Non-Destructive Label-Free Monitoring of Drug Intake in Live Cells using ATR FT-IR Spectroscopy

Abstract

Drug resistance is one of the major challenges in treatment of cancer. The study of the intake of drugs by cancer cells therefore is vital for elucidating the mechanism of drug resistance. Currently to quantify the intake of drugs involve destructive methods such as lysing the cell at each time point of analysis followed by UV-Vis or fluorescence measurements. With this approach, different batches of cell are used for each time point, increasing the biological variability, and it is not possible to perform further analysis on the same cell sample. Attenuated total reflection Fourier transform infrared (ATR FT-IR) is a promising non-destructive label-free while chemically specific technique for analysis of biomedical samples. In this work we demonstrated the quantification of drugs (e.g. doxorubicin), in situ, using the ATR FT-IR method to obtain the drug diffusion profile in the live cell. HeLa cells grown on a multi-bounce ATR crystal were treated with 20 micromolar of doxorubicin, a concentration level that is relevant to cancer studies, and FT-IR spectra were collected in a time course using a MCT detector. Quantification of doxorubicin in the cell was made using the signature peak at 1284 cm-1 showing the accumulation of the drug in cells as a function of time.The results from the ATR FT-IR measurements have shown that the doxorubicin concentration in the living cell increases from 0 to >50 micromolar after 2 hours of treatment demonstrating the partitioning effect of the drug in the cell. Furthermore, the cells also present a signature spectrum, which allows to follow the cell viability in parallel with the drug intake. This is a fast, cost-effective and chemically selective method which does not require sophisticated equipment and can be adapted easily.