Figure 4

Protein sensing: (a) Fluorescence image of a three channel bilayer-coated microfluidic device. The left and center channels contained supported bilayers containing 0.5 mol% ortho-rhodamine B and 5 mol% biotin PE in POPC. The right channel was nearly identical, but the bilayer lacked biotin PE. The red dashed line corresponds to the region from which fluorescent intensity profile measurements were made before and after introduction of proteins. (b) Average channel intensity as a function of time before and after the introduction of streptavidin (blue diamonds), avidin in the bilayer with biotin-PE (red squares) and avidin in the bilayer without biotin-PE (green triangles). Experimental line profiles of the microfluidic channels before and after the addition of (c) 300 nM streptavidin, (d) 300 nM avidin and (e) 300 nM avidin into the right, center, and left channels, respectively. A 10× air objective was used for all measurements and experiments were run in 10 mM PBS buffer with 150 mM NaCl at a bulk pH of 7.2.