K-ras Mutation Detection by Hybridization to a Polypyrrole DNA Chip

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Abstract
Background: Detection of mutations in cancer-related genes is of major importance for both basic knowledge and clinical practice. Several strategies have been developed to diagnose these alterations. We describe a method based on polypyrrole DNA chip technology to detect K-ras gene mutations in tumors. Methods: An oligodeoxynucleotide array was constructed on a silicon device by copolymerization of 5′-pyrrole-labeled oligodeoxynucleotides and pyrrole. The samples to be analyzed were then amplified by PCR, and the single-stranded biotin-labeled amplified DNA was specifically hybridized to the addressed probes. Perfectly matched duplexes were detected by fluorescence microscopy using R-phycoerythrin as the detection label. The developed methodology was applied to genotype assignment of K-ras in human samples. The genotypes of 75 DNA genomic samples from colorectal cancer patients were analyzed side by side using direct DNA sequencing and a polypyrrole DNA chip. Results: The chip method unequivocally defined all of the genotypes. Mutations present at Conclusions: This probe array assay is a rapid and reliable procedure that may be used to detect mutations.