Chem. Pharm. Bull.(オピニオン)

A new signal amplification strategy based on thionine (TH)-doped magnetic gold nanospheres as labels and horseradish peroxidase (HRP) as enhancer holds promise to improve the sensitivity and detection limit of the immunoassay for carcinoembryonic antigen (CEA), as a model protein. This immunoassay system was fabricated on a carbon fiber microelectrode (CFME) covered with a well-ordered anti-CEA/protein A/nanogold architecture. The reverse micelle method was initially used for the preparation of TH-doped magnetic gold nanospheres (nanospheres), and the synthesized nanospheres were then labeled on HRP-bound anti-CEA as a secondary antibody (bionanospheres). Sandwich-type protocol was successfully introduced to develop a new high-efficiency electrochemical immunoassay with the labeled bionanospheres toward the reduction of H2O2. Under optimized conditions, the linear range of the proposed immunoassay without HRP as enhancer was 1.2−125 ng/mL CEA, whereas the assay sensitivity by using HRP as enhancer could b...

Ultrasensitive electrochemical immunosensor for clinical immunoassay using thionine-doped magnetic gold nanospheres as labels and horseradish peroxidase as enhancer.

The reaction between biologically green synthesized silver nanoparticles (Ag NPs) and mercury (II) ions was introduced as a new and high potential colorimetric sensor for the selective recognition and monitoring of mercuric ions in aqueous samples. The green synthesized silver nanoparticles were characterized with surface plasmon resonance (SPR) ultraviolet spectroscopy (UV–vis), SEM and X-ray diffraction analysis (XRD) techniques. The fresh biologically synthesized silver nanoparticles are yellowish-brown in color due to the intense SPR absorption band. In the presence of Hg 2+ , the yellow Ag NPs solution was turned to colorless, accompanying the broadening and blue shifting of SPR band. The sensitivity and selectivity of green prepared Ag NPs toward other representative transition-metal ions, alkali metal ions and alkaline earth metal ions were studied. Also the effect of the concentration of Hg 2+ to the Ag NPs was considered and the LOD for mercury (II) ion was 2.2 × 10 −6  mol L −1 . The proposed method has been successfully used for the determination of mercury (II) ions in various water samples.

Highly selective Hg2+ colorimetric sensor using green synthesized and unmodified silver nanoparticles

Bufadienolides from animal and plant sources.

Bufadienolides of plant and animal origin

Simultaneous HPLC assay of 1-adamantanamine hydrochloride (amantadine) and its four related compounds [2-adamantanamine hydrochloride (2-ADA), 1-adamantanmethylamine (ADAMA), 1-(1-adamantyl)ethylamine hydrochloride (rimantadine) and 3,5-dimethyl-1-adamantanamine hydrochloride (memantine)] in phosphate-buffered saline (pH 7.4) after pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was developed. Phosphate-buffered saline samples were mixed with borate buffer and NBD-F solution in acetonitrile at 60 degrees C for 5 min and injected into HPLC. Five derivatives were well separated from each other. The lower limits of detection of amantadine, 2-ADA, ADAMA, rimantadine and memantine were 0.008, 0.001, 0.0008, 0.0015 and 0.01 microg/mL, respectively. The coefficients of variation for intra- and inter-day assay were less than 6.4 and 8.2%, respectively. The method presented was applied to a binding study of these compounds to human alpha(1)-acid glycoprotein. While affinity constants and capacities for ADAMA, rimantadine and memantine were calculated by means of Scatchard plots, those for the others were not determined. ADAMA, rimantadine and memantine were bound with different affinities and capacities. These results indicate that NBD-F is a good candidate as a fluorescent reagent to simultaneously determine amantadine and its four related compounds by HPLC after pre-column derivatization. Our method can be applied to binding studies for protein.

Simultaneous liquid chromatographic assay of amantadine and its four related compounds in phosphate-buffered saline using 4-fluoro-7-nitro-2,1,3-benzoxadiazole as a fluorescent derivatization reagent.

A selective determination method for mercury(II) ion in water by reversed‐phase high performance liquid chromatography (HPLC) has been developed. A water sample of 5 mL was put into a 10‐mL centrifuge tube with a stopper. Then, 1 mL of 2‐mol/L (M) acetate buffer solution of pH 5.5 was added into the centrifuge tube. After mixing the contents, 1 mL of 0.5 M tetrabutylammonium bromide (TBA‐Br) solution and 0.3 mL of 1‐octanol were added. A mercury ion was extracted into an organic layer by shaking the contents for 10 min. The organic layer of 8 µL was injected into a C18 column with an eluent of methanol/water/0.5 M TBA‐Br (65:31:4, v/v), and the effluent was monitored at 255 nm. The detected mercury compound was estimated as [(TBA+)2 · HgBr4 2−]0. The correlation coefficient of the calibration curves (metal concentration vs. peak area), obtained with 5 mL of mercury standard, was more than 0.999 over the range of 10 ng/mL (ppb) to 10 µg/mL (ppm). The detection limit of Hg ion in a 5‐mL solution wa...

