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. 2023 Dec 4;39(50):18410–18423. doi: 10.1021/acs.langmuir.3c02567

Figure 2.

Figure 2

Tuning of the surface densities of two biotinylated species of similar size. (A) Schematic drawing of the surface functionalization: ① SLB formation, ② streptavidin (SAv) monolayer formation, and ③ co-adsorption of b-FITC and biotin. (B) Fluorescence intensity at saturation, normalized against the intensity at full b-FITC coverage, measured with confocal microscopy for surfaces functionalized with different mixing ratios of b-FITC and biotin. The horizontal axis shows the fractional surface coverage, Γb-FITC,sat/Γas, of the b-FITC fluorophore (co-adsorbed with free biotin) predicted according to eq 4. The linear trend as demonstrated by the black dashed line through the origin confirms the validity of eq 4. Conditions: cb-FITC + cbiotin = 14 μM was kept constant, with cb-FITC and cbiotin determined according to eq 4 (εstagnant < 0.25).