Facile preparation of poly-(styrene-co-maleic anhydride) encapsulated Iridium(III) complexes as highly efficient electrochemiluminescence indicators for sensitive immunoassay of CYFRA 21-1

Exploring facile strategy for developing highly efficient emitters using water-insoluble luminophores has become a vital topic in electrochemiluminescence (ECL) immunoassay. In this work, an ECL-active and water-dispersive iridium(III) complex-based polymer dots (IrPdots) was fabricated by encapsulating water-insoluble tris[1-phenylisoquinolinato-C2, N] iridium(III) complexes [Ir(piq)3] into poly-(styrene-co-maleic anhydride) (PSMA) matrix by a controllable nanoprecipitation process. The obtained IrPdots generated strong ECL signals in the presence of tri-n-propylamine (TPrA) and were used to label detection antibody (Ab2) to act as ECL probes to indicate the signal changes when analyzing target antigen. To construct a sandwich immunosensor, Pd nanoparticles (NPs) decorated MoS2/Ti3C2Tx MXene nanocomposites (MoS2/Ti3C2Tx MXene/Pd) were fabricated as substrates to bind capture antibody (Ab1), which could further amplify ECL signals via a coreaction-accelerating pathway to improve the detection sensitivity. When the cytokeratin 19 fragment 21-1 (CYFRA 21-1) was chosen as model analyte, the developed immunosensor displayed a good linear relationship ranging from 0.1 pg/mL to 50 ng/mL with a low detection limit of 95 fg/mL (S/N = 3) was achieved as well. This research proposed a facile and effective method of fabricating IrPdots as ECL probes for immunoassay using water-insoluble iridium complexes, which expanded the application scope of those water-insoluble luminophores for aqueous bioanalysis.

Automated summary

This research developed an easy and effective method for fabricating water-dispersible iridium polymer dots (IrPdots) as electrochemiluminescence (ECL) probes using water-insoluble iridium complexes. The IrPdots generated strong ECL signals and were used for signal changes during target antigen analysis. A sandwich immunosensor was constructed using Pd nanoparticles decorated MoS2/Ti3C2Tx MXene nanocomposites as substrates for capture antibodies, which amplified ECL signals and improved detection sensitivity. The developed immunosensor showed good linearity and low detection limit for the model analyte cytokeratin 19 fragment 21-1 (CYFRA 21-1).