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Gialdini I, Hendrix J, Lamb DC. There is more to scanning than meets the eye: Raster Image Correlation Spectroscopy. Biochim Biophys Acta Gen Subj 2025; 1869:130818. [PMID: 40354833 DOI: 10.1016/j.bbagen.2025.130818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2024] [Revised: 05/05/2025] [Accepted: 05/09/2025] [Indexed: 05/14/2025]
Abstract
Raster Image Correlation Spectroscopy (RICS) is a confocal image analysis method that can measure the diffusion and interactions of fluorescently labeled molecules in real time in solution and in living cells. RICS is easy to implement on commercial confocal microscopes and allows detailed investigations of complex biological systems and pathways. The method is especially robust for measurements in living cells using commonly used labels such as fluorescent proteins. Moreover, since its invention in 2005, the robustness and applicability of RICS has been significantly increased to allow, e.g., straightforward kinetic analyses, advanced image segmentation, parameter mapping, and multi-species analysis. In this review, we describe the methodological principles of RICS in a manner that is accessible to a broad readership, position RICS in relation to other fluorescence fluctuation techniques, highlight recent methodological advances and present exemplary applications of the method. With this review, we hope to facilitate the implementation of this powerful method into the everyday repertoire of confocal imaging approaches.
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Affiliation(s)
- Irene Gialdini
- Department Chemie and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jelle Hendrix
- Dynamic Bioimaging Lab, Advanced Optical Microscopy Centre and Biomedical Research Institute, Hasselt University, Agoralaan C (BIOMED), Hasselt, Belgium.
| | - Don C Lamb
- Department Chemie and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany.
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2
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Dhar M, Berg MA. Efficient, nonparametric removal of noise and recovery of probability distributions from time series using nonlinear-correlation functions: Photon and photon-counting noise. J Chem Phys 2024; 161:034116. [PMID: 39028845 DOI: 10.1063/5.0212157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/28/2024] [Indexed: 07/21/2024] Open
Abstract
A preceding paper [M. Dhar, J. A. Dickinson, and M. A. Berg, J. Chem. Phys. 159, 054110 (2023)] shows how to remove additive noise from an experimental time series, allowing both the equilibrium distribution of the system and its Green's function to be recovered. The approach is based on nonlinear-correlation functions and is fully nonparametric: no initial model of the system or of the noise is needed. However, single-molecule spectroscopy often produces time series with either photon or photon-counting noise. Unlike additive noise, photon noise is signal-size correlated and quantized. Photon counting adds the potential for bias. This paper extends noise-corrected-correlation methods to these cases and tests them on synthetic datasets. Neither signal-size correlation nor quantization is a significant complication. Analysis of the sampling error yields guidelines for the data quality needed to recover the properties of a system with a given complexity. We show that bias in photon-counting data can be corrected, even at the high count rates needed to optimize the time resolution. Using all these results, we discuss the factors that limit the time resolution of single-molecule spectroscopy and the conditions that would be needed to push measurements into the submicrosecond region.
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Affiliation(s)
- Mainak Dhar
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Mark A Berg
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
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3
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Hodge SR, Berg MA. Nonlinear measurements of kinetics and generalized dynamical modes. I. Extracting the one-dimensional Green's function from a time series. J Chem Phys 2021; 155:024122. [PMID: 34266246 DOI: 10.1063/5.0053422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Often, a single correlation function is used to measure the kinetics of a complex system. In contrast, a large set of k-vector modes and their correlation functions are commonly defined for motion in free space. This set can be transformed to the van Hove correlation function, which is the Green's function for molecular diffusion. Here, these ideas are generalized to other observables. A set of correlation functions of nonlinear functions of an observable is used to extract the corresponding Green's function. Although this paper focuses on nonlinear correlation functions of an equilibrium time series, the results are directly connected to other types of nonlinear kinetics, including perturbation-response experiments with strong fields. Generalized modes are defined as the orthogonal polynomials associated with the equilibrium distribution. A matrix of mode-correlation functions can be transformed to the complete, single-time-interval (1D) Green's function. Diagonalizing this matrix finds the eigendecays. To understand the advantages and limitation of this approach, Green's functions are calculated for a number of models of complex dynamics within a Gaussian probability distribution. Examples of non-diffusive motion, rate heterogeneity, and range heterogeneity are examined. General arguments are made that a full set of nonlinear 1D measurements is necessary to extract all the information available in a time series. However, when a process is neither dynamically Gaussian nor Markovian, they are not sufficient. In those cases, additional multidimensional measurements are needed.
