Electrochemical And Electrochemical Chemiluminescent Sensors Based On G-C₃N₄ Nanomaterials And Its Composite

In recent years,graphite phase carbon nitride has been widely used in the fields of life analysis and biomedicine due to its good biocompatibility and semiconductor properties.Based on this,the graphite phase carbon nitride involved electrochemical and electrogenerated electrochemiluminescence systems are constructed.The potential application of these systems in the field of life analysis and biosensing were discussed.The main research contents are as follows:1.2-dimensional graphitic carbon nitride(g-C₃N₄)nanosheets were synthesized from thiourea and urea through pyrolysis method,which was confirmed by transmission electron microscopy(TEM),Fourier transform infrared(FT-IR)spectroscopy,atomic force microscopy(AFM),and electrochemical techniques.Excellent biocompatibility of g-C₃N₄ makes its suitable for the sufficient immobilization of glucose oxidase with improved catalytic behavior.The electrochemical oxidation behavior of glucose was chosen as the model to study the sensing performance of GOx/g-C₃N₄ nanocomposite modified glassy carbon electrode in neutral condition.Several impact factors,such as the mixing ratio of g-C₃N₄ and GOx,the modified amount of GOx/g-C₃N₄ suspension,the applied potential,and the p H values,were investigated.Under the optimal condition,glucose can be linearly detected in the range of 50?M to 2m M with the sensitivity of 21.7?A m M^-1 cm^-2.The detection limit was evaluated as 5?M with the signal-to-noise ratio of 3.The modified electrode exhibited good reproducibility and long-term stability,which is applicable for the detection of glucose in real samples.2.Zn O nanoparticles were coupled with g-C₃N₄ nanosheets to form functional nanocomposite through hydrothermal method.The morphologies of nanocomposite were characterized by TEM and XRD.The results revealed that the addition of g-C₃N₄ can efficiently inhibit the growth of Zn O along the c-axis to obtain smaller size Zn O nanoparticles,which could bring the enhanced electrochemical response.Hydrogen peroxide was selected as a model to investigate the electrochemical behavior of nanocomposite in neutral condition.Compared with pure Zn O and g-C₃N₄ modified electrodes,the oxidation of H₂O₂ could be greatly enhanced at the Zn O/g-C₃N₄ modified electrode,revealing that the coupling of g-C₃N₄ with metal oxide could significantly improve its conductivity and electrochemical response.As a result,H₂O₂ could be sensitively detected at the modified electrode in the range of5?M to 0.2 m M.The proposed method could be successfully used in the detection of H₂O₂ in tap water samples with satisfactory results.3.Zn Ga₂O₄ nanoparticles was incorporated with g-C₃N₄ nanosheets to form Zn Ga₂O₄/g-C₃N₄ nanocomposites through hydrothermal method.The morphologies of synthesized nanocomposites were characterized by TEM,XRD,spectral and electrochemical methods,respectively.The nanocomposites exhibited greatly enhanced fluorescence with the maximum emission peak shifted from 380 nm to 450nm.Strong cathodic electrogenerated chemiluminescence(ECL)signal of Zn Ga₂O₄/g-C₃N₄ nanocomposites was obtained in the neutral condition,which was much stronger than those of pure materials.ECL resonance energy transfer(ECL-RET)occurred between Zn Ga₂O₄/g-C₃N₄ and gold nanoparticle/graphene nanocomposites,resulting in apparent decrease of ECL signal.Based on which,a label-free ECL aptasensor for thrombin was fabricated.The sensor showed high sensitivity,wide linearity,and good selectivity for the detection thrombin in the range of 1.37 f M-27.4 p M with a detection limit of 0.55 f M(3?).The proposed method was applied in the detection thrombin in serum samples with satisfied results.This work revealed a new role of spinel-type semiconductor oxides in the fabrication of ECL sensor for the sensitive detection of various proteins.