Microfabricated solenoids and Helmholtz coils for NMR spectroscopy of mammalian cells

NMR-microprobes based on solenoids and Helmholtz coils have been microfabricated and NMR-spectra of mammalian cells have successfully been taken. The microfabrication technology developed for these probes consists of three electroplated copper levels for low resistance coils and three SU-8 layers for the integration of microchannels. This technology allows fabricating solenoids, Helmholtz and planar coils on the same wafer. The coils have inner diameters in the range of 160 to 400 microm and detection volumes of 5 to 22 nL. The solenoid and Helmholtz coils show improved RF-field characteristics compared to a planar coil fabricated with the same process. The fabricated solenoid has a particularly low resistance of only 0.46 Omega at 300 MHz. Moreover, it is very sensitive and has a very uniform RF-field, but shows large line width. The Helmholtz coils are slightly less sensitive, but display a far narrower line width, and are therefore a good compromise. With a Helmholtz coil, a SNR of 620 has been measured after one scan on 9 nL pure water. An NMR-microprobe based on a Helmholtz coil has also been used to take spectra of CHO cells that have been concentrated in the sensitive region of the coil with a mechanical filter integrated into the channel.     

手性荧光传感器的研究进展

随着手性化合物在制药、不对称合成、生物科学及临床医学等领域应用的增长,迫切需要发展一种快速、灵敏的对映异构体检测技术。手性荧光传感器引起了人们的高度关注。近年来,发展了很多手性荧光传感器并对手性化合物表现出较高的选择性和灵敏度。该文综述了以1,1'-联-2-萘酚衍生物、杯芳烃衍生物、高分子聚合物、纳米材料、金属有机多孔材料为骨架的手性荧光传感器,总结了其在手性化合物识别中的应用,并展望了手性荧光传感器的发展方向。     

4-(2-Pyridylazo)-resorcinol as a possible analytical reagent for the colorimetric estimation of cobalt,lead, and uranium ,

4-(2-Pyridylazo)-resorcinol has been synthesized, and its uses as an analytical reagent for the colorimetric estimation of cobalt, uranium and lead have been investigated. It has been shown to be the most sensitive reagent for the colorimetric estimation of cobalt, the most sensitive watersoluble reagent for the colorimetric estimation of uranium, and the first published water-soluble reagent for the colorimetric estimation of lead.     

Metal selective flame ionization detection after supercritical fluid chromatography

This work describes the construction and operation of a flame ionization detector for the selective detection of metal-containing compounds after capillary supercritical fluid chromatography. Using optimal conditions for achieving metal sensitive flame ionization responses which have been established for the detector after capillary gas chromatography, initial evaluation of the detector after SFC proved promising. Like the carbon sensitive FID, it appears that the metal sensitive FID is compatible with SFC when pure carbon dioxide is used as the mobile phase. Response characteristics were found to be similar to those observed when the detector is used in gas chromatography.     

Synthetic and analytical studies on colour reagents-IX The reactions of phthaleinazo compounds with the alkaline earths

Some new phthaleinazo compounds-o,o'-dihydroxyazo compounds-have been prepared by coupling chromotropic acid, R-acid, and 2-hydroxy-3-naphthoic acid with bis-diazotized diaminophthaleins. These compounds have been found to be very sensitive colour reagents for alkaline earths in alkaline media, and in particular, bis(chromotropeazo)phenolphthalein is the most sensitive yet found.     

Kinetic-spectrophotometric determination of sulfide by its reaction with resazurin

A sensitive, rapid and selective method for the determination of sulfide based on its reaction with resazurin at pH 7 is described. The method is simple and has the great advantage of being free from interference of other sulfur anions and thus sulfide can be easily determined at trace levels in the presence of other sulfur compounds. The method has been applied to some synthetic samples and a spring water sample. The importance of sulfide compounds in biological processes has been widely demonstrated [1]. However, most of the methods used so far are either not sensitive enough or require complicated and expensive instruments; or are subjected to interferences from other sulfur compounds. Therefore, more sensitive, simple and selective methods are still required.     

Kinetic-spectrophotometric determination of sulfide by its reaction with resazurin

A sensitive, rapid and selective method for the determination of sulfide based on its reaction with resazurin at pH 7 is described. The method is simple and has the great advantage of being free from interference of other sulfur anions and thus sulfide can be easily determined at trace levels in the presence of other sulfur compounds. The method has been applied to some synthetic samples and a spring water sample. The importance of sulfide compounds in biological processes has been widely demonstrated [1]. However, most of the methods used so far are either not sensitive enough or require complicated and expensive instruments; or are subjected to interferences from other sulfur compounds. Therefore, more sensitive, simple and selective methods are still required.     

