Electrochemical And Colorimetric Sensing Based On Some Special Organic Indicator

The electrochemical and colorimetric sensors continue to retain an important position in the development of sensor.Electrochemical and colorimetric sensors has caught the interest of the researchers due to its high sensitivity,good stability,easy operation,low cost have been widely applied in the field of environmental monitoring,medical research and food testing.In recent years,due to the heavy metal ions,inorganic anion and biological small molecules cause serious harm to the environment and human health.Therefore,establish an accurate,rapid and convenient biological analysis method for metal ions,inorganic anions and biological small molecules is very important.In this paper,several electrochemical and colorimetric sensors platforms based on stability and low cost of organic indicator are designed and successfully applied to the analysis of inorganic anions and biological small molecules monitoring.The paper mainly has three aspects as follows:1.Using organic indicator 1-?2-pyridine azo?-2-naphthol?PAN?as electron transfer medium and the synergistic effect between PAN and electrochemical reduction graphene?ERGO?make it easily immobilized on the surface modified electrodes,PAN/ERGO modified electrodes was successful achieved.The preparation and electrochemical sensing of the modified electrode were characterized by scanning electron microscopy?SEM?,energy spectrum?EDS?and cyclic voltammetry?CV?.Proof-concept experiments demonstrated that the proposed PAN/RGO modified electrode detects nitrite exhibited a good electrical catalysis.Linear range for 7.49-1752.6mM and 1752.6-3500mM,the corresponding limit of detection were 0.67mM and 1.44mM?and applied to real samples of yellow water and tap water.2.Using organic indicator pyrocatechol violet?PV?provides binding sites and copper ions(Cu²⁺)through complexing reaction formed the PV-Cu²⁺complex.We successfully fabricated a colorimetric sensing platform for rapid and sensitive detection of cysteine?CySH?by using the indicator displacement assay?IDA?in PV-Cu²⁺system.By the stronger affinity of the Cu²⁺receptor toward CySH than toward PV leads to the release of PV indicator from the PV-Cu²⁺complex,which in turn modulates an optical signal changed in sensing system,the limit of detection was 4.6mM.Furthermore,the studied the application of the colorimetric sensor in molecular logic gates and test paper in this paper.It's expected to be applied to on-site detection.3.Which introduction of organic indicating 1-?2-pyridine azo?-2-naphthol as optical signal indicator,and provides binding sites and aluminium ions(Al³⁺)through special complexing reaction formed the PAN-Al³⁺complex.Because of PAN molecules not fluorescent signal,and PAN-Al³⁺complex has a strong fluorescent signal.We successfully fabricated a colorimetric and fluorescent double channel sensing platform based on the indicator displacement assay detection of lysine?Lys?.The sensing mechanism of the colorimetric sensor was studied by scanning electron microscopy,fourier transform infrared spectroscopy,fluorescence spectrum and UV-Vis spectroscopy.Based on the above research,we completed colorimetric and fluorescent double channel for Lys detection in the liquid phase with the limit of detection were 0.3mM and 0.23mM.And the realization of molecular logic gate operation and test application.