Cytotoxicity of CdSe-based quantum dots incorporated in glass nanoparticles evaluated using human keratinocyte HaCaT cells.

CdSe quantum dots (QDs) are potential fluorescent reagents, but leakage of Cd and Se often induces cytotoxicity. Here we prepared CdSe-based QDs with glass to reduce their leakage and examined their cytotoxicity using keratinocyte cells. The cytotoxicity of the QDs with glass was obviously lower than that of the commercial QDs with polymer, suggesting their safety for biological applications.

2-Hydrazinoquinoline: a reactive matrix for matrix-assisted laser desorption/ionization mass spectrometry to detect gaseous carbonyl compounds.

The sensitivity, range of applications, and reaction mechanism of 2-hydrazinoquinoline as a reactive matrix for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were examined. Using a reaction chamber (125L) equipped with a stirring fan and a window for moving the MALDI-MS plate and volatile samples in and out, the sensitivities of 2-hydrazinoquinoline to gaseous aldehydes (formaldehyde, acetaldehyde, propionaldehyde, and n-butyraldehyde) and ketones (acetone, methyl ethyl ketone, and methyl isobutyl ketone) were determined to be at least parts per million (ppm) levels. On the other hand, carboxylic acids (formic acid, acetic acid, propionic acid, and butyric acid) and esters (ethyl acetate, pentyl acetate, isoamyl acetate, and methyl salicylate) could not be detected by 2-hydrazinoquinoline in MALDI-MS. In addition to 2,4-dinitrophenylhydrazine, a common derivatization reagent for analyzing carbonyl compounds quantitatively in gas chromatography and liquid chromatography, the dissolution of 2-hydrazinoquinoline in an acidic solution, such as trifluoroacetic acid, was essential for its function as a reactive matrix for MALDI- MS.

From metal-organic framework to intrinsically fluorescent carbon nanodots.

Highly photoluminescent carbon nanodots (CNDs) were synthesized for the first time from metal-organic framework (MOF, ZIF-8) nanoparticles. Coupled with fluorescence and non-toxic characteristics, these carbon nanodots could potentially be used in biosafe color patterning.

Highly luminescent CdSe/Cd(x)Zn(1-x)S quantum dots coated with thickness-controlled SiO2 shell through silanization.

A silanization technique of hydrophobic quantum dots (QDs) was applied to SiO(2)-coated CdSe/Cd(x)Zn(1-x)S QDs to precisely control the SiO(2) shell thickness and retain the original high photoluminescence (PL) properties of the QDs. Hydrophobic CdSe/Cd(x)Zn(1-x)S core-shell QDs with PL peak wavelengths of 600 and 652 nm were prepared by a facile organic route by using oleic acid (OA) as a capping agent. The QDs were silanized by using partially hydrolyzed tetraethyl orthosilicate by replacing surface OA. These silanized QDs were subsequently encapsulated in a SiO(2) shell by a reverse micelles synthesis. The silanization plays an important role for the QDs to be coated with a homogeneous SiO(2) shell and retain a high PL efficiency in water. Transmission electron microscopy observation shows that the shells are 1-9 nm with final particle sizes of 10-25 nm, depending on the initial QD size. In the case of short reaction time (6 h), the QDs were coated with a very thin SiO(2) layer because no visible SiO(2) shell was observed but transferred into the water phase. The silica coating does not change the PL peak wavelength of the QDs. The full width at half-maximum of PL was decreased 4 nm after coating for QDs emitting at both 600 and 652 nm. The PL efficiency of the SiO(2)-coated is up to 40%, mainly determined by the initial PL efficiency of the underlying CdSe/Cd(x)Zn(1-x)S QDs.

Various Au nanoparticle organizations fabricated through SiO2 monomer induced self-assembly.

