A simple method was created and implemented through the technology of ink-jet printing to study the effects of three chemical factors (chemical reagents) to the ninhydrin reaction. The effects of each single reagent and their interactions on the reaction were studied in one experiment. The three reagents all have effects on ninhydrin reaction, and the effects under the different combinations of reagents were presented on a chip. This work was completed efficiently with a smaller experimental workload compared with the traditional method.

抄録全体を表示

The electrocatalytic activity of an N,N-diethylaniline-grafted carbon (DEA/PFC) electrode was utilized to improve the sensitivity in the cathodic detection of free chlorine. Voltammetric curves showed a well-defined cathodic peak of free chlorine on DEA/PFC, lowering the overlap with that of dissolved oxygen. Amperometric measurements were applied for the determination of free chlorine for a concentration range of 4 orders of magnitude. The results showed that measurements of the amperometric response with DEA/PFC can be used as the basis for a simple, accurate, and rapid method to determine free chlorine.

抄録全体を表示

In the present work, a simple and sensitive turn-on fluorescence method for DNA detection was developed. It was explored based on the N-methyl mesoporphyrin IX (NMM)/G-quadruplex DNA system as a reporter and exonuclease III (Exo III)-aided target recycling amplification to ensure sensitivity. Our method showed an ultra-wide detection range from 10 fM to 100 nM with a low linear detection limit of 0.76 nM. It also had excellent selectivity in a selectivity experiment.

抄録全体を表示

Biological specimens such as cells, tissues and biofluids (urine, blood) contain mixtures of many different biomolecules, all of which contribute to a Raman spectrum at any given point. The separation and identification of pure biochemical components remains one of the biggest challenges in Raman spectroscopy. Multivariate curve resolution, a matrix factorization method, is a powerful, yet flexible, method that can be used with constraints, such as non-negativity, to decompose a complex spectroscopic data matrix into a small number of physically meaningful pure spectral components along with their relative abundances. This paper reviews recent applications of multivariate curve resolution by alternating least squares analysis to Raman spectroscopic and imaging data obtained either in vivo or in vitro from biological and medical samples.

抄録全体を表示

In this paper, we demonstrate a new promising resonance Raman (RR)-based method for the determination of Fe³⁺ concentrations in aqueous solutions. Iron ions were quantified at a low concentration range by employing hydroxylamine hydrochloride as the reductant, and phenanthroline as the complexing agent, thereby reducing Fe³⁺ to Fe²⁺. The addition of Fe³⁺ to the detection reagent resulted in a rapid color change from colorless to orange-red, together with an obvious new RR band appearing at 1459 cm⁻¹. Herein, the RR intensity of the phenanthroline-Fe²⁺ complex strengthened with increasing Fe³⁺ concentration, which was identified from the variation of the Raman spectra. Therefore, we successfully detected Fe³⁺ at lower concentrations using the proposed method, illustrating its great potential for the detection of Fe³⁺ with abundant RR fingerprint information. More importantly, the proposed method exhibited a wide liner range from 0.05 to 10 μg/mL.

抄録全体を表示

In the present work, a practical method that combines excitation-emission matrix fluorescence with a second-order calibration method based on an alternating trilinear decomposition (ATLD) algorithm was developed in order to simultaneously and directly determine the contents of warfarin (WAR) and aspirin (ASA) in human plasma and urine samples, even in the presence of unknown interferences. With the pre-estimated component number of 4, the obtained average spiked recoveries were 105.4 ± 7.8 and 104.2 ± 8.3% for WAR, 96.5 ± 2.8 and 91.2 ± 2.3% for ASA in human plasma and urine samples, respectively. Furthermore, the figures of merit were calculated and also inter- and intra-day experiments were performed that proved the proposed method is of great significance to the monitoring of clinical administration and also being a simple sample pretreatment at low-cost.

抄録全体を表示

Two sulfonated polyimide (SPI) thin films were prepared with water and THF/water mixed solvents, respectively. The SPI thin film prepared with THF/water showed more than 5 times higher proton conductivity than that prepared with water mixed solvent at low relative humidity (RH) and 298 K. In this study, polarized optical microscopy (POM), grazing incidence small angle X-ray scattering (GISAXS), and p-polarized multiple angle incidence resolution spectrometry (pMAIRS) were carried out to investigate liquid crystalline (LC) optical ordered structure, organized structure, and molecular orientation. The molecular ordered parts using LC properties in the SPI thin films exhibited an almost identical structure under the low RH condition. On the other hand, the molecular orientation of the imide C=O groups in the non-ordered parts, which could not be detected by POM and GISAXS, showed different angles. The proton conductivity under low RH conditions is affected by the degree of the molecular orientation in the non-ordered parts of the SPI thin films.

