The Construction Of Electrochemiluminescence Biosensor Based On Nanomaterials To Detect Soybean Agglutinin And MicroRNA

Electrochemiluminescence?ECL?is a chemiluminescence phenomenon induced by electrochemical methods.The ECL analysis technology combines the advantages of electrochemical and chemiluminescence analysis method,and exhibits a high sensitivity,good selectivity,wide linear range,fast analysis speed,and good controllability of reaction.Soybean agglutinin?SBA?,as a member of the lectin family,is a non-fiber carbohydrate and an important anti-nutrient.It has anticancer activity against leukemia,breast cancer,gastric cancer and meningeal cancer.MicroRNAs?miRNAs?are a class of non-coding single-stranded RNA molecules encoded by endogenous genes.They are involved in many aspects of the innate immune response and can be used for human cancer detection,diagnosis,prognosis,and possible treatment.Therefore,developing accurate and sensitive detection strategies of SBA and miRNA is of great significance in the bioanalysis field.Part 1 A novel ECL biosensor for sensitive detection of soybean agglutinin based on AuPt@C₆₀ nanoflowers enhanced N-?aminobutyl?-N-?ethylisoluminol?A sandwich electrochemiluminescence?ECL?biosensing system for soybean agglutinin?SBA?detection was developed with AuPt@C₆₀ nanoflowers(AuPt@C₆₀NFs)as a novel co-reactant accelerator to enhance the performance of N-?aminobutyl?-N-?ethylisoluminol??ABEI?.In this strategy,nanoflower-liked AuPt@C₆₀ complex served as a matrix for loading a large sum of ABEI and galactosamine?Gal?by Au-N and Pt-N bonds to achieve the nanocomposite Gal-ABEI-AuPt@C₆₀ NFs.Dissolved oxygen was used as a co-reaction reagent,while AuPt@C₆₀ complex acted as a co-reactant accelerator for dissolved oxygen to enhance the ECL emission of ABEI.Gal,as an identifying element,was highly loaded by electrodeposited gold nanoparticles?Dp Au?on the electrode to recognize SBA,and further combine with Gal-ABEI-AuPt@C₆₀ NFs to form a sandwich model.As a result,the proposed SBA biosensor exhibited a wide linear range from 1.0 ng·m L^-1 to 5.0?g·mL^-1 and a low detection limit of 0.33 ng·m L^-1.In addition,the biosensor displayed an excellent selectivity and an acceptable stability and reproducibility.The combination of AuPt@C₆₀ NFs and ABEI provided a new ECL sensing platform without exogenous co-reactant.Part 2 An ECL biosensor for microRNA-155 detection based on H₂O₂ quenched hydroxide-dependent ECL emission of PFO NPsIt was found that carboxyl functionalized-poly?9,9-di-n-octylfluorenyl-2,7-diyl?polymer nanoparticles?PFO NPs?exhibited a strong hydroxide?OH^–?-dependent ECL emission at+1.25 V in the absence of exogenous species and dissolved oxygen?O₂?as coreactants.Moreover,hydrogen peroxide?H₂O₂?can efficiently quench such an OH^–-dependent ECL emission of PFO NPs.As a result,a“signal-off-on”ECL biosensing platform for microRNA-155?miRNA-155?was developed.Firstly,PFO NPs were modified onto the electrode to capture DNA duplex tracklocker.In the presence of H₂O₂in test solution,the ECL signal of PFO NPs was quenched by H₂O₂ to obtain a signal-off state.Subsequently,the DNA walker produced through the target miRNA-155-triggered catalytic hairpin assembly?CHA?walked along the DNA duplex track-locker to output amounts of G-rich short chain,forming a hemin/G-quadruplex.With the consumption of H₂O₂ by hemin/G-quadruplex,the ECL signal would be restored to a signal-on state,thus achieving a detection of miRNA-155.The detection limit was low as 12.2 amol·L^-1.Furthermore,our proposed biosensor demonstrated a tremendous selectivity and admirable stability,and exhibited a satisfactory performance for determinating intracellular mi RNA-155.The integration of PFO NPs with an excellent ECL performance and H₂O₂ with a high quenching effect on the ECL emission of PFO NPs will provide an attractive ECL platform for bioanalysis and clinical diagnosis.Part 3 A novel potential-regulated ratiometric ECL sensing strategy based on poly?9,9-di-n-octylfluorenyl-2,7-diyl?for micro RNA detectionExploring different signal conversion mechanisms to build ratiometric ECL biosensors has attracted more and more attention.The general ratiometric sensing strategies are based on the signal conversion between two different ECL emitters.It was found that poly?9,9-di-n-octylfluorenyl-2,7-diyl?polymer nanoparticles?PFO NPs?had two anodic ECL emissions.One was the ECL-1,which was detected stably at+1.25 V when the scanning potential range was set as 0?+1.25 V.The other was ECL-2,which was detected stably at approximately+1.95 V when the scanning potential range was set as 0?+2.0 V.The ECL-1 at a lower potential exhibited a strong ECL signal without any other substances?including dissolved O₂?as a co-reacant.In addition,H₂O₂ has an opposite effect on two ECL emissions,namely quenching ECL-1 and enhancing ECL-2,which can facilitate the construction of a novel potential-regulated ratiometric ECL biosensor.The combination of target?miRNA-155?induced strand displacement amplification?SDA?reaction and the secondary targets initiated hybridization chain reaction?HCR?would introduce a large amount of glucose oxidase?GOx?on the electrode surface.The H₂O₂ generated in-situ during the enzymatic reaction can be used as a quencher and enhancer for ECL-1 and ECL-2,respectively,thereby achieving a ratiometric detection of miRNA-155.The detection limit is as low as 17 amol·L^-1.Such a strategy based on the opposite effect of H₂O₂ generated in-situ by enzymatic reaction on two ECL emissions of the same ECL illuminator in the case of two different scanning potentials will provide a new idea for ECL ratio detection and expand the application of PFO NPs in bioanalysis.