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Herein, we first reported a facile synthesis method for fabrication of highly photoluminescent carbon quantum dots (CQDs) using sodium alginate as the carbon source and histidine as both the nitrogen source and functional monomer by one-pot hydrothermal synthesis. The as-prepared CQDs gave a high quantum yield of 32%. By employing the new CQDs and rhodamine B (RhB), we demonstrated a simple, facile, sensitive, and accurate ratiometric sensor for detection of Hg2+ and biological thiols. The photoluminescence of CQDs in the ratiometric sensor can be selectively and intensively suppressed by Hg2+ due to strong electrostatic interaction between the surface functional groups of the CQDs and Hg2+. When glutathione (GSH) was introduced into the “Turn Off” CQDs-RhB-Hg2+ sensing system, the fluorescence of the CQDs can be recovered rapidly due to the stronger affinity between thiol and Hg2+, while the fluorescence of the RhB remained constant in this sensing process. Based on the above principle, the ratiometric strategy for detecting Hg2+ and GSH can be achieved readily, and gives satisfactory limit of detections (LODs) of 30 and 20 nM for Hg2+ and GSH, respectively. The dual-emission fluorescent CQDs-RhB sensor does not need the complicated molecular design and the synthesis of dual-emission fluorophores. Meanwhile, the feasibility of the proposed method for analysis of water samples, food samples, and biological samples (plasma from mice oxidative stress study) was investigated. The developed ratiometric nanosensor is proven to be facile, with less sample consumption, rapid, lost cost, highly sensitive, and very selective for Hg2+ and biological thiol detection, which offers a new approach for environmental, food, and biological analysis.

β-Cyclodextrin–phenylethanoid glycosides inclusion complex was prepared and its releasing characteristic was investigated in this study. The results, obtained from Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction, indicated that phenylethanoid glycosides (PG) were able to form an inclusion complex with β-cyclodextrin (β-CD). This complex exhibited different spectroscopic features, thermal stability and crystalline structure from PG. Molecular simulation results showed the benzene rings of PG incorporating into the hydrophobic cavity of β-CD during the complex formation. Furthermore, the releasing rate of the included PG in the inclusion complex was positively correlated with temperature and it was slightly higher in 0.5 % HCl solution than in water. These results suggested that the complexation technique using β-CD was a promising strategy for increasing the applications of PG in food and healthcare industries.

A purified fraction of water-soluble polysaccharides was isolated from Glycyrrhiza uralensis Fisch using ion exchange and size exclusion chromatography. The present study was undertaken to discuss the preliminary immunoregulation mechanism of glycyrrhiza polysaccharide (GP) by cytochemistry and quantitative analyses, and intracellular enzyme measurement of macrophages. Acid phosphatase (ACPase), adenosine triphosphatase (ATPase), acid α-naphthyl acetate esterase (ANAE) and succinate dehydrogenase (SDH) in macrophages were stained with different methods. The results indicate that GP increased the production of ACPase, ATPase, ANAE and SDH; the activities of lysozyme (LSZ) and superoxide dismutase (SOD) of macrophages were also induced by GP. Our data suggest that the beneficial therapeutic effects of GP may be attributed partly to its ability to modulate macrophage immune functions.