CELL-TO-CELL SCANNING IN CAPILLARY ELECTROPHORESIS

A widespread limitation in using cell-based biosensors for repetitive chemical analysis is loss of agonist-induced response caused by recept or desensitization. We overcome this problem by scanning an array of i mmobilized cells underneath a capillary electrophoresis column outlet. In this way, electrophoretically fractionated components that exit th e separation capillary are always directed onto cells previously unexp osed to receptor agonists. To demonstrate this concept of response rec overy using a scanning format, we have chosen the bradykinin B-2 recep tor system in the NG108-15 cell line, which is known to undergo desens itization. Whereas four subsequent injections of 250 mu M bradykinin s eparated by 120 s are found to reduce the NG108-15 cell response marke dly, scanning to new cells can fully restore the response during the s eparation, Furthermore, by pretesting individual NG108-15 cells for an agonist response and then later scanning back to the same cell, we ac hieved a 100% success rate in detecting bradykinin in subsequent elect rophoretic separations.