Showing papers in "Analytical Sciences in 2014"
TL;DR: This review summarizes progress in the field of near-infrared (NIR) fluorophores achieved during the last decade from the viewpoint of chemistry, with particular focus on the recent developments of BODIPY and rhodamine derivatives.
Abstract: This review summarizes progress in the field of near-infrared (NIR) fluorophores achieved during the last decade from the viewpoint of chemistry. Those compounds are of wide interest in bioanalysis and bioimaging, such as in vivo fluorescence imaging. Particular focus is placed on the recent developments of BODIPY and rhodamine derivatives, which belong to the most evolved NIR fluorophores. The data compiled in this review, including the chemical structures and optical properties of all compounds introduced, provide readers of this article with an overview of the field of NIR fluorophores.
146 citations
TL;DR: The results showed that the proposed DPPH assay could be used as a standard method to evaluate the antioxidant capacity of food additives and the RSD(R)/RSD(r) values of TEAC were lower than, or nearly equal to, those of IC50 of the four antioxidants, suggesting that the use ofTEAC was effective for reducing the variance among the laboratories.
Abstract: An inter-laboratory evaluation study was conducted in order to evaluate the antioxidant capacity of food additives by using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Four antioxidants used as existing food additives (i.e., tea extract, grape seed extract, enju extract, and d-α-tocopherol) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) were used as analytical samples, and 14 laboratories participated in this study. The repeatability relative standard deviation (RSD(r)) of the IC50 of Trolox, four antioxidants, and the Trolox equivalent antioxidant capacity (TEAC) were 1.8-2.2%, 2.2-2.9%, and 2.1-2.5%, respectively. Thus, the proposed DPPH assay showed good performance within the same laboratory. The reproducibility relative standard deviation (RSD(R)) of IC50 of Trolox, four antioxidants, and TEAC were 4.0-7.9%, 6.0-11%, and 3.7-9.3%, respectively. The RSD(R)/RSD(r) values of TEAC were lower than, or nearly equal to, those of IC50 of the four antioxidants, suggesting that the use of TEAC was effective for reducing the variance among the laboratories. These results showed that the proposed DPPH assay could be used as a standard method to evaluate the antioxidant capacity of food additives.
119 citations
TL;DR: Liquid-liquid extraction of lanthanide ions using N,N-dioctyldiglycolamic acid (DODGAA) was comprehensively investigated, together with fluorescence spectroscopic characterization of the resulting extracted complexes in the organic phase, and revealed that the extracted Eu(3+) ions were completely dehydrated by complexation with DODGAA.
Abstract: Liquid-liquid extraction of lanthanide ions (Ln(3+)) using N,N-dioctyldiglycolamic acid (DODGAA) was comprehensively investigated, together with fluorescence spectroscopic characterization of the resulting extracted complexes in the organic phase. DODGAA enables the quantitative partitioning of all Ln(3+) ions from moderately acidic solutions, while showing selectivity for heavier lanthanides, and provides remarkably high extraction separation performance for Ln(3+) compared with typical carboxylic acid extractants. Furthermore, the mutual separation abilities of DODGAA for light lanthanides are higher than those of organophosphorus extractants. Slope analysis, loading tests, and electrospray ionization mass spectrometry measurements demonstrated that the transfer of Ln(3+) with DODGAA proceeded through a proton-exchange reaction, forming a 1:3 complex, Ln(DODGAA)3. The stripping of Ln(3+) from the extracting phase was successfully achieved under acidic conditions. Time-resolved laser-induced fluorescence spectroscopy revealed that the extracted Eu(3+) ions were completely dehydrated by complexation with DODGAA.
46 citations
TL;DR: It was observed that enantiomer elution orders of the three monosaccharides derivatization with L-Trp were reasonably reversed when derivatized with D-TrP, and it was revealed that borate anions were required for simultaneous enantioseparation with HPLC.
