Leilei Peng

Interests

Teaching

Spectroscopy, engineer programming.

Research

Fluorescence lifetime microscopy, superresolution, deep tissue imaging

Courses

Scholarly Contributions

Chapters

• Peng, L. (2020). Fourier multiplexed lifetime imaging. In Multiplexed Imaging, Methods in Molecular Biology Series. Springer Nature.

Journals/Publications

• Xu, D., Ding, J. B., & Peng, L. (2022). Depth random-access two-photon Bessel light-sheet imaging in brain tissue. Optics express, 30(15), 26396-26406.
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  Two-photon light-sheet fluorescence microscopy enables high-resolution imaging of neural activity in brain tissue at a high frame rate. Traditionally, light-sheet microscopy builds up a 3D stack by multiple depth scans with uniform spatial intervals, which substantially limits the volumetric imaging speed. Here, we introduce the depth random-access light-sheet microscopy, allowing rapid switching scanning depth for light-sheet imaging. With a low-cost electrically tunable lens and minimum modification of an existing two-photon light-sheet imaging instrument, we demonstrated fast random depth hopping light-sheet imaging at 100 frames per second in the live brain slice. Through depth random-access, calcium activities for an astrocyte were recorded on four user-selected detection planes at a refreshing rate of 25 Hz.
• Peng, L. (2021). Fourier Multiplexed Fluorescence Lifetime Imaging. Methods in molecular biology (Clifton, N.J.), 2350, 157-172.
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  Fluorescence lifetime imaging microscopy (FLIM) is a widely used functional imaging method in bioscience. Fourier multiplexed FLIM (FmFLIM), a frequency-domain lifetime measurement method, explores the principle of Fourier (frequency) multiplexing to achieve parallel lifetime detection on multiple fluorescence labels. Combining FmFLIM with a confocal scanning microscope allows multiplexed 3D lifetime imaging of cells and tissues. FmFLIM can also be integrated with the scanning laser tomography imaging method to perform 3D multiplex lifetime imaging of whole embryos and thick tissues.
• Peng, L. (2020). Structured illumination imaging with quasi periodic patterns. Journal of Biophotonics.
• Puleo, J. I., Roman, M. R., Parker, S. S., Watson, A. W., Eliato, K. R., Peng, L., Saboda, K., Roe, D., Ross, R., Gertler, F. B., & Mouneimne, G. (2019). Mechanosensing during directed cell migration requires dynamic actin polymerization at focal adhesions. Journal of Cell Biology.
• Peng, L. (2017). Bessel wavelength-encoded structured illumination light sheet microscopy. Biomedical Optics Express.
• Zhou, W., Peng, L., & Xu, D. (2017). Cellular resolution multiplexed FLIM tomography with dual-color Bessel beam. Biomedical Optics Express, 7(2), 570-578.
• Xu, D., & Peng, L. (2016). Bessel beam fluorescence lifetime tomography of live embryos (Conference Presentation). OPTICAL METHODS IN DEVELOPMENTAL BIOLOGY IV, 9716.
• Xu, D., & Peng, L. (2016). High resolution multiplexed functional imaging in live embyros. DESIGN AND QUALITY FOR BIOMEDICAL TECHNOLOGIES IX, 9700.
• Zhang, H., Li, Y. u., Zhao, M., & Peng, L. (2015). Full Field Nonlinear Structured Illumination Microscopy with STED. BIOPHYSICAL JOURNAL, 108(2), 477A-477A.
• Zhao, M., Wan, X., Li, Y., Zhou, W., & Peng, L. (2015). Multiplexed 3D FRET imaging in deep tissue of live embryos. SCIENTIFIC REPORTS, 5.
• Li, Y. u., Zhao, M., Wan, X., Zhou, W., & Peng, L. (2014). Quantifying Protein Conformation Heterogeneity in Live Cells by Fourier Lifetime Excitation-Emission Matrix Spectroscopy. BIOPHYSICAL JOURNAL, 106(2), 796A-797A.
• Zhao, M., Li, Y., & Peng, L. (2014). FPGA-based multi-channel fluorescence lifetime analysis of Fourier multiplexed frequency-sweeping lifetime imaging. OPTICS EXPRESS, 22(19), 23073-23085.
• Zhao, M., Li, Y., & Peng, L. (2014). Parallel excitation-emission multiplexed fluorescence lifetime confocal microscopy for live cell imaging. OPTICS EXPRESS, 22(9), 10221-10232.
• Zhao, M., Wan, X., Zhou, W., & Peng, L. (2014). 4D Multiplexed Functional Imaging in Deep Tissue. BIOPHYSICAL JOURNAL, 106(2), 606A-606A.
• Zhao, M., Zhang, H., Li, Y., Ashok, A., Liang, R., Zhou, W., & Peng, L. (2014). Cellular imaging of deep organ using two-photon Bessel light-sheet nonlinear structured illumination microscopy. BIOMEDICAL OPTICS EXPRESS, 5(5), 1296-1308.
