PREPARATION OF HIGH-PREFERMANCE ANTIMICROBIAL AGENT BASED ON ZnO/GQD-PEI NANOCOMPOSITES

A method of preparing an antimicrobial agent based on ZnO/GQD-PEI composites, comprising:

• step (1)
• adding 1-10 g of citric acid (CA) to a 50 ml beaker and liquifying the citric acid by heating to 200° C. for 30 min to obtain an orange liquid;
• adding an aqueous sodium hydroxide solution to the orange liquid in a dropwise fashion to neutralize pH to 7.0;
• dialyzing the reaction mixture in Nanopure water for one day to obtain a GQD suspension;
• step (2)
• diluting the GQD suspension obtained in step (1) to 0.2-2 mg/mL with deionized water;
• dispersing polyethyleneimine (PEI) into the diluted GQD suspension under ultrasonic processing for 10 min to obtain a homogeneous dispersion with a concentration of 5-15 mg/mL;
• adding 0.05-0.2 g of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC.HCl) to the reaction mixture;
• treating the reaction mixture by sonication for 20 min;
• adding additional EDC.HCl (0.2-0.5 g) to the reaction mixture under ultrasonic treatment for another 20 min and continuously stirring the reaction mixture for 24 h to produce GQD-PEI;
• and
• step (3)
• dispersing 0.2-1 g of an alkali source in 50 mL of ethanol by magnetic stirring for 30 min to produce solution A;
• dispersing 0.5-2 g of a zinc source in 100 mL of ethanol by magnetic stirring for 30 min to produce solution B;
• slowly dispersing the GQD-PEI obtained in step (2) in the solution B under sonicaiton and dropwise adding the solution A to the reaction mixture under continuous stirring to start the reaction;
• heating the reaction mixture at 80-100° C. for 3-7 h;
• at last, washing the reaction mixture with ethanol and deionized water and dispersing the resulting product in an aqueous phase again to produce ZnO/GQDs-PEI nanocomposites.