Abstract: Three reducing monosaccharides (glucose; Glc, galactose; Gal, and mannose; Man) were derivatized with L-tryptophan (L-Trp) under alkaline conditions. The DL-Gal and DL-Man derivatives were chirally resolved by HPLC with an acidic mobile phase, but the DL-Glc derivative was not. All of the three DL-monosaccharide derivatives were simultaneously enantioseparated using HPLC with a SunShell RP-AQUA column (C28) and a basic mobile phase. The optimum mobile phase conditions consisted of 5 mM phosphate and 25 mM tetraborate buffer (pH 9.6) at 20° C. With this system, resolution of D- and L-isomers of the Glc, Gal and Man derivatives were approximately 1.7, 2.2 and 2.4, respectively. When the three monosaccarides were derivatized with L-phenylalanine instead of L-Trp, DL-Gal and DL-Man were enantioseparated under both acidic and basic conditions, but DL-Glc was not. It was observed that enantiomer elution orders of the three monosaccharides derivatized with L-Trp were reasonably reversed when derivatized with D-Trp. It was also revealed that borate anions were required for simultaneous enantioseparation with HPLC.
32 citations
TL;DR: Rolling circle amplification catalyzed by φ29 DNA polymerase offers a simple method for DNA amplification in the presence of a circular DNA template and its complimentary primer, which could be a universal technology for biosensing in fields of medical- and food-related industries.
Abstract: Rolling circle amplification (RCA) catalyzed by φ29 DNA polymerase offers a simple method for DNA amplification in the presence of a circular DNA template and its complimentary primer. RCA continuously produces long single-strand DNA using the strand displacement activity of polymerase during DNA synthesis. This property allows one to monitor the progress of a reaction by means of electrophoresis or fluorescence measurements, and has eventually allowed the application of RCA to signal increments in the sensing of a variety of molecular species. Originally, RCA was successfully applied for the detection of specific DNA, such as single nucleotide polymorphisms. In addition, the conjugation of an antibody with a primer achieves efficient signal enhancement in antigen detection, and mRNA can also be specifically detected. Since RCA is a carry-over contamination-resistant, cost-effective, and user-friendly method of DNA amplification, RCA could be a universal technology for biosensing in fields of medical- and food-related industries.
29 citations
TL;DR: Changes in fluorescence intensity of CuNPs allowed for the analysis of Pb(2+) with rapidity (<10 min), simplicity (label-free), high sensitivity (LOD 0.4 nM), high selectivity (no interference from other metal ions) and at low-cost (without any labels and sophisticated operation).
Abstract: Polythymine (poly T)-templated copper nanoparticles (CuNPs) were demonstrated as novel and sensitive fluorescence probes for the detection of Pb(2+) based on the fluorescence quenching effect. The as-prepared CuNPs displayed strong fluorescence emission. However, the fluorescence of CuNPs was readily quenched in the presence of Pb(2+). These changes in fluorescence intensity of CuNPs allowed for the analysis of Pb(2+) with rapidity (<10 min), simplicity (label-free), high sensitivity (LOD 0.4 nM), high selectivity (no interference from other metal ions) and at low-cost (without any labels and sophisticated operation). We validated the practicality of using CuNPs for the determination of Pb(2+) in environmental samples through analyses of tap water samples.
29 citations
TL;DR: A new method for directly using unprocessed biological specimens as templates for the TaqMan assay, which could avoid hindering fluorescence detection, even if the templates were used directly.
Abstract: We have developed a new method for directly using unprocessed biological specimens as templates for the TaqMan assay. DNA extraction and purification had been believed to be required for the assay, but our new method could avoid hindering fluorescence detection, even if the templates were used directly. Saliva was needed to be put on water-soluble paper and dried, and hairs were cut to be about 10 mm long. This method could reduce both the time and effort involved, and also the risk of contamination. It should prove to be very valuable for genetic diagnoses in various fields.
29 citations
TL;DR: A new colorimetric method that is simple, rapid and cost effective for the determination of arsenic(III) in water samples is presented, based on changes in the absorbance of difluoroboron-curcumin (BF2-Curcumin), prepared by the reaction of borontrifluaride diethyletherate and curcumin.
