AVS 46th International Symposium
    Biomaterial Interfaces Group Wednesday Sessions
       Session BI-WeP

Paper BI-WeP18
Genetic Diagnostics Using SIMS Detection of Unlabeled DNA

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: T.J. Whitaker, Atom Sciences, Inc.
Authors: T.J. Whitaker, Atom Sciences, Inc.
K.F. Willey, Atom Sciences, Inc.
Correspondent: Click to Email
We are developing a new DNA chip technology that uses secondary ion mass spectrometry (SIMS) to determine genetic diagnostic information from unlabeled DNA. Genosensor chips, or DNA chips, typically contain arrays of single-stranded oligodeoxynucleotide (ODN) probes. Each probe has a known sequence and is attached at a specific site on the chip. The sequence of an unknown target DNA is determined by binding single strands of the target to the probes. This binding, or hybridization, ideally will occur only where the target sequence is complimentary to the probe sequence. Evidence of the binding is generally obtained by detecting fluorescent or radioactive labels attached to the target DNA. The new technology uses peptide nucleic acids (PNA) instead of ODNs for the probes. PNA is a DNA analog in which the phosphate and deoxyribose are replaced with polyamides. PNA binds to DNA with the same A-T, G-C rules as DNA/DNA hybrids but has slightly higher melting temperatures, offering the potential for greater discrimination between single-base mismatches. As opposed to DNA, which contains one phosphate along the backbone at each base, PNA contains no phosphorus. We have exploited this difference by using a simple SIMS analysis to detect molecular fragments containing phosphorus. The existence of phosphorus positively identifies the hybridization of unlabeled DNA to PNA probes. This method and a simplified, relatively inexpensive SIMS instrument are currently being developed under funding from the National Institutes of Health.@footnote 1@ @FootnoteText@ @footnote 1@This work is supported by the National Institutes of Health under contract 2 R44 HG01596-02. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health.