Multiple-Signal Amplification Strategy to Fabricate an Ultrasensitive Electrochemiluminescence Magnetic Immunosensor for Detecting Biomarkers of Alzheimer’s Disease via Iridium-Based Self-Enhancing Nanoemitters
Chenji Dai, Yaoyao Xu, Libing Ke, Mengjiao Zhu, Rongxiu Deng, Xuedong Wang, Yuyang Zhou
Abstract
Alzheimer’s disease (AD) is characterized by progressive memory loss and cognitive decline, significantly impairing the daily life of elderly individuals. The low abundance of blood-based biomarkers in AD necessitates higher analytical technique requirements. Herein, one novel iridium-based ECL self-enhanced nanoemitter (TPrA@Ir-SiO 2 ) was unprecedentedly reported, and it was further used to construct an ultrasensitive ECL magnetic immunosensor by a multiple-signal amplification strategy to unequally sensitively and accurately detect the AD blood-based biomarker (P-tau181) in this work. The initial signal amplification was accomplished via incorporating a new efficient iridium-based luminophore named Ir(mdq) 2 (acac) and a corresponding coreactant into silica nanoparticles to successfully obtain TPrA@Ir-SiO 2 . In addition, the specific and high-affinity interactions between streptavidin and biotin were subsequently employed to further facilitate signal amplification. Based on the advantages of the luminophore itself and the high-affinity interactions between biotin and streptavidin, the corresponding ECL immunosensor proposed in this work exhibited remarkable sensitivity, covering a wide linear range from 0.1 pg/mL to 0.1 μg/mL, and achieved an ultralow limit of detection of 68.58 fg/mL (S/N = 3), and it also exhibited outstanding recovery (98–104%) and RSD (1.92–4.86%) in the detection of serum samples by the spiking method. These remarkable results undoubtedly demonstrate the potential of self-enhanced ECL nanoemitters combined with a synergistic signal amplification strategy bearing streptavidin–biotin in detecting AD blood-based biomarkers, providing accurate and reliable solutions for early diagnosis and monitoring of AD, which would open a new avenue to effectively reduce the burden on AD patients’ families and society in the future.