Fig. 1

Selective biotin retention on the surface of brain endothelial cells. Biotin tags were placed on the surface of primary endothelial cells derived from rat liver, lung or brain through conjugation of biotin-NHS with primary amines of cell-surface proteins. After incubating cells at 37 °C for varying time-points to allow for the endocytic removal of the biotin tags, the remaining cell-surface biotin was measured through binding of avidin-FITC (a). Endothelial targeting by differential retention of cell-surface biotin tags was assessed by the ratio of avidin-FITC binding between different cell types with time (b). Results are displayed as mean ± SEM, n = 2 independent experiments (intercalating time-points), triplicate measures. One-phase decay non-linear regression