Position-specific release of DNA from a chip by using photothermal denaturation

A photothermal method to recover specific DNA fragments fixed in place on a DNA chip is described. This method uses infrared (IR) laser irradiation to thermally denature and release specific DNA immobilized in a specific area of a chip. A 1053-nm IR laser beam with an intensity of 10–100 mW is focused on the target area at a resolution of 10 μm, and the DNA fragments are released from the chip surface. We have demonstrated that DNA fragments containing different numbers of base pairs (231–799 bp) fixed in place on the DNA chip can be separately recovered. There are enough quantities of recovered DNA fragments that can be amplified by using polymerase chain reaction (PCR). The photothermal method coupled with the DNA chip can therefore be used in highly sensitive purification of DNA and will have many applications in the DNA chip technology.