Capillary Electrophoresis Coupled On-Line with Inductively Coupled Plasma Atomic Emission Spectrometry for Elemental Speciation

Capillary electrophoresis (CE) has become a powerful analytical technique for the separation of a variety of analytes ranging from small inorganic ions to large biomolecules such as proteins and nucleic acids. A selective and sensitive detector for CE has been one of the most important and challenging prerequisites for the growth of CE. On-column UV-Vis detectors are commonly used to determine the analytes separated by CE. However, these detectors are often not very selective. Other detection techniques such as mass spectrometry, laser induced fluorescence, amperometry, and inductively coupled plasma spectrometry have been investigated to provide a more sensitive and selective detection for the target analytes. However, relatively few studies have been published on the use of inductively coupled plasma atomic emission spectrometry (ICP-AES) as a means of detection in CE separation.     

Thermospray liquid chromatographic-mass spectrometric method for the analysis of metribuzin and its metabolites

A thermospray liquid chromatographic-mass spectrometric (TSP LC-MS) method has been developed for the analysis of the herbicide metribuzin and its three major metabolites in plant tissue. Metribuzin and its metabolites exhibited widely varying sensitivities in positive-ion TSP, with metribuzin being the most sensitive and deaminated diketo metribuzin being the least sensitive. All four compounds of interest were detected in an extract of a soybean plant which had been treated with metribuzin.     

The Cobalt-Thiocyanate Reaction for the Detection of Cobalt and Thiocyanate

Summary 1. Alkali-thiocyanate is a sensitive reagent for the detection of cobalt in presence of 40 to 50% acetone. Ferric iron can be made harmless by addition of an excess of fluoride. A procedure has been developed for the application of the reaction as a micro-and macro test for cobalt. Cupric copper gives a sensitive reaction and must be removed. The thiocyanate is preferable to cyanate as a reagent. 2. A procedure has been described for the micro detection of thiocyanate by evaporating a drop of the solution to be tested with a small drop of cobalt sulfate and moistening the residue with acetone. The formation of a distinctly green solution indicates the presence of thiocyanate. Nitrite interferes.     

A spectroscopic off-on probe for simple and sensitive detection of carboxylesterase activity and its application to cell imaging

A new resorufin-based spectroscopic probe, 7-(p-acetoxyphenylmethyloxy)-3H-phenoxazin-3-one (1), has been developed for detecting carboxylesterase activity. The probe is designed by introducing p-acetoxyphenylmethyloxy as a bifunctional moiety to resorufin. The p-acetoxyphenylmethyloxy moiety not only quenches the spectroscopic signal of resorufin, but also serves as a recognition unit for carboxylesterase. As a result, the prepared latent spectroscopic probe 1 shows very low background signal, which is rather desired for achieving sensitive detection. The specific cleavage of the carboxylic ester bond by carboxylesterase induces the hydrolysis of the probe, resulting in the release of resorufin and thereby the recovery of both color and fluorescence signal. This behaviour leads to the development of a simple and sensitive fluorescent method for assaying carboxylesterase activity, with a detection limit of 8.6 × 10(-5) U mL(-1), which is much more sensitive than the existing fluorescence approaches. Moreover, experimental results showed that the probe 1 is cell membrane permeable, and its applicability has been demonstrated for monitoring carboxylesterase activity in HeLa cells.     

Oxidizing mechanism of podophyllotoxin and its derivatives by sodium persulfate

The oxidizing mechanism of podophyllotoxin and its derivatives by sodium persulfate has been studied by laser flash photolysis and pulse radiolysis. The formation and decay processes of transient species of podophyllotoxin and its derivatives have been observed, and a series of rate constants for the formation and decay of transient species have been determined. It has been found that there is a light (UV) sensitive group on the C-4 of podophyllotoxin and two light (UV) sensitive groups on the C-4 and C-4' of 4'-demethylepipodophyllotoxin.     

DBD Dyes as Fluorescence Lifetime Probes to Study Conformational Changes in Proteins

Previously, [1,3]dioxolo[4,5‐f][1,3]benzodioxole (DBD)‐based fluorophores used as highly sensitive fluorescence lifetime probes reporting on their microenvironmental polarity have been described. Now, a new generation of DBD dyes has been developed. Although they are still sensitive to polarity, in contrast to the former DBD dyes, they have extraordinary spectroscopic properties even in aqueous surroundings. They are characterized by long fluorescence lifetimes (10–20 ns), large Stokes shifts (≈100 nm), high photostabilities, and high quantum yields (>0.56). Here, the spectroscopic properties and synthesis of functionalized derivatives for labeling biological targets are described. Furthermore, thio‐reactive maleimido derivatives of both DBD generations show strong intramolecular fluorescence quenching. This mechanism has been investigated and is found to undergo a photoelectron transfer (PET) process. After reaction with a thiol group, this fluorescence quenching is prevented, indicating successful bonding. Being sensitive to their environmental polarity, these compounds have been used as powerful fluorescence lifetime probes for the investigation of conformational changes in the maltose ATP‐binding cassette transporter through fluorescence lifetime spectroscopy. The differing tendencies of the fluorescence lifetime change for both DBD dye generations promote their combination as a powerful toolkit for studying microenvironments in proteins.     

