kT-Scale interactions between supported lipid bilayers.

We use total internal reflection microscopy (TIRM) and confocal laser scanning microscopy (CSLM) to study supported lipid bilayer (SLB)-modified silica colloids with various SLB compositions (e.g., PEGylated vs. non-PEGylated) that control colloidal and bilayer stability. Measured and predicted potentials accurately capture stable configurations. For unstable conditions when SLBs adhere, fuse, or spread between surfaces, SLB structures are connected to effective potentials as well as time-dependent behavior. In all cases, directly measured and inferred interactions are well described by steric interactions between PEG brushes and van der Waals weakened by substrate roughness. Our findings quantify non-specific kT-scale interactions between SLB-modified colloids and surfaces, which enables the design of such systems for use in biomedical applications and studies of biomolecular interactions.