Abstract: This work presents a new colorimetric method that is simple, rapid and cost effective for the determination of arsenic(III) in water samples. The method is based on changes in the absorbance of difluoroboron-curcumin (BF2-curcumin), prepared by the reaction of borontrifluoride diethyletherate ((C2H5)2OBF3) and curcumin. The BF2-curcumin was dissolved in 60% ethanol, which yielded an orange solution with the maximum absorbance at 509 nm. Upon the addition of arsenic(III), the color of the BF2-curcumin solution changed from orange to blue and the absorbance was measured by UV-visible spectrometry at 632 nm. The BF2-curcumin was applicable in both solution and coated resin. Under the optimal conditions, the detection limits achieved by means of UV-visible spectrometry, naked-eye detection with BF2-curcumin solution and naked-eye detection with BF2-curcumin-coated resin were found to be 0.26, 25 and 30 μM, respectively.
28 citations
TL;DR: A TRDP-based capillary chromatography, referred to as tube radial distribution chromatography (TRDC), where the outer phase serves as a pseudo-stationary phase under laminar flow conditions, has been developed as one of the applications of TRDP.
Abstract: The author herein reviews a specific microfluidic behavior exhibited by mixed-solvent solutions in a microspace, coined as the tube radial distribution phenomenon (TRDP). The specific fluidic behavior was observed in the following solution systems: ternary water-hydrophilic/hydrophobic organic solvents, water-surfactant, water-ionic liquid, and fluorous/organic solvents. When the mixed homogeneous solutions were delivered into a microspace under certain conditions, the solvent molecules were radially distributed in the microspace, generating inner and outer phases with a kinetic liquid-liquid interface. The TRDP was fundamentally evaluated by fluorescence microscopy, phase diagrams construction, and the elution behaviors of solutes in a capillary tube. A TRDP-based capillary chromatography, referred to as tube radial distribution chromatography (TRDC), where the outer phase serves as a pseudo-stationary phase under laminar flow conditions, has been developed as one of the applications of TRDP. We have also investigated TRDP-based extraction, chemical reaction, and mixing processes, coined as tube radial distribution extraction (TRDE), tube radial distribution reaction (TRDR), and tube radial distribution mixing (TRDM), respectively. The concept and experimental findings regarding TRDP, TRDC, TRDE, TRDR, and TRDM are described in this review.
27 citations
TL;DR: The technical aspects of the time-resolved ICP-MS measurement technique for elemental and multiparametric analysis of single cells, which can be achieved similar to that by a flow cytometer are highlighted.
Abstract: Time-resolved inductively coupled plasma mass spectrometry (ICP-MS) has attracted much attention for elemental and multiparametric analysis of single cells, instead of a classical bulk analysis of large amount of cells after a dissolution. In the time-resolved measurement, cells are directly introduced into the plasma via nebulizing or micro drop dispensing, and then ion plumes corresponding to single cells are individually detected with a high time resolution. The sensitivity and cell throughput in the measurement strongly depend on the time resolution. A high cell introduction efficiency into the plasma supports for a reduction of cell consumption. Biomolecules can also be measured through the attachment of elemental tags, and then the amount distribution of elements and biomolecules in single cells can be evaluated, while providing information concerning cell-to-cell variations. By applying ICP time-of-flight mass spectrometry (ICP-TOFMS), multiparametric analysis of elements and biomolecules can be achieved similar to that by a flow cytometer. This article highlights the technical aspects of the time-resolved ICP-MS measurement technique for elemental and multiparametric analysis of single cells.
27 citations
TL;DR: The performance and usefulness of the newly-developed imaging devices are demonstrated through their applications to pharmaceutical tablets and polymers, and a comparison among NIR, infrared (IR) and Raman imaging are made.
Abstract: The purpose of this review article is to outline the recent progress in near-infrared (NIR) imaging technology with particular emphasis on new instrumentation. Superior features of NIR imaging such as suitability for nondestructive and in-situ analysis, transmission ability, availability of optical fibers, high-speed monitoring and stability are very attractive not only for laboratory-based studies but also for diverse practical applications. In this review, introduction to chemical imaging is described, and then, a comparison among NIR, infrared (IR) and Raman imaging are made. Furthermore, the features of new NIR imaging instruments developed by our research group in collaboration with Yokogawa Electric Corporation and Sumitomo Electric Industries, Ltd. are discussed. Finally, some examples of applications of NIR imaging are introduced. Particularly, the performance and usefulness of the newly-developed imaging devices are demonstrated through their applications to pharmaceutical tablets and polymers.
