▎ 摘　　要

NOVELTY - Preparing graphene-based composite material comprises (i) preparing iron oxide-silicon dioxide, (ii) synthesizing iron oxide-silicon dioxide/graphene oxide composite material, (iii) DNA pre-processing, (iv) determining adsorption performance of iron oxide-silicon dioxide/graphene oxide composite material, (v) drawing ssDNA working curve, and (vi) detecting the actual sample. USE - The composite material is useful for chemiluminescence detection of DNA (claimed). ADVANTAGE - The method is simple, has high sensitivity and high selectivity (claimed), and is environmentally friendly. DETAILED DESCRIPTION - Preparing graphene-based composite material comprises (i) preparing iron oxide-silicon dioxide: taking 150 ml round-bottomed flask, adding 36 ml ethanol and 4 ml ultrapure water, adding 0.3000 g of purified iron oxide nanoparticles, ultrasonic oscillating for 15-20 minutes, mechanical stirring, adding 5 ml aqueous ammonia and 2 ml ethyl orthosilicate, reacting at 10 degrees C constant temperature for 12 hours, collecting the product by external magnetic field and vacuum drying in an oven at 50 degrees C, (ii) synthesizing iron oxide-silicon dioxide/graphene oxide composite material: dissolving 0.2 g of graphene oxide in 100 ml ultrapure water, adding 3 mg of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 28 mg of hydroxysuccinimide, magnetic stirring for 30 minutes, ultrasound processing for 30 minutes to form a uniform dispersion, adding 200 mg of the silylated modified product iron oxide-silicon dioxide-amino terminal, ultrasonic processing for 30 minutes, stirring at 80 degrees C for 2 hours, magnetic separating, respectively washing with ultra-pure water and ethanol, vacuum drying in an oven at 50 degrees C and grinding, (iii) DNA pre-processing: taking A and B chains of the DNA sequence, complementary pairing two chains, attaching single-stranded DNA (ssDNA) to the tube wall very lightly, directly opening, and centrifuging before opening the lid, (iv) determining adsorption performance of iron oxide-silicon dioxide/graphene oxide composite material: adding the composite material into the 50 ml colorimetric tube, adding the ssDNA solution of known concentration, measuring the luminous intensity by flow injection chemiluminescence, calculating the saturation adsorption capacity of iron oxide-silicon dioxide/graphene oxide composite material to ssDNA based on the concentration of ssDNA solution at the transition point of the luminous intensity, (v) drawing ssDNA working curve: preparing a series of ssDNA-A standard solutions by adding the same amount of ssDNA-B solution, under the optimum experimental conditions (optimal pump speed of main/auxiliary pump, sodium hydroxide/luminol/hydrogen peroxide concentration), measuring chemiluminescence intensity of the system and drawing the working curve, and (vi) detecting the actual sample: taking four 100 ml colorimetric tubes for the experiment, determining the chemiluminescence intensities of four colorimetric tubes by flow chemiluminescence method, measuring the labeled spikes and obtaining the concentration of ssDNA-A was by drawing a good working curve. An INDEPENDENT CLAIM is also included for chemiluminescence detection of DNA using the iron oxide-silicon dioxide/graphene oxide composite material, comprising using flow injection chemiluminescence (i) determining blank: starting the main pump and vice pump, injection valve in the injection position, hydrogen peroxide, sodium hydroxide and phosphate buffered saline as reference solution and luminol solution combined flow for 50 seconds, the chemiluminescence intensity I0, (ii) separating and enrichment of ssDNA-A: completely adsorbing ssDNA-A with iron oxide-silicon dioxide/graphene oxide composite material on the bottom of the beaker with a magnet, and (iii) detection ssDNA-A: starting the main pump and vice pump, the injection valve in the injection position, hydrogen peroxide, sodium hydroxide and iron oxide-silicon dioxide/graphene oxide composite material, adsorbing complete ssDNA-A sample and luminol solution, reacting for 50 second to produce the chemiluminescence intensity I1, and the actual luminescence intensity is Delta I 1 is I1-I0, under the same conditions, ssDNA-B, which was not mismatched with ssDNA-A iron oxide-silicon dioxide/graphene oxide composite material to the solution, when the chemiluminescence intensity I2, the actual luminous intensity of Delta I2 is I2-I0 and this can be generated by the actual ssDNA-A chemiluminescence intensity Delta I is Delta I1- Delta I2, and (iv) reacting ssDNA-B with the residual ssDNA-A on the composite material, desorbing and reusing the composite material.