A novel method has been developed to fabricate the assembly of Au colloidal nanoparticles (NPs) using SiO(2) monomers. The key strategy was the use of a controlled sol-gel procedure including hydrolysis, deposition, and condensation of tetraethyl orthosilicate (TEOS). Namely, the assembly of Au NPs was created by the anisotropic deposition of SiO(2) monomers and subsequent permanent fixing by the growth of a SiO(2) shell. Various assemblies of Au NPs such as dimer, trimer, and pearl-chain morphology were fabricated by systematically changing the concentration and injection speed of TEOS. A longitudinal plasmon resonance band was observed as a result of the assembly of Au NPs and can be tuned from visible to near-infrared by altering the length of pearl-chain morphology. In addition, single Au NP was homogeneously coated with a SiO(2) shell by means of controlling the deposition rate of SiO(2) monomers during a Stöber synthesis without the use of a silane coupling agent or bulk polymer as the surface primer to render the Au surface vitreophilic. The Au NPs (mean size 11.4 nm in diameter) were thus encapsulated into SiO(2) beads with a wide range of sizes (from 20 to 50 nm in diameter). These pure SiO(2)-coated Au beads with tunable shell thickness should be crucial for biosensors, particularly as Raman-tag particles.

Testicular metastasis of colon cancer masquerading a hydrocele of testis.

A case of testicular metastasis of colon cancer, which clinically mimicked a hydrocele of the testis, is presented. Imaging study suggested a scrotal hydrocele, but slow yet gradual enlargement of the hydrocele and the past history of colon cancer prompted an orchiectomy for the pathologic diagnosis and treatment. The pathologic diagnosis was testicular metastasis of colon cancer. Testicular metastasis presenting as a hydrocele is unusual, and imaging and macroscopic findings useful for the differential diagnoses are discussed. A brief review of pertinent literature is also included.

Photoluminescent Ozone Sensor with Enhanced Sensitivity by Using CdSe/ZnS Quantum Dots Modified with Gold and Platinum.

We report photoluminescence-based ozone sensing using composite films composed of gold or platinum and red-emitting CdSe/ZnS core-shell quantum dots. The sensing efficiency of quantum dots is enhanced by the addition of noble metals. The composite films undergo reversible changes in photoluminescence intensity (measured at excitation/emission wavelengths of 365/652 - 659 nm) in the presence of ppm levels of ozone in air at 25°C and at atmospheric pressure. The sensitivity of the composite films does not saturate with ozone in the 0.5 - 200 ppm concentration range. When compared with a quantum dot-only film, the composite films show higher sensitivities to 0.5 ppm ozone of 27% (gold) and 43% (platinum). When compared with a quantum dot-only film, the photoluminescence of the gold- or platinum-palladium alloy-based film recovers faster after the removal of ozone in the surrounding atmosphere. Thus, platinum- or gold-conjugated quantum-dot films form sensor modules for the reversible and highly sensitive detection of ozone under the tested ambient conditions.

MicroRNA-206 is highly expressed in newly formed muscle fibers: implications regarding potential for muscle regeneration and maturation in muscular dystrophy.

miR-1, miR-133a, and miR-206 are muscle-specific microRNAs expressed in skeletal muscles and have been shown to contribute to muscle development. To gain insight into the pathophysiological roles of these three microRNAs in dystrophin-deficient muscular dystrophy, their expression in the tibialis anterior (TA) muscles of mdx mice and CXMD(J) dogs were evaluated by semiquantitative RT-PCR and in situ hybridization. Their temporal and spatial expression patterns were also analyzed in C2C12 cells during muscle differentiation and in cardiotoxin (CTX)-injured TA muscles to examine how muscle degeneration and regeneration affect their expression. In dystrophic TA muscles of mdx mice, miR-206 expression was significantly elevated as compared to that in control TA muscles of age-matched B10 mice, whereas there were no differences in miR-1 or miR-133a expression between B10 and mdx TA muscles. On in situ hybridization analysis, intense signals for miR-206 probes were localized in newly formed myotubes with centralized nuclei, or regenerating muscle fibers, but not in intact pre-degenerated fibers or numerous small mononucleated cells, possibly proliferating myoblasts and inflammatory infiltrates. Similar increased expression of miR-206 was also found in C2C12 differentiation and CTX-induced regeneration, in which differentiated myotubes or regenerating fibers showed abundant expression of miR-206. However, CXMD(J) TA muscles contained smaller amounts of miR-206, miR-1, and miR-133a than controls. They exhibited more severe and more progressive degenerative alterations than mdx TA muscles. Taken together, these observations indicated that newly formed myotubes showed markedly increased expression of miR-206, which might reflect active regeneration and efficient maturation of skeletal muscle fibers.

