ANALYSIS OF BIOSENSOR CHIPS FOR IDENTIFICATION OF NUCLEIC-ACIDS

Two novel DNA-sequencing methods are described that use DNA hybridizat ion biosensor chips. These two techniques involve either labeling the free nucleic acid with enriched stable isotopes or hybridizing DNA wit hout labels to immobilized peptide nucleic acid (PNA) and detecting th e phosphorus present in the DNA but not in the PNA. Sputter-initiated resonance ionization microprobe analysis was used to detect the presen ce of enriched tin isotope-labeled DNA and of phosphorus in natural DN A as a means to identify the presence of DNA after hybridization to ol igodeoxynucleotides (ODNs) or PNAs, respectively, immobilized on a bio sensor chip. The data clearly demonstrate that excellent discriminatio n between complementary and noncomplementary sequences can be obtained during hybridization of DNA to either ODNs or PNAs. The capability to detect different enriched stable isotope-labeled DNAs simultaneously allows high degrees of multiplexing which may be very advantageous for hybridization kinetics studies in complex systems, as well as signifi cantly increasing the speed of analysis. Alternatively, by using natur al DNA with PNA biosensor chips, discrimination for single-point mutat ion could be increased because of improved hybridization kinetics and direct analysis of genomic DNA may become possible without amplificati on, Both methods have the potential to provide a rapid method for DNA/ RNA sequencing, diagnostics, and mapping.