We successfully analyzed the concentrations of five amino acids in commercially available dietary amino acid supplements by using terahertz time-domain spectroscopy (THz-TDS) with an error of ± 12% for the best reproduced components. We also succeeded in analyzing tablets of the supplements wrapped in paper, and thus showed the merit of using THz waves for the nondestructive quantitative analysis of packaged samples by employing the fact that THz waves are capable of passing through several types of packaging material. The ability of THz waves to pass through the paper made it possible to perform a quantitative analysis using the same standard spectra as those used for an unwrapped sample, and the accuracy of a direct quantitative analysis of a packaged sample was almost the same as that of an unwrapped sample.

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An electrochemical system has been developed in order to assay the effect of hydrophobic molecules on the bioluminescence of bacterial luciferase (BL). The inhibition of BL luminescence by the long-chain n-alkyl alcohol has been examined using this system. The 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol and 1-dodecanol inhibited the BL reaction in a dose-dependent manner. The IC₅₀ value, that is, the inhibitor concentration required to decrease the luminescence intensity by half, of these alcohols decreased with increasing the alkyl chain-length of the alcohols. In contrast, the shorter chain 1-hexanol did not inhibit the BL luminescence at all in the examined concentration range. These results indicate that the molecular size and hydrophobicity of the n-alkyl alcohol are the key factors to the inhibitory potency of the BL reaction. The IC₅₀ values are in agreement with values obtained for the bioluminescence of the firefly luciferase system. The proposed electrochemical BL luminescence system will be used for an inhibitory assay of hydrophobic drugs, such as general anesthetics on protein functions.

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Boron doped graphite nano particles were used as functioning elements for creation of electrodes for the detection of uric acid in biological samples. The electrode obtained in this manner was capable of oxidizing ascorbic acid at lower potentials. This provided a desirable solution to the interfering problem encountered in the detection of uric acid in biological samples caused by ascorbic acid. The detectable concentrations for uric acid ranged from 5.0 to 130 μM. The applicability of the electrode was experimentally demonstrated by the successful direct detection of uric acid in real urine samples.

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Anchorage-dependent cells growing over a substratum require stable adhesion areas on the surface for the next cellular activities. The adhesion is achieved by some contact points called focal adhesions. Because focal adhesions were distributed randomly, a trial to control the positions of focal adhesion with a specific order may cause interesting effects like as cytoskeleton rearrangement, which may induce and transfer new signals to the nucleus. Here, we cultured human osteoblasts over two sorts of nanopatterned surfaces with different pattern densities fabricated by using laser interference lithography and the nanoimprinting technique. Of the two nanopatterns, cells over the nanopattern with low pattern density showed relatively higher adaptation to the topography with guided filopodia protrusion. However, cells over the dense nanopattern showed difficulty in finding suitable paths for migration, as judged from the activities of filopodium formation and the presence of a shovel-like feature at the tip of each filopodium.

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Piezoelectric inkjet printing of polymers and proteins holds great promise for fabrication of miniaturized bioelectronic devices, such as biochips and biosensors. In this study, a bienzymatic glucose biosensor prototype based on poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) (PEDOT-PSS), glucose oxidase (GOD), and horseradish peroxidase (HRP) was fabricated by a piezoelectric inkjet printer. An aqueous bioelectrical ink containing PEDOT-PSS, GOD, and HRP was prepared and printed on an indium-tin-oxide (ITO)-coated poly(ethylene terephthalate) (PET) film. The PEDOT-PSS/GOD/HRP sensor was covered with a cellulose acetate membrane. The use of bienzymatic sensing combined with conducting polymers via piezoelectric inkjet printing showed a synergistic effect resulting in significant amplification of the response signal. The glucose sensor reached steady-state current density within 3 s, indicating a fast response time, and exhibited a linear dose-dependent electrochemical response with high sensitivity. The overall result demonstrates that a glucose sensor with high sensitivity could be readily fabricated by a piezoelectric inkjet printing system.

