Abstract
Upconverting nanoparticles (UCNPs) offer great potential for single-molecule labeled biosensing because of their background-free detection and high photostability. However, the weak intensity emitted by one individual UCNP, inherent to its low intrinsic upconversion efficiency, represents a challenge to tackle when imaging single UCNPs. The motivation for this work is to study how diverging surface plasmon polaritons (SPPs) can be used in the imaging of individual UCNPs. The analytical solution to describe the SPP coupling and the diverging mode propagation is derived. Numerical simulations are conducted, and their results are in excellent agreement with the analytical solution. The phenomenon is also studied experimentally by using diverging SPPs to excite UCNPs immobilized on a gold surface and imaging their emissions. The results show that the detection of single UCNPs over a large area is possible. This work offers a novel approach toward single-molecule digital detection in biosensor applications.
| Original language | English |
|---|---|
| Article number | e00426 |
| Journal | Laser and Photonics Reviews |
| DOIs | |
| Publication status | E-pub ahead of print - 2025 |
| MoE publication type | A1 Journal article-refereed |
Funding
This work was under three projects funded by the Research Council of Finland: Printed Intelligence Infrastructure with decision 358621, Digital Single Molecule Detection with Plasmonic-Enhanced Up-Conversion (DISIMO) with decisions 363445 and 363570, and Photonics Research and Innovation (PREIN) with decisions 368651 and 368653.
Keywords
- biosensing application
- digital detection
- diverging surface plasmon polariton
- single-molecule imaging
- upconverting nanoparticles