An electrochemical aptasensor based on gold@polypyrrole composites for detection of lead ions.

This work describes an electrochemical aptasensor for determination of lead ions (Pb2+). Composites prepared from gold nanoparticles and polypyrrole (Au@PPy) with good electrical conductivity were used to modify the surface of a screen printed carbon electrode for amplifying the current signal. Single strand DNA was immobilized on the electrode and binds lead(II) as confirmed by cyclic voltammetry at voltage of -0.2 V~0.6 V. Differential pulse voltammetry, measured at 0.10 V (vs.  Ag/AgCl), was used to monitor the interaction between aptamer and lead(II) using hexacyanoferrate as an electrochemical probe. In the presence of Pb2+, the aptamer forms a G-quadruplex, and the peak current is increased. By this method, Pb2+ can be detected in the range of 0.5-10 nM with a low detection limit of 0.36 nM. The aptasensor was successfully applied to the determination of Pb2+ in polluted soil and baby's nail. The method showed outstanding sensitivity and selectivity in detecting Pb2+, therefore is considered to have great potential in developing an environmental monitoring platform. Graphical abstract Schematic illustration of Pb2+ detection procedure and principle using an electrochemical aptasensor.

Cost-effective production of recombinant human interleukin 24 by lactose induction and a two-step denaturing and one-step refolding method.

Recombinant human interleukin 24 (rhIL24) is a member of the interleukin 10 (IL10) family of cytokines with novel therapeutic properties. Human IL24 possesses three N glycosylation sites and a disulfide bridge. The cost and composition of culture media is critical for commercial-scale production of recombinant proteins in E. coli. Addition of yeast extract and glucose to medium enhances rhIL24 production, and the use of lactose instead of IPTG for induction drops the cost and decreases toxicity. In addition, a two-step denaturing and one-step refolding (2DR) strategy improves rhIL24 production. The 2DR strategy replaces a more conventional approach for protein solubilization and refolding. LC-MS/MS provides definitive identification and quantitative information on rhIL24. Single-step purified rhIL24 displayed biological activity on HepG2 hepatocellular carcinoma cells, but no effect on L02 cells. Proliferation analysis suggests that rhIL24 may have potential use as a medication. In the present study, we developed a simple process for producing quality product with high purity. The expression and purification of rhIL24 described here may be a step towards inexpensive large-scale production.

Anti-Hyperlipidemia and Gut Microbiota Community Regulation Effects of Selenium-Rich Cordyceps militaris Polysaccharides on the High-Fat Diet-Fed Mice Model.

Supplementation of polysaccharides is a promising gut microbiota-targeted therapeutic method for obesity and metabolic diseases. Biological activities of Cordyceps militaris polysaccharides have been well reported, but the effect of selenium (Se)-rich C. militaris polysaccharides (SeCMP) on obesity and associated metabolic disorder and gut microbiota composition has been rarely studied. This study aimed to investigate the anti-obesity and gut microbiota modulatory effect of crude polysaccharides separated from Se-rich C. militaris on a high-fat diet (HFD)-fed C57BL/6J mice model. Mice were treated with a normal diet (CHOW), HFD alone, HFD plus C. militaris polysaccharides (CMP), or low/medium/high dosage of SeCMP for 8 weeks. Body weight, fat content, serum lipid, appetite hormone, lipid gene expression, inflammation cytokines, thermogenic protein, short-chain fatty acids (SCFAs), and gut microbiota structure of the mice were determined. Compared with HFD-fed mice, the serum triglyceride and low-density lipoprotein cholesterol (LDL-C) in the SeCMP-200 group were decreased by 51.5% and 44.1%, respectively. Furthermore, serum lipopolysaccharide-binding proteins (LBP), adiponectin level, and pro-inflammation gene expression in the colon and subcutaneous fat were inhibited, whereas anti-inflammation gene expression was improved, reflecting SeCMP-200 might mitigate obese-induced inflammation. Meanwhile, SeCMP-200 promoted satiety and thermogenesis of obese mice. It also significantly decreased gut bacteria, such as Dorea, Lactobacillus, Clostridium, Ruminococcus, that negatively correlated with obesity traits and increased mucosal beneficial bacteria Akkermansia. There was no significant difference between CMP and SeCMP-100 groups. Our results revealed a high dose of SeCMP could prevent HFD-induced dyslipidemia and gut microbiota dysbiosis and was potential to be used as functional foods.