Application Of Ru（bpy）₃²⁺ Functionalized Zinc-based MOF In Electrochemicalluminescence Immunosensor

Nowadays,human beings still face the threat of death from cancer and other diseases,which is one of the main reasons that threaten human safety and health problems,therefore,it is important to take preventive measures in the early diagnosis of cancer through the accurate detection of tumor markers.Electrochemiluminescent（ECL）immunosensors are a new class of electrochemical biosensors for antigen-antibody reactions that combine the sensitivity of ECL sensing technology with immunoassays,and the new ECL sensing technology has broad application prospects in the field of clinical diagnosis.In this study,we designed various signaling strategies based on Ru（bpy）₃²⁺luminescent functionalized metal organic backbone（MOF）as an immunosensing platform and constructed a series of ECL immunosensors for the detection of various tumor markers.The research work is as follows:1.Construction of an ECL immunosensor with MnO₂/PDA as a signal burst probe for the detection of alpha-fetoprotein（AFP）:in this work,Ru（bpy）₃²⁺@TMU-3 with a large specific surface area and rich mesoporous structure was used as the immunomodification platform;Manganese dioxide/polydopamine nanocomposite（MnO₂/PDA）with good biocompatibility is used as a signal tag to connect more detection antibodies（Ab₂）,which enables sensitive determination of AFP.The prepared sensor has a simple construction process,fast detection speed and high sensitivity.It has a good linear range between 10^-5 ng·mL^-1 and 5 ng·mL^-1,and the detection limit is as low as 10.7 fg·mL^-1（S/N=3）.2.Development of an ECL immunosensor with a dual signal amplification strategy for the sensitive detection of AFP:In this work,in situ growth of cobalt-iron bimetallic oxides（CoFeLDO）on the surface of molybdenum disulfide nanoflowers（MoS₂ NFs）and in situ reduction of gold nanoparticles（AuNPs）to obtain gold nanoparticles/cobalt-iron bimetallic oxides/molybdenum disulfide nanoflowers（AuNPs/CoFeLDO/MoS₂NFs）by in situ growth method.MoS₂ NFs and CoFeLDO nanomaterials can promote the co-reactive reagent potassium persulfate（K₂S₂O₈）to produce more sulfate radicals(SO₄^·-),which can achieve double ECL signal amplification.The immunosensing platform was constructed with the detection of different AFP concentrations,the ECL signal was proportional to the logarithm of different AFP concentrations,and the linear range of this immunosensor was 10^-5 ng·mL^-1-100 ng·mL^-1 with a detection limit of 3.23 fg-mL-1（S/N=3）.3.A Cu⁺-depleted signal amplification mechanism of the ECL immunosensor was designed for the sensitive detection of CEA.The mechanism is based on the following principle:this work uses Zn-MOF-Ru-TEA as the immunomodification platform and CuNiOS/gold nanoparticle composites（CuNiOS/AuNPs）as the signal probe.This mechanism has the following advantages:（1）the enrichment of the luminescent group Ru（bpy）₃²⁺and the co-reactant（TEA）in the same metal-organic skeleton not only shortens the redox electron transfer distance,but also greatly increases the luminescence efficiency of the luminescent group;（2）the presence of Cu⁺/Cu²⁺ion pairs Cu⁺depletion generates Cu²⁺that promotes the production of more TEA radicals by TEA,triggering a Cu⁺depletion-based signal amplification mechanism.The results showed that the immunosensor exhibited good linearity in the concentration range of 10^-5 ng·mL^-1 to 80 ng·mL^-1 CEA with a detection limit of 3.43 fg·mL^-1（S/N=3）.