▎ 摘　　要

NOVELTY - Preparation of dual-ratio biosensor involves (1) dissolving anthraquinone (AQ) and reduced graphene oxide (rGO) in ultrapure water, obtaining AQ dispersion and rGO dispersion, mixing, dispersing in ultrapure water, obtaining AQ-rGO composite material dispersion, (2) taking glassy carbon electrode and grinding with aluminum oxide powder of different particle sizes, obtaining polished glassy carbon electrode, ultrasonically processing in ethanol and water and drying in air, obtaining treated glassy carbon electrode (GCE), (3) modifying the AQ-rGO composite material dispersion to the surface of the treated glassy carbon electrode, naturally drying at room temperature, obtaining modified glassy carbon electrode (AQ-rGO/GCE), (4) modifying gold nanoparticles on the sensing interface of AQ-rGO/GCE, obtaining modified material, (5) mixing ferrocene labeled linear aptamer (Fc-apt) and methylene blue labeled hairpin aptamer (MB-HR), reacting, modifying, heat-preserving, and fixing. USE - Preparation of dual-ratio biosensor for detecting aflatoxin B1 (claimed) in food. ADVANTAGE - The method produces dual-ratio biosensor with high detection sensitivity and stability. Compared with the hairpin aptamer, the binding effect of the linear aptamer with their target aflatoxin B1 is more likely to occur, therefore, the target aflatoxin B1 concentration causing the hairpin aptamer to carry the change of the MB signal molecule can be used as the concentration point of the qualitative analysis of aflatoxin B1. The qualitative analysis of aflatoxin B1 in the food is realized. DETAILED DESCRIPTION - Preparation of dual-ratio biosensor involves (1) dissolving anthraquinone (AQ) and reduced graphene oxide (rGO) in ultrapure water, obtaining AQ dispersion and rGO dispersion, using cell shredder to process the rGO dispersion, mixing the treated rGO dispersion with the AQ dispersion, magnetically stirring, centrifuging and water washing, obtaining AQ-rGO composite material, dispersing in ultrapure water, obtaining AQ-rGO composite material dispersion, storing at room temperature for later use, (2) taking the glassy carbon electrode and grinding with aluminum oxide powder of different particle sizes in sequence, obtaining polished glassy carbon electrode, ultrasonically processing in ethanol and water and drying in air, obtaining treated glassy carbon electrode (GCE), (3) modifying the AQ-rGO composite material dispersion prepared in step (1) to the surface of the treated glassy carbon electrode in step (2), naturally drying at room temperature, obtaining modified glassy carbon electrode (AQ-rGO/GCE), (4) modifying gold nanoparticles on the sensing interface of AQ-rGO/GCE prepared in step (3), obtaining modified material, (5) mixing ferrocene labeled linear aptamer (Fc-apt) and methylene blue labeled hairpin aptamer (MB-HR), reacting under certain temperature conditions, obtaining solution (Fc-apt-MB-HR), modifying Fc-apt-MB-HR on the sensing interface of the modified material, heat-preserving, and fixing. An INDEPENDENT CLAIM is included for usage of the dual-ratio biosensor for detecting aflatoxin B1, which involves using the dual-ratio biosensor, different concentrations of aflatoxin B1 solution, Tris-hydrochloric acid solution, saturated silver/silver chloride electrode as reference electrode, and platinum wire electrode as counter electrode, and phosphate-buffered saline buffer solution.