Novel plant flavonoid electrochemical sensor based on in-situ and controllable double-layered membranes modified electrode.

Identification and quantification of plant flavonoids are critical to pharmacokinetic study and pharmaceutical quality control due to their distinct pharmacological functions. Here we report on a novel plant flavonoid electrochemical sensor for sensitive and selective detection of dihydromyricetin (DMY) based on double- layered membranes consisting of gold nanoparticles (Au) anchored on reduced graphene oxide (rGO) and molecularly imprinted polymers (MIPs) modified glassy carbon electrode (GCE). Both rGO-Au and MIPs membranes were directly formed on GCE via in-situ electrochemical reduction and polymerization processes step by step. The compositions, morphologies, and electrochemical properties of membranes were investigated with X-ray powder diffractometry (XRD), Fourier transform infrared spectrum (FTIR), Field emission scanning electron microscopy (FESEM) combined with various electrochemical methods. The fabricated electrochemical sensor labeled as GCE│rGO-Au/MIPs exhibited excellent performance in determining of DMY under optimal experimental conditions. A wide linear detection range (LDR) ranges from 2.0×10-8 to 1.0×10-4 M together with a low limit of detection (LOD) of 1.2×10-8 M (S/N = 3) were achieved. Moreover, the electrochemical sensor was employed to determine DMY in real samples with satisfactory results.

GEO-PGS composite shows synergistic and complementary effect on Escherichia coli and improvement of intestinal dysfunction.

Palygorskite (PGS) is a kind of clay minerals with the property of absorbent capacity, and ginger essential oil (GEO) is a kind of natural antibacterial substances. In the present study PGS was used as carrier of GEO, and thus, a kind of new anti-bacterial composite GEO-PGS has been obtained. Characterization, inhibitory effect of GEO-PGS on Escherichia coli (E. coli) and its function of improvement of intestinal health would be investigated. Results showed that characterization analysis of GEO-PGS (FTIR, TG-DSC, BET, Zeta potential, specific surface area, total pore volume and size, TEM observation) demonstrated combination of GEO and PGS, and GEO was absorbed on the surface of PGS, partially filled the micropores of PGS. GEO-PGS had obvious inhibitory effect on E.coli, in combination of the antibacterial activity of GEO and bacteria-absorbed capability of PGS. GEO-PGS also had ameliorating effect on enteritis and intestinal dysfunction in vivo, which might be related to the inhibition of gene expression of inflammatory cytokines (TLR2, IL-6, TNFα, and IL-8). In conclusion, the novel composite GEO-PGS has the potential usage as functional component having effect of improving intestinal health.

Molecular and Phenotypic Characterization Revealed High Prevalence of Multidrug-Resistant Methicillin-Susceptible Staphylococcus aureus in Chongqing, Southwestern China.

Methicillin-susceptible Staphylococcus aureus (MSSA) accounts for ∼40% of staphylococcal infections in China. However, the molecular characterization of MSSA is not well described. In this study, 124 MSSA strains collected in 2013 from a comprehensive teaching hospital in Chongqing, Southwestern China, were subjected to antibiotics susceptibility testing and molecular typing, including multilocus sequence typing, staphylococcal protein A (spa) gene typing, accessory gene regulator (agr) typing, pulsed-field gel electrophoresis (PFGE) typing, Panton-Valentine leukocidin (pvl) gene detection, and antibiotic-resistant gene detection. MSSA strains exhibited high genetic heterogeneity. A total of 10 PFGE groups, 26 sequence types, and 47 spa types were identified. Type I (62.9%) was the most frequent agr type, followed by type II (15.3%), type IV (11.3%), and type III (10.5%). The prevalence of pvl genes was 27.4% (34/124). Notably, 44.4% (55/124) of MSSA strains were multidrug resistance (MDR), and MDR isolates were mostly resistant to penicillin, erythromycin, and clindamycin. The resistance gene blaZ was present in 84.7% of strains, ermC was present in 85.5% of strains, ermA was present in 28.2% of strains, tetK was present in 16.1% of strains, tetM was present in 6.5% of strains, and aacA-aphD was present in 2.6% of strains. These data demonstrated the high prevalence of MDR MSSA in Chongqing, thereby indicating the need to control MSSA infection.