Nanoscale patterning of antigen on silicon substrate to examine mast cell activation

Rat Basophilic Leukemia (RBL) cells are immobilized and stimulated on micro- and nanometer scale patterns of supported lipid bilayers. The patterns are realized as the photolithographically patterned polymer is mechanically peeled away in one contiguous piece in solution. The 0.36 μm² to 4,489 μm² patches can contain both fluorescent lipids and lipid-linked antigen and provide a synthetic biological substrate for analysis of cell surface receptor-mediated events. 100-nm unilamellar lipid vesicles spread to form a supported lipid bilayer on a thermally oxidized silicon surface as confirmed by fluorescence recovery after photobleaching (FRAP). Aggregation of fluorescently labeled receptors is observed as their coincidence with the patterned antigen. Cell morphology is analyzed with scanning electron microscopy (SEM). Thus, a novel method has been developed for patterning antigen, capturing and immobilizing cells via specific receptors, and spatially controlling antigenic stimulus on the nanoscale.