Raw data underlying the results presented in a manuscript, entitled: Multiplexed near-IR detection of single-molecule fluorescence fluctuations using a single superconducting nanowire single photon detector.

This folder contains all raw data underlying the results presented in a manuscript, entitled:

Multiplexed near-IR detection of single-molecule fluorescence fluctuations using a single superconducting nanowire single photon detector

Authored by:

Abhilash Kulkarni 1, Niusha Bagheri 1, Jerker Widengren 1,*

1 Royal Institute of Technology (KTH), Experimental Biomolecular Physics, Dept. Applied Physics, Albanova University Center 106 91 Stockholm, Sweden

* Corresponding author ([e-mail])

The data files are grouped into the different techniques used to generate them and refer to the figures/tables in the manuscript where the extracted results are presented.

ABSTRACT:

Fluorescence-based single-molecule and fluctuation spectroscopy in the near-IR can open 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, much thanks to high sensitivity in the near-IR (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 analysed, 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 anti-bunching signatures. It can also be generalized to other modalities than FCS, including single-molecule detection, confocal microscopy and imaging.

ACKNOWLEDGMENTS

This work was supported by the Knut and Alice Wallenberg Foundation via Wallenberg Center for Quantum Technology (WACQT), and the Swedish Foundation for Strategic Research (SSF, ITM17-0491, BENVAC RMX18-0041).