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Gandhi SA, Sanders MA, Granneman JG, Kelly CV. Four-color fluorescence cross-correlation spectroscopy with one laser and one camera. BIOMEDICAL OPTICS EXPRESS 2023; 14:3812-3827. [PMID: 37497523 PMCID: PMC10368031 DOI: 10.1364/boe.486937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/14/2023] [Accepted: 04/18/2023] [Indexed: 07/28/2023]
Abstract
The diffusion and reorganization of phospholipids and membrane-associated proteins are fundamental for cellular function. Fluorescence cross-correlation spectroscopy (FCCS) measures diffusion and molecular interactions at nanomolar concentration in biological systems. We have developed an economical method to simultaneously monitor diffusion and complexation with the use of super-continuum laser and spectral deconvolution from a single detector. Customizable excitation wavelengths were chosen from the wide-band source and spectral fitting of the emitted light revealed the interactions for up to four chromatically overlapping fluorophores simultaneously. This method was applied to perform four-color FCCS that we demonstrated with polystyrene nanoparticles, lipid vesicles, and membrane-bound molecules. Up to four individually customizable excitation channels were selected from the broad-spectrum fiber laser to excite the diffusers within a diffraction-limited spot. The fluorescence emission passed through a cleanup filter and a dispersive prism prior to being collected by a sCMOS or EMCCD camera with up to 1.8 kHz frame rates. The emission intensity versus time of each fluorophore was extracted through a linear least-square fitting of each camera frame and temporally correlated via custom software. Auto- and cross-correlation functions enabled the measurement of the diffusion rates and binding partners. We have measured the induced aggregation of nanobeads and lipid vesicles in solution upon increasing the buffer salinity. Because of the adaptability of investigating four fluorophores simultaneously with a cost-effective method, this technique will have wide application for examining macromolecular complex formation in model and living systems.
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Affiliation(s)
- Sonali A. Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Matthew A. Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Christopher V. Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
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Gandhi SA, Sanders MA, Granneman JG, Kelly CV. Four-color fluorescence cross-correlation spectroscopy with one laser and one camera. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.30.526256. [PMID: 36778294 PMCID: PMC9915509 DOI: 10.1101/2023.01.30.526256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The diffusion and reorganization of phospholipids and membrane-associated proteins are fundamental for cellular function. Fluorescence cross-correlation spectroscopy (FCCS) measures the diffusion and molecular interactions at nanomolar concentration in biological systems. We have developed a novel, economical method to simultaneously monitor diffusion and oligomerization with the use of super-continuum laser and spectral deconvolution from a single detector. Customizable excitation wavelengths were chosen from the wide-band source and spectral fitting of the emitted light revealed the interactions for up to four spectrally overlapping fluorophores simultaneously. This method was applied to perform four-color FCCS, as demonstrated with polystyrene nanoparticles, lipid vesicles, and membrane-bound molecules. Up to four individually customizable excitation channels were selected from the broad-spectrum fiber laser to excite the diffusers within a diffraction-limited spot. The fluorescence emission passed through a cleanup filter and a dispersive prism prior to being collected by a sCMOS or EMCCD camera with up to 10 kHz frame rates. The emission intensity versus time of each fluorophore was extracted through a linear least-square fitting of each camera frame and temporally correlated via custom software. Auto- and cross-correlation functions enabled the measurement of the diffusion rates and binding partners. We have measured the induced aggregation of nanobeads and lipid vesicles in solution upon increasing the buffer salinity. Because of the adaptability of investigating four fluorophores simultaneously with a cost-effective method, this technique will have wide application for examining complex homo- and heterooligomerization in model and living systems.
