Fluorescence derivatization of the oligosaccharides released from glycoconjugates is widely used for precise structural characterization. To ensure labeling of the oligosaccharides, a large excess of fluorescence reagents is usually added to the reaction tube. Therefore, any excess reagents and by-products of the labeling reaction should be removed by several column chromatographies, including using a cellulose cartridge or spin columns. However, these purification steps are often time-consuming, expensive, and laborious. In this study, we found that 1,2-dichloroethane extraction could effectively and easily purify pyridylaminated oligosaccharides with a high recovery rate.

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The present article reports the application of hexamethylsilazane (HMDS) modified filter paper for ultrasensitive detection of Hg²⁺, Co²⁺ and Zn²⁺. By chemical vapor deposition of HMDS, a highly hydrophilic filter paper was fabricated to a low wetting (hydrophobic) substrate. The water contact angle (θ) of modified paper was ∼128°, whereas scanning electron and atomic force microscopy confirmed the surface modification. Using chromogenic reagents, a one-step assay for aforementioned ions was demonstrated onto pristine as well as hydrophobic paper. The assay was completed in less than 10 min and the end-result was in form of a color change that could be easily read by the naked eye. The limit of detection on modified paper was 0.5 ppb, which was 5-order of magnitude superior to that observed on pristine paper. The proposed method was successfully applied for semi-quantitative determination of Hg²⁺ ions in real wastewater samples.

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An ultra-high-performance liquid chromatograph–triple quadrupole mass spectrometry has been established and validated for the simultaneous quantification of 15 bile acids in four traditional animal medicines and their preparations. The separations of bile acids were performed on an Agilent ZORBAX Eclipse XDB-C18 column (50 × 2.1 mm; 1.8 μm) with methanol–0.1% formic acid as the mobile phase. Glycyrrhetinic acid was added as internal standard owing to its similar physiochemical properties with the bile acids. Using this condition, detected in the multiple reaction monitoring mode, the 15 bile acids, including three groups of isomers, were well quantified individually. Method validation showed that the linear regression relationship (r², 0.9993 – 0.9999), precisions (intra-day RSD, 0.96 – 4.31%; inter-day, 1.73 – 4.43%), and recovery (95.3 – 120.9%) were all satisfactory. The analysis results showed that bear bile and bezoar (Niu Huang) as well as their formulations contained large amounts of most of the 15 bile acids. In addition, this research revealed for the first time the presences of bile acids in animal waste medication used in traditional medicine from two clinics, Hei-Bing-Pian (discharges of wild boar) and Trogopterus Dung. The established method could be used for the quantification of other bile- or animal waste-based crude drugs and their formulated products.

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An electrochemical detection system for an isothermal DNA amplification method using an ion-selective electrode (ISE) was developed as a low-cost, simple and real-time monitoring system. The system is based on potentiometry using an ethidium ion (Et⁺) selective electrode that relies on monitoring DNA amplification by measuring potential changes in the reaction solution containing ethidium bromide (EtBr) as an intercalator to DNA. With progressing primer generation-rolling circle amplification (PG-RCA) under isothermal condition at 37°C, EtBr is bound to the newly formed DNA, resulting in a lowered free EtBr concentration in the sample solution. In this case, the Et⁺ ISE potential allows real-time monitoring of the PG-RCA reaction in the range of 10 nM – 1 μM initial target DNA.

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A novel organic-inorganic hybrid optical sensor (NUS) was designed and prepared in two steps: the grafting of 3-(isocyanatopropyl)trimethoxysilane onto the surface of SBA-15, and then the attachment of naphthalene-1-amine. The obtained materials were characterized using low-angle XRD, N₂ adsorption-desorption, TGA, FT-IR, and TEM techniques. A fluorescence study revealed that the NUS was a highly selective optical sensor for the detection of Cr₂O₇²⁻ among various anions, including F⁻, I⁻, Cl⁻, Br⁻, CO₃²⁻, HCO₃⁻, NO₃⁻, H₂PO₄⁻, CH₃COO⁻, and NO₂⁻ with a good linearity between the fluorescence intensity and the concentration of Cr₂O₇²⁻ as well as a detection limit of 1.2 × 10⁻⁷ M in a 100% aqueous medium. Moreover, the applicability of real samples of the sensor is also discussed.

