Dieter Schmalzing

Immunoassay for thyroxine (T4) in serum using capillary electrophoresis and micromachined devices

As part of our ongoing effort to develop electrophoretic assay technology for clinical diagnostics, we describe a competitive immunoassay for the determination of serum thyroxine (T4) based on electrophoresis and laser induced fluorescence (LIF). Measurements of total T4 are useful for the clinical evaluation of thyroid function. A fluorescein thyroxine conjugate was utilized in conjunction with a polyclonal antibody preparation as assay reagents. Capillary electrophoresis (CE) conditions tolerant of the direct injection of serum without extraction or other sample preparation steps were developed and used for quantitation of total T4 in serum. We have been exploring the use of micromachined devices with arrays of channels for high assay throughput. Our assay protocol was carried in a microchip format. The results illustrate that gains in speed can be additionally achieved, with the electrophoretic separation of free from bound labelled T4 being performed in about 15 s for serum samples.

Capillary electrophoresis-based immunoassays.

This review covers the progress and developments in the field of capillary electrophoresis immunoassay (CEIA) over the past three years. Because many excellent descriptions of the principles of these methods are available (e.g., in the reviews listed in this article), no elementary introduction is given to the field of immunoassays (IAs) or CEIAs. This report focuses exclusively on experimental results, dividing the CEIA papers into the categories of direct, indirect, and microchip electrophoretic immunoassays. In the last section, a brief summary of the current status of the CEIA field is presented.

Recent developments in DNA sequencing by capillary and microdevice electrophoresis

The present review covers papers published in the years 1997 and 1998 on DNA sequencing by capillary and microdevice electrophoresis. The article does not include other electrophoretic DNA applications such as analysis of oligonucleotides, genotyping, and mutational analysis. Capillary gel electrophoresis (CGE) is starting to become a viable competitor to slab gel electrophoresis for DNA sequencing. Commercially available multicapillary array sequencers are now entering sequencing facilities which to date have totally relied on traditional slab gel technology. CGE research on DNA sequencing therefore becomes increasingly concerned with the critical task of fine‐tuning the operational parameters to create robust sequencing systems. Electrophoretic microdevices are being considered the next technological step in DNA sequencing by electrophoresis.

BIOMEMS-768 DNA Sequencer

The Whitehead Institute has developed an automated DNA sequencer that will go into final Genome Center testing during the summer of 2001. The system comprises a total of 768 separation channels distributed over two plates. The working elements are 50-cm × 25-cm, 384-lane microfabricated glass elements, which undergo alternating electrophoresis and regeneration under use with an exchangeable sieving matrix. The microfluidic and sample transfer devices needed to service the plates are integrated into the same compact instrument. Concurrently with the instrument development we have developed all the protocols, materials and surface preparations to achieve matrix-limited separations of single-stranded DNA in the microfabricated plate format.