Synthesis of Cd-free water-soluble ZnSe(1-x)Te(x) nanocrystals with high luminescence in the blue region.

Cd-free core-shell nanocrystals (ZnSe(1-x)Te(x)/ZnS, 0

Development of Technologies for Sensing Ozone in Ambient Air.

Ozone (O3) gas is widely used as a strong oxidizing agent for many purposes, such as the decomposition/removal of organic contaminants and photoresist, and the deodorization/disinfection of air and water. However, ozone is highly toxic to the human body when the air concentration exceeds about 1 ppm. Therefore, there is increasing demand for simple, sensitive, reliable, and cost-effective techniques for sensing ozone gas. This article describes the features, advantages, and disadvantages of the available, practical techniques for sensing ozone gas in ambient air. The advantages of optical gas sensors as next-generation sensors is specifically introduced. The features of photoluminescent, semiconductor nanoparticles (quantum dots, QDs) as bright phosphors with the potential for various applications is further explored. Lastly, recent research results demonstrating the ozone sensitivity of photoluminescent CdSe-based core-shell quantum dots are presented. These results strongly suggest that optical ozone sensing using photoluminescent quantum dots is a promising technique.

Encapsulation of emitting CdTe QDs within silica beads to retain initial photoluminescence efficiency.

Highly luminescent silica beads (30 nm-2 mum slashed circle) incorporating CdTe quantum dots (QDs) were prepared via a two-step preparation procedure, namely a modified Stöber synthesis and a subsequent reverse micelle route. In the modified Stöber synthesis, the silica molecules are deposited on the surface of the QDs. After this first step, these coated QDs were incorporated into silica beads via a reverse micelle route. Inductively coupled plasma analysis revealed a red-emitting silica bead of 30 nm in diameter thus prepared encapsulated roughly 14 CdTe QDs. These glass beads (30-40 nm slashed circle) retained the initial photoluminescence (PL) efficiencies of the colloidal QDs (27 and 65% for the green- and red-emitting beads, respectively). The protection of QDs by a silica layer at the first step, together with the short total reaction time, is the main reason for the retention of the PL efficiency. The size of the glass beads can be easily controlled over the wide range by adjusting the injection speed and the ratio of chemicals used for the reverse micelle preparation. Since the original efficiency was maintained in the beads and is the highest ever reported for QD-containing silica beads, the method presented here is of significant importance for applications of silica beads to biological probes.

Determination of orthophthalaldehyde in air using 2,4-dinitrophenylhydrazine-impregnated silica cartridge and high-performance liquid chromatography.

A new method is described for the determination of orthophthalaldehyde in air which is used for the disinfection of various instruments (e.g. endoscopes) in hospital. Orthophthalaldehyde in air was collected with a silica gel cartridge impregnated with acidified 2,4-dinitrophenylhydrazine (DNPH-cartridge) and derivatives were analyzed by high-performance liquid chromatography (HPLC). In this study, the derivatization was examined by comparing the process with three phthalaldehyde isomers (ortho-, iso- and tere-). In the case of iso- and tere-phthalaldehyde, derivatives synthesized with excess of aldehyde consisted mainly of mono-derivatives, and derivatives synthesized with excess of DNPH consisted mainly of bis-derivative. In the case of orthophthalaldehyde, derivative consisted of only bis-derivative and mono-derivative was never observed under any conditions. Orthophthalaldehyde was completely retained by the DNPH-cartridge during air sampling, however, the derivatization reaction was incomplete and unreacted orthophthalaldehyde was flushed from the cartridge during the subsequent solvent extraction process. Unreacted orthophthalaldehyde and DNPH reacted again in the extraction solvent solution. Immediately after the solvent extraction, both mono- and bis-DNPhydrazone derivatives of orthophthalaldehyde were present in the solution. However, over time, the mono-derivative decreased and bis-derivative increased until only the bis-derivative was left allowing accurate determination of the orthophthalaldehyde concentration. The transformation of mono-derivative to bis-derivative was faster in polar aprotic solvents such as acetonitrile, dimethyl sulfoxide and ethyl acetate. Transformation was found to occur most quickly in acetonitrile solvent and was completed in 4 h in this case. It was possible to measure orthophthalaldehyde in air as bis-derivative using a DNPH impregnated silica cartridge and HPLC analysis.