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Novel magnetic molecularly imprinted composites were prepared through a facile method using sulfadimethoxine (SDM) as template. The inorganic magnetic nanoparticles were linked with the organic molecularly imprinted polymer (MIP) through irreversibly covalent bond. So, the resulted composites showed excellent stability and reusability under acidic elution conditions. The magnetic MIP composites showed good selectivity, high binding capacity and excellent kinetics toward SDM. Adopting the magnetic MIP composites as extraction material, an off-line magnetic solid-phase extraction (SPE)/high performance liquid chromatography (HPLC) method was established. The calibration curve was linear in the range of 0.05 – 15 mg kg⁻¹ (r² = 0.9976). The LOD and LOQ were 0.016 and 0.052 mg kg⁻¹, respectively, while the recoveries were in the range of 89.3 – 107.0%. These novel magnetic MIP composites may become a powerful tool for the extraction of template from complex samples with good efficiency.

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Herein, we applied hypericin (Hyp) for the detection of DNA on streptavidin-functionalized magnetic beads (SA-MB) through non-covalent π-π stacking interaction between 1-pyrenebutanoic acid (PBA) and Hyp. Briefly, the target DNA (tDNA) was hybridized to morpholino oligonucleotide (MO) that was immobilized on the surface of SA-MB. PBA was incorporated to the backbone of tDNA by means of phosphate-zirconium-carboxylate coordination reaction. Then, fluorescent Hyp was linked to PBA via π-π stacking interaction. Under the optimal conditions, this biosensor displayed a good linear relationship between the fluorescence intensity and the tDNA concentrations in the range from 1 to 100 nM with a low detection limit of 2.9 nM. The mismatch type in a specific DNA sequence can also be efficiently discriminated. Compared with some other reports, this method is more convenient, and has great potential for practical applications.

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Conjugates of semiconductor quantum dots (QDs) and organic dyes have been receiving attention as fluorescence biological sensing materials. In designing such sensors, a most important parameter is the number of organic-dye molecules that conjugate to a QD. If a precise separation method was developed, it might be possible to control conjugation without knowing the exact number of conjugated dye molecules per QD. In this study, the difference in linear velocities in a gel filtration column between CdSe/ZnS QDs and 5-(and 6)-carboxynaphthofluorescein succinimidyl ester is used. The velocities differ because the hydrophilicity of CdSe/ZnS QDs is much higher than that of the organic dye; hence, CdSe/ZnS-organic-dye conjugation can be controlled by changing the fraction number. Furthermore, the concentrations of CdSe/ZnS QDs and organic dye in fractionated solutions can be determined by measuring fluorescence spectra, and we demonstrate a fluorescence-type pH sensor based on the conjugate, which has a pH-sensitivity range from 7.5 – 9.5.

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This paper describes a plasma-diagnostic method using an enhancement factor on the Boltzmann distribution among emission lines of iron atom in an argon radio-frequency inductively-coupled plasma (ICP). It indicated that Boltzmann plots of the atomic lines having lower excitation energies (3.4 to 4.8 eV) were well fitted on a straight line while those having more than 5.5 eV deviated upwards from a linear relationship. This observation could be explained by the fact that ICP is not in a complete thermodynamic equilibrium between direct excitation to energy levels of iron atom, ionization of iron atom, and radiative decay processes to the ground state. Especially, the recombination of iron ion with captured electron should accompany cascade de-excitations between closely-spaced excited levels just below the ionization limit, the rates of which become slower as a whole; as a result, these high-lying levels might be more populated than the low-lying levels as if a different LTE condition coexists on the high energy side. This overpopulation could be quantitatively estimated using an enhancement factor (EF), which was a ratio of the observed intensity to the expected value extrapolated from the normal distribution on the low energy side. The EFs were generally small (less than 3); therefore, the cascade de-excitation process would slightly contribute to the population of these excited levels. It could be considered from variations of the EF that the overpopulation proceeded to a larger extent at lower radio-frequency forward powers, at higher flow rates of the carrier gas, or at higher observation heights. The reason for this is that the kinetic energy of energetic particles, such as electrons, becomes reduced under all of these plasma conditions, thus enabling the high-lying levels to be more populated by cascade de-excitation processes from iron ion rather than by collisional excitation processes with the energetic particles. A similar Boltzmann analysis using the EF was also carried out in emission lines of nickel atom, which confirmed the conclusion concerning the atomic lines of iron.

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An on-cell aptamer sensor has the potential to reveal cell–cell communications by signalling molecules. We attempted to design new fluorescent aptamer sensors for the sensing of IFN-γ and adenine compounds on cells. BODIPY-labeled external quencher-free aptamer sensors have allowed a turn-on detection of the target molecule with improved off/on efficiency.

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