The specific aims of this project are to develop new photoremoval silyl groups and 2-photon protecting groups. These or other photoremoval groups will be used in the optimized in situ synthesis of DNA sequences at specific locations on a surface. A new version of APEX (arrayed primer extension) will be developed that uses RNA templates and reverse transcriptase to detect and analyze RNA sequences using DNA primer arrays. Caged biotin and caged iminodiacetic acid/nitrilotriacetic acid (IDA/NTA) will be applied to the fabrication of multichannel arrays of biosensor proteins, including carbonic anhydrase and antibodies. Molecular photolithography will be used to create patterned and gradient surfaces of cell adhesion and chemotactic molecules. Novel patterned protein and cell immobilization methods will be investigated involving caged aldehydes (via our previously-developed dimethoxybenzoylformate (DMBF) group). A caged chemotactic peptide will be prepared.