An integrated plastic microfluidic device was designed and fabricated for bacterial detection and identification. The device, made from poly(cyclic olefin) with integrated graphite ink electrodes and photopatterned gel domains, accomplishes DNA amplification, microfluidic valving, sample injection, on-column labeling, and separation. Polymerase chain reaction (PCR) is conducted in a channel reactor containing a volume as small as 29 nL; thermal cycling utilizes screen-printed graphite ink resistors. In situ gel polymerization was employed to form local microfluidic valves that minimize convective flow of the PCR mixture into other regions. After PCR, amplicons (products) are electrokinetically injected through the gel valve, followed by on-chip electrophoretic separation. An intercalating dye is admixed to label the amplicons; they are detected using laser-induced fluorescence. Two model bacteria, Escherichia coli O157 and Salmonella typhimurium, were chosen to demonstrate bacterial detection and identification based on amplification of several of their unique DNA sequences. The limit of detection is about six copies of target DNA.

Tissue samples (plasma, saliva, serum or urine) from 169 patients classified as either normal or having one of seven possible diseases are analysed across three 96-well plates for the presences of 37 analytes using cytokine inflammation multiplexed immunoassay panels. Censoring for concentration data caused problems for analysis of the low abundant analytes. Using fluorescence analysis over concentration based analysis allowed analysis of these low abundant analytes. Mixed-effects analysis on the resulting fluorescence and concentration responses reveals a combination of censoring and mapping the fluorescence responses to concentration values, through a 5PL curve, changed observed analyte concentrations. Simulation verifies this, by showing a dependence on the mean florescence response and its distribution on the observed analyte concentration levels. Differences from normality, in the fluorescence responses, can lead to differences in concentration estimates and unreliable probabilities for treatment effects. It is seen that when fluorescence responses are normally distributed, probabilities of treatment effects for fluorescence based t-tests has greater statistical power than the same probabilities from concentration based t-tests. We add evidence that the fluorescence response, unlike concentration values, doesn’t require censoring and we show with respect to differential analysis on the fluorescence responses that background correction is not required.

We report the demonstration of miniaturized capillary isoelectric focusing (CIEF) in plastic microfluidic devices. Conventional CIEF technique was adapted to the microfluidic devices to separate proteins and to detect protein-protein interactions. Both acidic and basic proteins with isoelectric points (pI) ranging from 5.4 to 11.0 were rapidly focused, mobilized, and detected in a 1.2 cm long channel (50 microm deep x 120 microm wide) with a total analysis time of 150 s. In a device with a focusing distance of 4.7 cm, the separation efficiency for a basic protein, lysozyme, was achieved as high as 1.5 x 10(5) plates, corresponding to 3.2 million plates per meter. We also experimentally confirmed that IEF resolution is essentially independent of focusing length when the applied voltage is kept the same and within a range that it does not cause Joule heating. Further, we demonstrated the use of miniaturized CIEF to study the interactions between two pairs of proteins, immunoglobulin G (IgG) with protein G and anti-six histidine (anti-6xHis) with 6xHis-tagged green fluorescent protein (GFP). Using this approach, protein-protein interactions can be detected for as little as 50 fmol of protein. We believe miniaturized CIEF is useful for studying protein-protein interactions when there is a difference in pI between a protein-protein complex and its constitutent proteins.

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We have designed and generated a 90-mer oligonucleotide that contains a single adduct of benzo[a]pyrene diol epoxide (BPDE) and that is fluorescently labeled. The known amount of BPDE adduct in a given length of DNA makes this probe a useful standard for DNA damage assay. The BPDE-90-mer was fluorescently labeled with tetramethylrhodamine to allow for high sensitivity detection with laser-induced fluorescence (LIF). The binding of both double-stranded and single-stranded BPDE-90-mer with three anti-BPDE antibodies was studied using affinity capillary electrophoresis (CE). Formation of antibody complex with BPDE-90-mer results in a shift in migration time from that of the unbound BPDE-90-mer. Affinity CE/LIF studies suggest that antibody 8E11 has high-affinity suitable for immunoassay of BPDE-DNA adducts. A competitive immunoassay using the fluorescent probe and CE/LIF is demonstrated for the analysis of BPDE-DNA adducts in A549 human lung carcinoma cells incubated with 2.5, 5, and 10 microM BPDE for 2 h. The design of the 90-mer probe is flexible to substitute different DNA damage types with relative ease. The fluorescent 90-mer is composed of six shorter oligonucleotides. The sequence of the two center oligonucleotides may be changed depending on the desired DNA lesion measurement. By inserting different damaged oligonucleotides, a variety of DNA damage systems can be investigated using the same CE/LIF approach.