Inorganic arsenic compounds and methylated metabolites induce morphological transformation in two-stage BALB/c 3T3 cell assay and inhibit metabolic cooperation in V79 cell assay.

We have performed two-stage transformation assay using BALB/c 3T3 cells to determine initiating and promoting activities of disodium arsenate, sodium arsenite, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). Treatment with these arsenic compounds at the initiating stage induced significant numbers of transformed foci when cells were post-treated with 12-O-tetradecanoylphorbol-13-acetate (TPA). Disodium arsenate was active at the concentrations of 15-30 microM, sodium arsenite 5-20 microM, and DMAA 1-2 mM. MMAA required 10 mM to induce cell transformation. The concentrations of these compounds (except DMAA) that induced transformation were highly growth-inhibitory (more than 50%). DMAA induced transformation foci at growth inhibition levels of 66 to 84%. In experiments on promoting activity, cells pretreated with a sub-threshold dose of 20-methylcholanthrene (MCA, 0.2 microg/ml) or sodium arsenite (10 microM) were used. Transformation was enhanced by post-treatment with disodium arsenate (1-10 microM), sodium arsenite (0.5-2 microM), and MMAA (200-1000 microM), but not with DMAA. Studies of gap junctional intercellular communication using the V79 cell metabolic cooperation assay showed that the arsenic compounds (except DMAA) exhibited inhibitory activity. Thus, most arsenicals were shown to have not only initiating activity, but also promoting activity. In addition, inorganic arsenicals, especially trivalent sodium arsenite, were more active than organic ones and exhibited promoting activity at one-order of magnitude lower than initiating activity. These results suggest that from the viewpoint of human hazard, more attention should be paid to the tumor promoting activity of inorganic arsenic compounds.

Analysis of herbicides in water using temperature-responsive chromatography and an aqueous mobile phase.

A simple and rapid method has been developed for herbicides in water using temperature-responsive liquid chromatography (LC) and a column packed with poly(N-isopropylacrylamide) (PNIPAAm), a polymer anchored on the stationary-phase surface of modified silica. PNIPAAm reversibly changes its hydrophilic/hydrophobic properties in water in response to temperature. The method was used to determine five sulfonylurea and three urea herbicides. Separation was achieved with a 10 mM ammonium acetate (pH 3.0) isocratic aqueous mobile phase, and by changing the column temperature. The analytes were extracted from water by off-line solid-phase extraction (SPE) with an N-vinyl-pyrrolidone polymer cartridge. The average recoveries of the eight herbicides from spiked pure water, tap water and river water were 70-130% with relative standard deviations (RSDs) of <10%. The limits of quantitation (LOQ) of the eight herbicides were between 1 and 4 microg l(-1).

Effect of arsenic-contaminated irrigation water on agricultural land soil and plants in West Bengal, India.