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The main types of analytical procedures used in thermal-lens spectroscopy and microscopy, which are based on photometric reactions in (i) aqueous solutions, (ii) organo-aqueous mixtures, (iii) polymer-containing (nonionic surfactants or polyethylene glycol) aqueous solutions, (iv) water-organic extraction systems, and (v) two-phase aqueous extraction systems, were compared from the viewpoint of both reproducibility and sensitivity. This comparison was made by examples of the determination of cobalt and iron for batch conditions, flow determination, and detection in HPLC, flow-injection analysis (FIA), and μFIA. It was revealed that for all five types, the real analytical efficiency (a decrease in the limit of detection (LOD) as compared to spectrophotometry) is primarily determined by the reaction conditions, provided that excitation of the thermal lens is the same. Aqueous solutions provide more efficient optimization of reaction conditions than do those in organo-aqueous solutions and solvent-extraction water-organic mixtures. The best results are achieved when shifting to polymer-containing aqueous solutions and two-phase aqueous extraction systems, which decreases in the LODs by a factor of 20 – 100%.

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Tripodal “broom” molecule derivatives containing π electrons were used as ionophores of silver ion-selective electrodes. The ability of the electrodes to detect silver ions was evaluated using the Nernst equation. When allyl- and propargyl-type tripodal broom molecules, and a propargyl-type monopodal analog were used in the electrode, Nernstian responses for silver ions were observed, indicating that π electrons play an important role in the detection of silver ions. In the presence of interfering metal ions, the selectivity for silver ions was affected by the number and density of π electrons in the ionophore. The electrode containing the allyl-type tripodal broom molecule was used to accurately determine the concentration of glucosamine hydrochloride in a real sample.

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Two procedures were proposed for the specific recovery of fluorescent derivatives of glycoprotein-derived oligosaccharides and tryptic glycopeptides using certain plant lectins. The first was based on the salting out of oligosaccharide-lectin conjugates with ammonium sulfate. Oligosaccharides specifically bound to lectins were recovered free from lectins using ethanol precipitation after dissolution in water. This method enabled group separation of 2-aminopyridine-labeled oligosaccharides derived from ovalbumin to galacto-oligosaccharides and agalacto-oligosaccharides by Ricinus communis agglutinin, and to high mannose- and hybrid-type oligosaccharides by wheat-germ agglutinin. Fractional precipitation based on differences in affinity for concanavalin A was accomplished by adding an appropriate concentration of methyl α-mannoside as an inhibitor. In the second method, tryptic digests of glycoproteins were mixed with a lectin solution, and the glycopeptide-lectin conjugates were specifically trapped on a centrifugal ultrafiltration membrane with cut-off of 10 kD. Trapped glycopeptides, as retentates, were passed through membranes by resuspension in diluted acid. This method is particularly useful for the enrichment of glycopeptides in protease digestion mixtures for glycosylation analyses by liquid chromatography–mass spectrometry.

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Horseradish peroxidase (HRP) and thionine (Th) were co-adsorbed onto a porous carbon-felt (CF) from a mixed solution of HRP and Th to fabricate a CF-based bioelectrocatalytic flow-detector for H₂O₂. The resulting HRP and Th co-adsorbed CF (HRP/Th-CF) was successfully used as a working electrode unit of a highly sensitive amperometric flow-H₂O₂-biosensor. Differing from the ordinary mediator-based HRP biosensors, which detect mediated currents (i.e., the reduction current of the oxidized form of the mediators), the present HRP/Th-CF-based H₂O₂-biosensor directly detects the reduction current of the oxidative HRP-intermediates (i.e., compound I and II) based on a direct electron transfer (DET) between a HRP-redox active heme center and the CF electrode, because co-adsorbed Th together with HRP facilitate the DET. Various adsorption conditions (i.e., HRP concentration, Th concentration, ionic strength, pH, adsorption time) were optimized to obtain excellent sensor performances. When an air-saturated 0.1 M phosphate buffer (pH 7.0) was used as a carrier at 3.25 ml/min and the applied potential of – 0.05 V vs. Ag/AgCl, the HRP/Th-CF-based flow-H₂O₂-biosensor exhibited excellent analytical performances (i.e., sensitivity, 3.55 μA/μM; linear range, 0.1 to 10 μM; lower detection limit, 0.03 μM; K_m^app, 36.2 μM; I_max, 158 μM; sample throughput, ca. 60 samples/h).

