catalisadores automotivos. Esse método de síntese foi utilizado porque permite a obtenção de fases cristalinas com pós homogêneos e porosos. Os pós obtidos a 300 ºC/4 h foram calcinados a 700 e 900 ºC/4 h e caracterizados pelas técnicas de análise termogravimétrica, difração de raios X e microscopia eletrônica de varredura. As perovskitas obtidas foram monofásicas, manométricas, porosas e com propriedades adequadas para aplicação em catálise automotiva.

Synthesis of alumina powder by the urea–glycine–nitrate combustion process: a mixed fuel approach to nanoscale metal oxides

Main objective of present work is to study the efficiency of mixed fuel towards solution combustion synthesis of alumina powder, which otherwise prepared by single fuel and study of properties of final product with mixed fuel approach. Two different fuels, glycine and urea, along with aluminium nitrates have been used to prepare nanophase alumina powder. Different fuel to oxidizer ratios and different percentage combination of two fuels were used to prepare six samples. In all samples, nanoscale particle size obtained. Parameter which continuously changes the results of various characterisations is percentage combination of two fuels. In case where percentage of urea is higher than glycine reaction takes place with high exothermicity and hence crystallinity in product phase, whereas glycine promotes amorphous character. With mixed fuel approach, crystallinity can be enhanced easily, by calcinations of powder product at low temperature, because due to mixed urea and glycine, there is already some fraction of crystallinity observed. Overall mixed fuel approach has ability to produce nanophase alumina powder with wide range of particles size.

Efficient Simultaneous Tumor Targeting Delivery of All-Trans Retinoid Acid and Paclitaxel Based on Hyaluronic Acid-Based Multifunctional Nanocarrier

An amphiphilic hyaluronic acid (HA)-g-all-trans retinoid acid (HRA) conjugate was successfully developed as a tumor-targeting nanocarrier for potentially synergistic combination chemotherapy of all-trans retinoid acid (ATRA) and paclitaxel (PTX). The HRA conjugate was synthesized by an imine reaction between HA-COOH and ATRA-NH2. PTX-loaded HRA nanoparticles possessed a high loading capacity, nanoscale particle sizes, and good biocompatible characteristics. Cell viability assays indicated that PTX-loaded HRA nanoparticles exhibited concentration- and time-dependent cytotoxicity. Moreover, they displayed obvious superiority in inducing the apoptosis of tumor cells. Cellular uptake analysis suggested that HRA nanoparticles could be efficiently taken up by cells via endocytic pathway and transport into the nucleus, contributing to HA receptor-mediated endocytosis and ATRA-induced nuclear translocation, respectively. Moreover, in vivo imaging analysis indicated that the accumulation of DiR-loaded HRA nanoparticles in tumor was increased obviously after intravenous administration as compared to free DiR solution, which confirmed that the HRA nanoparticles could assist the drugs targeting to the tumor. Furthermore, PTX-loaded HRA nanoparticles exhibited greater tumor growth inhibition effect in vivo with reducing the toxicity. Therefore, HRA nanoparticles can be considered as a promising targeted codelivery system for combination cancer chemotherapy.

Surface alkaline-acidic and photocatalytic properties of MMoO4 (M = Fe2+, Co2+, Ni2+) nanoparticles in different media conditions

MMoO4 (M = Fe2+, Co2+, Ni2+) nanocrystaline particles with similar nanoscale particle size were synthesized by a salt aqueous solution reaction. UV–Vis absorbance spectra show that the nanoparticles are of good light absorbance in UV–Vis light region and narrow band gap. The variation in oxidation–reduction potential (ORP) of selected methyl orange aqueous solution due to the presence of the nanoparticles is measured in various conditions. The light absorption and the ORP determine the photodegradation rate of the aqueous methyl orange solution on the nanoparticles. The ORP is clearly also a necessary and useful parameter in research on and applications of the photocatalysis.

Block Copolymer Crosslinked Nanoassemblies Co-Entrapping Acridine Yellow and Doxorubicin for Cancer Theranostics

