Biomedical subjects

Joann J Lu

Publications and source records attributed to Joann J Lu.

4 recordsLinked to original sources

PubMed2006

A robust cross-linked polyacrylamide coating for microchip electrophoresis of dsDNA fragments.

Surface derivatization plays an important role in microchip electrophoresis. It not only enhances the resolution, but also improves the reproducibility. So far, the most popularly used derivatization method for glass microchannels is to covalently attach a layer of linear polyacrylamide (LPA) to the channel surfaces. However, LPA coating has two problems: incomplete coverage and limited lifetime. To address these issues, we have recently developed a cross-linked polyacrylamide (CPA) derivatization protocol and demonstrated it for high-resolution protein separations by CIEF, CGE, and CZE. In this report, we used this protocol to coat microchip channels and exhibited the reliability and robustness of CPA coating for microchip electrophoresis of DNA molecules. dsDNA fragments were used as our test samples. High resolutions were obtained for fragments ranging from 100 bp to 10 kpb. After more than 800 runs, the CPA-coated microchannels still performed well and comparable resolutions were maintained throughout these runs.

Acrylic Resins↗

PubMed2006

Comprehensive protein profiling by multiplexed capillary zone electrophoresis using cross-linked polyacrylamide coated capillaries.

We have recently developed a new process to create cross-linked polyacrylamide (CPA) coatings on capillary walls to suppress protein-wall interactions. Here, we demonstrate CPA-coated capillaries for high-efficiency (>2 x 10(6) plates per meter) protein separations by capillary zone electrophoresis (CZE). Because CPA virtually eliminates electroosmotic flow, positive and negative proteins cannot be analyzed in a single run. A "one-sample-two-separation" approach is developed to achieve a comprehensive protein analysis. High throughput is achieved through a multiplexed CZE system.

Acrylic Resins↗

PubMed2003

Electric field-decoupled electroosmotic pump for microfluidic devices.

An electric field-free electroosmotic pump has been constructed and its pumping rate has been measured under various experimental conditions. The key component of the pump is an ion-exchange membrane grounding joint that serves two major functions: (i) to maintain fluid continuity between pump channels and microfluidic conduit and (ii) to ground the solution in the microfluidic channel at the joint through an external electrode, and hence to decouple the electric field applied to the pump channels from the rest of the microfluidic system. A theoretical model has been developed to calculate the pumping rates and its validity has been demonstrated.

Electricity↗

PubMedDate not supplied

Replaceable cross-linked polyacrylamide for high performance separation of proteins.

An alternative sieving matrix, replaceable cross-linked polyacrylamide (rCPA), was developed for sodium dodecyl sulfate capillary gel electrophoresis (SDS-CGE) separation of proteins. This rCPA could be conveniently pressurized into separation capillaries under a pressure of 80 psi. SDS-CGE separations using this matrix generated high resolutions for a wide range (approximately 4 kD to approximately 300 kD) of proteins. When compared to the most frequently used sieving matrixes, the rCPA permitted the highest resolutions with comparable or increased separation speed for protein separations.

Acrylic Resins↗