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Multiplexed Near-IR Detection of Single-Molecule Fluorescence Fluctuations Using a Single Superconducting Nanowire Single-Photon Detector
KTH, School of Engineering Sciences (SCI), Applied Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Bio-Opto-Nano Physics.ORCID iD: 0000-0002-2922-1566
KTH, School of Engineering Sciences (SCI), Applied Physics, Bio-Opto-Nano Physics.ORCID iD: 0000-0003-3200-0374
2025 (English)In: ACS Photonics, E-ISSN 2330-4022, Vol. 12, no 4, p. 2233-2241Article in journal (Refereed) Published
Abstract [en]

Fluorescence-based single-molecule and fluctuation spectroscopy in the near-IR can open avenues for biomolecular dynamic studies in biological media with suppressed autofluorescence and scattering background. However, further implementation is limited by the lower brightness of NIR fluorophores and available single-photon detector technologies that are still to be explored and adapted. Superconducting nanowire single-photon detectors (snSPDs) have found increasing use in quantum optics and optical communication applications thanks to high sensitivity in the near-infraed (NIR), low dark-counts, no after-pulsing, and high time resolution. Here, we present characterization of fluorescence intensity fluctuations from single vesicles and NIR fluorophores based on fluorescence correlation spectroscopy (FCS), specifically taking advantage of these snSPD properties. We present a concept allowing multiplexed readouts based on only one snSPD, in which the emitted photons are separated by their emission wavelength into different optical paths, thereby translating the emission wavelengths into different arrival times onto the snSPD. This concept allows one-laser-one-detector, dual-color fluorescence cross-correlation spectroscopy (FCCS) measurements, with fluorescence intensity fluctuations of two fluorophore species separately analyzed and cross-correlated. It is shown how two fluorophore species in a sample can be distinguished by their different blinking kinetics, fluorescence lifetimes, and/or diffusion properties. Apart from differences in emission spectra, the presented concept for multiplexing using a single detector can also be applied to distinguish emitters by properties such as polarization, coherence lengths, and fluorescence bunching and antibunching signatures. It can also be generalized to other modalities than FCS, including single-molecule detection, confocal microscopy, and imaging.

Place, publisher, year, edition, pages
American Chemical Society (ACS) , 2025. Vol. 12, no 4, p. 2233-2241
Keywords [en]
antibunching, fluorescence correlation spectroscopy, multiplexing, photon correlations, photophysics, quantum photonics, time-correlated single-photon counting
National Category
Atom and Molecular Physics and Optics Condensed Matter Physics
Identifiers
URN: urn:nbn:se:kth:diva-363124DOI: 10.1021/acsphotonics.5c00224ISI: 001455033500001Scopus ID: 2-s2.0-105003016014OAI: oai:DiVA.org:kth-363124DiVA, id: diva2:1956374
Note

QC 20250507

Available from: 2025-05-06 Created: 2025-05-06 Last updated: 2025-05-07Bibliographically approved

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Kulkarni, AbhilashBagheri, NiushaWidengren, Jerker

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