The Preparation Of Ferric Oxide Nanozymes And Their Application In Colorimetric Biosensor

Nanozyme is a new artificial enzyme accompanied by the development of nanotechnology.It has the unique physical and chemical properties of nanomaterials and the high catalytic activity of natural enzymes.Compared with natural enzymes and traditional mimic enzymes,nanozymes have the advantages of simple preparation,low cost,high stability,easy modification and excellent catalytic activity.Nanozymes have been widely used in medicine,food,agriculture,industry and environment.Among them,iron oxide?Fe₃O₄?nanoparticles are one of the first nanozymes with mimic enzyme activity and are widely used in colorimetric sensing analysis because of their magnetic separation and mimic enzyme properties.To further improve the catalytic activity of mimetic enzymes,Fe₃O₄ nanoparticles were modified by sodium lignosulfonate?SL?and then further capped by copper peroxide?CP?nanoparticles.High-performance colorimetric sensor was constructed for the sensitive detection of hydrogen peroxide?H₂O₂?and glutathione?GSH?.The specific research contents are as follows:?1?SL modified Fe₃O₄ nanoparticles?SL-Fe₃O₄?were synthesized by one-step solvothermal method using SL as modifier and reducing agent.The morphology and composition of SL-Fe₃O₄ nanoparticles was characterized by scanning electron microscopy?SEM?,X-ray diffractometry?XRD?,Fourier transform infrared spectroscopy?FTIR?,X-ray energy spectrometer?EDS?and zeta potential analyzer.Subsequently,the 3,3',5,5'-tetramethylbenzidine reaction was catalyzed to form a blue product in the presence of H₂O₂.The results show that SL-Fe₃O₄ nanoparticles exhibit excellent catalytic activity,which is more than that of natural horseradish peroxidase,and the catalytic mechanism is consistent with the ping-pong mechanism.Finally,a colorimetric sensor for sensitive detection of H₂O₂ and GSH was established with linear ranges of 0.5?150 and 0.5?25 ?M,with detection limits of 0.139 and 0.08 ?M.?2?On the basis of the previous work,Fe₃O₄@CP nanocomposites were further synthesized through adsorption of Cu²⁺ by electrostatic adsorption.The morphology and composition of Fe₃O₄@CP nanoparticles were characterized by SEM,XRD,FTIR and EDS.The peroxidase activity of Fe₃O₄@CP nanoparticles was further studied.The results show that it has excellent catalytic activity and the catalytic mechanism follows the ping-pong mechanism.Based on this,a colorimetric sensor for sensitive detection of H₂O₂ and GSH was constructed with linear ranges of0.2?300 and 0.2?40 ?M,respectively,with detection limits of 0.110 and 0.05 ?M,respectively.Further,it was successfully applied to the detection of GSH content in actual serum samples,andthe recovery was 98.3?104.0 %,and the relative standard deviation was 3.3?8.4 %.