Construction And Application Of Electrochemiluminescence Sensor Based On Functional Nanomaterials

Electrochemiluminescence（ECL）is a luminescence phenomenon resulting from electrochemical and chemiluminescence reactions on or near the electrode surface.As a combination of electrochemical and chemiluminescent techniques,ECL is widely used in the field of analytical field owing to its high intuitiveness,low background,and ease of operation.In recent years,various nanomaterials with different sizes,shapes,chemical compositions,and unique properties have been used to construct ECL sensors.Functional nanomaterials can improve the sensing performance of ECL sensors in different ways.Firstly,nanomaterials with excellent luminescent properties can replace molecular-based ECL emitters.Additionally,nanomaterials with huge specific surface area can be used to load ECL luminophores or biorecognition molecules.Moreover,nanomaterials with excellent electrical conductivity or catalytic properties can serve to amplify the ECL signal.Despite of the great progress,the development of functional nanomaterial-based ECL sensor still faces the following challenges:（1）certain novel nano-luminophores exhibit high ECL efficiency,but their poor stability has limited their sensing application.（2）The sensitivity of most ECL systems constructed by nanomaterials is still not as good as that of traditional ECL systems(Ru（bpy）₃²⁺/TPr A,luminol/H₂O₂),and appropriate strategies need to be taken to enhance their ECL signal.Based on this,this paper makes full use of the advantages of functional nanomaterials to construct two ECL sensors with high stability and excellent sensitivity using the“signal-on”and“signal-off”strategies,respectively.The specific research contents are described as follows.（1）Preparation of bifunctional dendritic SiO₂-enriched Cs Pb Br₃nanocrystals with high electrochemiluminescence stability by in situ growth synthesis for dopamine determination.In this study,bifunctional dendritic SiO₂-enriched Cs Pb Br₃ nanocrystals（Cs Pb Br₃@DF-d SiO₂）with high electrochemiluminescence stability were prepared by in situ growth approach,and a sensing platform for dopamine detection was constructed.Firstly,the as-synthesized d SiO₂ was modified by amination and long-chain alkylation with two silanes to obtain bifunctional d SiO₂（DF-d SiO₂）.Subsequently,Cs Pb Br₃ nanocrystals were grown within the inner channel of DF-d SiO₂at room temperature to form Cs Pb Br₃@DF-d SiO₂ nanocomposites.The ECL stability of prepared nanocomposites were remarkablly enhanced on account of the coordination interaction between amino groups of DF-d SiO₂ and Pb atoms of Cs Pb Br₃ nanocrystals as well as the hydrophobic interaction between long-chain alkyl of DF-d SiO₂ and surface ligands of Cs Pb Br₃ nanocrystals.Meanwhile,considering the hydrophobic effect of long-chain alkyl can protect the Cs Pb Br₃nanocrystals from water,the nanocomposites kept a relatively strong ECL value even after 12 days storage at room temperature and preserved a comparatively stable ECL emission under continuous electrochemical scanning.Based on above advantages,a highly sensitive dopamine sensing platform based on“signal off”strategy was established.The sensor showed a linear range from 25p M to 100 n M with a detection limit of 8.3 p M.Compared with other methods,the proposed ECL sensor exhibited outstanding stability,selectivity and reproducibility,which holds enormous potential for practical clinical diagnosis in the future.（2）Signal-amplified ECL immunosensor based on CdTe quantum dots-embedded TiO₂nanoflowers as signal probes and Fe₃O₄@SiO₂ nanoparticles as magnetic separable carriers.In this work,a sandwich-structured electrochemiluminescence immunosensor was constructed using CdTe quantum dots-embedded TiO₂ nanoflowers（CdTe/TiO₂ NFs）as signal probes and Fe₃O₄@SiO₂ as magnetic separable scaffolds.CdTe/TiO₂ NFs displayed remarkably stronger ECL signal than original CdTe QDs,which can be explained as follow.On the one hand,the 3D-layered structure of TiO₂ NFs endowed them enormous specific surface areas,providing a large number of immobilization sites for CdTe QDs enrichment.On the other hand,TiO₂ NFs can promote the decomposition of S₂O₈^2-and improve the utilization of intermediate radicals,raising the ECL efficiency of CdTe QDs.The ECL enhancement can be attributed to the synergistic effect of above two mechanisms.Subsequently,a“signal-on”-type sandwich immunosensor was established based on this composites for carcinoembryonic antigen（CEA）detection with CdTe/TiO₂ NFs as the signal label for Ab₂ loading and Fe₃O₄@SiO₂ as the magnetic separation carrier for Ab₁ immobilization.The whole immune reaction was proceeded in aqueous solution.Benefiting from outstanding ECL response of CdTe/TiO₂ NFs and superb magnetic separation property of Fe₃O₄@SiO₂,ultra-sensitive detection for CEA could be achieved by a simple operation with a calculated detection limit of 0.3 pg/m L and a linear range of 1 pg/m L to 100 ng/m L.This work not only offers more inspiration for the design of ECL signal amplification strategies,but also opens up hopeful avenues for CEA immunoassays.