Electrochemiluminescence Properties Of Perovskite And G-C₃N₄ Nanomaterials And Application In Immunosensor

Electrochemiluminescence?ECL?is a kind of chemiluminescence which is excited by electrochemical method.It is a combination of chemiluminescence and electrochemistry.ECL analysis method does not need excited light source,is free from stray light interference,has the advantages of easy assembly of equipment and easy operation,and shows good sensitivity and selectivity in practical application.Therefore,the detection technology based on this analysis method has been widely used in food,medicine,environment and other related fields.With the development of optoelectronic research,many kinds of nanomaterials with excellent properties have been studied.In this thesis,the the ECL properties of two perovskite nanomaterials were studied.The ECL signal amplification strategy under the affect of coreaction accelerator was explored.And a ratiometric ECL method using single ECL luminophore of graphite carbon nitride?g-C₃N₄?for the determination of Cu²⁺and a biomarker was established.The main research contents are as follows:1.Tunable electrochemiluminescence properties of CsPbBr₃ perovskite nanocrystals using mixed-monovalent cations.By replacing part of Cs⁺by Rb⁺,a series of Rb_xCs_1-xPbBr₃ NCs were prepared,which exhibit narrow photoluminescence?PL?with the full width at half-maximum about 19²3 nm.After continuously injecting holes to produce different charged state radicals,an annihilation ECL was observed,implying the as-prepared Rb_xCs_1-xPbBr₃ NCs are in electron-rich state.In the presence of 2-dibutyaminoethanol as co-reactant,strong andodic ECL of Rb_xCs_1-xPbBr₃ NCs was obtained.As the x value increased from 0 to 0.8,the ECL peak potential position was moved from 1.25 V to 1.80 V with the ECL spectrum peak shifted from 512 to 468 nm,indicating the tunable ECL properties.The Rb_0.2Cs_0.8PbBr₃ NCs has longer PL lifetime,higher PL and ECL intensity than those of CsPbBr₃ NCs.A simple approach for tuning the ECL properties of perovskite is demonstrated by mixed-monovalent cation perovskite-based nanocrystals.2.Enhancement of ECL CH?NH₂?₂PbBr₃ in aqueous phase by TiO₂ nanoparticles and carbon nanotubes.With tripropylamine as the co-reactant,a perovskite nanomaterial of CH?NH₂?₂PbBr₃ NCs was generated strong anodic ECL in the aqueous phase.When TiO₂ NPs was mixed with CH?NH₂?₂PbBr₃ NCs on the surface of the glass carbon electrode?GCE?,or dispersed in the supporting electrolyte,the ECL intensity of CH?NH₂?₂PbBr₃ NCs was increased,with the maximum factor of 4.8,indicating that TiO₂ NPs is the accelerant for the ECL of CH?NH₂?₂PbBr₃ NCs.When mixing with carbon nanotubes?CNTs?,CH?NH₂?₂PbBr₃ NCs the impedance of CH?NH₂?₂PbBr₃ NCs-CNTs|GCE is reduced,enhancing the ECL intensity by a mximum factor of 10.4.When mixing with both of TiO₂ NPs and CNTs,the ECL intensity of CH?NH₂?₂PbBr₃ NCs-TiO₂ NPs-CNTs|GCE can be increased by a factor of 17.6.Based on the quenching effect of dopamine to ECL of CH?NH₂?₂PbBr₃ NCs-TiO₂ NPs-CNTs|GCE,the ECL method is applied to the determination of dopamine in the linear range of 0.003-10?M,with the detection limit of 2.9 nM.3.A ratiometric electrochemiluminescence method using single luminophore of g-C₃N₄ for ultrasensitive determination of alpha fetoprotein.The ratiometric ECL method is good at self-correction,which is helpful to to ontain stable ECL signal.Usually,two ECL luminophores are used to perform ratiometric ECL measurement.As a result,the electrode preparation process is complicated.The differences between the ECL luminophores will result in the discount in self-correction efficiency.But a ratiometric ECL sensor using single ECL luminophore is scare.In this work,a high sensitive ratiometric ECL method for the determination of Cu²⁺was established by using porous g-C₃N₄ as ECL luminophore in combined with an anodic stripping voltammetry.In this method,Cu²⁺is first enriched and deposited electrochemicaly on the surface of g-C₃N₄-CNTs-|GCE.As Cu has little effect on the cathodic ECL of g-C₃N₄,the ECL intensity is used as the reference signal in the ratiometric ECL.Then a square wave potential of 0.6 V is applied for 6 s to oxidize Cu into Cu²⁺.Because the freshly dissolved Cu²⁺is distributed mainly within the Helmholtz layer of the electrode,the ECL of g-C₃N₄ is quenched by Cu²⁺with much higher efficiency.By using the ECL intensity ratio of(Cu²⁺)g-C₃N₄-CNTs-|GCE to?Cu?g-C₃N₄-CNTs-|GCE measured by potentiostatic method as the signal indictor,the limit of detection is as low as 0.5 pM in the ratiometric ECL method for the determination of Cu²⁺.In the immunoanalysis,the signal antibody was labeled with CuS NPs.After immunorecognition,the concentration of Cu²⁺in the immunocomplex was determined by the ratiometric ECL method,which can be used to quantify the concentration of target antigen.By using alpha fetoprotein as the model the biomarker,the limit of detection was about 0.1 fg/mL.It was shown that the influence of the difference in electrode modification and ECL measurement conditions on the determination of Cu²⁺are suppressed greatly in the ratiometric ECL method.The combination of ECL with electrochemical enrichment and biometallization is a useful strategy to enhance the sensitivity and reproducibility in ratiometric ECL method.