抄録全体を表示

Resonant acoustic^® mixing (RAM) technology is a system that performs high-speed mixing by vibration through the control of acceleration and frequency. In recent years, real-time process monitoring and prediction has become of increasing interest, and process analytical technology (PAT) systems will be increasingly introduced into actual manufacturing processes. This study examined the application of PAT with the combination of RAM, near-infrared spectroscopy, and chemometric technology as a set of PAT tools for introduction into actual pharmaceutical powder blending processes. Content uniformity was based on a robust partial least squares regression (PLSR) model constructed to manage the RAM configuration parameters and the changing concentration of the components. As a result, real-time monitoring may be possible and could be successfully demonstrated for in-line real-time prediction of active pharmaceutical ingredients and other additives using chemometric technology. This system is expected to be applicable to the RAM method for the risk management of quality.

抄録全体を表示

The Raman spectroscopy of pharmaceutical cocrystals based on caffeine and oxalic acid in nanosized pores of mesoporous silica has been demonstrated at various molar amounts. The Raman peak shifts of caffeine molecules express the existence of pharmaceutical cocrystals in mesoporous silica. The molar amount dependence of the peak shifts describes that caffeine and oxalic acid cocrystallized on the surface of the nanosized pores and piled up layer by layer. This is the first report that shows the Raman spectroscopy is a powerful tool to observe the synthesis of pharmaceutical cocrystals incorporated in the nanosized pores of mesoporous silica. The results indicate a way to control the size of cocrystals on a nanometer scale, which will provide higher bioavailability of pharmaceuticals.

抄録全体を表示

In the present study, we propose a simple and sensitive method for the determination of total amino acids without any separation steps. The procedure described here is based on the ninhydrin derivatization reaction with amino acids, followed by surface-enhanced Raman scattering (SERS) measurements of the producing mixtures. A good linear correlation of excess ninhydrin SERS signals and the log values of the total amino acids concentrations is obtained; the detection limit of the method is 4.3 × 10⁻⁹ mol L⁻¹. The derivatization reaction is reliable and the whole experimental procedure is very simple. The sensitivity of the proposed protocol allows quantitative analysis of total amino acids at picomole levels without any separation procedures. On the basis of the conventional ninhydrin reaction, we put forward a simple SERS method for determining the total amino acids concentrations with high sensitivity, which is a promising way for routine detection.

抄録全体を表示

Voltage-induced infrared spectra of annealed spin-cast thin films of ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) (molar ratio, 3:1) were measured in a stepwise cyclic external electric field. Most of the observed infrared bands originated from the β ferroelectric crystalline phase. The voltage-induced spectral changes were decomposed into zeroth- (original), first-, and second-derivative spectra, and were attributed to the rotational motions of the polymer chains and the vibrational Stark effect. The values of the original spectral absorbance change ratios, ΔA/A, for the 849-cm⁻¹ band (CF₂ symmetric stretching, a₁) and the 884-cm⁻¹ band (CH₂ rocking, b₂) of the film exhibited double minimum and maximum peak hysteresis loops, respectively. The intensity of each band increased or decreased suddenly near a coercive field of ±0.6 MV/cm. These sudden intensity changes were attributed to the rotational inversion of the polymer chains that are associated with ferroelectricity.

抄録全体を表示

Here, we report on near-infrared and ATR/FT-IR spectroscopic measurements of magnesium stearate and potato starch powder blends. In the pharmaceutical and food industries, magnesium stearate is commonly used as a supplement in powder blends or granules for the purpose of lubrication and to minimize aggregation and adherence. However, excessive blending of magnesium stearate (MgSt) may lead to unwanted effects, and more particularly during the manufacturing of products. Upon blending, the IR bands due to both CH symmetric and anti-symmetric stretching modes decreased and displayed a frequency shift to higher wavenumber as the blending duration increased. The NIR and the auto-correlation spectra were collected during the duration of blending in real-time. The auto-correlation spectra indicated the disaggregation of starch particles and a following effect of excessive blending. We suggest that the disaggregation of starch and the following process can be monitored by NIR and the auto-correlation spectra.

抄録全体を表示

The development of a stimulated Raman scattering (SRS) microscope with a wavefront modulation unit is presented. In the apparatus, two beams for introducing the SRS process were focused into the sample with an objective lens. In the pathway of the Stokes beam, which is one of the two incident beams, a spatial light modulator (SLM) was located. Using the SLM, the wavefront of the Stokes beam was modulated to make the shape of the focal point a concentric circular pattern. By this spot shaping technique, the area where the SRS signal generates is restricted. The instrument response function (IRF) of the SRS microscope was examined by measuring the SRS intensity while scanning the sample position. From the result, the width of the IRF was reduced by about 15% by the wavefront modulation. It is suggested that the introduction of SLM is a way to improve the IRF of vibrational spectroscopic microscopes.

