Nuclear fast red as highly sensitive "off/on" fluorescent probe for detecting guanine.

A novel fluorescence method for the determination of guanine was developed based on the fluorescence enhancement of Cu(2+)-nuclear fast red complex in the presence of guanine in Tris-HCl buffer. The complex of Cu(2+) with nuclear fast red resulted in a dramatic quenching of the fluorescence intensity. Nuclear fast red were dissociated from the complex with the addition of guanine due to the strong interaction between guanine and Cu(2+), which caused the fluorescence enhancement. The enhanced fluorescence intensity was well proportional to the concentration of guanine in the range of 4.96 × 10(-8)-1.09 × 10(-6)mol/L with the limit of detection 1.9 × 10(-8)mol/L. The method has been applied successfully to the determination of guanine in serum and DNA samples, and the recoveries were from 96.0% to 104.8%.