Peroxidase-mediated Modifying And Degradation Of Carbon Nanomaterials

Since the discovery of fullerene(C60),it has been widely used in many fields such as disease treatment,biosensors,due to its good functions for radical scavenging and electron transfer.The application of C60 derivatives is broader than C60.The ion potential energy(IP)of Mn(Ⅲ)is as high as 7.55 eV,which is higher than the ion potential energy of fullerene 7.14 eV,so can be used for the synthesis of C60 derivatives.Biocatalysis is the use of biological enzymes and other biological organisms to catalyze various chemical reactions with the advantage of mild reaction conditions,strong specificity,and no damage to environmental.Manganese peroxidase(MnP)is a glycosylated extracellular enzyme that can be produced by white rot fungi under their own metabolic conditions.With the application of MnP,hydrogen peroxide can oxidize Mn(Ⅱ)to Mn(Ⅲ).In this dissertation,we hope combining the enzyme-catalyzed reaction with the known organic synthesis reaction of C60 derivatives to establish an enzymatic cycloaddition reaction method for C60 derivatives at room temperature.In this study,C60 in toluene was transferred to the aqueous phase by ultrasonic transfer methods to obtain the colloidal dispersion of C60 for cycloaddition with 1,3-cyclohexanedione.Compared with the characterized date from the synthesis of C60 derivatives using Mn(OAc)3 as catalyst,we use four kinds of analysis method,MALDI-TOF MS,1H-NMR(400 MHz),UV-vis(CDCl3+CS2),IR v/cm(KBr)to prove that the synthesis of C60[3+2]cyclization addition products,named dihydrofuran-mixed C60 derivatives,can be achieved using MnP as a catalyst,achieving the synthese of C60 derivatives with the bio-enzyme catalytic method.Biodegradation of carbon nanomaterials has always been a concern in the field of environmental safety.Double-walled carbon nanotubes(DWCNTs)are formed by rolling two graphite layers in an axial direction.Due to the intermolecular interaction forces,DWCNTs are easily tangled into bundles,which limits their dissolution and dispersion in aqueous solutions,prevents the possibility of interaction with enzymes.DWCNTs were mixed with horseradish peroxidase(HRP)ultrasound to achieve the dispersion in water by non-covalent manner.In the process of degradation,UV-vis,Raman,NIR,TEM(HRTEM)and other methods were used to monitor the length,semiconductivity,and surface defect degree of DWCNTs.Finally,it was found that HRP can degrade DWCNTs.