Figure 1.

In vitro testing of the MN-Ex10-Cy5.5 probe. A: Cell-binding assays showed concentration-dependent preferential uptake of experimental MN-Ex5-Cy5.5 and MN-Ex10-Cy5.5 probes by the β-cell line compared with the control probe. There was no difference in uptake between the experimental and control probes by the pancreatic carcinoma cell line (control). B: Competition assays showed that accumulation of the experimental probes was dose-dependently blocked by free exendin-4 peptide. Fluorescence microscopy demonstrated concentration-dependent internalization of experimental probe in the βTC-6 cells (C) and in intact murine islets (D). Accumulation of the control probe was negligible in both cells and isolated islets (red, Cy5.5 dye; blue, DAPI nuclear stain). Magnification bar = 50 μm.