Natural killer cell cytotoxicity assay with time-resolved fluorimetry

A new time-resolved fluorimetric method for the measurement of natural killer (NK) cell cytotoxicity has been developed by labelling the target cell K562 with a new synthesized fluorescence marker KLUK. The method has advantages of higher sensitivity, time-saving, good reproducibility and has no radioactivity problems. A satisfactory result is obtained by comparing it with 51Cr release method. It demonstrates that the new marker provides an alternative to currently used radioactive markers for the assessment of in vitro cellular cytotoxicity.

Determination of trace gadolinium by catalytic kinetic fluorimetry

There was a significant catalytic effect of trace Gd(III) ions on the oxidative reaction of potassium persulfate with Saffron T in the acetic acid–sodium acetate buffer solution. Thus, a catalytic kinetic fluorimetry method for the determination of trace Gd(III) ions was established. The factors such as acidity, concentration of reagents, reaction time, and temperature as well as influence of coexisting ions were discussed. The optimum reaction conditions were established. The apparent rate constant and apparent activation energy of the reaction were determined. The linear range is 0.02–0.10 lgáml-1,and the detection limit is 7.27 9 10-4lgáml-1. This method was used for the determination of gadolinium in the samples of lanthanum acetate with RSD of 0.9 %–3.1 %.

标本因素对荧光定量PCR法测定乙肝病毒DNA的影响

目的探讨脂血、溶血标本及血清标本常温储存48小时和4℃保存7天对乙肝病毒DNA(HBVDNA)荧光定量测定结果的影响。方法:将乙肝大三阳血清标本进行即时检测、412保存7d后检测、室温保存48h检测及高脂血和非脂血、溶血血清和未溶血血清同时作HBVDNA荧光定量PCR,并两两间进行配对t检验。结果乙肝大三阳溶血与未溶血血清标本、脂血和非脂血血清标本HBVDNA含量都在同一数量级。血清标本在室温下短期贮存(48h内)、4℃保存7d内分别与即时检测HBV-DNA含量比较均无统计学意义(P>0.05)。结论脂血、溶血,血清标本不同储存温度及时间对HBV-DNA定量结果测定无影响。

Co－fluorescence Enhancement System Based on Lanthanum（Ⅲ） for Determination of Terbium（Ⅲ）

The phenomenon of fluorescence enhancement for the system of terbium( Ⅲ ) with trimesic acid [ ben-zene-1, 3, 5-tricarboxylic acid (TMA)] in the presence of an excase of La￣(3+) in gelatin aqusous solution wasstudied. The fluorescence intensity of Tb￣Ⅲ -TMA system can be greatly increased by La￣(3+) , which causedthe largest enhancement of the fluorescence intensity over two orders of magnitude. The intermolecular transfer of energy was responsible for the mechanism of the fluorascence enhancement. Gelatin plays animportant role for the stabilization of the system. The system, having the maximum excitation and emis-sion wavelengths at 260 nm and 549 nm, respectively, shows a constant fluorescence interisity over the pHrange 4～6. The fluorescence intensity is a linear function of Tb￣(3+) concentration in the range of 8. 0 ×10 ￣(-9)～ 2. 6 × 10￣(-7) mol· L￣(-1) and the limit of detection is 2.0 × 10￣(-9) mol·L￣(-1) . The optimized procedurewas used for the determination of trace amount of terbium in rare earth oxides and international standardreference rocks with satisfactory results.

Organic Solvents Enhanced Spectrofluorimetric Method for Determination of Laccase Activity

A novel fluorimetric method for determination of laccase activity in organic solvents is proposed, based on the oxidation ofo-phenylenediamine (1,2-diaminobenzene, OPDA) catalyzed by laccase yielding 2,3-diaminophenazine. The optimal conditions for laccase in organic media areT=55°C, pH=6.5, 1.0×10?2mol/L OPDA, 1.25 mL ethanol, 1.25 mL 1,4-dioxane and 1.25 mL acetone. The linear range of the method proposed in ethanol, 1,4-dioxane and acetone media were 0.44–19.33, 0.11–20.85, 0.38–21.05 U with the detection limit of 0.088, 0.022, 0.076 U, respectively. The proposed method has been applied to the analysis of laccase activity of real samples with more accurate and sensitive than that of the previous method reported.

