Sensing Study Of Antioxidant Activity Of Flavonoids Based On Guanine@nanocomposite Modified Electrode

Interaction between dietary flavonoids and albumins plays an important role in the bioavailability and bioactivity of flavonoids.Therefore,the influence of this interaction on the antioxidant activity of flavonoid has attracted much interests.DNA?deoxyribonucleic acid?,as a carrier of biological genetic information,plays an important role in cells.During the entire growth of an organism,DNA is susceptible to various environmental stresses and is damaged?such as certain physical or chemical factors?,leading to cancer and distortion.Guanine is an important biomarker for DNA oxidative damage.Therefore,it is of great significance to study the preparation of biosensor based on guanine damage and the detection of antioxidant activity of flavonoids.The main results of this paper are as follows:?1?a ceric reducing/antioxidant capacity assay?CRAC assay?was employed here to investigate the effects of albumin-flavonoid interaction on the antioxidant activity of seven common flavonoids.The results obtained from CRAC assay were also compared separately with the results from the spectrophotometric methods including DPPH and FRAP assays.All the flavonoids show a decreasing in the antioxidant activity detected by CRAC assay,indicting a“masking effect”of BSA-flavonoid interaction.At the same time,cyclic voltammetry was used to study the relationship between the antioxidant capacity of different flavonoids and their structure.?2?MoS₂ nanosheets were successfully prepared by ultrasonic method and characterized by scanning electron microscopy?SEM?.The MoS₂ nanosheets and chitosan-mixed guanine were modified to form a modified film on the surface of the electrode to prepare a G-CS/MoS₂-CS/GCE modified electrode.Due to the co-catalytic function of MoS₂ nanosheets,the damage process on the electrode surface can simulate the antioxidant protection mechanism in vivo.The antioxidants were tested on the three flavonoids?quercetin,quercetin,catechin?using the modified electrode,and the relationship between the antioxidant activity of the three flavonoids and their structure was investigated.The electrode was tested on the actual sample.The prepared sensor has a good linear range,detection limit,sensitivity,stability,and the like.Finally,the interaction between guanine and chitosan was studied by theoretical calculation.?3?The electrochemically active and more conductive nitrogen-doped graphene materials were prepared by nitrogen doping method and characterized by scanning electron microscopy.Polythene oxide is a conductive polymer with good conductivity.Electropolymerization is used to electropolymerize polysulfonium onto the surface of the electrode,and then guanine is applied to the surface of the electrode to prepare a G/NG/PTH/GCE modified electrode.The antioxidant activity of the three flavonoids was measured using the prepared electrode and the samples were tested.