Spectrophotometric determination of DNA using a near infrared probe 1,1'-disulfobutyl-3,3,3',3'-tetramethylindotricarbocyanine

A direct spectrophotometric determination of DNA in solution has been developed using a near infrared probe, 1,1'-disulfobutyl-3,3,3',3'-tetramethylindotricarbocyanine (DSTCY). In pH = 7.5 Tris-HCl buffer, the reaction of DSTCY with DNA was complete within 10 min at room temperature in the presence of cetyltrimethylammonium bromide (CTAB), which leaded to a sharp increase of the absorbance at 474 nm. The concentration of DNA can be determined in such wavelength with the linear range of 0.5-8.0 microg ml(-1) and the detection limit of 45 ng ml(-1).