The process begins a DNA chip array assay by hybridizing the target sample with DNA on the chip. Hybridization occurs when the fluorescent labeled target DNA finds complementary portions within the DNA array. Hybridization conditions depend on the length of the probe, the chemical content of the labeled target, temperature and concentration of the reaction, and type of fluorescent label. The goal of DNA chip developers is to enhance the hybridization reaction with different types of probes, DNA chip surfaces, and hybridization. Detection The Affymetrix fluorescence detection system requires a laser confocal scanning instrument.
Fluorescent detection is convenient and cost effective.
Affymetrix expression monitoring technologies detect 1 in 100,000 nucleotides. Some manufactures of DNA chip technologies use radioactive labeling and variations on the fluorescent probe method to detect hybridization patterns. Enhancing detection methods is also a current research goal of array manufactures. Microspheres are microscopic beads that carry molecules required to perform diagnostic tests on their surface. The microspheres are carboxylated to allow coupling of DNA or protein.