抄録全体を表示

The temperature thawing, as called tempering, of triacylglycerols (TAGs) is an important processing method in food productions, such as chocolates, cream, confections, and spreads. Especially, melt-mediation by temperature thawing is famous in chocolate production for controlling the polymorphic crystalline forms and accelerating crystallization. In the present study, we investigated the α-melt structure of 1,3-dipalmitoyl-2-oleoyl-sn-glycerol (POP), one of the major continuants of cacao butter, under a phase transition from its melt to γ-crystal with in-situ attenuated total reflection-infrared (ATR-IR) spectroscopy. The differential IR spectrum between α-melt via temperature thawing (α-melt mediation) and melt via simple cooling revealed that crystal-like local ordered structures remained in part in the α-melt, and that they acted as nuclei for a rapid phase transition to the γ-crystal. The changes to the γ-crystal occur in the local ordered structures at first from the glycerol moiety to the acyl chains in the crystallization, providing an important suggestion concerning the mechanism for the acceleration of crystallization to the γ-form via α-melt mediation.

抄録全体を表示

The secondary structure of full-length Aβ(1–40) and Aβ(1–42) peptides in films has been investigated with IR and vibrational circular dichroism (VCD) spectroscopy. From IR spectra, it is shown that the prepared films of Aβ(1–40) and Aβ(1–42) mainly comprise the β-sheet conformation that is characteristic of aggregated and fibrous Aβ. In the VCD spectra, the Aβ(1–42) film shows an intense and sharp band with left-handed optical activity at around 1625 cm⁻¹, while the Aβ(1–40) film shows a weak and broad band with right-handed activity at around 1630 cm⁻¹. The wavenumbers are characteristic of the β-sheet conformation. It has been clarified that the aggregated Aβ(1–42) adopts the β-sheet conformation with reverse optical activity compared with the aggregated Aβ(1–40). The left-handed optically active β-sheet of the aggregated Aβ(1–42) may contribute to the formation of protofibrils, which are a cause for the higher neurotoxicity of Aβ(1–42) fibrils than Aβ(1–40) fibrils.

抄録全体を表示

Tretinoin is known to be a pharmaceutical drug for treating acne vulgaris, keratosis pilaris, and acute promyelocytic leukemia. In order to reveal the possible conformers of tretinoin, the energies of all the conformers through rotational bonds have been evaluated by systematic rotor search analysis. The intramolecular interactions ranging from strong hydrogen bonds to weak van der Waals forces present in tretinoin have been distinguished with the help of electron density mapping and wavefunction analysis. The global reactivity descriptors and Fukui functions of tretinoin have been calculated and discussed. The sites suitable for electrophilic attack and nucleophilic attack have been identified with the help of Hirshfeld partitioning. The vibrational spectroscopic signature of tretinoin and mixed mode band assignments have been elucidated with the help of experimental and simulated spectra.

抄録全体を表示

In this research, a sensitive and selective method for detecting one of the most toxic insecticides, “carbofuran”, in rice and soybean is presented. This method is based on the coupling reaction of diazonium ion combined with a surface-enhanced Raman scattering technique. Diazonium ion produced from p-aminothiophenol reacts specifically with carbofuran phenol from the hydrolysis of carbofuran. The generated azo compounds attach to the surface of silver nanoparticles via the Ag–S bond. Therefore, a strong Raman intensity can be obtained. The concentration of carbofuran can be determined by following the intensity of the peak at 1201 cm⁻¹, attributed to the C–N stretching vibration of the azo compound. The result shows a good linear correlation (R² = 0.9786) against carbofuran concentrations (0.1 – 5 ppm) with a detection limit of 0.452 ppm. Our proposed protocol is insignificantly influenced by various common interferences. Moreover, this method has been successfully validated to determine carbofuran concentrations in rice and soybean with detection limits of 0.446 and 0.520 ppm, respectively.

抄録全体を表示

The characterization of fractures is of vital importance for studies in many industries. In the present work, we used terahertz reflection measurements to identify simulated gaps of different widths that resemble fractures. The time interval between pulses (Δt) was proportional to the distance between the interfaces. In addition, fast Fourier transform (FFT) corresponding to the waveforms was also employed to distinguish the gaps. The widths in frequency were found to be inversely proportional to that of the gaps. In general, both terahertz time-domain spectroscopy (THz-TDS) and terahertz frequency-domain spectroscopy (THz-FDS) can achieve the measurement of the gaps of micro size.

