John Kulman, Ph.D., a principal investigator at the Puget Sound Blood Center (PSBC), described his investigations aimed at further enhancing the performance of Bio-Rad Laboratories’ ProteOn™ XPR-36 System. The device is designed for drug discovery, with a workflow that allows it to simultaneously monitor 36 interactions in real time.
“SPR is largely underutilized,” Dr. Kulman argued, “due to cost and time limitations for producing high-quality ligands, difficulties in regenerating the ligand-coupled surface between runs, and, finally, throughput limitations inherent in the instrumentation.”
Dr. Kulman said that if these limiting factors were removed from the experimental design, quantitative evaluation of the mechanism of action of a drug candidate could be much more easily integrated into a drug-development program.
“Our approach is a blend of basic science and industrial engineering design, the end result of which is much faster and cheaper throughput without compromising data quality.”
In order to simplify the workflow, Dr. Kulman developed a calcium-dependent immunocapture platform. The approach employs ligands generated by small-scale transient transfection of mammalian cells that are purified on-chip, so there is no upstream purification of ligand. Rather, the process of plasmid generation is the only rate-limiting step in ligand production. Since regeneration back to the capture agent is achieved cleanly and rapidly at millimolar concentrations of EDTA, the same capture agent can be used continuously for multiple experimental runs.
At this time, the ProteOn is not certified for clinical diagnostic applications, but Dr. Kulman believes that the throughput capacity of the instrument makes it ideal for clinical labs that process multiple patient samples. Toward this end, he and his colleagues at the PSBC are developing new diagnostic applications for a spectrum of bleeding disorders collectively known as autoimmune thrombocytopenias.
“By integrating multiplexed SPR with other high-throughput platforms such as multimode plate readers and flow cytometry, we can do some exciting stuff, we can cover a lot of ground, from biophysical studies to drug discovery and clinical diagnostics.”