"Proteins are crucial structural and functional elements of life, and frequent targets of intervention. Short protein sequences, conventionally defined as peptides, have emerged as indispensable tools in biotechnology: peptides may represent short linear protein structures, and in some cases they even mimic more complex discontinuous structures. Custom-made synthetic peptides cost down to ca. 30 EURO (decamer, few mg, moderate purity); yet, a comprehensive screening program can easily cost 100,000'es of EUROs, and the cost of the screening program may itself be prohibitive due to the logistics of assaying many individual peptides. Thus, the pharmaceutical and biotechnology industries, as well as academia, encounter significant economic and logistical barriers, when they attempt to apply peptide-based screening programmes in the exploitation of ""-omics"" information. In the current proposal, we will use novel photochemistry to synthesise large arrays of peptides on chips the size of a stamp (from a few thousand up to more than a hundred thousand defined peptides) reducing the cost of synthesis to a few cents per peptide. To detect analyte interactions with individual peptide moieties, we use both label-dependent optical detection (10e4 to 10e5 different peptides per chip), as well as label-independent recording of binding kinetics measuring rates and strengths of interactions simultaneously for up to 2000 peptides. Bioinformatics will be used to interpret microarray data, and guide the design of subsequent iterative peptide microarrays thereby greatly enhancing the number of peptide specificities that otherwise can be handled at the level of a single peptide chip. This will allow acquisition of peptide and protein data at an unprecedented scale and quality, at a fraction of the cost and time associated with other current technologies. For the SME's, this project will support their innovation and validation, and provide significant new market possibilities."