Nanogen, Inc.

Ling Wang

Xiao Xu

Michael James Heller

James P O'Connell

Ronald George Sosnowski

Michael I Nerenberg

Ray R Radtkey

David Canter

Elaine M Weidenhammer

Brenda F Kahl

This application includes methods for detecting single nucleotide polymorphisms (SNPs) in a sample using an electronically addressable microchip having a plurality of test sites. A sample nucleic acid is electronically biased, concentrated at, and immobilized to a test site on the microchip. A mixture comprising a first labeled probe and a second labeled probe is electronically hybridized to the sample nucleic acid to form first or second hybridized complexes. The first labeled probe is perfectly complementary to the first sample nucleic acid and the second labeled probe is complementary to the sample nucleic acid and contains a nucleotide that forms a mismatch with the nucleotide at the site of the polymorphism. The first or second hybridized complexes are detected by determining a signal intensity of the label of the first or second probe.

Methods for determination of single nucleic acid polymorphisms using a bioelectronic microchip

The present invention presents techniques useful in methods for gene expression monitoring, and other nucleic acid hybridization assays, that utilize microelectronic arrays to drive the transport and hybridization of nucleic acids. Particularly, methods for normalizing the signals of individual microlocations by the use of an internal control sequence probe are provided. These methods are particularly useful for hybridization assays in which a quantitative comparison of the hybridization of several different sequences at a plurality of microlocations is desired, such as in gene expression analyses.

Quantitative analysis methods on active electronic microarrays

Methods are provided for the analysis and determination of the nature of single nucleic acid polymorphisms (SNPs) in a genetic target. In one method of this invention, the nature of the SNPs in the genetic target is determined by the steps of providing a plurality of hybridization complexes arrayed on a plurality of test sites on an electronically bioactive microchip, where the hybridization complex includes at least a nucleic acid target containing a SNP, a stabilizer probe having a sequence complementary to the target sequence and/or reporter probe, and a reporter probe having a selected sequence complementary to either the stabilizer or the same target sequence strand wherein a selected sequence of the reporter includes either a wild type nucleotide or a nucleotide corresponding to the SNP of the target. In accordance with the invention, the stabilizer, reporter and target amplicons are hybridized using electronic assistance of the microchip system such that base-stacking energies are utilized in discerning among other identifying indicators, the presence of wild type or polymorphism sequence. Applications include disease diagnostics, such as for the identification of polymorphisms in structural genes, regulatory regions, antibiotic or chemotherapeutic resistance conferring regions, or for SNPs associated with speciation or used for determination of genetic linkage.

Methods for determination of single nucleic acid polymorphisms using bioelectronic microchip

The present invention presents methods for gene expression monitoring that utilize microelectronic arrays to drive the transport and hybridization of nucleic acids. Procedures are described for generating mRNA expression samples for use in these methods from populations of cells, tissues, or other biological source materials, that may differ in their physiological and/or pathological state. Provided in the invention are methods for generating a reusable nucleic acid transcript library from mRNA in a sample of biological material. In order to improve gene expression monitoring on the microelectronic arrays, the transcripts are amplified to produce sample nucleic acid amplicons of a defined length. Because multiple sample amplicons may be selectively hybridized to controlled sites in the electronic array, the gene expression profiles of the polynucleotide populations from different sources can be directly compared in an array format using electronic hybridization methodologies. Also provided in the invention are methods for detecting the level of sample amplicons using electronically assisted primer extension detection, and utilizing individual test site hybridization controls. The hybridization data collected utilizing the improved methods of the present invention will allow the correlation of changes in mRNA level with the corresponding expression of the encoded protein in the biological source material, and thus aid in studying the role of gene expression in disease.

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San Diego, CA, United States of America

Ling Wang