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Fluorescence lifetime imaging through scattering media. Sci Rep 2023; 13:3066. [PMID: 36810512 PMCID: PMC9944959 DOI: 10.1038/s41598-023-30055-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 02/15/2023] [Indexed: 02/24/2023] Open
Abstract
Fluorescence lifetime determination has proven to be useful, e.g. identification of molecules, quantitative estimation of species concentration and determination of temperatures. Lifetime determination of exponentially decaying signals is challenging if signals of different decay rates are being mixed, resulting in erroneous results. Such issues occur when the contrast of the measurement object is low, which can be limiting in applied measurements due to spurious light scattering. A solution is presented here where structured illumination is used to enhance image contrast in fluorescence lifetime wide-field imaging. Lifetime imaging determination was carried out using Dual Imaging Modeling Evaluation (DIME), and spatial lock-in analysis was used for removing spurious scattered signal to enable fluorescence lifetime imaging through scattering media.
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Zhao BW, Chen XD, Wang EH, Zheng Y, Du B, Li S, Dong Y, Guo GC, Sun FW. Stimulated emission assisted time-gated detection of a solid-state spin. APPLIED OPTICS 2020; 59:6291-6295. [PMID: 32749291 DOI: 10.1364/ao.397499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
The nitrogen vacancy (NV) center in diamond is studied widely for magnetic field and temperature sensing at the nanoscale. Usually, the fluorescence is recorded to estimate the spin state of the NV center. Here we applied a time-gating technique to improve the contrast of the spin-dependent fluorescence. A NIR pulsed laser pumped the stimulated emission of the NV center and depleted the spontaneous emission that was excited by a green laser. We changed the relative delay between the NIR laser and the green laser. Then the spontaneous emission of the NV center in varied time windows was extracted by comparing the fluorescence intensities with and without the NIR laser. The results showed that the spin-dependent fluorescence contrast could be improved by approximately 1.8 times by applying the time gating. The background of the environment was eliminated due to temporal filtering. This work demonstrates that the stimulated emission assisted time-gating technique can be used to improve the performance of an NV center sensor in a noisy environment.
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Das S, Liang YC, Tanaka S, Ozeki Y, Kao FJ. Synchronized subharmonic modulation in stimulated emission microscopy. OPTICS EXPRESS 2019; 27:27159-27167. [PMID: 31674582 DOI: 10.1364/oe.27.027159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
In this work, we have demonstrated a stimulated emission (SE)-based pump-probe microscopy with subharmonic fast gate synchronization, which allows over an order of magnitude improvement in signal-to-noise ratio. Critically, the alternative way of modulation is implemented with the highest possible frequency that follows the lasers' repetition rate. Its working is based on a homemade frequency divider that divides the repetition frequency (76 MHz) of the Ti:sapphire (probe) laser to half of the repetition frequency, 38 MHz, which is used to synchronously drive the pump laser and to provide the reference signal for the ensuing lock-in detection. In this way, SE can be detected with sensitivity reaching the theoretical (shot noise) limits, with a much lower time constant (0.1 ms) for faster image acquisition.
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Li D, Qin W, Xu B, Qian J, Tang BZ. AIE Nanoparticles with High Stimulated Emission Depletion Efficiency and Photobleaching Resistance for Long-Term Super-Resolution Bioimaging. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1703643. [PMID: 28977700 DOI: 10.1002/adma.201703643] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/16/2017] [Indexed: 06/07/2023]
Abstract
Stimulated emission depletion (STED) nanoscopy is a typical super-resolution imaging technique that has become a powerful tool for visualizing intracellular structures on the nanometer scale. Aggregation-induced emission (AIE) luminogens are ideal fluorescent agents for bioimaging. Herein, long-term super-resolution fluorescence imaging of cancer cells, based on STED nanoscopy assisted by AIE nanoparticles (NPs) is realized. 2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TTF), a typical AIE luminogen, is doped into colloidal mesoporous silica to form fluorescent NPs. TTF@SiO2 NPs bear three significant features, which are all essential for STED nanoscopy. First, their STED efficiency can reach more than 60%. Second, they are highly resistant to photobleaching, even under long-term and high-power STED light irradiation. Third, they have a large Stokes' shift of ≈150 nm, which is beneficial for restraining the fluorescence background induced by the STED light irradiation. STED nanoscopy imaging of TTF@SiO2 -NPs-stained HeLa cells is performed, exhibiting a high lateral spatial resolution of 30 nm. More importantly, long-term (more than half an hour) super-resolution cell imaging is achieved with low fluorescence loss. Considering that AIE luminogens are widely used for organelle targeting, cellular mapping, and tracing, AIE-NPs-based STED nanoscopy holds great potential for many basic biomedical studies that require super-resolution and long-term imaging.
