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Lee M, Kannan S, Muniraj G, Rosa V, Lu WF, Fuh JYH, Sriram G, Cao T. Two-Photon Fluorescence Microscopy and Applications in Angiogenesis and Related Molecular Events. TISSUE ENGINEERING PART B-REVIEWS 2021; 28:926-937. [PMID: 34541887 DOI: 10.1089/ten.teb.2021.0140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The role of angiogenesis in health and disease have gained considerable momentum in recent years. Visualizing angiogenic patterns and associated events of surrounding vascular beds in response to therapeutic and laboratory-grade biomolecules have become a commonplace in regenerative medicine and the biosciences. To aid imaging investigations in angiogenesis, the two-photon excitation fluorescence microscopy (2PEF), or multiphoton fluorescence microscopy is increasingly utilized in scientific investigations. The 2PEF microscope confers several distinct imaging advantages over other fluorescence excitation microscopy techniques - for the observation of in-depth, three-dimensional vascularity in a variety of tissue formats, including fixed tissue specimens and in vivo vasculature in live specimens. Understanding morphological and subcellular changes that occur in cells and tissues during angiogenesis will provide insights to behavioral responses in diseased states, advance the engineering of physiologically-relevant tissue models and provide biochemical clues for the design of therapeutic strategies. We review the applicability and limitations of the 2PEF microscope on the biophysical and molecular-level signatures of angiogenesis in various tissue models. Imaging techniques and strategies for best practices in 2PEF microscopy will be reviewed.
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Affiliation(s)
- Marcus Lee
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Sathya Kannan
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Giridharan Muniraj
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Vinicius Rosa
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Wen Feng Lu
- Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| | - Jerry Y H Fuh
- Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| | - Gopu Sriram
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - Tong Cao
- Faculty of Dentistry, National University of Singapore, Singapore, Singapore
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Mehravar S, Cromey B, Kieu K. Characterization of multiphoton microscopes by the nonlinear knife-edge technique. APPLIED OPTICS 2020; 59:G219-G224. [PMID: 32749336 DOI: 10.1364/ao.391881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/24/2020] [Indexed: 06/11/2023]
Abstract
Imaging submicron fluorescent microspheres are the standard method for measuring resolution in multiphoton microscopy. However, when using high-energy pulsed lasers, photobleaching and heating of the solution medium may deteriorate the images, resulting in an inaccurate resolution measurement. Moreover, due to the weak higher-order response of fluorescent microspheres, measuring three-photon resolution using three-photon fluorescence (3PEF) and third-harmonic generation (THG) signals is more difficult. In this report, we demonstrate a methodology for complete characterization of multiphoton microscopes based on second- and third-harmonic generation signals from the sharp edge of GaAs wafers. This simple methodology, which we call the nonlinear knife-edge technique, provides fast and consistent lateral and axial resolution measurement with negligible photobleaching effect on semiconductor wafers. In addition, this technique provides information on the field curvature of the imaging system, and perhaps other distortions of the imaging system, adding greater capability compared to existing techniques.
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Zhang Y, Nallathamby PD, Vigil GD, Khan AA, Mason DE, Boerckel JD, Roeder RK, Howard SS. Super-resolution fluorescence microscopy by stepwise optical saturation. BIOMEDICAL OPTICS EXPRESS 2018; 9:1613-1629. [PMID: 29675306 PMCID: PMC5905910 DOI: 10.1364/boe.9.001613] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/02/2018] [Accepted: 03/05/2018] [Indexed: 05/07/2023]
Abstract
Super-resolution fluorescence microscopy is an important tool in biomedical research for its ability to discern features smaller than the diffraction limit. However, due to its difficult implementation and high cost, the super-resolution microscopy is not feasible in many applications. In this paper, we propose and demonstrate a saturation-based super-resolution fluorescence microscopy technique that can be easily implemented and requires neither additional hardware nor complex post-processing. The method is based on the principle of stepwise optical saturation (SOS), where M steps of raw fluorescence images are linearly combined to generate an image with a [Formula: see text]-fold increase in resolution compared with conventional diffraction-limited images. For example, linearly combining (scaling and subtracting) two images obtained at regular powers extends the resolution by a factor of 1.4 beyond the diffraction limit. The resolution improvement in SOS microscopy is theoretically infinite but practically is limited by the signal-to-noise ratio. We perform simulations and experimentally demonstrate super-resolution microscopy with both one-photon (confocal) and multiphoton excitation fluorescence. We show that with the multiphoton modality, the SOS microscopy can provide super-resolution imaging deep in scattering samples.
