The objective of this contract is to develop a magnetic nanosensor platform originally invented at Stanford University and subsequently licensed to MagArray, Inc. It is close to homogeneous assay format as opposed to heterogeneous assay format and thus will provide speed, convenience and less consumed reagents. Furthermore, the magnetic array reader is of high sensitivity, low cost, and shoe box size. These desirable attributes will eventually allow MagArray to rapidly, quantitatively, and cost-effectively assess the abundance of tumor markers in cancer patients. The technology essentially includes three steps: First, protein or DNA targets are selectively captured using antibody (or oligo) probes on the surface of an array of magnetic sensors (called spin valve sensors, similar to the read heads in computer hard disk drives). Then, the targets are recognized using secondary biotinylated antibodies/oligos. Finally, the secondary antibodies/oligos are 'stained' with magnetic nanotags coated with streptavidin. The spin valve sensors will detect the tiny magnetic fields generated only by the magnetic nanotags (10-100 nm in diameter) bound to the sensor surface, so the sensor array can be interrogated electronically to identify and quantify the protein/DNA targets with no or minimal washing steps to remove the magnetic nanotags not bound to the sensor surface.