Fishing for Proteins

"Fishing" turns out to be a fast, simple, and ultrasensitive method of protein detection, which researchers have demonstrated on prostate specific antigen (PSA), according to a new report published in the 26 September issue of the journal, Science. Detecting PSA at extremely low concentrations could permit early detection of recurrent prostate cancer in men and perhaps breast cancer in women, say authors Jwa-Min Nam and others.

The researchers' fishing tackle included a "hook" in the form of gold nanoparticles carrying DNA tags and "bait" in the form of latex microparticles with iron oxide cores that carry PSA antibodies. Together, the two kinds of particles attract and capture the "fish" or protein, and the PSA binds with the DNA.

The team could then separate their quarry from the gear using a magnetic field and a simple wash step, and identify the protein by analyzing the liberated DNA sequence. Although the PSA system was used for proof-of-concept, note the authors, the approach should be applicable to almost any target with known antibodies.

—Laura Kennedy

26 September 2003