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Affiliation(s)
- Stuart R Hodge
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Mark A Berg
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
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4
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Scales N, Swain PS. Resolving fluorescent species by their brightness and diffusion using correlated photon-counting histograms. PLoS One 2019; 14:e0226063. [PMID: 31887113 PMCID: PMC6936799 DOI: 10.1371/journal.pone.0226063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 11/19/2019] [Indexed: 12/27/2022] Open
Abstract
Fluorescence fluctuation spectroscopy (FFS) refers to techniques that analyze fluctuations in the fluorescence emitted by fluorophores diffusing in a small volume and can be used to distinguish between populations of molecules that exhibit differences in brightness or diffusion. For example, fluorescence correlation spectroscopy (FCS) resolves species through their diffusion by analyzing correlations in the fluorescence over time; photon counting histograms (PCH) and related methods based on moment analysis resolve species through their brightness by analyzing fluctuations in the photon counts. Here we introduce correlated photon counting histograms (cPCH), which uses both types of information to simultaneously resolve fluorescent species by their brightness and diffusion. We define the cPCH distribution by the probability to detect both a particular number of photons at the current time and another number at a later time. FCS and moment analysis are special cases of the moments of the cPCH distribution, and PCH is obtained by summing over the photon counts in either channel. cPCH is inherently a dual channel technique, and the expressions we develop apply to the dual colour case. Using simulations, we demonstrate that two species differing in both their diffusion and brightness can be better resolved with cPCH than with either FCS or PCH. Further, we show that cPCH can be extended both to longer dwell times to improve the signal-to-noise and to the analysis of images. By better exploiting the information available in fluorescence fluctuation spectroscopy, cPCH will be an enabling methodology for quantitative biology.
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Affiliation(s)
- Nathan Scales
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - Peter S. Swain
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
- School of Biological Sciences, University of Edinburgh, Mayfield Road, Edinburgh EH9 3BF, United Kingdom
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5
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Abdollah-Nia F, Gelfand MP, Van Orden A. Three-State DNA Hairpin Conformational Dynamics Revealed by Higher-Order Fluorescence Correlation Spectroscopy. J Phys Chem B 2019; 123:1491-1504. [DOI: 10.1021/acs.jpcb.8b10703] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Yu S, Du Z, Dong C, Ren J. In situ study of RSK2 kinase activity in a single living cell by combining single molecule spectroscopy with activity-based probes. Analyst 2019; 144:3756-3764. [DOI: 10.1039/c9an00178f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
FCS with the ABP strategy is a very promising method for studying endogenous protein kinases in living cells.
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Affiliation(s)
- Shengrong Yu
- School of Chemistry & Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai
- P. R. China
| | - Zhixue Du
- School of Chemistry & Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai
- P. R. China
| | - Chaoqing Dong
- School of Chemistry & Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai
- P. R. China
| | - Jicun Ren
- School of Chemistry & Chemical Engineering
- State Key Laboratory of Metal Matrix Composites
- Shanghai Jiao Tong University
- Shanghai
- P. R. China
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7
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Bouchaala R, Richert L, Anton N, Vandamme TF, Djabi S, Mély Y, Klymchenko AS. Quantifying Release from Lipid Nanocarriers by Fluorescence Correlation Spectroscopy. ACS OMEGA 2018; 3:14333-14340. [PMID: 30411065 PMCID: PMC6210065 DOI: 10.1021/acsomega.8b01488] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/15/2018] [Indexed: 06/08/2023]
Abstract
Understanding the release of drugs and contrast agents from nanocarriers is fundamental in the development of new effective nanomedicines. However, the commonly used method based on dialysis frequently fails to quantify the release of molecules poorly soluble in water, and it is not well-suited for in situ measurements in biological media. Here, we have developed a new methodology for quantifying the release of fluorescent molecules from lipid nanocarriers (LNCs) using fluorescence correlation spectroscopy (FCS). LNCs based on nanoemulsion droplets, encapsulating the hydrophobic Nile red derivative NR668 as a model cargo, were used. Our studies revealed that the standard deviation of fluorescence fluctuations in FCS measurements depends linearly on the dye loading in the nanocarriers, and it is insensitive to the presence of less-bright molecular emissive species in solution. In sharp contrast, classical FCS parameters, such as the number and the brightness of emissive species, are strongly influenced by the fluorescence of molecular species in solution. Therefore, we propose to use the standard deviation of fluorescence fluctuations for the quantitative analysis of dye release from nanocarriers, which is unaffected by the "parasite" fluorescence of the released dyes or the auto-fluorescence of the medium. Using this method, we found that LNCs remain intact in water, whereas in serum medium, they release their content in a temperature-dependent manner. At 37 °C, the release was relatively slow reaching 50% only after 6 h of incubation. The results are corroborated by qualitative observations based on Förster resonance energy transfer between two different encapsulated dyes. The developed method is simple because it is only based on the standard deviation of fluorescence fluctuations and, in principle, can be applied to nanocarriers of different types.
