| Uric acid,creatinine,and creatine are important metabolic intermediates or final products of protein and nucleic acid in human body,and thus the monitoring of their content is of great significance in clinical diagnosis,disease prevention and evaluation.Due to the defects and shortcomings of the existing detection methods such as expensive equipment,complex operation and low sensitivity,electrochemical sensor was constructed in this study to explore the detection of the three substances.In this study,nanoporous gold(NPG)with porous structure and superior sensing ability was used as a recognition element to modify the surface of glassy carbon electrode(GCE)to construct a NPG/GCE electrode.The electrochemical detection of uric acid,creatinine,and creatine was studied by combining the electrocatalytic activity of NPG towards small molecules with the specific catalytic activity of biological enzyme.Firstly,NPG was prepared by dealloying method,and then the mcrostructure of NPG was characterized by scanning electron microscope(SEM).The SEM image showed that the prepared NPG had a continuous nanoscale porous network structure.After NPG preparation,a NPG/GCE electrode was successfully constructed by loading NPG film on GCE surface.The electrochemical characterization results demonstrated that the sensing performance of GCE electrode modified with NPG was significantly improved,and NPG exhibited good electrocatalytic activity for uric acid.The linearity detection range of uric acid by the NPG/GCE electrode was 10～750μM with a sensitivity of 222.91 μA mM-1 cm-2 and a low detection limit of 0.06 μM.The NPG/GCE electrochemical sensor was used to detect uric acid in three actual urine samples,the deviation rates of the results detected by the NPG/GCE sensor and high performance liquid chromatography(HPLC)were all less than 10.28%.In addition,the recoveries of uric acid measured by the NPG/GCE electrochemical sensor ranged from 89%to 118%when different amounts of uric acid were added to the three urine samples.Based on the nucleophilic reaction between picric acid and creatinine under alkaline conditions and the electrochemical catalytic activity of NPG towards picric acid,the sensitivity of creatinine was indirectly detected by measuring the consumption of picric acid before and after Jaffe reaction using the NPG/GCE electrochemical sensor.The detection range of creatinine was 10～2000 μM with a sensitivity of 195.05 μA mM-1 cm-2 and a detection limit of 10 μM.Further,the detection time was only 20 min,which meet the requirements of practical application.For actual urine samples detection,the deviation rate between the detection results of the electrochemical sensor and the determination results of HPLC was small(4.17%),and the spiked recoveries of urine samples were between 92.50%and 117.40%.The synergistic catalytic activity of creatinase and sarcosine oxidase to generate H2O2 was combined with the specific electrocatalytic activity of NPG towards H2O2.The prepared NPG/GCE electrochemical sensor was used to determine H2O2 produced by creatine through the catalysis of creatinase and sarcosine oxidase,which indirectly realized the quantitative detection of creatine.The detection range of creatine was 10～300 μM,and the sensitivity is 111.98μA mM-1 cm-2 with a detection limit of 0.71μM.In addition,the spiked recoveries of creatine in diluted serum samples ranged from 96.43%to 103.34%,and the deviations were all lower than 3.57%.In summary,the NPG/GCE electrochemical sensor was successfully constructed based on the good catalytic performance and sensing ability of NPG.The quantitative detection of uric acid,creatine,and creatine was implemented using the NPG/GCE electrochemical sensor with short detection time,easy to operate,and strong antiinterference ability,which provides an important reference for the detection of actual samples. |
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