• Kim, S., Huang, H. e., Zhao, M., Zhang, X., Zhang, A., Semonov, M. V., MacDonald, B. T., Zhang, X., Abreu, J. G., Peng, L., & He, X. i. (2013). Wnt Stabilization of beta-Catenin Reveals Principles for Morphogen Receptor-Scaffold Assemblies. SCIENCE, 340(6134), 867-870.
• Kim, S., Huang, H., Zhao, M., Zhang, X., Zhang, A., Semonov, M. V., MacDonald, B. T., Zhang, X., Abreu, J. G., Peng, L., & Xi, H. e. (2013). Wnt stabilization of β-catenin reveals principles for morphogen receptor-scaffold assemblies. Science, 340(6134), 867-870.
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  PMID: 23579495;PMCID: PMC3788643;Abstract: Wnt signaling stabilizes β-catenin through the LRP6 receptor signaling complex, which antagonizes the β-catenin destruction complex. The Axin scaffold and associated glycogen synthase kinase-3 (GSK3) have central roles in both assemblies, but the transduction mechanism from the receptor to the destruction complex is contentious. We report that Wnt signaling is governed by phosphorylation regulation of the Axin scaffolding function. Phosphorylation by GSK3 kept Axin activated ("open") for β-catenin interaction and poised for engagement of LRP6. Formation of the Wnt-induced LRP6-Axin signaling complex promoted Axin dephosphorylation by protein phosphatase-1 and inactivated ("closed") Axin through an intramolecular interaction. Inactivation of Axin diminished its association with β-catenin and LRP6, thereby inhibiting β-catenin phosphorylation and enabling activated LRP6 to selectively recruit active Axin for inactivation reiteratively. Our findings reveal mechanisms for scaffold regulation and morphogen signaling.
• Zhang, H., Zhao, M., & Peng, L. (2013). Nonlinear structured illumination microscopy with surface plasmon resonance enhanced stimulated emission depletion. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 8590.
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  Abstract: Nonlinear structured illumination microscopy (SIM) allows full-field imaging at resolutions
• Zhao, M., Zhou, W., & Peng, L. (2013). Parallel multi-color fluorescence lifetime tomography in deep tissue. Bio-Optics: Design and Application, BODA 2013, BM4A.4.
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  Abstract: We present a deep tissue multi-color fluorescence lifetime imaging method based on scanning laser optical tomography and Fourier fluorescence lifetime excitation-emission matrix spectroscopy. We demonstrate FRET sensor measurements in live transgenic zebrafish embryo. Optics in the Life Sciences Congress Technical Digest © 2013 The Optical Society (OSA).
• Peng, L., Zhao, M., Huang, R., & Peng, L. -. (2012). Quantitative multi-color FRET measurements by Fourier lifetime excitation-emission matrix spectroscopy. Optics express, 20(24).
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  Förster resonant energy transfer (FRET) is extensively used to probe macromolecular interactions and conformation changes. The established FRET lifetime analysis method measures the FRET process through its effect on the donor lifetime. In this paper we present a method that directly probes the time-resolved FRET signal with frequency domain Fourier lifetime excitation-emission matrix (FLEEM) measurements. FLEEM separates fluorescent signals by their different phonon energy pathways from excitation to emission. The FRET process generates a unique signal channel that is initiated by donor excitation but ends with acceptor emission. Time-resolved analysis of the FRET EEM channel allows direct measurements on the FRET process, unaffected by free fluorophores that might be present in the sample. Together with time-resolved analysis on non-FRET channels, i.e. donor and acceptor EEM channels, time resolved EEM analysis allows precise quantification of FRET in the presence of free fluorophores. The method is extended to three-color FRET processes, where quantification with traditional methods remains challenging because of the significantly increased complexity in the three-way FRET interactions. We demonstrate the time-resolved EEM analysis method with quantification of three-color FRET in incompletely hybridized triple-labeled DNA oligonucleotides. Quantitative measurements of the three-color FRET process in triple-labeled dsDNA are obtained in the presence of free single-labeled ssDNA and double-labeled dsDNA. The results establish a quantification method for studying multi-color FRET between multiple macromolecules in biochemical equilibrium.
