Prof. Ahmed A. Heikal Profile

Prof. Ahmed A. Heikal

Professor at Univ of Minnesota Duluth

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Author

Publications (12)

Proceedings Article | 5 October 2023 Presentation + Paper

Conformational equilibrium analysis of mCerulean3–linker–mCitrine constructs using time-resolved fluorescence measurements in controlled environments

Clint McCue, Sarah Mersch, Sarah Bergman, Erin Sheets, Ahmed Heikal

Proceedings Volume 12681, 1268107 (2023) https://doi.org/10.1117/12.2679719

KEYWORDS: Sensors, Time resolved spectroscopy, Fluorescence, Fluorescence resonance energy transfer, Environmental sensing, Thermodynamics, Energy transfer, Proteins

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Proceedings Article | 3 October 2022 Presentation + Paper

Integrated laser-induced fluorescence spectroscopy of donor-linker-acceptor constructs for bioenvironmental sensing

Sarah Mersch, Malachy Brink, Rowan Simonet, Arnold Boersma, Erin Sheets, Ahmed Heikal

Proceedings Volume 12228, 1222804 (2022) https://doi.org/10.1117/12.2635951

KEYWORDS: Fluorescence resonance energy transfer, Sensors, Time resolved spectroscopy, Environmental sensing, Molecules, Anisotropy, Fluorescence spectroscopy, Molecular spectroscopy, Fluorescence correlation spectroscopy

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Proceedings Article | 1 August 2021 Presentation

Monitoring the metabolic activities of murine breast cancer cells in 2D and 3D cultures using nonlinear micro-spectroscopy of intrinsic NAD(P)H

Anh Q. Cong, Rafaela Lima Pimenta, Jon Holy, Ahmed Heikal

Proceedings Volume 11825, 118250B (2021) https://doi.org/10.1117/12.2597512

KEYWORDS: 3D acquisition, Breast cancer, Mode conditioning cables, Tumors, Fluorescence lifetime imaging, Collagen, 3D modeling, 3D image processing, Microscopy, Luminescence

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Proceedings Article | 20 August 2020 Presentation + Paper

Comparative studies of the fluorescence spectroscopy and dynamics of mCerulean3 and mTurquoise2.1 as donors in FRET pairing with mCitrine

Cody Aplin, Taryn Kay, Julie Beenken, Chioma Nwachuku, Emmanuel Tetteh-Jada, Ahmed Heikal, Arnold Boersma, Erin Sheets

Proceedings Volume 11497, 114970T (2020) https://doi.org/10.1117/12.2571138

KEYWORDS: Fluorescence resonance energy transfer, Sensors, Diffusion, Time resolved spectroscopy, Fluorescence correlation spectroscopy, Proteins, Molecules, Fluorescence spectroscopy

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Proceedings Article | 9 September 2019 Presentation + Paper

Integrated fluorescence approach for FRET analysis of environmental sensors

Cody Aplin, Taryn Kay , Robert Miller , Arnold Boersma, Erin Sheets, Ahmed Heikal

Proceedings Volume 11122, 111220E (2019) https://doi.org/10.1117/12.2531656

KEYWORDS: Fluorescence resonance energy transfer, Energy transfer, Energy efficiency, Time resolved spectroscopy, Anisotropy, Environmental sensing, Sensors, Spectroscopy

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Proceedings Article | 7 September 2017 Paper

Kinetics model for the wavelength-dependence of excited-state dynamics of hetero-FRET sensors

Jacob Schwarz, Ryan Leighton, Hannah Leopold, Megan Currie, Arnold Boersma, Erin Sheets, Ahmed Heikal

Proceedings Volume 10380, 103800S (2017) https://doi.org/10.1117/12.2274793

KEYWORDS: Fluorescence resonance energy transfer, Imaging spectroscopy, Molecular spectroscopy, Spectroscopy, Sensors, Anisotropy, In vivo imaging, Time resolved spectroscopy, Diffusion, Environmental sensing

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Proceedings Article | 3 October 2016 Paper

Fluorescence fluctuation analysis of BACE1-GFP fusion protein in cultured HEK293 cells

Spencer Gardeen, Joseph Johnson, Ahmed Heikal

Proceedings Volume 9956, 99560K (2016) https://doi.org/10.1117/12.2237183

KEYWORDS: Proteins, Luminescence, Confocal microscopy, Microscopy, Fluorescence correlation spectroscopy, Diffusion, Plasma, Molecules, Digital image correlation, Calibration

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Proceedings Article | 31 August 2015 Paper

