Amplified detection of DNA and analysis of single-base mismatches by the catalyzed deposition of gold on Au-nanoparticles

A novel amplification route for DNA detection based on the deposition of go ld on a 10 nm Au-colloid/avidin conjugate label acting as a 'seeding' catal yst, is described. Microgravimetric quartz-crystal-microbalance measurement s are employed to transduce the catalyzed deposition of gold on the piezoel ectric crystals. Three different DNA detection schemes are described: (i) a nalysis of a 27-base nucleic acid fragment; (ii) analysis of the entire M13 phi DNA (7229 bases); and (iii) detection of a single-base mismatch in a D NA. Ultrasensitive detection of DNA is accomplished by the catalyzed deposi tion of gold, detection limit similar to 1 x 10(-15) M.