TL;DR: It was found that the present synergism is ascribed to the formation of cationic ternary complexes, followed by ion exchange into the ionic liquid.
Abstract: Selective synergism for the extraction of lanthanoids(III) (Ln) with β-diketones such as 2-thenoyltrifluoroacetone, 2-naphthoyltrifluoroacetone, and benzoylacetone has been investigated in the presence of trioctylphosphine oxide as a hydrophobic neutral ligand in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as an ionic liquid. The extractability of heavier Ln was remarkably enhanced, resulting in a significant improvement in the separation of Ln. It was found that the present synergism is ascribed to the formation of cationic ternary complexes, followed by ion exchange into the ionic liquid.
TL;DR: An overview of a new method for rapid and sensitive microRNA detection from a small sample volume using a power-free microfluidic device driven by degassed poly-dimethylsiloxane (PDMS).
Abstract: Microfluidic devices are an attractive choice for meeting the requirements of point-of-care microRNA detection. A method using a microfluidic device can drastically shorten the incubation time because the device conveys sample molecules right straight to the surface-immobilized probe DNAs by hydrodynamic force. In this review, we present an overview of a new method for rapid and sensitive microRNA detection from a small sample volume using a power-free microfluidic device driven by degassed poly-dimethylsiloxane (PDMS). Two key technologies for this detection method are summarized. One of the methods relies on the coaxial stacking effect of nucleic acids during sandwich hybridization. This effect is also efficient for stabilizing sandwich hybridization consisting of small DNA and microRNA. The other is the laminar flow-assisted dendritic amplification, which increases the fluorescent signal by supplying two amplification reagents from laminar streams to surface-bound molecules. Utilizing both technologies, microRNA detection is possible with a 0.5 pM detection limit from a 0.5 μL sample corresponding to 0.25 attomoles, with a detection time of 20 min. Since microRNAs are associated with various human diseases, future studies of these technologies might contribute to improved healthcare and may have both industrial and societal impacts.
TL;DR: The recoveries and mass balances for all elements in all samples showed good agreements with the starting materials, and the sums of the concentrations of all species in the extract were 86-105% of the total As concentration in each case.
Abstract: The concentrations of 16 elements in 10 rice flour samples and the distribution of the elements in the rice grains from which the flour were made were determined by ICP-MS and ICP-OES after microwave-assisted digestion of the samples. Arsenic speciation analysis was carried out by HPLC-ICP-MS following heat-assisted extraction of the sample. The concentrations of inorganic As (As(III) and As(V)), monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) and their distribution in the rice grains were determined. Portions of the brown rice were polished/milled to different degrees to yield milled off samples and polished rice samples. All samples were powdered and analyzed for 16 elements and for As species. The recoveries and mass balances for all elements in all samples showed good agreements with the starting materials. As(III), As(V), MMAA and DMAA were detected, and the sums of the concentrations of all species in the extract were 86-105% of the total As concentration in each case.
TL;DR: Fundamental aspects of the needle-type extraction devices and its applications for the determination of trace organic compounds, especially volatile organic compounds (VOCs), in several sample matrices are described.
Abstract: A needle-type extraction device is one of the promising sample preparation devices for the gas chromatographic (GC) analysis of various organic compounds. The most remarkable advantage of this device is a simple and rapid desorption of the analytes by direct insertion of an extraction needle into a conventional GC injection port. In this review, fundamental aspects of the needle-type extraction devices and its applications for the determination of trace organic compounds, especially volatile organic compounds (VOCs), in several sample matrices are described.
TL;DR: This mini-review highlights some new aspects of related research efforts with a special focus on the interaction with sialic acid as a new class of molecular targets and other PBA-based strategies for drug delivery applications.
Abstract: Phenylboronic acid (PBA) derivatives are known to form reversible complexes with polyols, including sugars. This unique chemistry has provided many useful molecular bases for analytical and therapeutic applications. This mini-review highlights some new aspects of related research efforts with a special focus on the interaction with sialic acid as a new class of molecular targets and other PBA-based strategies for drug delivery applications.
