Surface plasmon resonance characterization of drug/liposome interactions.

Using Biacore's surface plasmon resonance-based biosensor technology, we developed experimental protocols and probed test conditions required to study drugs interacting with liposome surfaces. Liposome capture on hydrophobic alkane surfaces (Pioneer L1 chip) was reproducible and stable under variable conditions of pH, temperature, lipid content, cholesterol content, and buffer dimethylsulfoxide concentration. Importantly, drug binding responses were directly proportional to the amount of lipid captured, while the kinetics of drug binding and the magnitude of the responses correlated with a drug's chemical composition. In general, anionic drugs tended to rapidly dissociate from the surface, while cationic drugs displayed heterogeneous binding, suggesting partitioning within the lipid bilayer itself. The results illustrate how surface plasmon resonance can be used to establish passive transport properties of drugs.