• Zhao, M., Huang, R., & Peng, L. (2012). Quantitative multi-color FRET measurements by Fourier lifetime excitation-emission matrix spectroscopy. OPTICS EXPRESS, 20(24), 26806-26827.
• Zhao, M., Huang, R., & Peng, L. (2012). Quantitative multi-color FRET measurements by Fourier lifetime excitation-emission matrix spectroscopy. Optics Express, 20(24), 26806-26827.
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  PMID: 23187535;PMCID: PMC3601597;Abstract: Förster resonant energy transfer (FRET) is extensively used to probe macromolecular interactions and conformation changes. The established FRET lifetime analysis method measures the FRET process through its effect on the donor lifetime. In this paper we present a method that directly probes the time-resolved FRET signal with frequency domain Fourier lifetime excitation-emission matrix (FLEEM) measurements. FLEEM separates fluorescent signals by their different phonon energy pathways from excitation to emission. The FRET process generates a unique signal channel that is initiated by donor excitation but ends with acceptor emission. Time-resolved analysis of the FRET EEM channel allows direct measurements on the FRET process, unaffected by free fluorophores that might be present in the sample. Together with timeresolved analysis on non-FRET channels, i.e. donor and acceptor EEM channels, time resolved EEM analysis allows precise quantification of FRET in the presence of free fluorophores. The method is extended to three-color FRET processes, where quantification with traditional methods remains challenging because of the significantly increased complexity in the three-way FRET interactions. We demonstrate the time-resolved EEM analysis method with quantification of three-color FRET in incompletely hybridized triple-labeled DNA oligonucleotides. Quantitative measurements of the three-color FRET process in triple-labeled dsDNA are obtained in the presence of free single-labeled ssDNA and double-labeled dsDNA. The results establish a quantification method for studying multicolor FRET between multiple macromolecules in biochemical equilibrium. © 2012 Optical Society of America.
• Zhao, M., Zhou, W., & Peng, L. (2012). Multi-Color in vivo fluorescence lifetime tomography. Biomedical Optics, BIOMED 2012, JM3A.71.
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  Abstract: We present an in vivo multi-color fluorescence lifetime imaging method based on scanning laser optical tomography and Fourier fluorescence lifetime excitation-emission matrix spectroscopy. The system was tested with live transgenic zebrafish embryo. © 2012 OSA.
• Zhao, M., Zhou, W., & Peng, L. (2012). Multi-color in vivo fluorescence lifetime tomography. Digital Holography and Three-Dimensional Imaging, DH 2012, JM3A.71.
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  Abstract: We present an in vivo multi-color fluorescence lifetime imaging method based on scanning laser optical tomography and Fourier fluorescence lifetime excitation-emission matrix spectroscopy. The system was tested with live transgenic zebrafish embryo.
• Peng, L., Zhang, H., Zhao, M., & Peng, L. -. (2011). Nonlinear structured illumination microscopy by surface plasmon enhanced stimulated emission depletion. Optics express, 19(24).
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  Nonlinear structured illumination microscopy (SIM) in theory has unlimited resolution over a full field of view. However under a realistic signal-to-noise ratio and a limited photon budget, the performance of nonlinear SIM strongly depends on the behavior of the nonlinear effect. Saturated SIM (SSIM) is not ideal in biological applications due to its strong photobleaching. Stimulated emission depletion (STED) SIM will have high sensitivity, higher resolution and less photo toxicity than SSIM. However, the laser power necessary to support a strong full-field STED effect is not attainable with current laser technology. We experimentally proved that surface plasmon resonance enhances (SPR) near surface STED effect by a factor of 8, and therefore STED-SIM is feasible in the total internal reflection microscopy mode with SPR enhancement. Simulation analysis predicts that SPR enhanced 2D STED is strong enough for nonlinear SIM to achieve high-speed imaging at 30-nm resolution and single molecule sensitivity. The STED-SIM superresolution microscopy method would provide a solution for observing single molecule processes in vitro or on the basal membrane of live cells.
