Study And Application Of Poly Neutral Red Composite Nanomaterial Modified Electrode For Detection Of Biological Small Molecules

ObjectiveDopamine（DA）,uric acid（UA）and ascorbic acid（AA）are important small molecules existing in the human body and participate in the metabolism of organisms.Detection of DA,UA and AA content in human urine and the content of DA and AA in pharmaceutical preparations is of great significance for disease diagnosis and drug quality monitoring.Based on the reasons above,this study prepared sensitive probes with high sensitivity,low detection limit and wide detection range by chemically modified method to achieve rapid detection of DA,UA and AA.MethodsIn this study,poly neutral red（PNR）was prepared by electro-polymerization,and then the electrochemical conditions of graphene oxide（GO）were explored by cyclic voltammetry（CV）,and the PNR/partially reduced graphene oxide（r GO）modified glassy carbon electrode（GCE,PNR/rGO/GCE）was screened out with the best catalytic effect on DA,UA and AA.In addition,Fe₂O₃nanoparticles were introduced by electrodepositing Fe³⁺to prepare Fe₂O₃/PNR/rGO/GCE with better catalytic performance for the detection of DA and UA.Scanning electron microscopy（SEM）,X-ray diffraction（XRD）and infrared spectroscopy（IR）are used to characterize the morphology,composition and structure of composite nanomaterials.Finally,cycle voltammetry（CV）,and electrochemical impedance（EIS）,chronoamperometry（i-t）and differential pulse voltammetry（DPV）were used to analyze the catalytic performance of modified electrodes for DA,UA and AA,respectively.Results（1）It was found that the composite nanomaterials prepared had the best catalyst for DA,UA and AA when the concentration of GO is 0.5 mg/mL and the reduction potential is-0.8 V by screening the reduction condition of GO.（2）In the composite modified electrode（PNR/rGO/GCE）,the best catalytic performance was prepared when the NR concentration is 0.5 mmol/L,the number of scanning segments is 20 and the polymerization solution pH=7 by screening the preparation conditions of PNR.The detection limits of AA and UA by CV method are 0.18 mM and 0.015 mM,and the detection limit of AA by i-t method is 7.3 nM.The detection of UA,AA content in urine samples and AA content in vitamin C effervescent tablets can be achieved.（3）In the composite modified electrode（Fe₂O₃/PNR/rGO/GCE）,the optimal modified electrode was prepared when the concentration of Fe³⁺is 5 mM,the deposition temperature is 40℃ and the deposition time is 300 s by optimizing the preparation conditions of Fe₂O₃.The detection limits of Fe₂O₃/PNR/rGO/GCE for DA and UA by CV method were 0.23μM and 0.88μM,respectively.The detection limit of DPV were 0.23μM and 1.6μM,respectively.The detection of DA,UA content in urine samples and DA content in dopamine injection could be achieved.（4）After the introduction of Fe₂O₃,the linear detection range of modified electrode for DA was significantly increased and the detection limits for DA and UA were reduced by 1～2 orders of magnitude.ConclusionsIn the composite modified electrodes prepared in this experiment,PNR/rGO/GCE and Fe₂O₃/PNR/rGO/GCE were used to study the electrochemical catalytic performance of DA,UA and AA.It is shown that PNR/rGO/GCE is a DA and UA electrochemical sensing probe with high sensitivity and selectivity.The electrochemical sensing system built on the basis of two kinds of composite modified electrodes can be used for the detection of DA,UA and AA standards and actual samples,providing conditions for clinical application and drug quality control.