Aims: To develop block copolymer crosslinked nanoassemblies (CNAs) that co-entrap an imaging dye (Acridine Yellow: AY) and therapeutic agent (doxorubicin: DOX) as novel nanoparticle drug carriers for a combined application of drug delivery-based therapy and diagnostic imaging technologies (theranostics). Study Design: Physicochemical properties of AY-CNAs, such as molecular weight, particle size, surface charge, drug entrapment yield, and drug release profiles, were characterized prior to determining intracellular uptake profile, in vitro cytotoxicity, and in vivo tissue distribution patterns of the particles. Place and Duration of Study: Department of Pharmaceutical Sciences (University of Kentucky), between June 2012 and January 2013. Methodology: The AY-crosslinked CNAs (CNAs) were synthesized from biocompatible poly(ethylene glycol)-poly(aspartate) block copolymers by using AY as a crosslinker while DOX was physically entrapped in the particle through an ionic interaction. AY-CNAs and AY-CNAs with DOX were characterized to determine their particle properties (molecular weight, size, and optical properties), intracellular uptake and cytotoxicity in an in vitro cell culture system using human colon HT29 and lung A549 cancer cell lines, and tissue accumulation and tumor-preferential drug delivery efficiency ex vivo with a xenograft Research Article British Journal of Pharmaceutical Research, 3(4): 523-535, 2013 524 mouse tumor model. Results: AY-CNAs maintained nanoscale particle sizes (< 20 nm), fluorescence optical properties, and negative surface charge before and after drug entrapment. AY-CNAs with DOX were confirmed to kill cancer cells as effectively as free drug formulations, and to enhance intracellular uptake in vitro and tumor accumulation ex vivo. Conclusion: These results demonstrate that block copolymer nanoassemblies crosslinked with an imaging dye are promising platforms for the development of theranostic nanoparticle drug carriers.

Optical Analytical Technique for Carbonaceous Particles Using Laser-Induced Electro-Avalanche Fluorescence and Laser-Induced Incandescence

This report describes an optical sensing system for fine particle detection using a combination of two techniques: laser-induced breakdown spectroscopy (LIBS) and laserinduced incandescence (LII). We have improved laser measurement systems applied for small-particle analysis. We have determined elemental composition and density of particles using LIBS and have been able to measure particle size using LII. Controlling the power density of the light source of the present system allowed switching from LIBS to LII. LII temporal analysis was conducted using a streak camera, which was also used for LIBS analysis. The LII technique allows in situ measurement of the average primary particle size of nanoscale soot particles.

Effect of the milling process on the properties of CoFe2O4 pigment

Abstract In this study, CoFe 2 O 4 pigments were synthesised using both co-precipitation and conventional ceramic methods. Pigment particles prepared using the conventional ceramic method were subsequently milled to submicron size. The effects of the solvent, dispersant and milling type in the milling process were investigated. This study showed that planetary milling in a diethylene glycol (DEG) medium with sodium tripolyphosphate (STPP) was an effective method for producing submicron-sized pigment powders from pigments synthesised using the conventional method. With this method, submicron-sized pigment particles (approximately 190 nm) were obtained after milling for 4 h. Planetary milling was more efficient in reducing particle size compared to attrition milling. Co-precipitated pigment had a more intense black colour, due to the nanoscale particle size (

Facile solid-state synthesis of Li2MnSiO4/C nanocomposite as a superior cathode with a long cycle life

The Li2MnSiO4/C nanocomposite has been successfully synthesized at a relatively low temperature of 650 °C by a facile solid-state reaction using citric acid as the carbon source. The highly crystalline Li2MnSiO4 nanoparticles in the size of 20–50 nm are coated by a uniform carbon layer in a thickness of 2–5 nm. At a rate of 0.05 C, the Li2MnSiO4/C nanocomposite exhibits a discharge specific capacity as high as 268 mAh g−1 for the first cycle and a reversible capacity of about 136 mAh g−1 after 140 cycles at room temperature. Meanwhile, an improved rate performance is achieved by the Li2MnSiO4/C nanocomposite. These superior electrochemical properties could be attributed to the nanoscale particle size and the enhanced electronic conductivity.

Active and Stable Ni‐MgO Catalyst Coated on a Metal Monolith for Methane Steam Reforming under Low Steam‐to‐Carbon Ratios

AbstractA structured reaction system in the form of an Ni‐MgO catalyst reduced to nanoscale particle size and coated on a metallic monolith proved to be an active and stable system for methane steam reforming under a steam‐to‐carbon ratio of 1.5 and a temperature of 700 °C. The catalyst‐coated monolith exhibited higher stability and much higher CH4 conversion than the same catalyst in a catalyst particle bed reaction system. The high activity is attributed to the properties of the metal monolith and to the small size of the catalyst particles on the coating, while the stability is ascribed to the NiO‐MgO solid solution formed in the Ni‐MgO catalyst. These results are better than the corresponding ones obtained with a conventional Ni‐Al2O3 catalyst reported previously [1] and comparable to the ones presented in the literature, with the advantage of working under a low steam‐to‐carbon ratio.

