Multiplexed bead-based mesofluidic system for gene diagnosis and genotyping.

We have developed a novel multiplexed bead-based mesofluidic system (MBMS) based on the specific recognition events on the surface of a series of microbeads (diameter 250 µm) arranged in polydimethylsiloxane (PDMS) microchannels (diameter 300 µm) with the predetermined order and assembled an apparatus implementing automatically the high-throughput bead-based assay and further demonstrated its feasibility and flexibility of gene diagnosis and genotyping, such as ß-thalassemia mutation detection and HLA-DQA genotyping. The apparatus, consisting of bead-based mesofluidic PDMS chip, liquid-processing module, and fluorescence detection module, can integrate the procedure of automated-sampling, hybridization reactions, washing, and in situ fluorescence detection. The results revealed that MBMS is fast, has high sensitivity, and can be automated to carry out parallel and multiplexed genotyping and has the potential to open up new routes to flexible, high-throughput approaches for bioanalysis.

Multiplexed bead-based mesofluidic system for detection of food-borne pathogenic bacteria.

In the present study, a simple and rapid multiplexed bead-based mesofluidic system (BMS) was developed for simultaneous detection of food-borne pathogenic bacteria, including Staphylococcus aureus, Vibrio parahaemolyticus, Listeria monocytogenes, Salmonella, Enterobacter sakazakii, Shigella, Escherichia coli O157:H7, and Campylobacter jejuni. This system is based on utilization of isothiocyanate-modified microbeads that are 250 mum in diameter, which were immobilized with specific amino-modified oligonucleotide probes and placed in polydimethylsiloxane microchannels. PCR products from the pathogens studied were pumped into microchannels to hybridize with the oligonucleotide-modified beads, and hybridization signals were detected using a conventional microarray scanner. The short sequences of nucleic acids (21 bases) and PCR products characteristic of bacterial pathogens could be detected at concentrations of 1 pM and 10 nM, respectively. The detection procedure could be performed in less than 30 min with high sensitivity and specificity. The assay was simple and fast, and the limits of quantification were in the range from 500 to 6,000 CFU/ml for the bacterial species studied. The feasibility of identification of food-borne bacteria was investigated with samples contaminated with bacteria, including milk, egg, and meat samples. The results demonstrated that the BMS method can be used for effective detection of multiple pathogens in different foodstuffs.

A cost-effective Z-folding controlled liquid handling microfluidic paper analysis device for pathogen detection via ATP quantification.

A cost-effective microfluidic paper analysis device (µPAD) was developed with a special Z-folding design for controlling the fluidic flowing and substrate transportation. This presented µPAD can be easily fabricated through wax printing by using a solid ink printer which deposits wax onto the surface of a chromatographic paper, and then baked on a hotplate by penetrating the molten wax into the paper to create a hydrophobic barrier. After µPAD fabrication, liquid control and substrate transportation can be easily carried out by twice folding the µPAD following Z shape. The Z folding made two separated reagent holding zone connected while the detection reaction occurred with the connection. In this paper, a pathogens detection indicated by ATP quantification was took as a proof-in-principle application of using this presented µPAD, the limit of detection (LOD) was 1 µM for ATP detection and 2.6×10(7) CFU/mL for Salmonella live cell detection, which showed a great potential for Point-of-Care Testing (POCT) applications.