Ultrasensitive Determination Of Nitrogenous Substance Like Uric Acid Based On Multi-functional Nano Composites

Important nitrogen metabolites of life activities, such as uric acid, neurotransmitters such as dopamine, and antioxidants such as ascorbic acid,affect human life activities and healthy in the process of metabolism. Abnormal level of uric acid could lead to a series of metabolic disease, disorder concentration of dopamine will affect the human nervous system, ascorbic acid can affect human body health physiological mechanism. Therefore, it is very important to develop a high sensitivity, high specificity and accurate sensing method for use in important life activities and nitrogenous substance of antioxidants such as quantitative or qualitative detection, to maintain normal life activities. In this paper, combination of multi-functional nanocomposites which mainly engaged in the detection of nitrogenous substance research,specific as follows:Sensitive determination of uric acid by an electrochemically reduced graphene oxide/gold nanoparticle-chitosan?ERGO/AuNP-CS? composite modified glass carbon electrode?GCE?: It was constructed by directly electrochemical reduction of GO, and then assembly of AuNP-CS polycation on the surface. The surface morphologies of different modified electrodes like bare GCE, GCE/GO, GCE/ERGO, and GCE/ERGO/AuNP-CS were characterized by scanning electron microscopy?SEM?. The differential pulse voltammetric behaviors of the electrodes were investigated, indicating that the composite of ERGO/AuNP-CS exhibited excellent electrocatalytic oxidation activity to uric acid?UA?molecule. In 0.10 mol/L of phosphate buffer solution?pH=6.5? with a scanning rate of100 m V/s, the proposed composite electrode showed nice electrochemical response to UA with a linear range of 0.0500¹10 ?mol/L and a detection limit of 12.4 nmol/L. The electrode displayed good selectivity, reproducibility and stability, which can be well applied to determination of UA in human serum and urine samples with a recovery rate of 93.8¹04.1%.The accuracy of the electrode was also comparable to that of conventional spectrophotometry and uricase Kit methods, indicating that the proposed method can be of valuable in practical application on biomedical analysis field.Simultaneous detection of uric acid and ascorbic acid using an electrochemically reduced graphene oxide/ PDDA-Protected Pt Nanostructures Composite?ERGO/PDDA-Pt? modified glass carbon electrode?GCE?: The modified electrode was constructed by directly electrochemical reduction of GO, and then assembly of PDDA-Pt composite on the surface.The surface morphologies of PDDA-Protected Pt nanostructures were characterized by TEM.The electrochemical behaviors of UA and AA has been studied by CV and DPV. The sensor exhibited excellent electrocatalytic oxidation activity to UA and AA which can be detected without separation. In 0.10 mol/L of phosphate buffer solution?pH=5.5? with a scanning rate of 100mV/s, the proposed electrode showed excellent electrochemical response to UA and AA with a linear range of 0.050²0.0 ?mol/L and 2.50¹10 ?mol/L, the detection limit of 7.2nmol/L?S/N=3? and 0.15 ?mol/L, respectively. The electrode displayed good selectivity,reproducibility and stability, which can be well applied to determination of UA and AA in human serum samples with a recovery rate of 94.2¹02.2% and 96.9¹05.4%, respectively.The accuracy of the electrode was also comparable to that of conventional fluorescence spectrometry and uricase Kit methods, indicating that the proposed method is valuable in practical application on biomedical analysis field.Preparation of composite carbon nanodots nanomaterials and simultaneous determination of uric acid and nitrite: GQDs-CQDs-IL compound was prepared by ultrasonic Combination of MWCNTs, GO, IL?[BMIM]BF₄?. The morphologies of carbon nanometer materials were characterized by TEM, The electrochemical behaviors of uric acid are studied and nitrite was studied by CV, The sensor exhibited excellent electrocatalytic oxidation activity. The proposed electrode showed excellent electrochemical response to UA and NO_2-with a linear range of 0.15²0.0 ?mol/L and 0.20³0.0 ?mol/L, the detection limit of 0.0062 ?nmol/L?S/N=3? and 0.036 ?mol/L, respectively. which can be well applied to determination of UA and NO_2-in actual samples with a recovery rate of 96.0%¹01% and 99.8%¹02%,respectively. The accuracy of the electrode was also comparable to that of uricase Kit methods and spectrophotometric method, indicating that the proposed method is valuable in practical application on biomedical analysis field.Based on the function of polycation MWCNTs high load PtNP composite membrane for the sensitive determination of dopamine: GCE/?MWCNT-PDDA/PtNPs?-Nafion modifiedelectrodes was constructed by liquid phase reduction method and use PDDA will functionalization surface of MWCNTs. the morphology of composite material was characterization characterized by TEM. The electrochemical behaviors of DA was studied by CV and DPV, the composite membrane showed good electric catalytic oxidation activity to DA molecular. The experiment results show that the modified electrodes to dopamine electric catalytic linear range of 0.01³0 ?mol/L, the detection limit of 2.5 nmol/L?3S/N?. In addition,the electrode showed a stronger anti-jamming ability, good reproducibility and stability. This kind of carbon nanotubes, polyelectrolyte and precious metal nanoparticles as one of the construction of the nanocomposite for dopamine high sensitive electrochemical detection provides a better research platfor.