▎ 摘　　要

Graphene deposited with silver nanoparticles (AgNPs-beta-CD-Gr) has been synthesized by thermal reduction of graphene oxide and silver nitrate via beta-cyclodextrin (beta-CD). It offers a simple, green, and efficient procedure to yield nanocomposites with silver nanoparticles anchored on graphene support, uniformly and stably. Guanine and adenine were simultaneously detected on the modified electrode (AgNPs-beta-CD-Gr/GCE) by differential pulse voltammograms. The AgNPs-beta-CD-Gr/GCE obviously improved the voltammetric response of guanine and adenine demonstrating that the synergistic effect of silver nanoparticles and graphene can significantly enhance the detecting sensitivity of guanine and adenine. The electrochemical biosensor based on AgNPs-beta-CD-Gr exhibits wide linear ranges of 0.3-200 and 0.5-250 mu M with detection limits of 0.09 and 0.15 mu M for guanine and adenine, respectively. The proposed method was also applied for the measurement of trace-level of these purine bases in herring sperm DNA (dsDNA). The results suggest that the nanocomposite has a potential application for electrocatalytic biosensing.