Total arsenic withdrawn by the four shallow tubewells, used for agricultural irrigation in the arsenic-affected areas of Murshidabad district per year is 6.79 kg (mean: 1.79 kg, range: 0.56-3.53 kg) and the mean arsenic deposition on land per year is 5.02 kg ha(-1) (range: 2-9.81 kg ha(-1)). Mean soil arsenic concentrations in surface, root of plants, below ground level (0-30 cm) and all the soils, collected from four agricultural lands are 14.2 mg/kg (range: 9.5-19.4 mg/kg, n = 99), 13.7 mg/kg (range: 7.56-20.7 mg/kg, n = 99), 14.8 mg/kg (range: 8.69-21 mg/kg, n = 102) and 14.2 mg/kg (range: 7.56-21 mg/kg, n = 300) respectively. Higher the arsenic in groundwater, higher the arsenic in agricultural land soil and plants has been observed. Mean arsenic concentrations in root, stem, leaf and all parts of plants are 996 ng/g (range: <0.04-4850 ng/g, n = 99), 297 ng/g (range: <0.04-2900 ng/g, n = 99), 246 ng/g (range: <0.04-1600 ng/g, n = 99) and 513 ng/g (range: <0.04-4850 ng/g, n = 297) respectively. Approximately 3.1-13.1, 0.54-4.08 and 0.36-3.45% of arsenic is taken up by the root, stem and leaf respectively, from the soil.

Survey of volatile organic compounds found in indoor and outdoor air samples from Japan.

Indoor air quality is currently a growing concern, mainly due to the incidence of sick building syndrome and building related illness. To better understand indoor air quality in Japan, both indoor and outdoor air samples were collected from 50 residences in Iwate, Yamanashi, Shiga, Hyogo, Kochi and Fukuoka Prefectures. More than 100 volatile organic compounds (VOCs) were analyzed by thermal desorption-gas chromatography/mass spectrometry method. The most abundant class of compounds present in the indoor air samples were identified (i.e. alkanes, alkylbenzenes and terpenes). For 30% of the indoor air samples, the sum of each VOC exceeded the current provisional guideline value for total VOC (TVOC, 400 microg/m3). The major component of these samples included linear and branched-chain alkanes (possibly derived from fossil fuels), 1,4-dichlorobenzene (a moth repellent), alpha-pinene (emission from woody building materials) and limonene (probably derived from aroma products). As an unexpected result, one residence was polluted with an extremely high concentration of 1,1,1,2-tetrafluoroethane (720 microg/m3), suggesting accidental leakage from a household appliance such as a refrigerator. The results presented in this paper are important in establishing the Japanese target compound list for TVOC analysis, as well as defining the current status of indoor air quality in Japan.

Isomerization of aldehyde-2,4-dinitrophenylhydrazone derivatives and validation of high-performance liquid chromatographic analysis.

The most widely used method for qualitative and quantitative analysis of carbonyl compounds is the 2,4-dinitrophenylhydrazine method through the formation of 2,4-dinitrophenylhydrazone derivatives. However, this method may cause an analytical error because 2,4-dinitrophenylhydrazones have both E- and Z-stereoisomers. Purified aldehyde-2,4-dinitrophenylhydrazone demonstrated only the E-isomer. However under UV irradiation and the addition of acid, both E- and Z-isomers were seen. The spectral patterns of Z-isomers were different from those of E-isomers and the absorption maximum wavelengths were shifted towards shorter wavelengths by 5-8 nm. An equilibrium Z/E isomer ratio was observed in 0.02-0.2% (v/v) phosphoric acid solutions. In the case of acetaldehyde- and propanal-2,4-dinitrophenylhydrazones, the equilibrium Z/E isomer ratios were 0.32 and 0.14, respectively. However, when irradiated with ultraviolet light at 364 nm, the isomer ratios were increased beyond this constant ratio and reached 0.55 and 0.33, respectively. Zero-order rates for decreases of aldehyde derivatives were observed under UV irradiation (364 nm), however the decreases of concentration were not observed in phosphoric acid solutions. The best method for the determination of aldehyde-2,4-dinitrophenylhydrazones by HPLC is to add phosphoric acid to both the sample and the standard solution, to form a 0.02-1% acid solution.

Temperature- and pH-responsive aminopropyl-silica ion-exchange columns grafted with copolymers of N-isopropylacrylamide.

