Nanoparticle-Based Bio-Barcodes for the Ultrasensitive Detection of Proteins*
The development of comparable target amplification methods for proteins could substantially improve medical diagnostics and the developing field of proteomics. This chapter report a nanoparticle-based bio-barcode assay approach to detect a protein target, free prostate-specific antigen (PSA), at low attomolar concentrations. PSA was chosen as the initial target for these studies because of its importance in the detection of prostate and breast cancer, the most common cancers and the second leading cause of cancer death among American men and women, respectively. Identification of disease relapse after the surgical treatment of prostate cancer using PSA as a marker present at low levels could be extremely beneficial and enable the delivery of curative adjuvant therapies. The bio-barcode assay uses two types of probes, magnetic microparticles functionalized with PSA monoclonal antibodies and gold nanoparticles heavily functionalized with hybridized oligonucleotides.