Construction Of Pyocyanin Electrochemical Sensor Based On Metal-Organic Framework

Objective:In this study,pyocyanin（PYO）was used as the research object,metal-organic-frameworks（MOFs）were used as signal amplification elements,and the reduction current of PYO was used as output signal to construct electrochemical sensors for the sensitive detection of PYO.Methods:（1）New MOFs were prepared by using Cu and Ni as metal centers and hexahydroxy benzene（HHB）and homo-phthalic acid（H₃BTC）as organic ligands.（2）Scanning electron microscopy and fourier transform infrared spectrometer were used to investigate the morphology and structure of Cu-HHB,Cu-BTC,and Ni-HHB.Cyclic voltammetry was used to investigate the electrochemical characteristics of MOFs.（3）Cu-HHB and Cu-BTC were used to construct electrochemical sensors for PYO.The methods for detection of PYO were developed based on determination directly and determination combined with ferrocenemethanol（Fc）.Moreover,the single factor method was used to optimize the detection conditions.（4）The linear range,detection limit,stability,and anti-interference performance of detection techniques were investigated.（5）By changing the scanning potential,the mechanism of amplification of PYO signal by MOF was explored.Results:（1）The optimum conditions for detection of PYO based on Cu-HHB and Cu-BTC sensors were（1）The proportion of modified materials was MOF:CS=1:2.（2）The modification dosage was 4μL.（3）The scanning potential for direct determination was from 0.4 V to-0.5 V.（4）The incubation time for determination directly and determination combined with Fc were 15 min and 20 min,respectively.（5）The scanning rate for determination combined with Fc was 0.005 V/s.（2）Evaluation of methods.（1）Determination directly based on Cu-HHB:The linear range was 1μmol/L～80μmol/L,the standard curve equation was I=0.3831c+5.2846,and the detection limit was 179.6 nmol/L.The determination coefficient R² was 0.9957.（2）Detection combined with Fc based on Cu-HHB:The linear range was 1μmol/L～80μmol/L,the standard curve equation was I=0.0837c+2.5227,and the detection limit was 105.4nmol/L.The determination coefficient R² was 0.9997.（3）Determination directly based on Cu-BTC:The linear range was 1μmol/L～80μmol/L,the standard curve equation was I=0.3582c+5.2716,and the detection limit was 192.3 nmol/L.The determination coefficient R² was 0.9988.（4）Detection combined with Fc based on Cu-BTC:The linear range was 1μmol/L～80μmol/L,the standard curve equation was I=0.0647c+2.6282,and the detection limit was 136.3 nmol/L.The determination coefficient R²was 0.9974.The stability of the above methods was greater than 80%in seven days.There was almost no response to glucose,uric acid,ascorbic acid and dopamine.The standard recoveries of simulated samples were all above 94%.（3）The principle of MOF amplification of PYO:The selection of metal centers and organic ligands will affect the electroanalytical performance of MOF for PYO.The metal center（Cu）of MOF had catalytic activity for the redox conversion of PYO.Cu-MOF produced Cu²⁺in redox reaction,which can convert reduced PYO to oxidized PYO and amplify the reduction signal of PYO.When detect PYO combined with Fc,Fc can accelerate the conversion rate of Cu⁺/Cu²⁺,increasing the content of Cu²⁺,which could further amplify the PYO reduction signal.Conclusion:（1）MOFs such as Cu-HHB,Cu-BTC,and Ni-HHB with excellent electrochemical properties were synthesized.（2）Electrochemical sensors based on Cu-HHB and Cu-BTC were constructed,and PYO detection methods with low detection limit and good anti-interference and stability were established.（3）The metal center and organic ligand of MOF can affect the electroanalytical performance of MOF for PYO,and the Cu metal center of MOF had catalytic activity for the redox conversion of PYO.