Highly reproducible hybridization assay of zeptomole DNA based on adsorption of nanoparticle-bioconjugate.

A nanoparticle-bioconjugate was formed by homogeneous hybridization of one polynucleotide target with two oligonucleotide probes labelled by thiol and a nanoparticle, respectively. Deposition of the nanoparticle-bioconjugate on a gold surface by thiol-gold reaction was monitored in situ by quartz crystal microbalance (QCM) and applied for flow analysis of zeptomole amounts of polynucleotide. The formation in solution and adsorption of thiolated conjugates on gold could be fast, uniform and effective, and has been successfully exploited to construct a highly reproducible and sensitive platform for detection of target sequences. Being more rapid, reproducible, sensitive and amenable to automation than previously reported microgravimetric hybridization assays, this technology has great promise for practical applications in molecular diagnostics.