Multiscale diffusion of a molecular probe in a crowded environment: a concept

Megan Currie, Chang Thao, Randi Timerman, Robb Welty, Brenden Berry, Erin Sheets, Ahmed Heikal

Proceedings Volume 9584, 95840E (2015) https://doi.org/10.1117/12.2188746

KEYWORDS: Diffusion, Fluorescence correlation spectroscopy, Luminescence, Anisotropy, Proteins, Molecules, Refractive index, Polymers, Fluorescence spectroscopy, Time resolved spectroscopy

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Living cells are crowded with macromolecules and organelles. Yet, it is not fully understood how macromolecular crowding affects the myriad of biochemical reactions, transport and the structural stability of biomolecules that are essential to cellular function and survival. These molecular processes, with or without electrostatic interactions, in living cells are therefore expected to be distinct from those carried out in test tube in dilute solutions where excluded volumes are absent. Thus there is an urgent need to understand the macromolecular crowding effects on cellular and molecular biophysics towards quantitative cell biology. In this report, we investigated how biomimetic crowding affects both the rotational and translation diffusion of a small probe (rhodamine green, RhG). For biomimetic crowding agents, we used Ficoll-70 (synthetic polymer), bovine serum albumin and ovalbumin (proteins) at various concentrations in a buffer at room temperature. As a control, we carried out similar measurements on glycerolenriched buffer as an environment with homogeneous viscosity as a function of glycerol concentration. The corresponding bulk viscosity was measured independently to test the validity of the Stokes-Einstein model of a diffusing species undergoing a random walk. For rotational diffusion (ps–ns time scale), we used time-resolved anisotropy measurements to examine potential binding of RhG as a function of the crowding agents (surface structure and size). For translational diffusion (μs–s time scale), we used fluorescence correlation spectroscopy for single-molecule fluctuation analysis. Our results allow us to examine the diffusion model of a molecular probe in crowded environments as a function of concentration, length scale, homogeneous versus heterogeneous viscosity, size and surface structures. These biomimetic crowding studies, using non-invasive fluorescence spectroscopy methods, represent an important step towards understanding cellular biophysics and quantitative cell biology.

Proceedings Article | 5 September 2014 Paper

Time- and polarization-resolved cellular autofluorescence towards quantitative biochemistry on living cells

John Alfveby, Randi TImerman, Monica Soto Velasquez, Dhanushka W. P. Wickramasinghe, Jillian Bartusek, Ahmed Heikal

Proceedings Volume 9198, 91980U (2014) https://doi.org/10.1117/12.2062045

KEYWORDS: Anisotropy, Luminescence, Fluorescence lifetime imaging, Biochemistry, Digital image correlation, Mode conditioning cables, Microscopy, Molecules, Tissues, Confocal microscopy

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SPIE Journal Paper | 1 July 2008 Open Access

Integrated biophotonics approach for noninvasive and multiscale studies of biomolecular and cellular biophysics

Qianru Yu, Michael Proia, Ahmed Heikal

JBO, Vol. 13, Issue 04, 041315, (July 2008) https://doi.org/10.1117/12.10.1117/1.2952297

KEYWORDS: Luminescence, Diffusion, Anisotropy, Polarization, Fluorescence correlation spectroscopy, Fluorescence lifetime imaging, Confocal microscopy, Biomedical optics, Molecules, Cancer

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Proceedings Article | 1 November 2002 Paper

Multiphoton fluorescence microscopy in biology

Ahmed Heikal, Watt Webb

Proceedings Volume 4812, (2002) https://doi.org/10.1117/12.451382

KEYWORDS: Luminescence, Multiphoton fluorescence microscopy, Molecules, Microscopy, Absorption, Green fluorescent protein, Mode conditioning cables, Quantum efficiency, Fluorescence correlation spectroscopy, Spectroscopy

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Proceedings Article | 17 April 2000 Paper

Three-dimensional microfabrication using two-photon-activated chemistry

Stephen Kuebler, Brian Cumpston, Sundaravel Ananthavel, Stephen Barlow, Jeffrey Ehrlich, L. Erskine, Ahmed Heikal, D. McCord-Maughon, J. Qin, Harold Roeckel, Maria Cristina Rumi, Seth Marder, Joseph Perry

Proceedings Volume 3937, (2000) https://doi.org/10.1117/12.382799

KEYWORDS: Polymerization, Absorption, Chromophores, Microfabrication, Ultraviolet radiation, 3D optical data storage, Luminescence, Polymers, 3D image processing, Scanning electron microscopy

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Showing 5 of 12 publications

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