A signal amplification electrochemiluminescence biosensor based on Ru(bpy)₃²⁺ and β-cyclodextrin for detection of AFP

By combining two different materials, metal-organic frameworks (MOF) and β-cyclodextrins (β-CD), a signal amplification electrochemical luminescence (ECL) immunosensor was constructed to realize the sensitive detection of AFP. The indium-based metal-organic framework (In-MOF) was used as the carrier of Ru(bpy)₃²⁺, and Ru(bpy)₃²⁺ was immobilized by In-MOF through suitable pore size and electrostatic interaction. At the same time, using host-guest recognition, β-CD enriched TPA into the hydrophobic cavity for accelerating the electronic excitation of TPA, then, achieving the purpose of signal amplification. The signal amplification immunosensor structure is constructed among the primary antibody Ab₁ connected to the Ru(bpy)₃²⁺@In-MOF modified electrode, AFP, BSA and the secondary antibody (Ab₂) loaded with TPA-β-CD. The immunosensor has a good linearity in the range of 10^-5 ng/mL-50 ng/mL, and the low limit of detection (LOD) is 1.1 × 10^-6 ng/mL. In addition, the electrochemiluminescence immunosensor that we designed has strong stability, good selectivity and repeatability, which provides a choice for the analysis of AFP.