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 Cu2+–nuclear fast red complex in the presence of guanine in Tris–HCl buffer. The complex of Cu2+ 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 Cu2+, 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%.