Self-assembly and label-free fluorescent aptasensor based on deoxyribonucleic acid intercalated dyes for detecting lactoferrin in milk powder.

Lactoferrin (Lf), an iron-binding glycoprotein, regulates the immune system. It has broad-spectrum antimicrobial activity and is critical for child physical growth and development. As a common additive in the dairy industry, it is crucial to quantify LF content. This study established a self-assembly and universal fluorescence aptasensor for detecting LF in milk powder based on structure-selective dyes of PicoGreen intercalated in the label-free aptamer. Herein, the aptamer functions as both a specific recognition element against targets and a fluorescent signal reporter integrated with structure-selective dyes. First, the aptamer folds into a three-dimensional spatial structure based on complementary base pairings and intermolecular weak non-covalent interactions. Then, the dye is intercalated into the minor groove structures of the aptamer and triggers its potential fluorescent property. When the target exists, the aptamer binds to it preferentially, and its space structure unfolds. This causes the freeing of the subsequent dye and decreases the corresponding fluorescence. Hence, the reflected fluorescence signals could directly determine the target concentrations. Under the optimum conditions, a good linear relationship (R 2, 0.980) was obtained in the Lf range from 20 to 500 nM with a detection limit of 3 nM (2.4 mg/kg) and good specificity, as well as a reliable recovery of 95.8-105.1% in milk powder. In addition, the universality was also confirmed with a good performance by quickly changing the aptamers against other targets (chlorpyrifos, acetamiprid, bovine thyroglobulin, and human transferrin) or utilizing another fluorescence dye. Therefore, this self-assembly aptasensor provides a universal and concise strategy for effective detection.

Comprehensive analysis of Huanglian Jiedu decoction: Revealing the presence of a self-assembled phytochemical complex in its naturally-occurring precipitate.

The current study presents a comprehensive analysis to explore the compositions of both the supernatant and naturally-occurring precipitate of Huanglian Jiedu decoction employing ultra-high-performance liquid chromatography hyphenated with quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). Totally 109 constituents (32 alkaloids, 39 flavonoids, 12 iridoids, 9 phenolic acids, and 17 other compounds) were identified from accurate-mass measurements in full-scan MS/data-dependent MS/MS mode of acquisition. Furthermore, a quantitative method was developed for determination of 14 marker compounds in Huanglian Jiedu decoction. Experimental results revealed that all of these marker compounds were present in both the supernatant and naturally-occurring precipitate. Most notably, the contents of baicalin and berberine were significantly higher in the naturally-occurring precipitate than supernatant, presumably due to self-assembly complexation. The formation of the baicalin/berberine complex was comprehensively investigated by electrospray ionization (ESI)-MS, nuclear magnetic resonance (NMR), ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR), and fluorescence spectroscopy, etc. The morphology and size distribution of the baicalin/berberine self-assembled nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). This study provides fundamental scientific evidence of the presence of a self-assembled phytochemical complex in the naturally-occurring precipitate, enabling better understanding of Huanglian Jiedu decoction.

Peptide nucleic acid and amino acid modified peptide nucleic acid analysis by capillary zone electrophoresis.

A rapid, high resolution, and low sample consumption CZE method is developed for peptide nucleic acid (PNA) analysis for the first time. 30% v/v acetonitrile in PNA sample and 20% v/v acetonitrile in 50 mM borax-boric acid (pH 8.7) as BGE were employed after optimization. The calibration curves were linear for PNA concentration ranging from 1 to 50 µmol/L. LOD and LOQ of PNA were 0.2 and 1.0 µmol/L, respectively. Since the commercially available reagent gives rise to huge PNA peak and an apparent impurity peak, the purity of PNA was evaluated to be about 81.4% by CZE method, obviously lower than the supplier's purity value of 99.9% evaluated by RP-HPLC, and also lower than 94.8% determined with RP-HPLC by our research group. The CZE method takes only 5 min, needs only 90 nL PNA, much less than 20 min and 20 µL PNA in RP-HPLC method. Moreover, the CZE method is applicable for the analysis of glutamic acid modified and lysine modified PNAs, they show different migration time with their corresponding complementary PNAs. Our results show CZE provides a new choice for PNA and modified PNA analysis, also their purity or quality evaluation.

High-efficient energy recovery from organics degradation for neutral wastewater treatment based on radicals catalytic reaction of Fe2+/Fe3+-EDTA complexes.

A high-efficient photo-induced wastewater fuel cell (WFC) for neutral wastewater treatment was proposed in this paper based on radicals catalytic reaction of Fe3+/Fe2+- EDTA complexes in the system which has a lower redox potential than Fe3+/Fe2+ and can accelerate easily the conversion of slow catalytic step from Fe (III) to Fe (II). The results indicated that the WFC shows an excellent performance in a wide pH range of 5-9 and achieves optimal efficiency for organic degradation and electricity generation at pH 7.0. The removal ratio of organic pollutants (Rhodamine b, Phenol, and Methylene Blue) increased to 69.42%, 53.99% and 82.7% from 29.87%, 16.25% and 39% respectively after 3 h operation at an initial pH of 7.0. Meanwhile, the short-circuit current is up to 1.24-2.16 times that of the WFC without EDTA-ferrous complex. Furthermore, the system almost does not produce any sludge. The proposed WFC system can keep stable of Fe3+/Fe2+ in neutral solution and generate more intermediate active free radicals to treat neutral wastewater and recover the abundant chemical energy in organics.

[Standardized investigation on medicinal nature of ethnomedicine].

This article recorded the analysis and comparison between the medicinal nature theory of traditional Chinese medicine(TCM) and ethnomedicine(EM). The vocabulary of "medicinal nature" was suggested to indicate the properties of ethnomedicine. Based on the influence of TCM medicinal nature theory on EM in China, the application of medicinal nature theory in EM was divided into 3 classes, and the standardizing principles for EM medicinal nature were proposed. It was suggested that medicinal quality, flavor, tendency, tropism, degree and efficiency can be used for the classification standard for EM medicinal nature.