▎ 摘　　要

NOVELTY - A three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles/(2-hydroxypropyl)- beta -cyclodextrin nanometer composite material preparing method involves preparing iron (II,III) oxide-gold nanoparticles, preparing three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles by sonicating graphene oxide, adding L-cysteine under sonication, adding ammonia water, placing in an Erlenmeyer flask, heating, filtering, lyophilizing, dispersing in water, adding iron (II,III) oxide-gold nanoparticles, stirring, washing and freeze-drying to obtain three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles. The three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles is taken into Erlenmeyer flask, added with carbodiimide hydrochloride and N-hydroxysuccinimide, stirred, added with hydroxypropyl- beta -cyclodextrin, stirred, and subjected to hysteresis separation and freeze-drying to obtain the finished product. USE - Method for preparing three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles/(2-hydroxypropyl)- beta -cyclodextrin nanometer composite material for detecting guanine and adenine (claimed). ADVANTAGE - The method enables preparing three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles/(2-hydroxypropyl)- beta -cyclodextrin nanometer composite material with low detection limit and improved modified electrode sensitivity of two purine detection. DETAILED DESCRIPTION - A three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles/(2-hydroxypropyl)- beta -cyclodextrin nanometer composite material preparing method involves preparing iron (II,III) oxide-gold nanoparticles by adding 49-51 mg iron (II,III) oxide to 40-60 mL ultrapure water, after ultrasonic dispersion, adding 170-190 mu L 3-aminopropyltriethoxysilane under nitrogen atmosphere, stirring mechanically at room temperature for 6-8 hours, washing the black precipitate repeatedly and performing hysteresis separation separating, and vacuum drying to obtain aminated iron (II,III) oxide (iron (II,III) oxide-amine), taking 19-21 mg iron (II,III) oxide-amine powder, ultrasonically dispersing in 15-25 mL ultrapure water, adding 39-41 mg gold nanoparticles powder, stirring at room temperature for 2-4 hours, repeatedly washing and hysteresis separating, vacuum drying at 50 degrees C for 7-9 hours to obtain iron (II,III) oxide-gold nanoparticles, preparing three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles by sonicating 40 mg/20 mL graphene oxide for 15-25 minutes, adding 75-85 mg L-cysteine under sonication, adding 550-650 mu L ammonia water, placing in an Erlenmeyer flask, heating in an oil bath at 95 degrees C, reacting for 3-5 hours, filtering and lyophilizing to obtain three-dimensional graphene black solid powder, taking 29-31 mg three-dimensional-reduced graphene oxide, dispersing ultrasonically in 20-40 mL water, adding 29-31 mg iron (II,III) oxide-gold nanoparticles, stirring at room temperature for 2-4 hours, washing repeatedly and hysteresis and freeze-drying to obtain three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles. The three dimensional reduced graphene oxide/iron (II,III) oxide-gold nanoparticles at an amount of 19-21 mg is taken into 50 mL Erlenmeyer flask, added with 22.23-24.23 mg carbodiimide hydrochloride and 12.8-14.8 mg N-hydroxysuccinimide, stirred mechanically for 1-3 hours, added with 155-165 mg hydroxypropyl- beta -cyclodextrin, stirred at room temperature for 20-30 hours, and subjected to hysteresis separation and freeze-drying to obtain the finished product. An INDEPENDENT CLAIM is also included for a method for detecting guanine and adenine by an electrochemical sensor.