Electrical Properties of Nano Zinc Ferrites Prepared by Solution Combustion and Hydrothermal Methods

Zinc Ferrite (ZF) nanopowders relatively uniform size distributions ranging from 5 to 14 nm were prepared by solution combustion and hydrothermal methods. The PXRD showed cubic phase, spinel structure, and particle size in nanoscale. The SEM images confirm the agglomeration of the product composed of uniform nanoparticles of flakes type and spherical type in combustion and hydrothermal methods respectively. The purity check was done by FTIR. The optical band gap energy (Eg) obtained by UV-Vis spectra of the ZF nanopowders prepared by solution combustion and hydrothermal methods were found to be 1.985 eV and 1.99 eV respectively. The present study clearly shows that the distribution of the cations within the spinel lattice of the ferrite nanoparticles are strongly affected by the synthesis method used. Results suggest that the electrical properties depend on the particular method of preparation and sintering temperature of the prepared samples. The resistivity of the samples increased to the order of 103 by sintering the samples. It is observed that the activation energy (Ea) decreases with increasing the sintering temperature.

Amorphous Si/SiOx/SiO2 nanocomposites via facile scalable synthesis as anode materials for Li-ion batteries with long cycling life

Novel Si/SiOx/SiO2 nanocomposites were prepared via a facile and scalable wet synthesis. The amorphous structure, nanoscale particle size, and composition of the Si/SiOx/SiO2 material were characterized and its electrochemical performance as an anode for Li-ion batteries was evaluated. The material shows a stable cycling capacity of ∼600 mA h g−1 over 350 cycles with high coulombic efficiency of >99%.

SnO2 Nanoparticle‐Based Passive Capacitive Sensor for Ethylene Detection

A passive capacitor‐based ethylene sensor using SnO2 nanoparticles is presented for the detection of ethylene gas. The nanoscale particle size (10 nm to 15 nm) and film thickness (1300 nm) of the sensing dielectric layer in the capacitor model aid in sensing ethylene at room temperature and eliminate the need for microhotplates used in existing bulk SnO2‐resistive sensors. The SnO2‐sensing layer is deposited using room temperature dip coating process on flexible polyimide substrates with copper as the top and bottom plates of the capacitor. The capacitive sensor fabricated with SnO2 nanoparticles as the dielectric showed a total decrease in capacitance of 5 pF when ethylene gas concentration was increased from 0 to 100 ppm. A 7 pF decrease in capacitance was achieved by introducing a 10 nm layer of platinum (Pt) and palladium (Pd) alloy deposited on the SnO2 layer. This also improved the response time by 40%, recovery time by 28%, and selectivity of the sensor to ethylene mixed in a CO2 gas environment by 66%.

Characterization and Cytotoxicity Studies of Mixed Cu-La-Ce Nanocomplexes Prepared by Coprecipitation Approach

This work describes the mixed Cu-La-Ce nanocomplexes materials were synthesized by coprecipitation approach with aqueous solutions of copper nitrate, lanthanum nitrate and cerium nitrate. The nanocomplexes materials were characterized by TEM, with a particle size around nanoscale particle sizes (~50 nm) with high dispersion phenomena. Further, cell cytotoxicity and the percentage cell survival was determined by using 3-(4,5-dimethylthiazol-2-yl)-5 (3-carboxymethoxyphenol)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay on human fetal lung tissue cell (MRC-5). The experimental results show that the Cu-La-Ce nanocomplexes materials only minor cause cytotoxicity effect in cultured human cells.

High-rate capability of LiFePO 4 cathode materials containing Fe 2P and trace carbon

Carbon coating and nano-scale particle size are two impactful factors in improving the rate capability of LiFePO 4 cathode materials for lithium-ion batteries. However, both factors decrease the tap density of the materials and are possibly causing unfavorable effect on the volumetric capacity of the cathode materials and thus the batteries, which is undesirable in commercial application. In the present study, LiFePO 4 materials with moderate particle size of sub-micron and trace carbon content (0.5–0.9 wt.%) are synthesized by a mechanical activation method. High-electronic conductivity iron phosphides (Fe 2P/FeP) are in situ introduced into the LiFePO 4 materials and the amount is modified by the calcination temperature. Electrochemical testing shows that Fe 2P/FeP plays an important role in improving the high-rate capability of LiFePO 4 with moderate particle size. The product calcined at 700 °C, which has a high-tap density of 1.37 g cm −3 correlating to a specific surface area approximately of 4 m 2 g −1, possesses discharge capacities of 110 and 100 mAh g −1 at discharge rates of 5 C and 10 C, respectively. The introduction of Fe 2P/FeP in an amount of ca. 5 wt.% rather than carbon coating and the moderate particle size of LiFePO 4 are promising approaches to obtain LiFePO 4 cathode material of high-rate capability without unduly compromising its volumetric capacity.

