Highly sensitive and selective fluorescent assay for guanine based on the Cu2 +/eosin Y system

• A novel fluorescent sensor (eosin Y–Cu2 +) was shown for detecting guanine.
• The interaction of eosin Y, Cu2 + and guanine was discussed.
• The proposed method exhibits a high sensitivity and selectivity for guanine.

A fluorescent probe has been developed for the determination of guanine based on the quenched fluorescence signal of Cu2 +/eosin Y. Cu2 + interacted with eosin Y, resulting in fluorescence quenching. Subsequently, with the addition of guanine to the Cu2 +/eosin Y system, guanine reacted with Cu2 + to form 1:1 chelate cation, which further combined with eosin Y to form a 1:1 ternary ion-association complex by electrostatic attraction and hydrophobic interaction, resulting in significant decrease of the fluorescence. Hence, a fluorescent system was constructed for rapid, sensitive and selective detection of guanine with a detection limit as low as 1.5 nmol L− 1 and a linear range of 3.3–116 nmol L− 1. The method has been applied satisfactorily to the determination of guanine in DNA and urine samples with the recoveries from 98.7% to 105%. This study significantly expands the realm of application of ternary ion-association complex in fluorescence probe.

A novel fluorescent sensor, eosin Y–Cu2 + was shown for detecting guanine, based on the dramatic fluorescence quenching due to photoinduced electron transfer (PET) in complex of Cu2+–guanine–eosin Y. The proposed sensor exhibits a high sensitivity and selectivity for guanine.Figure optionsDownload as PowerPoint slide