Biomedical subjects

Rongsheng Lin

Publications and source records attributed to Rongsheng Lin.

3 recordsLinked to original sources

PubMed2005

Addressable electric fields for size-fractioned sample extraction in microfluidic devices.

Fraction collection following electrophoresis is of major importance for a variety of biological analyses. These assays typically need to identify specific fractions in the separated sample for further processing and require extraction of one or a group of fragments. In this paper, we have developed and characterized a technique to generate addressable electric fields for improved extraction during electrophoresis in microfluidic devices. The addressable electric field is achieved by applying a low bias voltage (1-2 V) to microelectrode pairs within the electrophoresis microchannel. Theoretical analysis shows the purity of the extracted sample can be improved as much as 30% over extraction without the shaped electric fields, and nearly 100% predicted yield can be achieved. We also describe the theoretical design of shaped electric fields by characterizing the optimal electrode geometry, field strength, channel configuration, and electrophoretic migration behavior needed for efficient band extraction.

DNA↗

PubMed2003

Selective extraction of size-fractioned DNA samples in microfabricated electrophoresis devices.

We have designed and constructed a microfabricated device for separation of double-stranded DNA fragments using a crosslinked sieving medium and spatially selective extraction of the desired fraction. Based on measuring the width and spacing of migrating bands, a narrow side channel is constructed perpendicular to the separation channel to collect the DNA fragments of interest. This selective collection technique was tested using a 100 base pair double-stranded DNA ladder. We successfully demonstrate selective extraction of the desired fragment with minimal interference from the adjacent bands in an electric field of 31 V/cm. We also achieve extraction of multiple DNA fragments using an array of microelectrodes in this side channel. The device uses cross-linked polyacrylamide gel matrix, allowing the separation to be performed in a distance of 1 cm or less and at a low electric field strength. Together with on-chip electrode, this design is amenable to integration with reaction chambers into a single device for portable genetic-based analysis.

DNA↗

PubMed2003

A versatile microfabricated platform for electrophoresis of double- and single-stranded DNA.

We demonstrate a versatile microfabricated electrophoresis platform, incorporating arrays of integrated on-chip electrodes, heaters, and temperature sensors. This design allows a range of different sieving gels to be used within the same device to perform separations involving both single- and double-stranded DNA over distances on the order of 1 cm. We use this device to compare linear and cross-linked polyacrylamide, agarose, and thermo-reversible Pluronic-F127 gels on the basis of gel casting ease, reusability, and overall separation performance using a 100 base pair double-stranded DNA ladder as a standard sample. While cross-linked polyacrylamide matrices provide consistently high-quality separations in our system over a wide range of DNA fragment sizes, Pluronic gels also offer compelling advantages in terms of the ability to remove and reload the gel. Agarose gels offer good separation performance, however, additional care must be exercised to ensure consistent gel properties as a consequence of the need for elevated gel loading temperatures. We also demonstrate the use of denaturing cross-linked polyacrylamide gels at concentrations up to 19% to separate single-stranded DNA fragments ranging in size from 18 to 400 bases in length. Primers differing by 4 bases at a read length of 30 bases can be separated with a resolution of 0.9-1.0 in under 20 min. This level of performance is sufficient to conduct a variety of genotyping assays including the rapid detection of single nucleotide polymorphisms (SNPs) in a microfabricated platform. The ability to use a single microelectrophoresis system to satisfy a wide range of separation applications offers molecular biologists an unprecedented level of flexibility in a portable and inexpensive format.

Acrylic Resins↗