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Affiliation(s)
- Redouane Bouchaala
- CNRS
UMR 7021, Laboratoire de Bioimagerie et Pathologies, University of
Strasbourg, 67401 Illkirch Cedex, France
- Laboratory
of Photonic Systems and Nonlinear Optics, Institute of Optics and
Fine Mechanics, University of Setif 1, 19000 Setif, Algeria
| | - Ludovic Richert
- CNRS
UMR 7021, Laboratoire de Bioimagerie et Pathologies, University of
Strasbourg, 67401 Illkirch Cedex, France
| | - Nicolas Anton
- CNRS
UMR 7199, Laboratoire de Conception et Application de Molécules
Bioactives, University of Strasbourg, 67401 Illkirch Cedex, France
| | - Thierry F. Vandamme
- CNRS
UMR 7199, Laboratoire de Conception et Application de Molécules
Bioactives, University of Strasbourg, 67401 Illkirch Cedex, France
| | - Smail Djabi
- Laboratory
of Photonic Systems and Nonlinear Optics, Institute of Optics and
Fine Mechanics, University of Setif 1, 19000 Setif, Algeria
| | - Yves Mély
- CNRS
UMR 7021, Laboratoire de Bioimagerie et Pathologies, University of
Strasbourg, 67401 Illkirch Cedex, France
| | - Andrey S. Klymchenko
- CNRS
UMR 7021, Laboratoire de Bioimagerie et Pathologies, University of
Strasbourg, 67401 Illkirch Cedex, France
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Rigler R, Widengren J. Fluorescence-based monitoring of electronic state and ion exchange kinetics with FCS and related techniques: from T-jump measurements to fluorescence fluctuations. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2018; 47:479-492. [PMID: 29260269 PMCID: PMC5982452 DOI: 10.1007/s00249-017-1271-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 10/30/2017] [Accepted: 12/03/2017] [Indexed: 11/01/2022]
Abstract
In this review, we give a historical view of how our research in the development and use of fluorescence correlation spectroscopy (FCS) and related techniques has its roots and how it originally evolved from the pioneering work of Manfred Eigen, his colleagues, and coworkers. Work on temperature-jump (T-jump) experiments, conducted almost 50 years ago, led on to the development of the FCS technique. The pioneering work in the 1970s, introducing and demonstrating the concept for FCS, in turn formed the basis for the breakthrough use of FCS more than 15 years later. FCS can be used for monitoring reaction kinetics, based on fluctuations at thermodynamic equilibrium, rather than on relaxation measurements following perturbations. In this review, we more specifically discuss FCS measurements on photodynamic, electronic state transitions in fluorophore molecules, and on proton exchange dynamics in solution and on biomembranes. In the latter case, FCS measurements have proven capable of casting new light on the mechanisms of proton exchange at biological membranes, of central importance to bioenergetics and signal transduction. Finally, we describe the transient-state (TRAST) spectroscopy/imaging technique, sharing features with both relaxation (T-jump) and equilibrium fluctuation (FCS) techniques. TRAST is broadly applicable for cellular and molecular studies, and we briefly outline how TRAST can provide unique information from fluorophore blinking kinetics, reflecting e.g., cellular metabolism, rare molecular encounters, and molecular stoichiometries.
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Affiliation(s)
- Rudolf Rigler
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Jerker Widengren
- Experimental Biomolecular Physics/ Department of Applied Physics, Royal Institute of Technology (KTH), Stockholm, Sweden.
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Su D, Hu X, Dong C, Ren J. Determination of Caspase-3 Activity and Its Inhibition Constant by Combination of Fluorescence Correlation Spectroscopy with a Microwell Chip. Anal Chem 2017; 89:9788-9796. [DOI: 10.1021/acs.analchem.7b01735] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Di Su
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, P. R. China
| | - Xiaocai Hu
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, P. R. China
| | - Chaoqing Dong
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, P. R. China
| | - Jicun Ren
- School of Chemistry & Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, P. R. China
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10
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Abdollah-Nia F, Gelfand MP, Van Orden A. Artifact-Free and Detection-Profile-Independent Higher-Order Fluorescence Correlation Spectroscopy for Microsecond-Resolved Kinetics. 1. Multidetector and Sub-Binning Approach. J Phys Chem B 2017; 121:2373-2387. [DOI: 10.1021/acs.jpcb.7b00407] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Farshad Abdollah-Nia
- Department of Physics and ‡Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Martin P. Gelfand
- Department of Physics and ‡Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | - Alan Van Orden
- Department of Physics and ‡Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
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