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Two amino acids, L-cysteine and tryptophan, could be simultaneously determined in an aqueous solution (pH 6.0) using a carbon nanotube paste electrode (CNPE) modified with p-aminophenol as a mediator. The results indicate that the electrode is efficient in terms of its electrocatalytic activity for the oxidation of L-cysteine, leading to an overpotential reduced by more than 550 mV. Using differential pulse voltammetry, we could measure L-cysteine and tryptophan in one mixture independently from each other by a potential difference of about 600 mV. Electrochemical techniques are used to determine the diffusion coefficients, kinetic parameters such as electron transfer coefficient, and the rates of electro-oxidation of L-cysteine at the surface of the p-aminophenol-modified CNPE. The peak current is found to depend linearly on L-cysteine and tryptophan concentrations within the ranges of 0.5 – 100 μmol L⁻¹ L-cysteine and 10.0 – 300 μmol L⁻¹ tryptophan. The detection limits for L-cysteine and tryptophan are found to be 0.3 and 5.7 μmol L⁻¹, respectively. The proposed method is also used for the determination of L-cysteine and tryptophan in urine, river water, blood plasma, and serum samples using standard addition methods.

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An amperometric horseradish peroxidase (HRP) biosensor based on multilayer films containing carbon nanotubes (CNTs) and HRP was developed. With the pH regulation of the dispersion solution of CNTs, the sensitivity of the HRP multilayer film biosensor is tunable by the control of the dissociation of CNTs. The successful formation of multilayers was confirmed by UV-visible spectroscopy. The features of multilayers were characterized by SEM and electrochemical impedance spectrum (EIS). The performance of the HRP biosensor is reported for the amperometric detection of phenols. The biosensor presented a linear response for catechol from 9.1 × 10⁻⁸ – 6.45 × 10⁻⁵ mol/L, with a sensitivity of 0.00554 A · L/mol and a detection limit of 8.5 × 10⁻⁸ mol/L. The study can provide a feasible simple approach for developing a new sensitivity tunable method for CNTs-based biosensors.

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Here, we proposed a simplified determination method for dioxin (polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls (PCBs)) toxic equivalency (TEQ; based on the World Health Organization-2006 toxicity equivalent factor) in environmental samples collected in Japan. This method has estimated the total TEQ from the concentrations of only five indicative congeners, namely, 2,3,4,7,8-pentachlorodibenzofuran; 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin; 1,2,3,7,8-pentachlorodibenzo-p-dioxin; and PCBs of IUPAC Nos. #126 and #105, which were obtained from a single GC/MS measurement using a combination of columns of 10-meter-long DB-5ms (injector side) and 20-meter-long DB-17ms (detector side). Applying this simplified determination method to various environmental samples (ambient air, river water, river sediment, and soil) showed that the estimated TEQ was in good agreement with TEQ obtained by the corresponding official methods. Moreover, this method could estimate the TEQ contributions of the four major dioxin sources in Japan: combustion by-products, pentachlorophenol formulations, chlornitrofen formulations and PCB products.

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A new non-aqueous capillary electrophoresis method is proposed for the separation and simultaneous determination of cimetidine, ranitidine, roxatidine, nizatidine and famotidine by using a 30-cm long × 75 μm i.d. fused silica capillary and UV detection at 214 nm. Using a temperature of 25°C, an applied voltage of 15 kV, and a background electrolyte consisting of methanol containing 10 mM ammonium acetate and 0.2% acetic acid allowed the analytes to be separated in less than 4 min. The limits of detection obtained ranged from 7 and 17 μg L⁻¹. The proposed method was successfully used to determine the analytes in pharmaceutical preparations and its results were checked against an HPLC method.

