One-pot green synthesis of Ag nanoparticles-graphene nanocomposites and their applications in SERS, H2O2, and glucose sensing

In this contribution, we demonstrate a green, cost-effective, one-pot preparative route toward Ag nanoparticles-graphene (AgNPs–G) nanocomposites in aqueous solution with the use of tannic acid (TA), an environmentally friendly and water-soluble polyphenol, as a reducing agent. Such AgNPs–G nanocomposites were synthesized through one-pot reduction of AgNO3 and GO by TA. We investigated surface enhanced Raman scattering (SERS) and electrochemical properties of the resultant AgNPs–G nanocomposites. It is found that such AgNPs–G nanocomposites show excellent SERS activity as SERS substrates and exhibit notable catalytic performance toward the reduction of H2O2. This enzymeless H2O2 sensor has a fast amperometric response time of less than 2 s. The linear range is estimated to be from 1 × 10−4 M to 0.01 M (r = 0.999) and the detection limit is estimated to be 7 × 10−6 M at a signal-to-noise ratio of 3. A glucose biosensor was further fabricated by immobilizing glucose oxidase (GOD) into chitosan–AgNPs–G nanocomposite film on the surface of a glassy carbon electrode (GCE). This sensor exhibits good response to glucose, and the linear response range is estimated to be from 2 to 10 mM (R = 0.996) at −0.5 V. The detection limit of 100 μM was achieved at a signal-to-noise ratio of 3. More importantly, we demonstrate successfully its application for glucose detection in human blood serum.