Impedimetric Biosensor for the Detection of Bacterial Lipopolysaccharide Based on Lectin-functionalized Gold Nanoparticle-Graphene Composites

摘要

We developed a simple impedimetric biosensor for the detection of bacterial lipopolysaccharide (LPS) based on lectin-functionalized gold nanoparticle (AuNP)-graphene (G) composites. The effects of AuNPs on G were investigated by comparison with the sensing surface in the absence of AuNPs. The results showed that the AuNPs formed a 3D microanocomposite on G, which increased the electroactive area from 7.03 x 10(-2) to 1.41 x 10(-1) cm(2), and also increased the heterogeneous electron transfer rate, which can improve the sensitivity of the biosensor. Concanavalin A (Con A) lectin was used as a molecular recognition element because of its specific interaction toward the carbohydrate groups in LPS. The increase in electron transfer resistance was in a logarithmically direct proportion to the LPS concentration and lowered the detection limit to 600 pg/L. The fabricated biosensor achieved the detection of LPS with good sensitivity, acceptable reproducibility, and stability. This method may hold promise for potential applications in glycomic biosensing.