Figure 2.

Schematic drawings (left) and results (right) of the three ELISAs. (a) Competitive ELISA of vitronectin against RGDfK and the antagonist IAC on an integrin α_vβ₃ coated plate. The absorbance of HRP-avidin is proportional to the amount of the biotinylated vitronectin on the plate. (b) Sandwich ELISA of NS-PEG5K (control), NS-RGDfK and NSIAC on an integrin α_vβ₃ coated plates. The absorbance of HR P-avidin is proportional to the amount of the blocker PEG 5K on NS and therefore, to the number of NS binding to the integrin α_vβ₃. (c) Competitive ELISA of NS-RGDfK against RGDfK and IAC on an integrin α_vβ₃ coated plates. The absorbance of HR P-avidin is proportional to the amount of the blocker PEG5K on NS and therefore, to the number of NS binding to the integrin α_vβ₃. All values are means of duplicate assays in the three ELISA experiments.

Abbreviations: ELISA, enzyme-linked immunosorbent assay; HRP, horse radish peroxidase; IAC, 4-[2-(3,4,5,6-tetrahydro-pyrimidin-2-ylamino)-ethyloxy]benzoyl-2-(S)- [N-(3-amino-neopenta-1-carbamyl)]-aminoethylsulfonylamino-h-alanine hydrochloride; NS, nanoshell; PEG, polyethylene glycol; RADfK, Arg-Ala-Asp-D-Phe-Lys; RGDfK, Arg-Gly-Asp-D-Phe-Lys.