TL;DR: A label-free fluorescent assay for the detection of trypsin by using oligonucleotide-templated silver nanoclusters (Ag NCs) and cytochrome c (Cyt c) has been demonstrated and possesses a high signal-to-background ratio, excellent selectivity and good biocompatibility, which makes it a promising bioanalysis for atrypsin activity assay.
Abstract: A label-free fluorescent assay for the detection of trypsin by using oligonucleotide-templated silver nanoclusters (Ag NCs) and cytochrome c (Cyt c) has been demonstrated. When negatively charged Ag NCs and positively charged Cyt c are mixed, they tend to form a hybrid complex, and then lead the fluorescence of Ag NCs to be quenched significantly due to electron transfer between Ag NCs and the heme cofactor of Cyt c. In the presence of trypsin, it catalyzes the hydrolytic cleavage of Cyt c to small peptide fragments, and releases the heme moiety from the Ag NCs/Cyt c complex; the quenched fluorescence restores therewith. By virtue of this specific response, the fluorescent biosensor has a linear range of from 0.7 to 4 μg mL(-1) and from 9 to 120 μg mL(-1) with a detection limit of 58.7 ng mL(-1). Aside from the easy manufacture aspect, our method also possesses a high signal-to-background ratio (~11), excellent selectivity and good biocompatibility, which makes it a promising bioanalysis for a trypsin activity assay.
TL;DR: The surface tension gradients in the front and rear sides of a 1-hexanol droplet exhibiting self-propelled motion were compared by a time-resolved quasi-elastic laser scattering method and indicated that the spontaneous alcohol droplet motion is governed by an imbalance in the Marangoni convection flow.
Abstract: The surface tension gradients in the front and rear sides of a 1-hexanol droplet exhibiting self-propelled motion were compared by a time-resolved quasi-elastic laser scattering method. The velocity of the alcohol droplet strongly correlated to the difference of the inverse of the recovery distances of the surface tensions between the front and rear sides. This result indicates that the spontaneous alcohol droplet motion is governed by an imbalance in the Marangoni convection flow, induced by an asymmetric surface tension distribution.
TL;DR: The proposed LFD shows great promise for in-field and point-of-care testing of disease-related circulating nucleic acid and protein biomarkers in biological fluids and could be used for the qualitative detections of DNA and/or protein.
Abstract: In this work, we present a simple and fast approach for simultaneous detection of nucleic acid and protein using gold nanoparticles (GNPs) and a lateral flow device (LFD). Sandwich-type immunoreactions and DNA hybridizations were performed simultaneously on the LFD by using DNA- and antibody-functionalized GNPs. The captured GNPs, due to the DNA hybridization and immunoreaction events on the LFD, produced characteristic red bands that could be used for the qualitative detections of DNA and/or protein. The proof of principle was demonstrated by using 60-mer DNA and rabbit IgG (R-IgG) model targets. The LFD was capable of detecting a minimum of 0.5 nM target DNA and 2 ng mL(-1) IgG simultaneously in 15 min. The proposed LFD shows great promise for in-field and point-of-care testing of disease-related circulating nucleic acid and protein biomarkers in biological fluids.
TL;DR: A cleanup method employing quick and simple solid-phase dispersive extraction (SPDE) was investigated for its potential use in the determination of vancomycin (VCM) in serum by liquid chromatography/mass-spectrometry (LC/MS), and SPDE was observed to be more rapid than conventional cartridge-type solid- phase extraction.
Abstract: A cleanup method employing quick and simple solid-phase dispersive extraction (SPDE) was investigated for its potential use in the determination of vancomycin (VCM) in serum by liquid chromatography/mass-spectrometry (LC/MS). SPDE was observed to be more rapid than conventional cartridge-type solid-phase extraction (SPE). In addition, in the analysis of viscous samples such as serum containing many proteins, SPDE could satisfactorily remove proteins even if deproteinization was not performed beforehand. The limit of detection (S/N = 3) and the limit of quantification (S/N > 10) of VCM by LC/MS were 0.05 and 0.2 ng/mL, respectively. The average recoveries of VCM from pooled serum spiked at 2, 10, and 100 ng/mL were 90.0, 90.8, and 98.6%, respectively. The repeatabilities were 7.5, 6.8, and 2.8%, and the intermediate precision values were 8.5, 6.8, and 7.0%, respectively. This suggests that the developed analytical method combing SPDE is useful for the determination of VCM in serum.
