▎ 摘　　要

NOVELTY - Composition comprises recombinant graphene oxide- streptococcal protein A composite material, where the composite material is conjugated on the polyethyleneimine and the mass ratio of the polyethyleneimine and the composite material is 1:1.5-2. USE - The composition is useful for purifying antibody, enriching antibodies, detecting pathogen and/or pre-treating biological sample (all claimed). DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the composite material comprising (i) activating graphene oxide; (ii) uniformly mixing 1 pts. wt. activated graphene oxide and 15-30 pts. wt. polyethyleneimine at room temperature, centrifuging to obtain the supernatant, separating the precipitate to obtain immobilized polyethyleneimine graphene oxide material; (iii) activating recombination streptococcus protein A; (iv) incubating immobilized polyethyleneimine graphene oxide material with activated recombination streptococcus protein A under oscillating conditions, centrifuging and separating the supernatant and washing, to obtain the final product.