Spectrofluorimetric Method for the Determination of Triamcinolone Acetonide

A simple and highly sensitive method for the determination of triamcinolone acetonide in pharmaceutical formulations is presented. The approach is based on the fluorescence of production of triamcinolone acetonide oxidized by concentrated sulfuric acid. The effect of H2SO4, β-cyclodextrin (β-CD), solvent and cetyltrimethylammonium bromide (CTMAB) were discussed. And two analytical systems were established. One is CTMAB system, the linear range is 0–4.6×10?6 mol/L, and the detection limit is 3.59×10?8 mol/L. The other is β-CD and ethanol system, the linear range is 0–2.3×10?6 mol/L and the detection limit is 1.91×10?8 mol/L. The selectivity of analysis, the analytical figures of optimization, and the accuracy of the method are demonstrated with the determination of triamcinolone acetonide in pharmaceutical preparations. Key words triamcinolone acetonide - fluorimetry - CTMAB - β-cyclodextrin - pharmaceutical analysis CLC number O 657.39 Foundation item: Supported by the National Natural Science Foundation of China (20275028)Biography: Pan Zu-ting (1945-), male, Professor, research direction: analytical chemistry.

Studies of Ce(Ⅲ)-ALC-F Interacting with Herring Sperm DNA by Electrochemical, Fluorimetric and UV-spectrophotometric Method

Ce(Ⅲ)-ALC-F complex can react with hsDNA to form an electrochemically non-active supermolecular complex Ce(Ⅲ)-ALC-F-DNA in the buffer solution of (CH2)6N4(pH=4.9), which results in the decrease of the peak current of Ce(Ⅲ)-ALC-F. This method can be applied to determine DNA concentration. In addition, by using fluorimetric and UV-spectrophotometric methods with studies of denatured DNA and the effect of NaCl solution , it is also found that the binding mode is intercalation.

Fluorescence Enhancement of Samarium－Thenoyl－trifluoroacetone－Cetyltrimethylammonium Bromide－Triton X－100 by Scandium

fluorescence enhancement phenomenon shown by adding scandium ion to thesamarium-thenoyltrifluoroacetone (TTA)-cetyltrimethylammonium bromide(CTMAB)-Triton X-100(TX-100) system was observed and the effect of the condi-tions on the system was studied in detail. The excitation and emission wavelengthswere 370 nm, 565 nm, 603 nm and 645 nm, respectively. The optimum conditionsforming Sm-Sc-TTA-CTMAB-TX-100 system were that the concentration of Sc￣(3+)was equal to 5.0× 10￣(-5) mol/L, pH was 7. 7. Under these conditions, the fluores-cence intensity can be increased about 10 times higher than that of the system con-taining no Sc￣(3+) , and it was a linear function of the concentration of samariumn therange of 1. 0 × 10￣(-9)-4. 0 × 10￣(-7) mol/L. The detection limit was 6. 0 ×10￣(-10) mol/L.This system was used for the spectrofluorimetric determination of samarium withsatisfactory results. The nature of enhanced fluorescence was explained using in-tramolecular and intermolecular energy transfer theory.

A Study of Fluorescence System of Eu-Chlorotetracycline-Benzoylacetone-CTMAB Multibasic Complex

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Spectrofluorimetric Determination of Trace Terbium(III) Using 2,6-Bis-(1'-phenyl-3'-methyl-5'-oxopyrazole-4')pyridinediacyl and N-Cetylpyridium Bromide

A new spectrofluorimetric method for determination of trace terbium based on its reaction with 2.6-his-(1'-phenyl-3'-methyl-5'- pyridinediacyl (H_2PMBPP) and N- cetylpyridium bromide (CPB). at an apparent pH=5.0 provided by a hexamethylenetetramine (5% w/w)-hydrochloric acid buffer,is propesed. The calibration graph is linear in the ran ge from

Selective Determination of Epinephrine by Using an Improved Modification of the Trihydroxyindole Method

A simple and selective method for the determination of epinephrine is put forward, which is an improved modification of the trihydroxyindole method. Experiment indicated that in borax buffer (pH=8.7) and with mercaptoethanol as the reducing reagent, dopa and dopamine did not form fluorescence products, so it is possible to determine epinephrine selectively.

