For example, the amino groups of peptides, proteins, RGD peptides, endothelial cell adhesion molecules (ECAMs), and YIGSR peptides may be coupled to hydroxyl groups using chemistries known to those skilled in the art including coupling by CDAP, cyanogen bromide, carbonyl diimidazole, diacid chlorides, or diisocyanates or via conversion of the hydroxyl to a leaving group such as triflate or p-tolue