A novel signal amplification strategy electrochemical immunosensor for ultra-sensitive determination of p53 protein

In this work, we fabricated a novel sandwich-type electrochemical immunosensor for quantitative and ultra-sensitive determination of tumor suppressor protein p53 by signal amplification strategy. Conductive polymers poly (3, 4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) has significantly effect on enhancing charge transfer and markedly increases the sensitivity of electrochemical immunosensing. Gold nanoparticles (AuNPs) as high conductivity nanocarriers were also used to capture monoclonal antibodies (Ab₁) due to their large specific surface areas. In addition, pH responsive zeolitic imidazolate framework (ZIF-8) was used to load the redox probe 2, 3-diaminophenazine (DAP) and the secondary antibodies (Ab₂) to form a sensitive-type ZIF-8-DAP-Ab₂ immunoprobe. After the sandwich-type immunoassay with the free p53 protein, with the release of probe DAP after the electrochemical signal amplificated by PEDOT:PSS and AuNPs, the ultra-sensitive and quantitative determination of p53 protein was realized with working range of 1-120 ng mL^-1 and low detection limit of 0.09 ng mL^-1. Besides, the fabricated electrochemical immunosensor exhibited good recovery, high sensitivity, reliability, and selectivity.