Unveiling the role of heterophase nanostructure in MnO2-based colorimetric sensors for ascorbic acid detection.

Nanozymes based on manganese oxide (MnO2) are demonstrated to be promising probes in colorimetric sensing applications. In this study, the r-MnO2/ß-MnO2 heterophase nanostructure was simply prepared by a calcination process with controllable temperature. The characterization of the nanostructured material was confirmed by SEM, UV-vis spectroscopy, Raman, TGA-DSC, and XRD analysis. The r-MnO2/ß-MnO2 exhibits a remarkably good catalytic activity in the oxidation process of 3,3',5,5'-tetramethylbenzidine (TMB) compared with the r-MnO2 or Mn2O3 nanostructure owing to its heterophase junctions. The enhanced performance of the colorimetric sensor for ascorbic acid (AA) detection was investigated using the r-MnO2/ß-MnO2 heterophase nanostructure as probe. The r-MnO2/ß-MnO2 material enhanced the monitoring of AA in the wide linear range from 1 µM to 50 µM with a limit of detection of 0.84 µM. This work presents a promising and straightforward approach for the construction of MnO2-based colorimetric sensor and their practical application in plant growth monitoring.

Circulation of influenza B lineages in northern Viet Nam, 2007-2014.

INTRODUCTION: Influenza B viruses circulate throughout Viet Nam, and their activities vary by region. There have been two antigenically distinct lineages of influenza B viruses co-circulating in the past 20 years; however, only one lineage is selected as a component of contemporary trivalent seasonal influenza vaccines. To improve the understanding of circulating influenza B lineages and influenza vaccine mismatches, we report the virus lineages circulating in northern Viet Nam over an eight-year period (2007-2014). METHODS: Lineages of 331 influenza B viruses were characterized by haemagglutination inhibition assay against standard reference ferret (Yamagata) and sheep (Victoria) antisera. Sequence analysis of the haemagglutinin gene was performed in 64 selected influenza B isolates. RESULTS: The proportion of influenza B lineages changed by year. The Yamagata lineage predominated in 2007, 2008 and 2012; the Victoria lineage predominated in 2009-2014 except 2012. The two lineages showed continuous evolution over time. The Northern Hemisphere's influenza vaccine components were mismatched with the predominant circulating viruses in 2007, 2009 and 2014. DISCUSSION: The seasonality of influenza B activity is more variable in tropical and subtropical regions than in temperate zones. Our data showed a common co-circulation of both influenza B lineages in northern Viet Nam, and it was difficult to predict which one was the predominant lineage. Quadrivalent influenza vaccines containing both lineages may improve the effectiveness of influenza vaccine programmes in the future.

Evaluation of Two Lateral-Flow Chromatographic Membrane Immunoassays for Rapid Detection of Influenza Virus in Limited Respiratory Specimens / 임상검사와정도관리

BACKGROUND: The diagnosis of influenza based on clinical grounds alone may be inaccurate, because the presenting symptoms of influenza are similar to those caused by other infectious agents. We evaluate two influenza rapid tests, SD BIOLINE Influenza Ag (Standard Diagnostic inc., Yongin, Korea) and QuickVueTM Influenza Test (Quidel corporation, San Diego, USA) with influenza virus culture and RT-PCR. METHODS: The two commercially available rapid test kits, SD BIOLINE Influenza Ag and QuickVueTM Influenza Test, for influenza virus detection were evaluated with 189 respiratory specimens collected during Dec. 2004 to Nov. 2005 in Vietnam and compared with viral culture and RT-PCR. RESULTS: Overall, the SD BIOLINE Influenza Ag and QuickVueTM Influenza Test showed high sensitivities (88.4% and 82.6%, respectively) and high specificities (99.0% and 99.0%, respectively), high positive predictive value (PPV) (98.7% and 98.6%, respectively) and high negative predictive value (NPV) (91.1% and 87.2%, respectively). CONCLUSION: Both SD BIOLINE Influenza Ag and QuickVueTM Influenza Test were easy to perform and showed high sensitivity and can be used as an additional tool for rapid diagnosis of influenza virus.