Analytical prospect of compact disk technology in immunosensing.

A sensitive and versatile methodology involving recordable compact disks as molecular screening surfaces and a standard optical CD/DVD drive as detector, is reported. Quantitative immunoanalysis, in microarray format, of a cancer marker (alpha-fetoprotein, AFP) and a selective herbicide (atrazine) on four types of audio-video disc was conducted. Enzyme or gold nanoparticle-labeled antibodies were used as tracers, forming a precipitate on the sensing disk surface. The principle of disk reading is based on capture of analog signals with the disk drive that were proportional to the darkness of the immunoreaction product. Detection limits for AFP (8.0 microg L(-1)) and for atrazine (0.04 microg L(-1)) were under the threshold needed to detect nonseminomatous testicular cancer, and below the maximum E.U. residue limit for drinking water, respectively. The described methodology improves the previous developments using CDs and highlights the enormous potential of immunoassay methods using standard audio-video disk surfaces in combination with the CD/DVD drive for clinical analysis, drug discovery, or high-throughput multiresidue screening applications.