TL;DR: The proposed modification of the common flow procedure results in the total elimination of the problem of precipitate deposition inside the flow manifold and has been adapted to a flow analysis system based on microsolenoid pumps combined with a dedicated optoelectronic detector fabricated specifically for this purpose.
Abstract: This paper presents a simple, rapid and effective method for ammonia determination in a flow analysis regime using Nessler's reagent. The proposed modification of the common flow procedure results in the total elimination of the problem of precipitate deposition inside the flow manifold. The improved procedure has been adapted to a flow analysis system based on microsolenoid pumps combined with a dedicated optoelectronic detector fabricated specifically for this purpose. This photometric device has been constructed in the form of a compact flow-through cell (70 μL total volume and 1 cm optical pathlength) integrated with 395 nm LED emitter and 405 nm LED-based detector. The presented analytical system is capable of ammonia determination in the submillimolar concentration range with a detection limit below 0.1 mM and high throughput (over 20 injections per hour).
TL;DR: Ratiometric pH sensing was achieved in an aqueous environment by a fluorescent CdSe/ZnS QD appended with a pH-sensitive organic dye, based on fluorescence resonance energy transfer (FRET), and it was found that a purification process is important for increasing the high-fluorescence intensity ratio of a ratiometric fluorescence pH-sensor.
Abstract: Dual pH-dependent fluorescence peaks from a semiconductor quantum dot (QD) and a pH-dependent fluorescent dye can be measured by irradiating with a single wavelength light, and the pH can be estimated from the ratio of the fluorescent intensity of the two peaks. In this work, ratiometric pH sensing was achieved in an aqueous environment by a fluorescent CdSe/ZnS QD appended with a pH-sensitive organic dye, based on fluorescence resonance energy transfer (FRET). By functionalizing the CdSe/ZnS QD with 5-(and 6)-carboxynaphthofluorescein succinimidyl ester as a pH-dependent fluorescent dye, we succeeded in fabricating sensitive nanocomplexes with a linear response to a broad range of physiological pH levels (7.5-9.5) when excited at 450 nm. We found that a purification process is important for increasing the high-fluorescence intensity ratio of a ratiometric fluorescence pH-sensor, and the fluorescence intensity ratio was improved up to 1.0 at pH 8.0 after the purification process to remove unreacted CdSe/ZnS QDs even though the fluorescence of the dye could not be observed without the purification process. The fluorescence intensity ratio corresponds to the fluorescence intensity of the dye, and this fluorescent dye exhibited pH-dependent fluorescence intensity changes. These facts indicate that the fluorescence intensity ratio linearly increased with increasing pH value of the buffer solution containing the QD and the dye. The FRET efficiencies changed from 0.3 (pH 7.5) to 6.2 (pH 9.5).
TL;DR: New analytical methods for studying biopolymer ε-poly-L-lysine (εPL) and Electrochemical studies showed new applications of εPL as an enzyme stabilizer and a reaction enhancer.
Abstract: This article describes new analytical methods for studying biopolymer e-poly-L-lysine (ePL). The produced amount of ePL in culture broth can be determined based on the precipitation of polycationic ePL with a colored heteropolymolybdate anion and the color change of the supernatant. The product can be separated and purified by precipitation with the tetraphenylborate anion and reprecipitation in the form of the hydrochloride salt. These methods have been applied advantageously to the screening of ePL-synthetase. Also, pyrophosphate can be determined colorimetrically based on the formation of 18-molybdopyrophosphate species. The pyrophosphate determination has been successfully applied to the assay of adenylation enzyme, which plays important roles in the biosynthetic mechanism. Under certain conditions, ePL associates with a redox enzyme, glucose oxidase. The effect of the adduction on the stability and reaction rate of the enzyme can be evaluated by measuring the bioelectrocatalytic current, which is related to the enzyme activity. Electrochemical studies showed new applications of ePL as an enzyme stabilizer and a reaction enhancer.