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An ultra-performance liquid chromatography/mass spectrometry method to simultaneously quantify vindoline, catharanthine, serpentine and ajmalicine in Catharanthus roseus cell line C20hi is reported. Samples were extracted with 1% acetic acid, basified to pH 10 with ammonia, then extracted with ethyl acetate, dried, reconstituted with methanol–1% acetic acid water solution (1:1, v/v) and analyzed using an acetonitrile–0.1% formic acid gradient as the mobile phase. Detection was carried out by electrospray ionization mass spectrometry in the positive-ion mode with selective ion monitoring. The analysis of one sample was achieved in 6 min. The limits of detection were 0.46 – 0.70 ng/ml in cell samples, and 0.10 – 0.16 ng/ml in medium samples. The linearity of detection was over the wide range of 1.00 – 6250.0 ng/ml. Intra- and inter-day accuracies (recovery 88.0 – 111.8%) and precision (RSD 1.25 – 7.81%) showed the performance of the assay. This method provides a more sensitive and high-throughput technique to quantify the four alkaloids in large amount of samples, and will be helpful in high-production cultivar screening.

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A method has been developed for speciation of total, total inorganic and organic arsenic (As) species in groundwater samples. The inorganic species of As^(III,V) were separated from organic forms by adsorbing on alumina (Al₂O₃) whereas the organic As was eluted out. The retained inorganic As species was eluted by 0.2 M HCl. Then eluent As^III and As^V were formed as complexes with ammonium pyrrolidinedithiocarbamate (APDC) and molybdate, respectively. Then As^III-PDC and As^V-molybdate complexes were quantitatively extracted into a non-ionic surfactant Triton X-114. The total As was determined by conventional preconcentration procedures. The resulting solutions of each method were determined by ETAAS with modifier. The main factors affecting the separation and cloud point extraction (CPE) were investigated in detail. The limits of detection values were found as 0.04 and 0.20 μg L⁻¹ for As^III and As^V, respectively, whereas limits of quantification were observed as 0.13 and 0.33 μg L⁻¹ for As^III and As^V, respectively. Standard addition method confirmed the accuracy. The recoveries of As^III and As^V were found in the range of 98 – 99%. The proposed method was applied to groundwater samples collected from different areas of Sukkur district.

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Sub-2 μm core-shell SiO₂/ZrO₂ composite microspheres with nonporous SiO₂ as the cores and ZrO₂ nanoparticles as the shells were synthesized by sol-gel method in the current work. The fabrication consisted of (1) preparing monodisperse silica spheres; (2) coating the spheres with zirconia nanoparticles in-situ; and (3) calcining the composite microspheres at 823 K. Then uniform, regular, and ordered arrays of nanometer-scale zirconia crystalline particles were formed and dispersed on the surfaces of nonporous silica microspheres. A potential deposition mechanism in the synthesis process was proposed according to isoelectric point theory and to observe microstructural characteristics. The result showed that this stationary phase also has an advantage in the separation of basic compounds in the normal phase.

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The composition dependence of the emission intensities was investigated in Cu-Ni as well as Ni-Zn binary alloy samples when a low-pressure argon laser-induced plasma was employed as the excitation source. The calibration curve in the Cu-Ni alloy system gave a linear relationship, implying that the selective evaporation of Cu or Ni atoms was caused less in those alloys having several chemical compositions. The Cu-Ni binary alloy has a solid solution phase all over the chemical compositions (all-proportional solid solution): Cu and Ni atoms form no intermetallic compounds but can occupy any positions of a face-centered cubic lattice without any particular interaction. This metallurgical structure would enable Cu and Ni atoms to be released from the sample surface individually, which means that the amount of ablation corresponds to the chemical composition of the alloy sample. For a comparison, a Ni-Zn binary alloy system was also investigated to find calibration curves yielding a nonlinear relationship, differing from those of the Cu-Ni alloy. The reason for this is that the Ni-Zn binary alloy has several metallurgical phases comprising different intermetallic compounds which would each vary the evaporation behavior of Zn. It should be paid attention in LIPS that the ablated composition after laser irradiation is sometimes different from the chemical composition, depending on the kinds of samples and their metallurgical structures.

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