Photonic-plasmonic coupling enhanced fluorescence for digital-resolution protein detection

Assays utilizing molecular fluorophores are common throughout life science research and diagnostic testing, although detection limits are generally limited by weak emission intensity, thus requiring many labeled target molecules to combine their output to achieve signal-to-noise greater than the background. Here, we describe how the synergistic coupling of plasmonic and photonic resonance modes can significantly boost the emission from fluorescent dye molecules without increasing the illumination intensity while utilizing a microscopy approach with a broad field of view. By optimally matching the resonant modes of a plasmonic fluor (PF) nanoparticle and a photonic crystal (PC) surface with the absorption and emission spectrum of the PF’s fluorescent dye, we observe a 52-fold improvement in signal intensity, enabling individual PFs to be observed and digitally counted, using an approach in which one PF tag represents detection of one target molecule. The photonic amplification from the PF can be attributed to the strong nearfield enhancement due to the cavity-induced activation of the PF, PC band structure-mediated improvement in collection efficiency of emitted photons, and increased rate of spontaneous emission. We demonstrate the applicability of the method by dose-response characterization of a sandwich immunoassay for human interleukin-6, a biomarker commonly used to assist diagnosis of cancer, inflammation, sepsis, and autoimmune disease. We achieve a limit of detection of 10 fg/ml, representing a capability three orders of magnitude lower than standard immunoassays.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Barya, Priyash

Contributors dc:contributor

• Cunningham, Brian T

• Biosensor
• Photonics
• Plasmonics
• Fluorescence
• Immunoassay

Statement dc:rights

• Copyright 2022 Priyash Barya

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/117602

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F117602