Late detection is the primary cause of poor survival rates from cancer treatments. Many in vivo and in vitro assays used for cancer detection have limited sensitivity due to the low abundance of markers and the limited brightness of the biological label. NanoComposix has developed a new class of ultrabright and ultrastable fluorescent nanoparticle probes, utilizing surface enhanced fluorescence (SEF) to increase the light emission from fluorophores near the surface of plasmon resonant metal nanoparticles. During this research contract, SEF nanotags with emissions ranging from the blue to the near infrared will be conjugated to antibodies and peptides for high specificity targeting. The efficacy of the SEF nanotags for ultrasensitive detection will be validated in microarray assays using PSMA, PS3 and HER2;in flow cytometry assays for the detection of PMSA expressing circulating tumor cells;and in imaging for detection of OVCARS ovarian and PMSA positive cancer cells. The brightness and stability of the SEF nanotags will increase the sensitivity of detection of cancer surface markers leading to new and improved cancer diagnostics.