A microplate assay for K-ras genotyping.

The paper presents a microplate hybridisation assay for the detection of codon 12 mutations of the K-ras protooncogene. Single-stranded target DNA, obtained from amplifying sample DNA with 5'-biotin and 5'-digoxigenin-labelled primers and subsequent strand separation, is hybridised with solid phase-fixed capture probes complementary to wild-type and mutated forms of K-ras. After stringent washing the duplex DNA is detected by an ELISA-like protocol incorporating photometric, fluorometric or luminometric detection. Application examples are shown in which the K-ras status was examined in peripheral blood cells, cell cultures, fresh and paraffin-embedded tumour tissue and in stool samples.

Quantitative polymerase chain reaction using a DNA hybridization assay based on surface-activated microplates.

A method for DNA quantification on microplates based on the hybridization between single-stranded target and solid-phase bound capture DNA is presented. Binding of the capture DNA to the microplates was attained by surface activation using organosilanes. Detection of hybridized DNA was performed by an enzyme-linked assay taking advantage of the labeled target DNA. Basic test characteristics are described and application examples are given demonstrating its feasibility for a quantitative PCR (QPCR). The QPCR was carried out by coamplifying an immunoglobulin complementarity determining region 3 (CDR3)-coding plasmid DNA with a synthetic internal standard (IS). IS and plasmid CDR3 both shared primer binding sites and produced length-identical amplicons. The amplified DNA was quantified following differential hybridization with IS- and plasmid-specific capture probes. Based on the product ratios of plasmid to IS, the initial amounts of plasmid DNA were calculated. This way, QPCR was shown to be capable of detecting initial concentration differences of plasmid DNA of about 30%.