• Zhang, H., Zhao, M., & Peng, L. (2011). Nonlinear structured illumination microscopy by surface plasmon enhanced stimulated emission depletion. OPTICS EXPRESS, 19(24), 24783-24794.
• Zhang, H., Zhao, M., & Peng, L. (2011). Nonlinear structured illumination microscopy by surface plasmon enhanced stimulated emission depletion. Optics Express, 19(24), 24783-24794.
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  PMID: 22109506;Abstract: Nonlinear structured illumination microscopy (SIM) in theory has unlimited resolution over a full field of view. However under a realistic signal-to-noise ratio and a limited photon budget, the performance of nonlinear SIM strongly depends on the behavior of the nonlinear effect. Saturated SIM (SSIM) is not ideal in biological applications due to its strong photobleaching. Stimulated emission depletion (STED) SIM will have high sensitivity, higher resolution and less photo toxicity than SSIM. However, the laser power necessary to support a strong full-field STED effect is not attainable with current laser technology. We experimentally proved that surface plasmon resonance enhances (SPR) near surface STED effect by a factor of 8, and therefore STED-SIM is feasible in the total internal reflection microscopy mode with SPR enhancement. Simulation analysis predicts that SPR enhanced 2D STED is strong enough for nonlinear SIM to achieve high-speed imaging at 30-nm resolution and single molecule sensitivity. The STED-SIM superresolution microscopy method would provide a solution for observing single molecule processes in vitro or on the basal membrane of live cells. © 2011 Optical Society of America.
• Zhao, M., & Peng, L. (2011). Multiplexed fluorescence lifetime image with fourier excitation-emission spectroscopy. Optics InfoBase Conference Papers.
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  Abstract: We report a Fourier transform lifetime spectroscopy method simultaneously measures fluorescence lifetime and intensity on multiple excitation and emission channels in 46 microseconds. The technique will allow fast imaging study of multicolor Förster resonance energy transfer. © 2010 Optical Society of America.
• Zhao, M., & Peng, L. (2011). Multiplexed fluorescence lifetime microscopy by frequency-sweeping Fourier spectroscopy. 2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011.
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  Abstract: We have developed a multiplexed fluorescence lifetime confocal scanning microscopy method based on frequency sweeping Fourier fluorescence lifetime spectroscopy. It simultaneously obtains nanosecond fluorescence lifetime images at multiple excitation wavelengths. © 2011 OSA.
• Zhao, M., & Peng, L. (2011). Multiplexed fluorescence lifetime microscopy by frequency-sweeping fourier spectroscopy. Optics InfoBase Conference Papers.
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  Abstract: We have developed a multiplexed fluorescence lifetime confocal scanning microscopy method based on frequency sweeping Fourier fluorescence lifetime spectroscopy. It simultaneously obtains nanosecond fluorescence lifetime images at multiple excitation wavelengths. © 2010 Optical Society of America.
• Peng, L., Zhao, M., & Peng, L. -. (2010). Multiplexed fluorescence lifetime measurements by frequency-sweeping Fourier spectroscopy. Optics letters, 35(17).
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  We report simultaneous measurements of fluorescence lifetimes at multiple excitation wavelengths with a Fourier transform frequency domain fluorescence lifetime spectrometer. The spectrometer uses a Michelson interferometer with its differential optical path length scanning at a 22,000 Hz scan rate. The scan speed of the optical delay varies linearly during each scan and creates interference modulations that sweep from -150 to 150 MHz in 45.5 micros. The frequency-sweeping modulation allows nanosecond fluorescence lifetime measurements within 45.5 micros. Because the interference modulation frequency is wavelength dependent, under the Fourier multiplexing principle, the spectrometer can perform lifetime measurements on multiple excitation wavelengths simultaneously.