Characterization and application of PBA fiber optic chemical film sensor based on fluorescence multiple quenching

The three types of structure of the pyrenebutyric acid of fiber optic chemical film sensor were stud-ied by fluorescence multiple quenching. They are, for different test samples and purposes, respectively general, three-way and combined. A tri-cup method was designed to demonstrate the multiple quenching of response mechanism, and a relationship formula of mathematical approach was established. The response mechanism was shown to include the dynamic quenching , inner-filter effects and/or resonance energy transfer. To show the response characterization in a series of organic and inorganic quenchers, a new concept of apparent quenching coefficient Kq was advanced. This kind of sensor has been used in continuous and in situ monitoring of the dissolution rate of drug tablets, on line and in situ monitoring of some organic therapeutic drugs in biological fluid and Cr( VI ) in industrial waste water. The measured data were examined and compared with HPLC or HPTLCS. Test results show that the sensors and

Near-Infrared Hydrophobic Probes as Molecular Light Switch for CMC Determination of Triton X-100 Solution

The fluorescence behavior of two near-infrared (NIR) chromophores with linear alkyl chains of different lengths, 2-[4'chloro-7'(3'ethyl-2'benzothiazolinylidene)-3',5'-(1''',3'''-propanediyl)-1',3',5'-heptantriene-1'-yl]-3-ethylbenzo- thiazolium iodide (Probe I) and 2-[4'chloro-7'(3'hexadecyl-2'benzothiazolinylidene)-3',5'-(1''',3'''-propanediyl)- 1',3',5'-heptantriene-1'-yl]-3-ethylbenzothiazolium iodide (Probe II), in aqueous solution containing different con-centrations of surfactants was studied. The fluorescence of the probe with a short chain (probe I) was completely quenched in water and aqueous solution containing a low concentration (below the critical micelle concentration, CMC) of surfactant Triton X-100. However, the fluorescence reappeared and reached maximum rapidly once the concentration of the surfactant approached the CMC. The probe with a long chain (probe II) displayed a similar fluorescence behavior but more dramatically fluorescent recovery in Triton X-100 system, which gave a direct in-dication for the micelle forming process and provided a simple method for the determination of the critical micelle concentration of the surfactant. The CMC values determined by this method were in good agreement with those ob-tained by other techniques. The fluorescence behavior of the two probes in other surfactant systems was also inves-tigated.

Fluorescence enhancing by alkaline degradation of tetracycline antibiotics and its application

Tetracycline antibiotics could be degraded after being beated in boiling-water bath in alkaline solution (in KOH medium).The fluorescence excitation and emission wavelengths of the degradation products changed and the fluorescence intensity increased by 5-190 folds as compared with that of antibiotics themselves It was considered that there occurred a nucleophilic ring rupture reaction to form the degradation products with lactome structure The mteraction of the lone pair electrons of oxygen on the degradation products with the conjugated π electrons induced the in crease of the delocalization for the conjugated electron system in the molecule and thus enhanced the fluorescence intensity.

Determination of sulfonamides with fluorescent inclusion complex of carbonic anhydrase and dansylamide

A new fluorimetric method for determination of sulfonamides was described based on the formation of a fluorescent inclusion complex of carbonic anhydrase(CA) with dansylamide(DNSA). The binding of DNSA to CA resulted in an enhancement in the fluorescence emission at 460 nm with excitation at 280 nm. Dissociation constants were determined for the carbonic anhydrase sulfonamide complexes. Linear calibration graphs of sulfonamides were obtained within a concentration range of 0- 0.058 μg/mL for DNSA; 0-0.344 μg/mL for sulfanilamide (SAN) and 0-0.286 μg/mL for P toluenesulfonamide (PTSN). The relative standard deviations were within 1.8%-4.2%. Limits of detection for DNSA, SAN and PTSN were 0.84, 19.5 and 6.1 ng/mL, respectively. The method was applied to the determination of sulfonamides in cow milk at ng/mL level.