Electrocatalysis Oxidation of Ammonia at PtPdRh Ternary Catalysts in an Acid Medium and Applied Fuel Cell Studies

This work describes the platinum-group metal electrocatalytic materials were synthesized by incipient wetness impregnation process combine with aqueous solutions of H2PtCl6, Pd(NO3)3 and Rh(NO3)3 that were coated on alumina substances employed as a model reaction test by ammonia (NH3) electrocatalysis oxidation (ECO) research for fuel cell applications. The electrocatalytic materials were characterized by dynamic light-scattering (DLS), with a particle size around nanoscale particle sizes with high dispersion phenomena. Further, ECO ability was determined by using cyclic voltammetry (CV) and linear sweep voltammograms (LSV) technique. The experimental results show that the significant reactivity of the PtPdRh ternary electrocatalysts in acid medium and the results also demonstrated that the potential and the current density of the main oxidation-reduction peak change for the PtPdRh ternary electrocatalyst.

Shell Cross-Linked Micelle-Based Nanoreactors for the Substrate-Selective Hydrolytic Kinetic Resolution of Epoxides

Shell cross-linked micelles (SCMs) containing Co(III)-salen cores were prepared from amphiphilic poly(2-oxazoline) triblock copolymers. The catalytic activity of these nanoreactors for the hydrolytic kinetic resolution of various terminal epoxides was investigated. The SCM catalysts showed high catalytic efficiency and, more significantly, substrate selectivity based on the hydrophobic nature of the epoxide. Moreover, because of the nanoscale particle size and the high stability, the catalyst could be recovered easily by ultrafiltration and reused with high activity for eight cycles.

The Influence of Calcination Temperature and Cytotoxicity Assessment of Honeycomb Platinum-Containing Cordierite Nanocomposite Catalysts via Incipient Wetness Impregnation Process

This work describes the platinum-containingcordieritenanocompositematerials were synthesized by incipient wetness impregnation process with aqueous solutions of H2PtCl6, Pd(NO3)3and Rh(NO3)3that were coated on cordierite ceramic honeycomb substances followed by calcinations temperature ranging from 973 to 1273 K. The nanocomposite materials were characterized by STEM, with a particle size around nanoscale particle sizes (~100 nm) with high dispersion phenomena. Further, cell cytotoxicity and the percentage cell survival was determined by using 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethoxyphenol)-2-(4-sulfophenyl)-2H-tetrazoli um (MTS) assay on human fetal lung tissue cell (MRC-5). The experimental results show that the platrinum-containingcordieritenanocompositematerials only minor cause cytotoxicity effect in cultured human cells.

Biogenic uraninite precipitation and its reoxidation by iron(III) (hydr)oxides: A reaction modeling approach

One option for immobilizing uranium present in subsurface contaminated groundwater is in situ bioremediation, whereby dissimilatory metal-reducing bacteria and/or sulfate-reducing bacteria are stimulated to catalyze the reduction of soluble U(VI) and precipitate it as uraninite (UO 2). This is typically accomplished by amending groundwater with an organic electron donor. It has been shown, however, that once the electron donor is entirely consumed, Fe(III) (hydr)oxides can reoxidize biogenically produced UO 2, thus potentially impeding cleanup efforts. On the basis of published experiments showing that such reoxidation takes place even under highly reducing conditions (e.g., sulfate-reducing conditions), thermodynamic and kinetic constraints affecting this reoxidation are examined using multicomponent biogeochemical simulations, with particular focus on the role of sulfide and Fe(II) in solution. The solubility of UO 2 and Fe(III) (hydr)oxides are presented, and the effect of nanoscale particle size on stability is discussed. Thermodynamically, sulfide is preferentially oxidized by Fe(III) (hydr)oxides, compared to biogenic UO 2, and for this reason the relative rates of sulfide and UO 2 oxidation play a key role on whether or not UO 2 reoxidizes. The amount of Fe(II) in solution is another important factor, with the precipitation of Fe(II) minerals lowering the Fe +2 activity in solution and increasing the potential for both sulfide and UO 2 reoxidation. The greater (and unintuitive) UO 2 reoxidation by hematite compared to ferrihydrite previously reported in some experiments can be explained by the exhaustion of this mineral from reaction with sulfide. Simulations also confirm previous studies suggesting that carbonate produced by the degradation of organic electron donors used for bioreduction may significantly increase the potential for UO 2 reoxidation through formation of uranyl carbonate aqueous complexes.