Determination of the binding of non-cross-linked and cross-linked gels to living cells by atomic force microscopy.

In this study, we first proposed a method to directly measure the interaction forces between nanoparticle gels and living cells by using the atomic force microscope (AFM). This was achieved by attaching the nanoparticles to a carrier silica probe with epoxy resin and then by directly measuring the interaction force between the probe and the living cells with the AFM. We subsequently used this technique to investigate the ability of triblock copolymer nanoparticle gels to bind to living B16F10 (mouse skin melanoma) cells. We particularly studied how the copolymer composition and structure, and the introduction of chemical cross-linking affected the adhesion magnitude. We found that a gel particle was capable to bind to a living melanoma cell. The binding strength of the particle was determined by the composition of the gel particle, where a composition change appeared to affect the number and type of chemical groups on the surface of the gel that could bind to the cell. The introduction of cross-links into the gel did not decrease the adhesion ability to a cell. Instead, it was seen that the adhesion could be increased, if a cross-linker was chosen that contained chemical groups that could bind with the cell and that preferred a conformation at the surface of the particle.