{"id":"doi:10.1002/advs.76670","kind":"article","title":"Radical-Mediated In Situ Fluorescence Dye Deposition: A Simple Interfacial Signal Amplification Reaction for Ultrasensitive Immunoassay on Barcode Beads","authors":["Zhang J","Wang Y","Huang X","Wu H","Lin Q","Gu H","Jiang L","Zhu L","Xu H"],"author_count":9,"year":2026,"published":"2026-07-20","venue":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","cited_by":0,"doi":"10.1002/advs.76670","arxiv_id":null,"nct_id":null,"source_url":"https://doi.org/10.1002/advs.76670","archive_url":"https://space-kitty.com/papers/doi:10.1002/advs.76670","updated":null,"pmid":"42474120","pmcid":"PMC13383694","openalex_id":null,"pdf_url":"https://europepmc.org/articles/PMC13383694/pdf","abstract":"Ultrasensitive detection of low-abundance protein biomarkers is crucial for early disease diagnosis but remains challenging for the conventional barcode beads-based suspension chip platform due to the limited detection sensitivity. Here, we report a conceptually novel reaction termed \"radical-mediated in situ fluorescence dye deposition\" (RIFD) as a simple interfacial signal amplification strategy to overcome the limitation. This first discovered RIFD follows a universal \"three-element principle\", where the coexistence of beads, free radicals, and dyes suffices for fluorescence labeling, eliminating the pre-conjugation of dyes to detection probes required in traditional methods. Mechanistic studies reveal that this radical-triggered RIFD possibly follows three distinct pathways, including amide condensation on lysine residues, covalent biphenyl formation on tyrosine residues, or radical-dye co-deposition. It facilitates local and ultrafast (within 5 min) dye-trapping specifically on target-positive barcode beads. Consequently, the established RIFD-based immunoassay achieves a limit of detection of 12 fg/mL for IL-10, a 100-fold improvement over the conventional suspension chip method, and also successfully differentiates Alzheimer's disease patients from healthy controls by quantifying low-abundance plasma p-Tau217. Multiplexed detection is further validated with a three-plex cytokines panel. Our reported RIFD represents a powerful in situ fluorescence labeling tool, advancing protein biomarker detection toward the sub-pg/mL level with broad implications for clinical diagnostics.","abstract_license":"CC-BY (article license as recorded by Europe PMC; abstract reproduced unmodified apart from markup removal)","license":"CC-BY","is_open_access":true,"retracted":false,"peer_reviewed":null,"categories":[],"details":null,"provenance":"europepmc","attribution":"Abstract of \"Radical-Mediated In Situ Fluorescence Dye Deposition: A Simple Interfacial Signal Amplification Reaction for Ultrasensitive Immunoassay on Barcode Beads\" by Zhang J, Wang Y, Huang X et al., https://doi.org/10.1002/advs.76670, used under its Creative Commons Attribution license (CC-BY); markup removed, otherwise unmodified.","topics":[{"slug":"neurodegeneration","name":"Alzheimer's, Parkinson's & Neurodegeneration","domain_slug":"medicine"}],"cited_in_dossiers":[]}