[Methods of isothermal nucleic acid amplification-based microfluidic chips for pathogen microorganism detection].

Rapid detection of pathogenic microorganisms is key to the epidemiologic identification, prevention and control of disease in the field of public health. PCR-based pathogen detection methods have been widely used because they overcome the time-consuming issues that traditional culture-based methods required including the limited window required by immunological detection. However, the requirement on precision temperature-controlled thermal cyclers severely limits their use in resource-limited areas. The detection methods of pathogenic microorganisms based on isothermal amplification of nucleic acids are free of dependence on high-precision temperature control equipment, but requirements for nucleic acids extraction, amplification and detection must be defined. In recent years, a number of alternative methods for pathogenic microorganism detection have been developed by combining microfluidic technology with nucleic acid isothermal amplification technology. By designing the chip structures, optimizing the injection modes, and utilizing multiple detection and quantitative methods, the integration of pathogen nucleic acid extraction, amplification and detection is achieved. The method provides advantages of less instrument dependence, decreased operator requirements, smaller sample size, and higher automation which are suitable for the rapid detection of pathogenic microorganisms in various environments. In this review, we summarize several microfluidic detection methods based on nucleic acid isothermal amplification for pathogens including amplification principles, injection methods and detection methods. These methods provide more capability for the rapid screening of pathogenic microorganisms which enhances the management of infectious diseases in the field of public health.

Determination of asperosaponin VI in dog plasma by high-performance liquid chromatography-tandem mass spectrometry and its application to a pilot pharmacokinetic study.

A sensitive and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the determination of asperosaponin VI in beagle dog plasma using glycyrrhizic acid as the internal standard (IS). Plasma samples were simply pretreated with methanol for deproteinization. Chromatographic separation was performed on a Hedera ODS-2 column using mobile phase of methanol-10 mm ammonium acetate buffer solution containing 0.05% acetic acid (71:29, v/v) at a flow rate of 0.38 mL/min. Asperosaponin VI and the IS were eluted at 2.8 and 1.9 min, respectively, ionized in negative ion mode, and then detected by multiple reaction monitoring. The detection used the transitions of the deprotonated molecules at m/z 927.5 → 603.4 for asperosaponin VI and m/z 821.4 → 645.4 for glycyrrhizic acid (IS). The assay was linear over the concentration range of 0.15-700 ng/mL and was successfully applied to a pilot pharmacokinetic study in beagle dogs.

Determination of the unstable drug otilonium bromide in human plasma by LC-ESI-MS and its application to a pharmacokinetic study.

Otilonium bromide (OB) degrades rapidly in plasma and readily undergoes hydrolysis by the plasma esterase. In this paper, an LC-ESI-MS method has been developed for the determination of OB in human plasma. The rapid degradation of OB in plasma was well prevented by immediate addition of potassium fluoride (KF, an inhibitor of plasma esterase) to the freshly collected plasma before prompt treatment with acetonitrile. The method was validated over the concentration range of 0.1-20ng/ml. The data of intra-run and inter-run precision and accuracy were within ±15%. The mean extraction recoveries for OB and the internal standard were higher than 93.0% and the matrix effects were negligible. The method has been successfully used in a pharmacokinetic study.