抄録全体を表示

In the present work, structural and spectroscopic investigations were carried out on a borreverine derivative. Borreverine is a class of alkaloid as well a natural antimalarial drug extracted from Borreria verticillata. With the aim of finding possible conformers, a detailed conformational analysis of a borreverine derivative was conducted utilizing density functional theory employing the B3LYP/6-31G(d,p) method. The crystallographic geometry was used for full geometry optimization, followed by a conformational analysis. The conformational investigation predicted the most stable conformer (conformer I), which was further compared with the initial crystallographic geometry (conformer V). The geometry optimization, vibrational frequency, and intensity of these two conformers (I and V) were calculated in the ground state using density functional theory with the B3LYP functional and 6-31G(d,p) basis set. The spectroscopic investigation was conducted using Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) techniques. Tentative vibrational assignments of some selective modes were presented utilizing the observed FT-IR, FT-Raman, and calculated spectra. The scaled and observed wavenumbers were found to be in good agreement. The molecular electrostatic potential was computed and plotted so as to elucidate the reactive sites of the molecule. Natural bond orbital studies were performed to investigate the intramolecular charge transfer that results in molecular stability.

抄録全体を表示

In this study, the feasibility of using copper oxide (CuO) as an interface for the coupling of liquid chromatography (LC) and Fourier-transform infrared (FTIR) spectroscopy was investigated. CuO exhibits low absorption in the 4000 to 1000 cm⁻¹ FTIR spectral region. In addition, LC-FTIR using CuO as the interface was extended to the analysis of sample mixtures containing benzamide and dioctyl sebacate; both analytes were successfully separated. After complete removal of the mobile phase, benzamide and dioctyl sebacate were successfully identified from the FTIR spectrum. Surprisingly, the interference from adsorbed water or conventionally used LC solvents in the FTIR spectrum was completely eliminated by using CuO particles as the interface in the off-line hyphenation of LC-FTIR. Based on these results, CuO demonstrates potential as an ideal interface for LC-FTIR analysis.

抄録全体を表示

In this research, near-infrared (NIR) spectroscopy in combination with moving window partial least squares-discrimination analysis (MWPLS-DA) was utilized to discriminate the variety of turmeric based on DNA markers, which correlated to the quantity of curcuminoid. Curcuminoid was used as a marker compound in variety identification due to the most pharmacological properties of turmeric possessed from it. MWPLS-DA optimized informative NIR spectral regions for the fitting and prediction to {–1/1}-coded turmeric varieties, indicating variables in the development of latent variables in discrimination analysis. Consequently, MWPLS-DA benefited in the selection of combined informative NIR spectral regions of 1100 – 1260, 1300 – 1500 and 1880 – 2500 nm for classification modeling of turmeric variety with 148 calibration samples, and yielded the results better than that obtained from a partial least squares-discrimination analysis (PLS-DA) model built by using the whole NIR spectral region. An effective and rapid strategy of using NIR in combination with MWPLS-DA provided the best variety identification results of 100% in both specificity and total accuracy for 48 test samples.

抄録全体を表示

Infrared p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) is a promising analytical tool for revealing the molecular orientation quantitatively of each chemical group in a thin film even with surface roughness. The spectra are often disturbed by noise and fringe, however, due to the multiple reflections in the substrate and the film, which makes the quantitative analysis very difficult. Therefore, improvement of the signal to noise (SN) ratio of the spectra is expected. Principal component analysis (PCA), in the present study, is first applied to the noise reduction for pMAIRS spectra of a poly(3-hexylthiophene) spin-coated thin film by employing the spin-speed as the experimental parameter. As a result, high quality pMAIRS spectra are readily obtained, with which highly reliable quantitative discussion is made.

抄録全体を表示

The molecular structural analysis of capture thread, including its viscid droplets of oriental golden orb-web spider Nephila clavata, has been performed by microscopic FT-IR spectroscopy. The obtained spectra of capture threads with and without viscid droplets indicate that the features in the region of 1400 – 1000 cm⁻¹ will be useful as marker bands for the degree of the dissolving of viscid droplet; further, the bands at 1395 and 1335 cm⁻¹ are attributable to the components of anchoring granules located at the inner side of viscid droplets. By recrystallization and its infrared measurements, the main chemical component of viscid droplets is assignable to glycosylated proline. It has also been demonstrated that the components of the anchoring granule of a viscid droplet are decomposed by UV irradiation, and that the molecular conformation of silk fiber protein of a capture thread is denatured at over 60°C, whereas the viscid droplets on a capture thread retain their structure.

抄録全体を表示