▎ 摘　　要

The detection of allergen sulfite is essential for food quality control and public health supervision. Here, a high-performance sulfite biosensor was developed from a sulfite oxidase enzyme (SOx) immobilized on silver nano-particles (AgNPs) decorated on 3D reduced graphene oxide (3D-rGO). 3D-rGO with high specific pore volume and high electroactive surface area is ideal as a supporting material. AgNPs further provide high electrical conductivity or fast charge transfer and serve as an enzyme anchoring site via a stable thiol bonding. The composite material was initially functionalized with the folic acid and cysteine namely rGO@Ag-Cys-FA before immobilized with the SOx. The resultant rGO@Ag-Cys-FA-SOx exhibits high sensitivity and selectivity towards sulfite detection, high bio-electrocatalytic activity, and fast heterogeneous electron transfer rate constant. The biosensor is also tested in a continuous flow injection system to demonstrate the practical use. Besides, the as-produced sensor in this work can be used in the real sample, which is the canned fruit product indicating its potential practical application.