Droplet-based Extraction of Hepatitis B Virus DNA in a Capillary

Detection and identification of extra virgin olive oil adulteration by GC-MS combined with chemometrics

In this study, an analytical method for the detection and identification of extra virgin olive oil adulteration with four types of oils (corn, peanut, rapeseed, and sunflower oils) was proposed. The variables under evaluation included 22 fatty acids and 6 other significant parameters (the ratio of linoleic/linolenic acid, oleic/linoleic acid, total saturated fatty acids (SFAs), polyunsaturated fatty acids (PUFAs), monounsaturated fatty acids (MUFAs), MUFAs/PUFAs). Univariate analyses followed by multivariate analyses were applied to the adulteration investigation. As a result, the univariate analyses demonstrated that higher contents of eicosanoic acid, docosanoic acid, tetracosanoic acid, and SFAs were the peculiarities of peanut adulteration and higher levels of linolenic acid, 11-eicosenoic acid, erucic acid, and nervonic acid the characteristics of rapeseed adulteration. Then, PLS-LDA made the detection of adulteration effective with a 1% detection limit and 90% prediction ability; a Monte Carlo tree identified the type of adulteration with 85% prediction ability.

Highly efficient capillary polymerase chain reaction using an oscillation droplet microreactor

The current work presents the development of a capillary-based oscillation droplet approach to maximize the potential of a continuous-flow polymerase chain reaction (PCR). Through the full utilization of interfacial chemistry, a water-in-oil (w/o) droplet was generated by allowing an oil-water plug to flow along a polytetrafluoroethylene (PTFE) capillary. The w/o droplet functioned as the reactor for oscillating-flow PCR to provide a stable reaction environment, accelerate reagent mixing, and eliminate surface adsorption. The capillary PCR approach proposed in the current research offers high amplification efficiency, fast reaction speed, and easy system control attributable to the oscillation droplet reactor. Experimental results show that the droplet-based micro-PCR assay requires lower reaction volume (2 μL) and shorter reaction time (12 min) compared with conventional PCR methods. Taking the amplification of the New Delhi metallo-beta-lactamase (NDM-1) gene as an example, the present work demonstrates that the oscillation droplet PCR assay is capable of achieving high efficiency up to 89.5% and a detection limit of 10 DNA copies. The miniature PCR protocol developed in the current work is fast, robust, and low-cost, thus exhibiting the potential for expansion into various practical applications.