Synthesis and Characterization of Photoactive Amphiphilic Polymers

We have synthesized light sensitive nano micelles for their applications as drug delivery agents. Various azo compounds having different dipole moment values have been covalently attached to an amphiphilic pegylated co‐polymer and their light sensitive behavior has been studied in both aqueous and organic media with ultra violet light to understand the light dependent supramolecular organization.     

固定酚红的交联聚乙烯醇光化学pH敏感膜

An optical pH sensitive membrane for optical pH sensors has been developed by covalently immobilizing phenol red on optical transparent cross-linked polyvinyl alcohol （PVA） membrane surfaces. The phenol red was first reacted with acrylamide to form a product of acrylamide grafted phenol red （AAGP）, then the AAGP was covalently immobilized to the PVA membrane via surface grafting-polymerization using Fe^2＋/H2O2 as initiator. The performance of the pH sensitive membrane was investigated and the results showed that the pH sensitive membrane has some features including a linear response scope from pH 6.5 to 8.5 closed with phenol solution, a rapid response time （〈：20 s）, good reproducibility, reversibility, excellent stability and easiness of fabrication. These show that the pH sensitive membrane can be used as a sensitive layer for optical pH sensor.     

Novel unsymmetrical squaraine dye bearing cyanoacrylic acid anchoring group and its photosensitization behavior

Aiming toward the development of far-red sensitive organic dyes, unsymmetrical squaraine dye bearing direct cyanoacrylate functionalized indole ring has been synthesized and characterized along with its utilization as photosensitizer for dye-sensitized solar cells. Upon dye-sensitized solar cell fabrication, this sensitizer exhibits its potentiality as a good far-red sensitive dye having photoconversion efficiency of 5.03% under the simulated solar irradiation at AM 1.5 conditions. This opens up further possibility to design efficient far-red sensitive dyes by judicious implementation of suitable donor moieties with extended π-conjugation.     

Poly(adenine) DNA-Templated Gold Nanocluster-Based Fluorescent Strategy for the Determination of Thiol-Containing Pharmaceuticals

The fluorescence intensity of poly(adenine) DNA-templated gold nanoclusters was shown to be significantly quenched by N-acetylcysteine through the formation of the Au-S metal-ligand bonds. On the basis of the fluorescence quenching phenomenon, a sensitive, turn-off, and label-free fluorescence method has been designed for the determination of thiol-containing pharmaceuticals using poly(adenine) DNA-templated gold nanoclusters as fluorescent probes. The assay exhibited sensitive determination of N-acetylcysteine with a linear dynamic range from 10?nM to 10?μM and a limit of detection of 3?nM. Furthermore, the proposed strategy was successfully applied for the determination of N-acetylcysteine levels in acetylcysteine granule samples. Thus, the method could provide a sensitive, simple, and rapid fluorescent sensing platform for the determination of thiol-containing pharmaceuticals.     

Separation and determination of metals as complexes of 1-nitroso-2-naphthol-6-sulphonic and 2-nitroso-1-naphthol-6-sulphonic acids

A sensitive ion-pair liquid-liquid extraction-spectrophotometric method has been developed for the determination of copper, palladium, iron and cobalt, based on the formation of metal complexes with 1-nitroso-2-naphthol-6-sulphonic acid or 2-nitroso-1-naphthol-6-sulphonic acid as primary ligand, and zephiramine as counter-ion. The coloured metal complexes obtained over different pH ranges are easily and quantitatively extracted into dichloromethane. The method has been tested with samples containing known amounts of copper, palladium, iron and cobalt in ultrapure water. The reagents provide a sensitive spectrophotometric method for determining these metals.     

The Rapid Measurement of ABO Blood Type by Using SPR(Surface Prasmon Resonance) Sensor

The conventional measurement of ABO blood-types is visual inspection method based on the aggregation reaction with monoclonal antibody. But, this method takes a long time (one night) and requires the skilled analyzer to decide the blood-types for the saliva and bloodstain sample. Therefore, the rapid and sensitive measurement of ABO blood type has been required for the saliva and bloodstain on the clothes. Surface prasmon resonance (SPR) is an optical technique, which has been applied to biosensing. In this study, the rapid and sensitive measurement of ABO blood-types were investigated by using SPR sensing system.     

New materials for ESR dosimetry

New materials for electron spin resonance (ESR) dosimetry have been investigated with the aim to find systems more sensitive than L-alanine accepted as a standard for high dose determinations. Among the investigated systems ammonium tartrate, 2-methylalanine, salts of formic acids and dithionates have been found to be more sensitive than alanine by a factor 2-10. The lower limit applies to tissue equivalent materials, while much higher sensitivities were obtained with formates and dithionates containing heavier atoms. The increased sensitivity was mainly attributed to suitable ESR properties of the room temperature stable radicals as regards spectral shape (narrow lines, little or no hyperfine structure) and microwave saturation properties (short relaxation times). The radical structures have when necessary been clarified by ENDOR spectroscopy, while the saturation properties have been screened by pulsed ESR measurements.