Nanoparticle-Based Bio-Barcode Assay Redefines “Undetectable” PSA and Biochemical Recurrence after Radical Prostatectomy*
This chapter reports the development of an undescribed gold nanoparticle bio-barcode assay probe for the detection of prostate-specific antigen (PSA) at 330 fg/mL, automation of the assay, and the results of a clinical pilot study designed to assess the ability of the assay to detect PSA in the serum of 18 men who have undergone radical prostatectomy for prostate cancer. Ultrasensitive prototype assays have been used to retrospectively interrogate the serum of men postprostatectomy to test the hypothesis that more sensitive PSA assays increase the prevalence of postprostatectomy PSA detection and identify biochemical recurrence with substantial lead times. The bio-barcode assay is an emerging diagnostic tool, based on advances in nanotechnology, used for the enzyme-free ultrasensitive detection of various protein and nucleic acid targets. In the case of proteins, the bio-barcode assay can be between one and six orders of magnitude more sensitive than conventional ELISA-based assays, depending on target and sample complexity.