▎ 摘　　要

NOVELTY - A protein-modified electrode comprises substrate electrode layer and graphene-hydrotalcite-graphene composite with carbon nitride fixed protein layer, where the graphene composite is prepared by peeling graphene oxide sheet, baking the sheet with melamine, adding deionized water to the mixture, adding protein solution and graphene-hydrotalcite-graphene composite with carbon nitride solution to the mixture to obtain protein layer, the hydrotalcite is cobalt aluminum hydrotalcite, protein is bovine hemoglobin, and substrate electrode is ionic liquid-modified carbon paste electrode. USE - Protein-modified electrode for use in electrochemical sensor that is utilized in detecting trichloroacetic acid (all claimed). ADVANTAGE - The protein-modified electrode has low detection limits, low Michaelis constant and wide detection range. DETAILED DESCRIPTION - A protein-modified electrode comprises substrate electrode layer and graphene-hydrotalcite-graphene composite with carbon nitride fixed protein layer, where the graphene-hydrotalcite-graphene composite with carbon nitride fixed protein layer is prepared by peeling graphene oxide sheet, baking the sheet with melamine, adding deionized water to the mixture, adding protein solution and graphene-hydrotalcite-graphene composite with carbon nitride solution to the mixture to obtain protein layer, the hydrotalcite is cobalt aluminum hydrotalcite, protein is bovine hemoglobin, and substrate electrode is ionic liquid-modified carbon paste electrode. The protein-modified electrode is prepared by adding divalent cobalt chloride hexahydrate, trivalent aluminum chloride hexahydrate and urea to round bottomed bottle containing certain volume of deionized water, where total metal ion concentration is 0.15 mol/l, stirring the mixture at 60-98 degrees C for 10-36 hours, filtering the mixture, washing filter cake with distilled water for 3-5 times, drying the cake to room temperature for 48 hours to obtain carbonate intercalated hydrotalcite-like sheet (LDH), weighing certain amount of carbonate intercalated LDH, dispersing the carbonate intercalated LDH in hydrochloric acid, stirring the mixture under nitrogen atmosphere for 12 hours, drying the mixture to room temperature for 12 hours to obtain chlorine ion intercalated LDH layer, weighing certain amount of chlorine ion intercalated LDH, dispersing the chlorine ion intercalated LDH in sodium nitrate solution, stirring the mixture under nitrogen atmosphere for 12 hours, drying the mixture to room temperature for 12 hours to obtain nitrate intercalated LDH, weighing certain amount of nitrate intercalated LDH, dispersing the nitrate intercalated LDH in formamide and dispersant, stirring the mixture under nitrogen atmosphere for 24 hours, centrifuging the mixture at 2000 revolutions/minute for 10 minutes, removing precipitate to room temperature for 12 hours to obtain nitrate intercalated LDH to obtain exfoliated LDH (ELDH), dispersing graphene oxide in formamide for 1 hour, centrifuging the mixture at 3000 revolutions/minute for 10 minutes, peeling off the graphene oxide to obtain graphene oxide, mixing the graphene oxide with ELDH colloidal solution completely, stirring the mixture at room temperature for 12 hours, centrifuging the mixture at 5000 revolutions/minute for 10 minutes, dispersing obtained brown black sediment in deionized water, putting the mixed solution into 25 ml reaction kettle, cooling the mixture naturally to room temperature, reacting the mixture at 160 degrees C for 6 hours to obtain graphene-ELDH hydrogel, storing the hydrogel, weighing 50 mg hydrogel, mixing the hydrogel with melamine, baking the hydrogel at 600 degrees C for 3 hours to obtain graphene-LDH-carbon nitride composite, adding graphite powder and iron liquid to mortar in mass ratio of 2:1, heating the mixture to 80 degrees C, adding 1 ml liquid paraffin as adhesive to the mixture, grinding the mixture, filling the mixture into glass tube, inserting copper wire as guide tube to obtain graphene-LDH-carbon nitride composite immobilized protein modified electrode (CILE), grinding surface of the CILE, adding graphene-LDH-carbon nitride composite to deionized water to obtain 0.5 mg slurry, adding 10 mg/ml hemoglobin to the slurry, adding 16 mu l obtained slurry on surface of the CILE, drying the CILE, dispersing 6 mu l chitosan acetate with concentration of 1 mg/ml on the CILE, and drying the CILE surface to obtain finished product.