Air stream-mediated vortex agitation of microlitre entities on a fluidic chip

The method presented in this paper uses air flux to induce spiral motion in small-scale (e.g., microlitre) fluid entities in an efficient, technologically convenient manner. The set-up entails a manifold that modulates the air flux and projects it onto a liquid-containing reservoir. The flow behaviour of the liquid phase has been visualized through the dissolution of rhodamine B crystallites and the motion of fluorescent microbeads. In addition, the method proved effective to restoring a suspension of spherical particles upon sedimentation, promoting displacement and capture of the beads within a microfluidic system.Peer reviewed: YesNRC publication: Ye

Modular ultrasonic Lysis system for rapid nucleic acid extraction and sample transfer of Bacillus spores

This paper describes the design, functioning and use of an ultrasonic modular system intended for rapid extraction and fragmentation of DNA from microbial organisms following sample collection in the field. PCR assessment of the DNA extracts revealed that the system can disrupt Bacillus atrophaeus spores, a simulant for Bacillus anthracis, in less than 1 min, providing a DNA yield equivalent to that of a commercial nucleic acid extraction method. Simulation of the transfer from a contaminated to a secure area confirmed that the sample remained confined within the module while the exterior surface can be decontaminated through immersion in a disinfectant solution.Peer reviewed: YesNRC publication: Ye

Extraction of nucleic acids from bacterial spores using bead-based mechanical cell lysis on a plastic chip

This paper describes an experimentally simple and efficient way of integrating bead-based mechanical cell lysis on a plastic chip. The chip is fabricated from machined slides of poly(methylmethacrylate) and accommodates a metal disk along with solid microbeads in a designated lysis chamber. Magnetic actuation of the metal disk induces collisions and frictional forces within the lysis matrix causing cell disruption. The efficiency of nucleic acid extraction was investigated using spores of Bacillus atrophaeus subsp. globigii and the amount of genomic DNA in the lysates has been quantified by real-time PCR. Compared to a standardized DNA extraction method based on BD GeneOhm\u2122 Lysis Kit, the yield was dependent on the composition of the lysis matrix, including size and relative amount of microbeads, along with instrumental parameters, such as duration and frequency of agitation. The interplay of these parameters should allow for optimizing lysis protocols to faithfully disrupt any particular type of cell without affecting the genetic material to be extracted.Peer reviewed: YesNRC publication: Ye

Portable bead-based fluorescence detection system for multiplex nucleic acid testing: a case study with Bacillus anthracis

This paper describes the design, functioning and use of a portable detection platform for multiplex nucleic acid testing. The system features a bead-supported DNA hybridization assay performed inside a microfluidic cartridge. Polystyrene particles modified with DNA capture probes are confined in the detection area and exposed to a solution of fluorescently labeled target DNA strands. The cartridge, fabricated from inexpensive thermoplastic polymers, allows for conducting up to eight assays in parallel. The detection instrument is equipped with a pneumatic module and a manifold lid serving as an interface to mediate fluid displacement on the cartridge. The fluorescence signal deriving from each assay is recorded by a semi-confocal fluorescence reader embedded in the detection platform. The compact design of the instrument and its level of integration make it possible to obtain an analytical result in less than 15 min, while only few manual steps need to be performed in between. A proof-of-concept demonstration involving Cy3-labeled, PCR-amplified genomic DNA confirms the ability to detect Bacillus anthracis in a multiplexed single-assay format using lef and capC genes. Limits of quantification are on the order of 1 7 109 copies/\u3bcL for lef targets. \ua9 2013 Springer-Verlag Berlin Heidelberg.Peer reviewed: YesNRC publication: Ye