Improved detection and therapy of breast neoplasia might benefit from nanodevices traveling inside mammary ducts. However, the decreasing size of branched mammary ducts prevents access to remote areas of the ductal system using a pressure-driven fluid-based approach. Magnetic field guidance of superparamagnetic submicron particles (SMPs) in a stationary fluid might provide a possible alternative but it is critical to first reproduce the breast ductal system to assess the use of such devices for future therapeutic & diagnostic ("theranostic") purposes. Here we describe the engineering of a portion of a breast ductal system using polydimethylsiloxane (PDMS) microfluidic channels with a total volume of 0.09 μl. A magnet was used to move superparamagnetic/fluorescent SMPs through a static fluid inside the microchannels. Non-neoplastic mammary epithelial S1 cells developed basoapical polarity as a flat monolayer on the PDMS surface when cultured in the presence of laminin 111, and incubation with SMPs did not result in detectable toxicity. Cells could not withstand the fluid pressure if microinjected directly in completed channels. Whereas, they readily covered laminin 111-coated PDMS surfaces when cultured in U-shaped "hemichannels" before completing the channels. This breast-on-chip model represents a critical step towards the mimicry of the tree-like ductal system of the breast for further testing and targeting of SMPs.
Current methods to screen for bacterial contamination involve using costly reagents such as antibodies or PCR reagents or time-costly growth in cultures. There is need for portable, real-time, multiplex pathogen detection technology that can predict the safety of food. Surface plasmon resonance (SPR) imaging is a sensitive, label-free method that can detect the binding of an analyte to a surface by the changes in refractive index that occur upon binding. We have designed a hybrid microfluidic biochip to perform multiplexed detection of single-celled pathogens using a combination of SPR and fluorescence imaging. The device consists of an array of gold spots, each functionalized with a capture biomolecule targeting a specific pathogen. This biosensor array is enclosed by a polydimethylsiloxane microfluidic flow chamber that delivers a magnetically concentrated sample to be tested. The sample is imaged by SPR on the bottom of the biochip and epi-fluorescence on the top. The prototype instrument was successfully able to image antibody-captured E. coli O157:H7 bacteria by SPR and fluorescence imaging. The efficiency of capture of these bacteria by the magnetic particles was determined using spectrophotometric ferric oxide absorbance measurements. The binding of the E. coli to each spot was quantified by measuring the percent of the gold spot area upon which the bacteria was bound and analyzed using NIH ImageJ software. This hybrid imaging approach of pathogenic E. coli detection coupled with an estimate of relative infectivity is shown to be a working example of a testing device for potential foodborne pathogens. ' International Society for Advancement of CytometryKey terms foodborne pathogens; microbes; detection; microfluidic; cytometry; imaging; surface plasmon resonance; E. coli O157:H7 THE increased incidence of fatal pathogen-contaminated food supplies places a new emphasis on the rapid detection and quantification of the foodborne pathogens. This issue has been further compounded by the fact that many high-risk foodborne pathogens are easily transmitted through food supplies, thus constituting a major public health problem. Accurate and rapid identification of pathogens in food is to facilitate timely and appropriate actions in the event of a contamination. Conventional pathogen detection methods involve enriching the sample and performing various mediabased metabolic tests (1). These detection methods are elaborate and typically require 2-7 days to obtain results. Detection using magnetic beads coated with pathogenspecific antibodies or enzyme-linked immunosorbent assays still require several hours for completing the tests (2,3). The oligonucleotide array method based on amplification and hybridization of DNA fragments of pathogenic bacteria also takes more than several hours (4). Some techniques also require rather expensive special instruments, such as flow cytometry (5) and real-time PCR (6). Hence, a rapid, label-free, and easy-to-use biosensor capable of detecting toxigenic bacteria in a few mi...
The clinical potential of circulating tumor cells (CTCs) in managing cancer metastasis is significant. However, low CTC isolation purities from patient blood have hindered sensitive molecular assays of these rare cells. Described herein is the ultra‐pure isolation of CTCs from patient blood samples and how this platform has enabled highly specific molecular (mRNA and miRNA) profiling of patient CTCs.
Due to a number of recent technological advances, a hand-held flow cytometer can be achieved by use of semiconductor illuminators, optical sensors (all battery powered) and sensitive cell markers such as immuno-quantum dot (Qdot) labels. The specific application described is of a handheld blood analyzer that can quickly process a drop of whole, unfractionated human peripheral blood by real-time, on-chip magnetic separation of white blood cells (WBCs) and red blood cells (RBCs) and further fluorescence analysis of Qdot labeled WBC subsets. Various microfluidic patterns were fabricated in PDMS and used to characterize flow of single cells and magnetic deflection of magnetically labeled cells. An LED excitation, avalanche photodiode detection system (SensL Technologies, Ltd., Cork, Ireland) was used for immuno-Qdot detection of WBC subsets. A static optical setup was used to determine the sensitivity of the detection system. In this work we demonstrate: valve-less, on-chip magnetic sorting of immunomagnetically labeled white blood cells, bright Qdot labeling of lymphocytes, and counting of labeled white blood cells. Comparisons of these results with conventional flow cytometric analyses are reported. Sample preparation efficiency was determined by labeling of isolated white blood cells. Appropriate flow rates were determined for optical detection and confirmed with flowing particles. Several enabling technologies required for a truly portable, battery powered, hand-held flow cytometer for use in future point-of-care diagnostic devices have been demonstrated. The combining of these technologies into an integrated handheld instrument is in progress and results on whole blood cell analysis are to be reported in another paper.
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