To describe a new high sensitivity, nanotechnology‐based technique for detecting DNA and disease‐related proteins.
Gold nanoparticles and magnetic microparticles are bound to single‐stranded DNA molecules that are complementary to segments of the target DNA. The nanoparticles also link to hundreds of strands of “barcode” DNA and in the presence of the target, each molecule binds to a gold nanoparticle and a magnetic microparticle. Applying a magnetic field enables the separation of the target molecules and their attachments. The DNA is removed from the molecules and detected by a chip‐based DNA procedure. As each nanoparticle links to a large number of strands of DNA, the method amplifies the signal from each target molecule. The technique can also detect proteins by replacing the complimentary DNA with antibodies.
This research shows that this technique can detect very low concentrations of DNA and proteins. Ten copies of anthrax DNA were detected in 30 μl of solution, a sensitivity comparable to polymerase chain reaction, and 18‐20 PSA molecules were detected in a 10 μl sample, a level of detection that is six orders of magnitude more sensitive than conventional assays. Recent research has also shown that the assay can detect ADDLs, which are biomarkers for Alzheimer's disease. The technologies are now being commercialised by Nanosphere, Inc.
These developments offer prospects in a wide range of clinical applications such as the rapid and simple diagnosis of a variety of diseases and single nucleotide polymorphisms tests for the detection of hypercoagulation disorders. Other potential applications include homeland security and environmental monitoring.
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