Programmed Self-Assembly of a Biosensor to Probe Cell Adhesion Interactions

Rarely in Nature are single molecule interactions used for cell adhesion. Rather, several different types of molecules or structures interact in concert to build effective adhesion. We are developing a biosensor that can probe the range of interactions from the single molecule level to the ensemble average of multiple interactions. To achieve this goal we have harnessed specificity to effect programmed self-assembly of magnetic particles. Using polymer linkers, we construct magnetic particle self-assemblies between a ligand and a membrane bound receptor. Through application of an external magnetic field, a force is exerted on the magnetic particles of the assembly. Particles are selectively removed via the external magnetic field based upon their binding force with the functionalized surface of model cell membranes. Using this technique, we report binding forces measured in the piconewton range. We show preliminary data indicating the efficiency of such a biosensor construction and propose its use for both the measurement of ligand-receptor binding strength and its potential application for the elucidation of cell adhesion mechanisms and mechanics.