TL;DR: The first stability-indicating HPLC method was developed and validated for azelastine HCl and was applied for the quality control and stability assessment of AZL in eye drops and nasal spray.
Abstract: The first stability-indicating HPLC method was developed and validated for azelastine HCl (AZL). The separation of AZL from its degradation products was achieved on a C18 column using acetonitrile-0.04 M phosphate buffer of pH 3.5 (32:68, v/v) as a mobile phase with UV-detection at 210 nm and naftazone as an internal standard. The method was rectilinear over the range of 0.2-20.0 μg mL(-1) with a detection limit of 7.05 ng mL(-1). The degradation behavior of AZL was studied under different ICH-recommended stress conditions along with a kinetic investigation; also, degradation products were identified by mass spectrometry. The method was applied for the quality control and stability assessment of AZL in eye drops and nasal spray. The obtained results were favorably compared with those obtained by a comparison method.
TL;DR: Effective analytical methods for the quantification of bisphenol A (BPA), alkylphenols (APs), phthalate esters (PEs), and perfluoronated chemicals (PFCs), which are chemicals used in the production of everyday commodities are focused on.
Abstract: Our modern society has created a large number of chemicals that are used for the production of everyday commodities including toys, food packaging, cosmetic products, and building materials. We enjoy a comfortable and convenient lifestyle with access to these items. In addition, in specialized areas, such as experimental science and various medical fields, laboratory equipment and devices that are manufactured using a wide range of chemical substances are also extensively employed. The association between human exposure to trace hazardous chemicals and an increased incidence of endocrine disease has been recognized. However, the evaluation of human exposure to such endocrine disrupting chemicals is therefore imperative, and the determination of exposure levels requires the analysis of human biological materials, such as blood and urine. To obtain as much information as possible from limited sample sizes, highly sensitive and reliable analytical methods are also required for exposure assessments. The present review focuses on effective analytical methods for the quantification of bisphenol A (BPA), alkylphenols (APs), phthalate esters (PEs), and perfluoronated chemicals (PFCs), which are chemicals used in the production of everyday commodities. Using data obtained from liquid chromatography/mass spectrometry (LC/MS) and LC/MS/MS analyses, assessments of the risks to humans were also presented based on the estimated levels of exposure to PFCs.
TL;DR: A fluorescence sulfide sensor was developed that responded linearly to sulfide in the range of 50 nM to 8 μM, and was capable of detecting sulfide as low as 5.5 nM, which provided a facile and sensitive scheme for sulfide analysis.
Abstract: In this work, we synthesized a trypsin-stabilized fluorescent gold nanocluster. It was found that sulfide interacted with the nanocluster, which could result in significant fluorescence quenching. With this quenching effect, a fluorescence sulfide sensor was developed. This sensor responded linearly to sulfide in the range of 50 nM to 8 μM, and was capable of detecting sulfide as low as 5.5 nM. This provided a facile and sensitive scheme for sulfide analysis; the mechanism of the sensor was also provided. The sensor was then tested for real sample analysis, and good recoveries were obtained. Furthermore, persulfate was found to be effective to remove the quenching of sulfide, and this interaction was adopted for an indirect analysis of persulfate.
TL;DR: The DOSY-qNMR method was successfully applied to quantify D-(+)-glucose in orange juice, apple juice, grape juice and grape juice, and the values agreed well with a conventional F-kit glucose method.