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Affiliation(s)
- Sonali A. Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA, 48201
| | - Matthew A. Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, USA, 40201
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, USA, 40201,Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI, USA. 48201
| | - Christopher V. Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA, 48201,Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI, USA. 48201,Corresponding author:
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Frey C, Pfeil J, Neckernuss T, Geiger D, Weishaupt K, Platzman I, Marti O, Spatz JP. Label‐free monitoring and manipulation of microfluidic water‐in‐oil droplets. VIEW 2020. [DOI: 10.1002/viw.20200101] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Affiliation(s)
- Christoph Frey
- Department of Cellular Biophysics Max Planck Institute for Medical Research Heidelberg Germany
- Institute for Molecular Systems Engineering University of Heidelberg Heidelberg Germany
| | - Jonas Pfeil
- Institute of Experimental Physics University of Ulm Ulm Germany
| | | | - Daniel Geiger
- Institute of Experimental Physics University of Ulm Ulm Germany
| | - Klaus Weishaupt
- Department of Cellular Biophysics Max Planck Institute for Medical Research Heidelberg Germany
- Institute for Molecular Systems Engineering University of Heidelberg Heidelberg Germany
| | - Ilia Platzman
- Department of Cellular Biophysics Max Planck Institute for Medical Research Heidelberg Germany
- Institute for Molecular Systems Engineering University of Heidelberg Heidelberg Germany
| | - Othmar Marti
- Institute of Experimental Physics University of Ulm Ulm Germany
| | - Joachim P. Spatz
- Department of Cellular Biophysics Max Planck Institute for Medical Research Heidelberg Germany
- Institute for Molecular Systems Engineering University of Heidelberg Heidelberg Germany
- Max Planck School Matter to Life Heidelberg Germany
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Antona S, Platzman I, Spatz JP. Droplet-Based Cytotoxicity Assay: Implementation of Time-Efficient Screening of Antitumor Activity of Natural Killer Cells. ACS OMEGA 2020; 5:24674-24683. [PMID: 33015484 PMCID: PMC7528335 DOI: 10.1021/acsomega.0c03264] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/04/2020] [Indexed: 06/11/2023]
Abstract
Natural killer (NK) cells are key players of the innate immune system. Due to their rapid cytotoxicity against infectious pathogens, hematologic malignancies, and solid tumors, NK cells represent solid candidates for cell-based immunotherapy. Despite the progress made in recent years, the heterogeneity in their cytotoxic behavior represents a drawback. With the goal of screening the intrinsic diversity of NK cells, droplet-based microfluidic technology is exploited to develop a single-cell time-efficient cytotoxicity assay. Toward this end, NK-92 cells are coencapsulated with hematological tumor cell lines in water-in-oil droplets of different sizes and their cytotoxic activity is evaluated. The effect of droplet-based confinement on NK cytotoxicity is investigated by controlling the droplet volume. The successful optimization of the droplet size allows for time efficiency compared to cytotoxicity assays based on flow cytometry. Additionally, the ability of individual NK-92 cells to kill multiple target cells in series is explored, expanding the knowledge about the serial killing process dynamics. The developed droplet-based microfluidic assay does not require the labeling of NK cells and represents a step toward developing of a forthcoming process for the selection of NK cells with the highest cytotoxicity against specific targets.
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Affiliation(s)
- Silvia Antona
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
| | - Ilia Platzman
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
| | - Joachim P. Spatz
- Department
of Cellular Biophysics, Max Planck Institute
for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
- Institute
for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, 69120 Heidelberg, Germany
- Max
Planck School Matter to Life, Jahnstraße 29, D-69120 Heidelberg, Germany
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Lignos I, Utzat H, Bawendi MG, Jensen KF. Nanocrystal synthesis, μfluidic sample dilution and direct extraction of single emission linewidths in continuous flow. LAB ON A CHIP 2020; 20:1975-1980. [PMID: 32352465 DOI: 10.1039/d0lc00213e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The rational design of semiconductor nanocrystal populations requires control of their emission linewidths, which are dictated by interparticle inhomogeneities and single-nanocrystal spectral linewidths. To date, research efforts have concentrated on minimizing the ensemble emission linewidths, however there is little knowledge about the synthetic parameters dictating single-nanocrystal linewidths. In this direction, we present a flow-based system coupled with an optical interferometry setup for the extraction of single nanocrystal properties. The platform has the ability to synthesize nanocrystals at high temperature <300 °C, adjust the particle concentration after synthesis and extract ensemble-averaged single nanocrystal emission linewidths using flow photon-correlation Fourier spectroscopy.
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Affiliation(s)
- Ioannis Lignos
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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