Catalytic Hairpin Assembly Strategy For The Construction Of Electrochemiluminescence Biosensor

Cancer biomarkers are a class of biomolecules that can objectively reflect the occurrence and development of cancer,which possessed great practical value in early cancer diagnosis and treatment.However,the expression level of cancer biomarkers in vivo is extremely low,which requires us to propose sensitive detection methods.Electrochemiluminescence?ECL?,the combination of electrochemistry and luminescence,has received great attention in bioanalysis in recent years,due to its high sensitivity,strong controllability and quick response.In addition,it is worth mentioning that the nucleic acid amplification strategies could further improve the detection sensitivity.Among the multiple nucleic acid amplification strategies,catalytic hairpin assembly?CHA?strategy has received wide attention in biosensing for its mild reaction conditions and simple operation.In this paper,we combined the CHA strategy with ECL technology to achieve sensitive detection of cancer biomarkers.The content of research includes the following two parts:?1?In this work,a sensitive electrochemiluminescence biosensor was fabricated for the detection of microRNA-21?miRNA-21?based on CHA strategy and Zr-based metal-organic frameworks?MOF-808?combined N-?aminobutyl?-N-ethylisoluminol?ABEI?functionalized Ag nanoparticles?MOF-808@Ag-ABEI?as signal tag.The CHA reaction between hairpin probe 1?HP1?and signal probe?the hairpin probe 2?HP2?modified with MOF-808@Ag-ABEI,abbreviated as MOF-808@Ag-ABEI-HP2?was triggered by miRNA-21 to introduce abundant MOF-808@Ag-ABEI-HP2 on the electrode surface,leading to a considerable ECL response and the sensitive detection of miRNA-21.The experimental results showed the proposed biosensor had a good linear relationship in the range of 100 aM to 500 pM for miRNA-21 detection,and the detection limit was 30 aM.?2?Despite the improved sensitivity of CHA strategies,only one target could be measured in most of the reported studies.Hence,we proposed an effective dual CHA?DCHA?strategy,based on which a sensitive ECL biosensor was constructed for miRNA-21 and mucin 1?MUC1?detection.First,miRNA-21 was used to trigger the CHA reaction?Cycle I?between the a-hairpin probe of hairpin probe 1?HP1?and signal probe?the hairpin probe 2?HP2?modified with CdS:Mn quantum dots?QDs?,abbreviated as CdS:Mn-HP2?,which introduced abundant CdS:Mn-HP2 on the electrode surface,leading to a considerable ECL response and the sensitive detection of miRNA-21.The experimental results showed the proposed biosensor had a good linear relationship in the range of 20 aM to 50 pM for miRNA-21 detection,and the detection limit was 11 aM.Subsequently,the second CHA process?Cycle II?between the b-hairpin probe of HP1 and signal probe?the hairpin probe 3?HP3?modified with Au nanoparticle?AuNPs?,abbreviated as AuNPs-HP3?was triggered by the MUC1-aptamer complex,which allowed copious amounts of AuNPs-HP3 to approach the CdS:Mn QDs.A decreased ECL signal was obtained due to the ECL resonance energy transfer?ECL-RET?effect between the CdS:Mn QDs and AuNPs;meanwhile,MUC1 was sensitively detected.The experimental results showed the proposed biosensor had a good linear relationship in the range of 1 fg mL^-1to 10 ng mL^-1for MUC1 detection,and the detection limit was 0.40 fg mL^-1.