Preparation Of Polyaniline Nanocomposites-modified Electrodes By Electrophoresis Deposition And Their Applications For The Detection Of Dopamine

Currently,polyaniline?PANI?modified electrodes are often used as dopamine?DA?chemical electrode sensors,DA is a neurotransmitter that plays an important role not only in the brain and central nervous system,but also related to the kidneys,hormones and cardiovascular system.Highly sensitive DA electrode sensors are essential for medical diagnosis and disease prevention.However,the morphology of the PANI material on the electrode directly affects the performance of the electrode.There are many ways to prepare the PANI modified electrode,such as drop coating,spin coating,electrochemical deposition and so on.However,these methods are not sufficient to solve the problem of material surface morphology control of the electrode surface.Therefore,solving the problem of electrode morphology control is the key to preparing a high sensitivity DA electrode sensor.In this paper,hydrochloric acid?HCl?,camphorsulfonic acid?CSA?and dodecylbenzenesulfonic acid?DBSA?were used as dopants to prepare pure polyaniline?PANI-HCl,PANI-CSA,PANI-DBSA?by chemical oxidative polymerization with aniline?An?.PANI electrode is prepared by electrophoretic deposition in a formic acid/acetonitrile colloidal system using indium tin oxide conductive glass?ITO?as the substrate.Successful control of the transfer of PANI morphology from material to electrode was observed by scanning electron microscopy?SEM?.In addition,the process of PANI-CSA morphology retained on the electrode surface was analyzed by a series of tests on PANI-CSA in formic acid/acetonitrile colloidal system as follows:The nanorod structure of PANI-CSA is first decomposed into nanoparticles and then recombined from the colloidal suspension on the electrode surface under the action of a direct current electric field.Finally,the prepared PANI-CSA electrode was used for the detection of DA by a chronoamperometry method with a sensitivity of 541.7?A mM^-1 cm^-2,the linear detection range is from 10?M to 5.5 mM with a detection limit of 0.64?M.In order to further improve the sensitivity of PANI electrode to DA detection,PANI/MIL-101 nanocomposites are prepared by chemical oxidative polymerization with PANI using the large specific surface area of MOFs?MIL-101?.PANI/MIL-101 nanocomposite electrodes were also prepared by electrophoretic deposition.The electrode morphology of PANI/MIL-101nanocomposites with different aniline and MIL-101 ratios was studied.The optimum ratio of aniline and MIL-101 was investigated by cyclic voltammetry?CV?and electrochemical impedance spectroscopy?EIS?.The results show that the PANI/MIL-101 nanocomposite electrode has the best morphology and electrochemical performance when m_MIL-101:m_An=0.4:1.The results of the chronoamperometry method also show that compared to the pure PANI electrode,the sensitivity of the PANI/MIL-101 nanocomposite electrode to DA is greatly improved,the sensitivity of DA is 745?A mM^-1 cm^-2,linear detection range is 10?M⁶.5 mM and lower limit of detection is 0.2?M.The PANI/MIL-101nanocomposite electrode exhibits such excellent performance,mainly due to the high specific surface area of MIL-101,which increases the specific area of the PANI film on the electrode surface,so that the electrode and the electrolyte solution have an effective effect and the interaction between PANI and DA is improved.Therefore,the PANI/MIL-101 nanocomposites prepared by this subject have great application prospects in the construction of DA electrode sensors.