Selective Determination of Mercury(II) Ion in Water by Solvent Extraction Followed by Reversed‐Phase HPLC

We investigated simultaneous high-performance liquid chromatographic (HPLC) determination of amantadine hydrochloride (AMA) and rimantadine hydrochloride (RIM) levels in rat plasma after fluorescent derivatization with o-phthalaldehyde and 2-mercaptoethanol. Afterwards, the method was applied to determine their pharmacokinetics. The retention times of AMA and RIM derivatives were 12.6 and 22.2 min and the lower limits of detection were 0.025 and 0.016 microg/mL, respectively. The coefficients of variation for intra- and inter-day assay of AMA and RIM were less than 5.1 and 7.6%, respectively. After i.v. administration of AMA or RIM to rats, the total body clearance and distribution volume at the steady-state of RIM were higher than those of AMA. Bioavailability of AMA and RIM was 34.9 and 37.2%, respectively. When AMA and RIM were p.o. co-administered, the area under the plasma concentration--time curve of RIM was significantly lower than that after RIM alone. On the other hand, pharmacokinetic parameters of AMA did not significantly change. These results indicate that our HPLC assay is simple, rapid, sensitive and reproducible for simultaneously determining AMA and RIM concentrations in rat plasma and is applicable to their pharmacokinetic studies. Also, co-administration of AMA and RIM may result in the lack of pharmacological effects of RIM.

Simultaneous determination of amantadine and rimantadine by HPLC in rat plasma with pre-column derivatization and fluorescence detection for pharmacokinetic studies.

A method for the determination of digoxin in human serum using a liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) technique is reported. Digoxin and the internal standard, [21,21,22-(2)H(3)]digoxin, were extracted from 250 mul of human serum using a solid phase extraction cartridge (Oasis HLB) and analyzed by LC/ESI-MS/MS in the selected reaction monitoring mode. The intra- and inter-assay reproducibility and accuracy were satisfactory within the quantification range of 0.20-3.20 ng/ml. The concentrations of digoxin in the serum samples obtained from digitalized patients (n=19) were in the range of 0.25-2.84 ng/ml, which were compared to those obtained by radioimmunoassay.

Determination of digoxin in human serum using stable isotope dilution liquid chromatography/electrospray ionization-tandem mass spectrometry.

A sensitive, simple and reliable method using high-performance liquid chromatographic (HPLC) assay of fluvoxamine (FLU), a selective serotonin reuptake inhibitor (SSRI), in rat plasma after pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was developed in this study. Extracted plasma samples were mixed with NBD-F at 60 degrees C for 5 min and injected into HPLC. Retention times of FLU and an internal standard (propafenone) derivative were 15.5 and 13.5 min, respectively. The calibration curve was linear over the range 0.015-1.5 microg/mL (r2 = 0.9985) and the lower limits of detection and quantification of FLU were 0.008 and 0.015 microg/mL, respectively, in 100 microL of plasma. The derivative sample was stable at 4 degrees C for 1 day. The coefficients of variation for intra-day and inter-day assay of FLU were less than 8.3 and 9.6%, respectively. Other SSRIs and centrally acting drugs did not interfere with the peak of the FLU derivative. The method was applied for analysis of the plasma samples from rats treated with FLU. These results indicate that the method presented is useful to determine the FLU levels in rat plasma of volumes as small as 100 microL and can be applied to pharmacokinetic studies.

Determination of fluvoxamine in rat plasma by HPLC with pre-column derivatization and fluorescence detection using 4-fluoro-7-nitro-2,1,3-benzoxadiazole.

Youichi Fujii

Papers

Simultaneous liquid chromatographic assay of amantadine and its four related compounds in phosphate-buffered saline using 4-fluoro-7-nitro-2,1,3-benzoxadiazole as a fluorescent derivatization reagent.

Selective Determination of Mercury(II) Ion in Water by Solvent Extraction Followed by Reversed‐Phase HPLC

Simultaneous determination of amantadine and rimantadine by HPLC in rat plasma with pre-column derivatization and fluorescence detection for pharmacokinetic studies.

Determination of digoxin in human serum using stable isotope dilution liquid chromatography/electrospray ionization-tandem mass spectrometry.

Determination of fluvoxamine in rat plasma by HPLC with pre-column derivatization and fluorescence detection using 4-fluoro-7-nitro-2,1,3-benzoxadiazole.