Research On A Novel Electrogenerated Chemiluminescence Biosensor For MicroRNA Determination And A Luminescence System Of BCNO Quantum Dots

MicroRNA(miRNA)is an endogenous,non-coding RNA molecule with a length of about22 nucleotides.It can regulate the expression of certain genes in life and participate in the regulation of cell cycle.It has been shown that there is a correlation between miRNA expression level and the onset and progression of disease.As biomarkers of diseases such as cancer,accurate and sensitive detection of miRNA has far-reaching significance for the diagnosis and treatment of diseases.However,miRNAs are intrinsically small in size,short in sequence and low in abundance in tumor cells.It is a challenge to establish an accurate and sensitive method for its detection.Electrogenerated chemiluminescence(ECL)assay has high application in the field of bioassay because of its advantages of good controllability,low background interference,high sensitivity and wide linear range.In order to solve the problem of low contents of biomarkers in early diagnosis,an increasing number of researchers are combining signal amplification strategies with electrochemiluminescence assays.The aim of the research work is to improve the sensitivity of miRNA detection methods in order to provide information for the early diagnosis of diseases such as cancer.1.Establish an ECL sensing method for highly sensitive detection of miRNAs using nucleic acid signals and nanomaterials signal amplification strategies.2.Synthesize a new type of ECL luminescent material.The thesis is divided into three chapters with the following main work.In chapter 1,firstly,the principle and common system of electroluminescence analysis were introduced.Secondly,the application and development trend of electroluminescence biosensor were summarized.Meanwhile,the signal amplification strategy and its application were reviewed.Finally,the research content and significance of this thesis were expounded.In chapter 2,a sensitive ECL biosensing platform was proposed for the determination of miRNA-21 by using Co-MOFs-ABEI/Ti3C2 Tx composites as ECL indicators and duplexspecific nuclease(DSN)assisted target recycling signal amplification strategy.Firstly,we synthesized Co-MOFs-ABEI/Ti3C2 Tx composites that has stable luminescence signals via one-pot process.With the assistance of DSN enzymes,a single miRNA-21 can cycle to produce multiple short-stranded DNA(S2 strand).In the presence of hemin,the S2 strand interacts with a large number of G-rich single-stranded DNA(probe DNA)to generate in situ hemin/G-quadruplex,which promotes H2O2 to catalyze the generation of a large number of reactive oxygen species to amplify ECL signals.Under the optimized experimental conditions,the ECL intensity increased linearly with the increase of miRNA-21 concentration in the range of 0.01 pM-10000 pM.The detection limit is 3.7 fM.In chapter 3,micron-scale bulk BCNO luminescent materials were generated by high temperature calcination,and then ultrasonic stripping was employed to form BCNO quantum dots with a size of 2.5 nm.At the same time,the optimal proportion of ECL properties was determined by changing the molar ratio of raw materials,and the ECL behavior of the quantum dots at this proportion was studied.BCNO quantum dots on the electrode surface could undergo a series of electron transfer processes in the presence of K2S2O8 and eventually emit light.In addition,the presence of hydrophilic groups such as-OH and-NH2 on the surface of BCNO quantum dots provides excellent water solubility and is therefore useful for practical applications in bioanalysis.Hence,BCNO quantum dots are expected to be further applied in the field of biomedical and clinical diagnosis because of its excellent electrochemiluminescent properties.