In Situ Study of the Drug-Target Protein Interaction in Single Living Cells by Combining Fluorescence Correlation Spectroscopy with Affinity Probes.

The drug-target protein interaction is the basis of drug screening and precise therapy in modern clinical medicine. How to acquire the information about the drug-target protein interaction in single living cell is a great challenge due to the shortage of efficient methods. Here we propose a new strategy for in situ studying the drug-target protein interaction in single living cells based on the competition of candidate drugs to the fluorescent probe-target complexes and fluorescence correlation spectroscopy (FCS) with a microfluidic chip. In this study, we used ABL kinase (target) as a model and synthesized a fluorescent probe (Cy3-dasatinib) with an affinity to the target using ABL inhibitor dasatinib as a precursor. We systematically investigated the association of the probe with targets and the dissociation of the drug-target complexes in the presence of candidate drug. We presented a new parameter IC