Abstract: This study works on D-(+)-glucose quantitative analysis using diffusion ordered-quantitative 1 H nuclear magnetic resonance spectroscopy (DOSY-qNMR), by which an analyte could be distinguished from interferences based upon a characteristic diffusion coefficient (D) in gradient magnetic fields. The D value of D-(+)-glucose in deuterium oxide at 30° C was 5.6 × 10 –10 m 2 /s at a field gradient pulse of between 5.0 × 10 –2 and 3.0 × 10 –1 T/m, distinguished from fructose, sucrose and starch. Good linearity (r 2 = 0.9998) was obtained between D-(+)-glucose (0.5 – 20.0 g/L) and the ratio of the resonance area of α-C1 proton (5.21 ppm) in D-(+)-glucose to that of the β-C1 proton (5.25 ppm) in D-glucuronic acid (50.0 g/L) as an internal standard. The DOSY-qNMR method was successfully applied to quantify D-(+)-glucose in orange juice (18.3 ± 1.0 g/L), apple juice (26.3 ± 0.4 g/L) and grape juice (45.6 ± 0.6 g/L); the values agreed well with a conventional F-kit glucose method.
TL;DR: This review describes the development of molecularly imprinted materials for selective separation and/or concentration of environmental pollutants, the quantitative concentration of which is usually difficult to determine because of their low level of concentration and existence of a large number of contaminants in environmental water.
Abstract: This review describes the development of molecularly imprinted materials for selective separation and/or concentration of environmental pollutants, the quantitative concentration of which is usually difficult to determine because of their low level of concentration and existence of a large number of contaminants in environmental water. The fragment imprinting technique allowed for the selective separation of endocrine disrupters and halogenated aromatic compounds, including bisphenol A, and chlorinated/brominated aromatic compounds by the specific structural recognition based on the breeds, position, and number of the substituents. Also, the interval immobilization technique provided the specific materials enabling selective concentration based on the interval recognition of ionic functional groups in the targeting compounds, so that the effective determinations were achieved for natural toxins and pharmaceuticals in environmental water. Additionally, a selective photodegradation of toxins and a stimulus responsible hydrogel by the similar molecular recognition ability were successfully carried out. We have summarized these techniques including our recent studies.
TL;DR: The result of the IMA level measurement in normal versus stroke rat serum suggests that the ACuB assay is likely to be a reliable and sensitive method for the detection of ischemic states.
Abstract: Myocardial ischemia (MI) induces many changes in the body, including pH decrease and electrolyte imbalance. No obvious symptoms of MI appear until irreversible cellular injuries occur. Since early treatment is critical for recovery from ischemia, the development of reliable diagnostic tool is demanded to detect the early ischemic status. Ischemia modified albumin (IMA), formed by cleavage of the last two amino acids of the human serum albumin (HSA) N-terminus, has been considered so far as the most trustworthy and accurate marker for the investigation of ischemia. IMA levels are elevated in plasma within a few minutes of ischemic onset, and may last for up to 6 h. In the present study, we developed a novel assay for the examination of IMA levels to ameliorate the known albumin cobalt binding (ACB) test established previously. We observed a stronger copper ion bound to the HSA N-terminal peptide than cobalt ion by HPLC and ESI-TOF mass spectrometric analyses. The copper ion was employed with lucifer yellow (LY), a copper-specific reagent to develop a new albumin copper binding (ACuB) assay. The parameters capable of affecting the assay results were optimized, and the finally-optimized ACuB assay was validated. The result of the IMA level measurement in normal versus stroke rat serum suggests that the ACuB assay is likely to be a reliable and sensitive method for the detection of ischemic states.
TL;DR: An overview of sensing using molecularly bridged gold nanoparticles (AuNPs) with nanometer-sized space is provided and it is possible to evaluate electron tunneling or electron transfer in an AuNP-molecule-AuNP junction by directly measuring the electrical resistivity of the two-dimensional network.
Abstract: The fabrication of electronic devices using individual molecules necessitates an adept control of the placement of molecules and tuning the space between them. This paper provides an overview of sensing using molecularly bridged gold nanoparticles (AuNPs) with nanometer-sized space. We have attempted to form a nanometer-sized space in a two-dimensional network consisting of a repeated sequence of an AuNP-molecule-AuNP junction. It is possible to evaluate electron tunneling or electron transfer in an AuNP-molecule-AuNP junction by directly measuring the electrical resistivity of the two-dimensional network. The resistivity of the two-dimensional sequence, in turn, depends on the size and conducting states of the molecules in each junction. The molecular junction in such nanometer-sized structures can be moved and rearranged to any location, enabling the rapid development of miniaturized compact electronic devices.