Self-Amplifying Cascade Strategy Triggered Au NPs Assembly for Ultrasensitive cTnI Detection with Dynamic Light Scattering

Abstract

Here we report an ultrasensitive dynamic light scattering (DLS) immunosensor for cardiac troponin I (cTnI) leveraging a novel Self-cascading reaction synergistic amplification strategy by using metal organic frameworks (MOF) materials. This synergistic amplification system was designed within combined enzymatic (glucose oxidase, GOD) catalysis, acid-responsive MOF disintegration, Fenton reaction and gold nanoparticles (Au NPs) stability modulation. When the target cTnI was present, sandwich structure was formed between multifunctional probes (Ab-GOD/Fe-MOF) and Ab modified 96-well plates, subsequently occurring self-cascading reactions with further addition of glucose: the glucose was oxidized into gluconic acid (creating an acidic micro-environment) by O2 under the catalysis of MOF - conjugated GOD and produced H2O2, the acidic micro-environment triggered the breakdown of Fe-MOF and the release of Fe2+, reacting with H2O2 via the Fenton reaction to etch the protective DNA layer that modified on Au NPs, enable the salt-induced aggregation of AuNPs. Crucially, the DLS assay achieved a low limit of detection (LOD) of 1.5 × 10-13 g/mL, furthermore, this cascade amplification strategy realized the quantitative detection of cTnI in clinical samples with high sensitivity and specificity.