One limitation in the development of biosensors for the early detection of disease is the availability of high specificity and affinity ligands for biomarkers that are indicative of a pathogenic process. Within the past 10 years, biopanning of phage displayed peptide libraries on intact cells has proven to be a successful route to the identification of cell-specific ligands. The peptides selected from these combinatorial libraries are often able to distinguish between diseased cells and their normal counterparts as well as cells in different activation states. These ligands are small and chemical methodologies are available for regiospecific derivatization. As such, they can be incorporated into a variety of different diagnostic and therapeutic platforms. Here we describe the methods utilized in the selection of peptides from phage displayed libraries by biopanning. In addition, we provide methods for the synthesis of the selected peptides as both monomers and tetramers. Downstream uses for the peptides are illustrated.