STANFORD, Calif--A new single-cell biological sensor system may someday allow rapid screening of cancer agents for biofunctional activity (see illustration on page 1). The test could be used, for example, to identify compounds that bind to or block receptors for biomolecules such as growth factors or other cytokines, or to highlight potentially harmful metabolites.
Richard N. Zare, PhD, who headed the research in the Department of Chemistry at Stanford University, told Oncology News International that the technique may have an "important impact in cancer research, depending on how well we develop a library of receptors that we can place on cells."
Cells with known receptors could be used as biosensors to screen compounds for the presence of the ligand that binds to that receptor, he said.
The technique uses the responses of single cells to detect individual biomolecules separated from complex chemical mixtures by capillary electrophoresis. This method solves a past problem with biological sensors in that a cell can respond to many different biological compounds. "So when a cell reacts to something in a mixture, it is difficult to identify just what the cell is responding to. Capillary electrophoresis allows us to identify the specific compounds that are triggering the reaction," Dr. Zare said.
How It Works
The separation of a compound takes place in a fused silica capillary with an inside diameter of 25 microns, a fraction of the size of a human hair. Each type of molecule moves through the liquid in the capillary at a different rate, depending on its electrical charge, size, shape, and other factors.
When a separated biomolecule reaches the end of the capillary (a process that takes between 5 and 30 minutes), it is directed onto the single-cell biosensor, positioned on a microscope. In this way, a tiny amount of a given chemical can be delivered to an individual cell.