This prospective study used antibody suspension bead arrays to identify biomarkers capable of predicting post-operative recurrence with distal metastasis in patients with colorectal cancer. One hundred colorectal cancer patients who underwent surgery were enrolled in this study. The median follow-up period was 3.9 years. The pre-operative plasma concentrations of 24 angiogenesisrelated molecules were analyzed with regard to the TNM stage and the development of post-operative recurrence. The concentrations of half of the examined molecules (13 ⁄ 24) increased significantly according to the TNM stage (P < 0.05). Meanwhile, a multivariate logistic regression analysis revealed that the concentrations of vascular cell adhesion molecule 1 (VCAM-1) and plasminogen activator inhibitor-1 (PAI-1) were significantly higher in the post-operative recurrence group. The VCAM-1 and PAI-1 model discriminated post-operative recurrence with an area under the curve of 0.82, a sensitivity of 0.75, and a specificity of 0.73. A leave-one-out cross-validation was applied to the model to assess the prediction performance, and the result indicated that the cross-validated error rate was 12.5% (12 ⁄ 96). In conclusion, our results demonstrate that antibody suspension bead arrays are a powerful tool to screen biomarkers in the clinical setting, and the plasma levels of VCAM-1 and PAI-1 together may be a promising biomarker for predicting post-operative recurrence in patients with colorectal cancer. (Cancer Sci 2010; 101: 1886-1890 C olorectal cancer (CRC) is one of the leading causes of death in Japan (http://ganjoho.ncc.go.jp/public/statistics/ index.html) and Western countries. (1) Despite recent advances in adjuvant chemotherapy and surgical techniques, 20-40% of patients die because of metastasis after curative surgery. (2) Tumor-node-metastasis (TNM) staging is well established and the most reliable system for predicting the outcome of CRC. In particular, the TNM staging system works very well for predicting the outcome of early stage I cancers and advanced stage IV cancers. However, the 5-year survival rate varies from 44% to 83% within TNM stage III, indicating that a wide variation in outcomes exists within each stage as a result of biological heterogeneity. (3) Thus, highly accurate predictors of post-operative recurrence are needed for patients with CRC who undergo curative surgery, as such predictors would likely contribute to the further improvement of the 5-year survival rate by justifying the addition of intensive adjuvant chemotherapy to the therapeutic regimens of subgroups with a high risk of post-operative recurrence. Therefore, the prediction of post-operative recurrence is regarded as one of the most important research themes in clinical settings and has been extensively studied, with particular attention given to the investigation of various molecular prognostic factors.In addition to the TNM stage, the carcinoembryonic antigen (CEA) level is routinely used to monitor recurrence in patients with CRC. (4) A large clinic...

A single-channel chip-based analytical microsystem that allows rapid flow injection measurements of the total content of organic explosive or nerve agent compounds, as well as detailed micellar chromatographic identification of the individual ones, is described. The protocol involves repetitive rapid flow injection (screening) assays--to provide a timely warning and alarm--and switching to the separation (fingerprint identification) mode only when harmful compounds are detected. While micellar electrokinetic chromatography, in the presence of sodium dodecyl sulfate (SDS), is used for separating the neutral nitroaromatic explosive and nerve agent compounds, an operation without SDS leads to high-speed measurements of the "total" explosives or nerve agent content. Switching between the "flow injection" and "separation" modes is accomplished by rapidly exchanging the SDS-free and SDS-containing buffers in the separation channel. Amperometric detection was used for monitoring the separation. Key factors influencing the sample throughput, resolution, and sensitivity have been assessed and optimized. Assays rates of about 360 and 30/h can thus be realized for the "total" screening and "individual" measurements, respectively. Ultimately, such development will lead to the creation of a field-deployable microanalyzer and will enable transporting the forensic laboratory to the sample source.