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Affiliation(s)
- Yide Zhang
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556,
USA
| | - Prakash D. Nallathamby
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556,
USA
- Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556,
USA
- Notre Dame Center for Nanoscience and Nanotechnology (NDnano), University of Notre Dame, Notre Dame, IN 46556,
USA
| | - Genevieve D. Vigil
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556,
USA
| | - Aamir A. Khan
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556,
USA
| | - Devon E. Mason
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556,
USA
- Departments of Orthopaedic Surgery and Bioengineering, University of Pennsylvania, Philadelphia, PA 19104,
USA
| | - Joel D. Boerckel
- Departments of Orthopaedic Surgery and Bioengineering, University of Pennsylvania, Philadelphia, PA 19104,
USA
| | - Ryan K. Roeder
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556,
USA
- Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556,
USA
- Notre Dame Center for Nanoscience and Nanotechnology (NDnano), University of Notre Dame, Notre Dame, IN 46556,
USA
| | - Scott S. Howard
- Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556,
USA
- Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556,
USA
- Notre Dame Center for Nanoscience and Nanotechnology (NDnano), University of Notre Dame, Notre Dame, IN 46556,
USA
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Doi A, Oketani R, Nawa Y, Fujita K. High-resolution imaging in two-photon excitation microscopy using in situ estimations of the point spread function. BIOMEDICAL OPTICS EXPRESS 2018; 9:202-213. [PMID: 29359097 PMCID: PMC5772575 DOI: 10.1364/boe.9.000202] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 12/06/2017] [Accepted: 12/10/2017] [Indexed: 05/06/2023]
Abstract
We present a technique for improving the spatial resolution of two-photon excitation microscopy; our technique combines annular illumination with an in situ estimation of the point spread function (PSF) used for deconvolution. For the in situ estimation of the PSF, we developed a technique called autocorrelation scanning, in which a sample is imaged by the scanning of two excitation foci that are overlapped over various distances. The image series obtained with the variation of the distance between the two foci provides the autocorrelation function of the PSF, which can be used to estimate the PSF at specific positions within a sample. We proved the principle and the effectiveness of this technique through observations of a fluorescent biological sample, and we confirmed that the improvement in the spatial resolution was ~1.7 times that of typical two-photon excitation microscopy by observing a mouse brain phantom at a depth of 200 µm.
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Affiliation(s)
- Atsushi Doi
- Olympus Corporation, 2-3 Kuboyama-cho, Hachioji-shi, Tokyo 192-8512, Japan
| | - Ryosuke Oketani
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasunori Nawa
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Katsumasa Fujita
- Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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Vigil G, Zhang Y, Khan A, Howard S. Description of deep saturated excitation multiphoton microscopy for super-resolution imaging. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2017; 34:1217-1223. [PMID: 29036132 DOI: 10.1364/josaa.34.001217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/30/2017] [Indexed: 05/23/2023]
Abstract
Here we recount the standard two-level model that describes saturated excitation (SAX) in multiphoton microscopy (MPM), a new technique for super-resolution fluorescence microscopy in scattering tissue, which requires no special chemistry and only simple modifications to a commercial MPM microscope. We use the model to study conditions required for improvements in MPM SAX resolution and experimental implementation strategies. Simulation results find zeros, or nodes, in the frequency response, which generate highly irregular point-spread functions (PSFs), such as rings and ripples, that contain spatial frequency content >3× larger than allowed by diffraction. These PSFs are a direct result of zeros in the frequency response of saturated fluorophores under specific excitation conditions. The impact on image quality is discussed using simulations of targets imaged with SAX PSFs. Further, we explore engineering sets of irregular PSFs by varying the excitation power and reconstructing super-resolution images from the set of captured images.
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Oketani R, Doi A, Smith NI, Nawa Y, Kawata S, Fujita K. Saturated two-photon excitation fluorescence microscopy with core-ring illumination. OPTICS LETTERS 2017; 42:571-574. [PMID: 28146530 DOI: 10.1364/ol.42.000571] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We demonstrated resolution improvement in two-photon excitation microscopy by combining saturated excitation (SAX) of fluorescence and pupil manipulation. We theoretically estimated the resolution improvement and the sidelobe effect in the point spread function with various pupil designs and found that the combination of SAX and core-ring illumination can effectively enhance the spatial resolution in 3D and suppress sidelobe artifacts. The experimental demonstration shows that the proposed technique is effective for observation with a depth of 100 μm in a tissue phantom and can be applied to 3D observations of tissue samples with higher spatial resolution than conventional two-photon excitation microscopy.
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Zhang Y, Vigil GD, Cao L, Khan AA, Benirschke D, Ahmed T, Fay P, Howard SS. Saturation-compensated measurements for fluorescence lifetime imaging microscopy. OPTICS LETTERS 2017; 42:155-158. [PMID: 28059202 DOI: 10.1364/ol.42.000155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Fluorophore saturation is the key factor limiting the speed and excitation range of fluorescence lifetime imaging microscopy (FLIM). For example, fluorophore saturation causes incorrect lifetime measurements when using conventional frequency-domain FLIM at high excitation powers. In this Letter, we present an analytical theoretical description of this error and present a method for compensating for this error in order to extract correct lifetime measurements in the limit of fluorophore saturation. We perform a series of simulations and experiments to validate our methods. The simulations and experiments show a 13.2× and a 2.6× increase in excitation range, respectively. The presented method is based on algorithms that can be easily applied to existing FLIM setups.
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