Fluorescent silver nanoclusters stabilized in guanine-enhanced DNA hybridization for recognizing different small biological molecules

Fluorescent DNA-stabilized Ag nanoclusters (DNA/Ag NCs) plays significant roles in biochemical detections due to their high fluorescence quantum yield, high stability and good biocompatibility. In this paper, two guanine-enhanced fluorescence DNA-stabilized silver nanoclusters were designed to study the effect of guanine coating degree on silver nanoclusters fluorescence and their interactions with small biological molecules. The results indicated that the degree of guanine coating had a slight influence on the fluorescence of the two DNA/Ag NCs, however, the two DNA/Ag NCs had different fluorescence response when interacting with different small biological molecules. The fluorescence of the DNA/Ag NCs wrapped in the guanine-rich strand could be quenched by small biomolecules such as ascorbic acid, dopamine and cysteine, while the fluorescence of the DNA/Ag NCs approached to the guanine-rich strand could only be quenched by dopamine and cysteine. Based on this interesting phenomenon, an analytical method for recognition of ascorbic acid, dopamine and cysteine from other small biological molecules can be established by measuring the fluorescence change of DNA/Ag NCs and a method for selective detection of ascorbic acid in the absence of dopamine and cysteines can be achieved by combining the two DNA/Ag NCs probe.