A kinetic fluorometric method for the determination of nucleic acids using a ternary equilibrium system of nucleic acids—iron (III) tetracarboxy phthalocyanine–poly-lysine coupled with the oxidation reaction between hydrogen peroxide and dl-tyrosine

Abstract

Using the oxidation reaction between hydrogen peroxide and dl-tyrosine as fluorescence indication, the evident tuning effect of nucleic acids on catalytic activity of mimetic enzyme iron (III) tetracarboxy phthalocyanine (FeC 4Pc) in the presence of poly-lysine was observed and studied. The oxidation reaction between hydrogen peroxide and dl-tyrosine with FeC 4Pc as catalyst gave an intensively fluorescent compound, which has an excitation wavelength of 325 nm and an emission wavelength of 418 nm. The fluorescence was quenched by a proper concentration of poly-lysine due to its association with FeC 4Pc and consequently the descent of the catalytic activity of FeC 4Pc, but recovered by addition of nucleic acids. Under optimal conditions, the recovered fluorescence is proportional to the concentration of nucleic acids. Based on the fact, a kinetic fluorescent method was developed for the determination of nucleic acids. The calibration graphs are linear over the range 10–2000 ng/mL both for fish sperm DNA (FS DNA) and calf thymus DNA (CT DNA). The corresponding detection limits are 1.04 ng/mL for FS DNA and 1.18 ng/mL for CT DNA, respectively. Four synthetic and three real nucleic acid samples were determined with satisfactory results.