What are the principles of DNA microarray?

DNA microarrays are based on the principle of the hybridization between nucleic acid strands. Complementary nucleic acid sequences have traits that allow them to specifically bind to each other by the formation of hydrogen bonds between the complementary nucleotide base pairs. Unknown samples of DNA sequence are known as the sample and the known sequence of DNA is called the probe. Fluorescent dyes are used for the labeling of samples, and at least 2 samples are hybridized to the chip. Non-specific binding sequences are washed off, and only the strongly paired strands will remain hybridized. Then the fluorescent labeled target sequence that is paired to the probe lets out a signal that relies on the strength of hybridization. After hybridization is completed, the surface of the DNA chip can be analyzed both quantitatively and qualitatively by using autoradiography, enzyme detection system, fluorescence detection system or laser scanning.