Simultaneous optical and fluorescent microscopic measurement of drug retention in single cancer cells

A single cancer cell was isolated and captured by a microfluidic single-cell biochip. The chip was made of glass and was fabricated by standard photolithography and wet etch process. Simultaneous optical observation and fluorescent measurement were achieved on the captured cancer cell. This was achieved by using red light to observe the cell; whereas the green fluorescent emission was measured photometrically to monitor the drug concentration. A CCD camera was used to image the cell morphology. At the same time, a PMT detector was used to monitor the cellular drug concentrations change in the single cell as a decrease in the cellular fluorescence intensity. Kinetic information of drug concentration change was obtained by analyzing the real time PMT data. This experiment revealed that during the efflux process, the anti-cancer drug (daunorubicin, DNR) decreased as the drug was pumped out of the cell because of multidrug resistance. The reversal effect of a multidrug resistance inhibitor (Sodium orthovanadate, OVN) on the cellular drug retention in single cancer cells was examined in this study. It was found that a higher cellular DNR concentration was resulted when OVN was present.