Research On New Methods Of Bioanalysis Based On Electrochemiluminescence Of Novel Materials And Various Signalamplification Strategies

Electrochemiluminescence（ECL）has gradually developed into a powerful analytical technique for biological analysis,environmental detection,luminescence equipment and imaging.ECL technology has been successfully commercialized in a wide range of clinical diagnoses by immunoassay,such as heart disease,thyroid,infection,tumor markers,etc.In this paper,a series of electrochemiluminescence biosensors with good performance were successfully constructed by using novel materials and multi-functional DNA structure,which were applied to highly sensitive detection of Cd²⁺,Mg²⁺,BRCA1and CEA.This paper divides the research work into the following two parts:1.In this work,a multifunctional signal probe with DNA network-loaded Ru（phen）₃²⁺and Ag nanocluster（Ag NCs）was assembled,and combined with a novel terbium organic gel to design a versatile electrochemiluminescence（ECL）biosensor for dual-potential“on”“off”assays of Cd²⁺and Mg²⁺.Firstly,target Cd²⁺-driven DNA walker-amplification process produced a large amount of output DNA,which was used to link the multifunctional DNA network（DNA Net）structure probes with both Ru（phen）₃²⁺and C-rich base to the terbium organic gel（TOG）-modified electrode.Thus the positive potential ECL signal of Ru（phen）₃²⁺was generated,and the negative-potential ECL signal of TOG was quenched by Ag NCs via resonance energy transfer and co-reactant-competition simultaneously,achieving dual signal“on”and“off”assay of Cd²⁺.Furthermore,the present Mg²⁺（second-target）specifically sheared the substrate of DNA enzyme on the electrode,releasing the DNA Net probes with Ru（phen）₃²⁺and Ag NCs to realize“off”and“on”detection of Mg²⁺by dual-potential signals.This strategy developed a new versatile biosensor by using dual-potential ECL probes and novel DNA network structure,and opened up a new way for multi-target detection by dual“on”“off”signals,which shows great potential in practical detection.The multifunctional sensing platform was also applied to Cd²⁺assay in rice.2.Based on ECL energy transfer of perylene diimide（PDI）-metal organic framework（IRMOF-3）,DNA nanoflower-Cd S QDs signal probe and DNA walking multiple amplification techniques,a novel bipotential ratiometric ECL biosensor was constructed for detecting dual targets.Firstly,graphene oxide was modified to the electrode by electrochemical reduction,then the electrochemiluminescent PDI@IRMOF-3 complex was modified byπ-πconjugation,and the dopamine（DA）probe was linked to quench ECL signal by DNA hybridization.In the presence of target BRCA1,it can form a bipedal DNA walker,which binds to the probe to keep DA away from the electrode and recover the ECL signal of PDI at-0.25 V.In the presence of magnesium ions,the cleavage active site of the DNA enzyme between the DNA bipedal walker and prober was recognized,so the prober DNA was sheared,and the bipedal walker was released to walk on the electrode to amplify ECL signal for BRCA1 detection.In the presence of CEA target,a large amount of output DNA was produced by fuel molecular driven-chain replacement cyclic amplification reaction,and the DNA nanoflower-Cd S QDs was connected to the electrode.The metal organic framework IRMOF-3 can transfer its excitation energy to Cd S QDs in a non-radiative way,thus increasing the ECL emission signal of Cd S QDs at-1.5 V.Both-0.25 V and-1.5 V show high ECL signal response.The ratio of ECL signals at double negative potential is used to detect the target,which simplifies the detection procedure and prevents false positive errors caused by single signals.It provides a new detection method for early tumor screening.