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Affiliation(s)
- Dongyu Li
- State Key Laboratory of Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, Zhejiang Provincial Key Laboratory for Sensing Technologies, Zhejiang University, Hangzhou, 310058, China
| | - Wei Qin
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Division of Life Science, State Key Laboratory of Molecular Neuroscience, Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Bin Xu
- State Key Lab of Supramolecular Structure and Materials, Jilin University, Changchun, 130012, China
| | - Jun Qian
- State Key Laboratory of Modern Optical Instrumentation, Centre for Optical and Electromagnetic Research, Zhejiang Provincial Key Laboratory for Sensing Technologies, Zhejiang University, Hangzhou, 310058, China
| | - Ben Zhong Tang
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Division of Life Science, State Key Laboratory of Molecular Neuroscience, Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Yu J, Sun X, Cai F, Zhu Z, Qin A, Qian J, Tang B, He S. Low photobleaching and high emission depletion efficiency: the potential of AIE luminogen as fluorescent probe for STED microscopy. OPTICS LETTERS 2015; 40:2313-2316. [PMID: 26393727 DOI: 10.1364/ol.40.002313] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a preliminary study which explores the potential of aggregation-induced emission (AIE) luminogen as a new fluorescent probe for STED microscopy. Compared with Coumarin 102, which is a commonly used organic fluorophore in STED microscopy, HPS, a typical AIE luminogen, is more resistant to photobleaching. In addition, HPS-doped nanoparticles have higher emission depletion efficiency than Coumarin 102 in organic solution. These two advantages of AIE luminogen can facilitate the improvement of spatial resolution, as well as long-term imaging, in STED microscopy. AIE luminogen will be a promising candidate for STED microscopy in the future.
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Chan JCK, Diebold ED, Buckley BW, Mao S, Akbari N, Jalali B. Digitally synthesized beat frequency-multiplexed fluorescence lifetime spectroscopy. BIOMEDICAL OPTICS EXPRESS 2014; 5:4428-36. [PMID: 25574449 PMCID: PMC4285616 DOI: 10.1364/boe.5.004428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 09/24/2014] [Accepted: 10/25/2014] [Indexed: 05/02/2023]
Abstract
Frequency domain fluorescence lifetime imaging is a powerful technique that enables the observation of subtle changes in the molecular environment of a fluorescent probe. This technique works by measuring the phase delay between the optical emission and excitation of fluorophores as a function of modulation frequency. However, high-resolution measurements are time consuming, as the excitation modulation frequency must be swept, and faster low-resolution measurements at a single frequency are prone to large errors. Here, we present a low cost optical system for applications in real-time confocal lifetime imaging, which measures the phase vs. frequency spectrum without sweeping. Deemed Lifetime Imaging using Frequency-multiplexed Excitation (LIFE), this technique uses a digitally-synthesized radio frequency comb to drive an acousto-optic deflector, operated in a cat's-eye configuration, to produce a single laser excitation beam modulated at multiple beat frequencies. We demonstrate simultaneous fluorescence lifetime measurements at 10 frequencies over a bandwidth of 48 MHz, enabling high speed frequency domain lifetime analysis of single- and multi-component sample mixtures.
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Affiliation(s)
- Jacky C. K. Chan
- Departments of Electrical Engineering, University of California, Los Angeles, CA 90095,
USA
| | - Eric D. Diebold
- Departments of Electrical Engineering, University of California, Los Angeles, CA 90095,
USA
- Department of Bioengineering, University of California, Los Angeles, CA 90095,
USA
| | - Brandon W. Buckley
- Departments of Electrical Engineering, University of California, Los Angeles, CA 90095,
USA
| | - Sien Mao
- Departments of Electrical Engineering, University of California, Los Angeles, CA 90095,
USA
| | - Najva Akbari
- Departments of Electrical Engineering, University of California, Los Angeles, CA 90095,
USA
| | - Bahram Jalali
- Departments of Electrical Engineering, University of California, Los Angeles, CA 90095,
USA
- Department of Bioengineering, University of California, Los Angeles, CA 90095,
USA
- Department of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095,
USA
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