This Small Business Innovation Research (SBIR) Phase I project proposes to apply Multi Photon Detection technique (MPD) to quantify proteins bound to a microarray of antibodies. The first arrays will target cytokines, the important secreted proteins that regulate the immune system. The goals of this project are to create an immunoassay based protein-chip for the concurrent measurment of all the cytokines down to the level of a few zeptomole/ sample, to implement improved P-chip designs using peptide nucleic acid linkers, and to study the levels of cytokines in cell cultures and human samples. By analyzing patterns of protein expression and their post-translational modifications, correlations of functions and/or of disease states with specific protein expression patterns are expected to be established.<br/><br/>The commercial applications of this project are in the area of medical diagnostics.