We have designed copolymers of N-isopropylacrylamide, environmentally-responsive polymers, which respond to temperature and other external stimuli. In this study, we designed and synthesized copolymers that introduced ion-exchange groups. These copolymers responded to the temperature and the pH, and the copolymer-grafted aminopropyl silica beads were used as HPLC packing materials. This stationary phase altered the properties from hydrophilic to hydrophobic and from charge to non-charge by temperature and pH changes. We studied the separations of organic acids and phenylthiohydantoin-amino acids using environmentally-responsive chromatography, and confirmed the effects of the ion-exchange groups. The elution behaviors of these samples were controlled by the temperature changes without organic solvents in the mobile phase. It was confirmed that the interactions between the solute and stationary phase could be freely controlled by the temperature and the pH. Environmentally-responsive chromatography is expected to be applicable to the separation of pharmaceuticals and biomolecules, such as peptides, proteins and nucleic acids.

High-performance liquid chromatographic assay for amiodarone N-deethylation activity in human liver microsomes using solid-phase extraction.

A selective and sensitive assay for amiodarone N-deethylation activity in human liver microsomes by high-performance liquid chromatography (HPLC) with UV detection is reported. The extraction of desethylamiodarone from incubation samples was performed by means of an original solid-phase extraction (SPE) procedure using a polymeric reversed-phase sorbent (Oasis HLB). The method was validated for the determination of desethylamiodarone with respect to specificity, linearity, precision, accuracy, recovery, limit of quantitation and stability. Amiodarone N-deethylation activity from low to high substrate concentrations using human liver microsomes was precisely determined without a concentration step. This method is applicable to the study in vitro of the metabolism of amiodarone.

Survey of arsenic and other heavy metals in food composites and drinking water and estimation of dietary intake by the villagers from an arsenic-affected area of West Bengal, India.

An investigation of arsenic, copper, nickel, manganese, zinc and selenium concentration in foodstuffs and drinking water, collected from 34 families and estimation of the average daily dietary intake were carried out in the arsenic-affected areas of the Jalangi and Domkal blocks, Murshidabad district, West Bengal where arsenic-contaminated groundwater (mean: 0.11 mg/l, n=34) is the main source for drinking. The shallow large diameter tubewells, installed for agricultural irrigation contain an appreciable amount of arsenic (mean: 0.094 mg/l, n=10). So some arsenic can be expected in the food chain and food cultivated in this area. Most of the individual food composites contain a considerable amount of arsenic. The mean arsenic levels in food categories are vegetables (20.9 and 21.2 microg/kg), cereals and bakery goods (130 and 179 microg/kg) and spices (133 and 202 microg/kg) for the Jalangi and Domkal blocks, respectively. For all other heavy metals, the observed mean concentration values are mostly in good agreement with the reported values around the world (except higher zinc in cereals). The provisional tolerable daily intake value of inorganic arsenic microg/kg body wt./day) is: for adult males (11.8 and 9.4); adult females (13.9 and 11); and children (15.3 and 12) in the Jalangi and Domkal blocks, respectively (according to FAO/WHO report, the value is 2.1 microg/kg body wt./day). According to WHO, intake of 1.0 mg of inorganic arsenic per day may give rise to skin lesions within a few years. The average daily dietary intake of copper, nickel and manganese is high, whereas for zinc, the value is low (for adult males: 8.34 and 10.2 mg/day; adult females: 8.26 and 10.3 mg/day; and children: 4.59 and 5.66 mg/day) in the Jalangi and Domkal blocks, respectively, compared to the recommended dietary allowance of zinc for adult males, adult females and children (15, 12 and 10 mg/day, respectively). The average daily dietary intake of selenium microg/kg body wt./day) is on the lower side for the children (1.07 and 1.22), comparable for the adult males (0.81 and 0.95) and slightly on the higher side for the adult females (1.08 and 1.26), compared to the recommended value (1.7 and 0.9 microg/kg body wt./day for infants and adults, respectively).