• Yuan, J., Peng, L., Bouma, B. E., & Tearney, G. J. (2010). Quantitative FRET measurement by high-speed Fluorescence Excitation and Emission spectrometer. Optics Express, 18(18), 18839-18851.
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  PMID: 20940777;Abstract: Förster resonance energy transfer (FRET) is an important method in studying biochemistry reactions. But quantifying FRET rapidly is difficult to do because of crosstalk between free donor, free acceptor and FRET fluorescent signals when only excitation or emission property of a FRET sample is measured. If FRET is studied with excitation-emission matrix (EEM) measurements, because the fluorescence intensity maxima of donor, acceptor, and FRET emissions occupy different regions within the EEM, FRET fluorescence can be easily separated out by linear unmixing. In this paper, we report a novel high-speed Fourier Fluorescence Excitation Emission spectrometer, which simultaneously measures three projections of EEM from a FRET sample, which are excitation, emission and excitationemission cross-correlation spectra. We demonstrate that these three EEM projections can be measured and unmixed in approximately 1 ms to provide rapid quantitative FRET in the presence of free donors and acceptors. The system can be utilized to enable real-time biochemistry reaction studies. © 2010 Optical Society of America.
• Yuan, J., Peng, L., Bouma, B. E., & Tearney, G. J. (2010). Quantitative FRET measurement by high-speed fluorescence excitation and emission spectrometer. OPTICS EXPRESS, 18(18), 18839-18851.
• Zhao, M., & Peng, L. (2010). Multiplexed fluorescence lifetime measurements by frequency-sweeping Fourier spectroscopy. OPTICS LETTERS, 35(17), 2910-2912.
• Zhao, M., & Peng, L. (2010). Multiplexed fluorescence lifetime measurements by frequency-sweeping Fourier spectroscopy. Optics Letters, 35(17), 2910-2912.
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  PMID: 20808366;PMCID: PMC3640859;Abstract: We report simultaneous measurements of fluorescence lifetimes at multiple excitation wavelengths with a Fourier transform frequency domain fluorescence lifetime spectrometer. The spectrometer uses a Michelson interferometer with its differential optical path length scanning at a 22,000 Hz scan rate. The scan speed of the optical delay varies linearly during each scan and creates interference modulations that sweep from -150 to 150 MHz in 45.5 μs. The frequency-sweeping modulation allows nanosecond fluorescence lifetime measurements within 45.5 μs. Because the interference modulation frequency is wavelength dependent, under the Fourier multiplexing principle, the spectrometer can perform lifetime measurements on multiple excitation wavelengths simultaneously. © 2010 Optical Society of America.
• Peng, L., Gardecki, J. A., Bouma, B. E., & Tearney, G. J. (2008). Fourier fluorescence spectrometer for excitation emission matrix measurement. OPTICS EXPRESS, 16(14), 10493-10500.
• Peng, L., Gardecki, J. A., Bouma, B. E., & Tearney, G. J. (2008). Fourier fluorescence spectrometer for excitation emission matrix measurement. Optics Express, 16(14), 10493-10500.
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  PMID: 18607462;Abstract: We demonstrate a fluorescence spectrometer that utilizes principles of Fourier transform spectroscopy to measure excitation emission matrices (EEM) rapidly and with high spectral resolution. For this EEM fluorometer, incoherent excitation light is first input into a differential-delay scanning Michelson interferometer. Light from the output port excites sample fluorescence. The fluorescence remitted from the sample is directed to a second Michelson interferometer, whose differential-delay scanning is synchronized with the first interferometer. The EEM is obtained by twodimensional Fourier analysis of the detected signal from the output port of the second interferometer. EEM results from the system are verified by comparing with results from a standard spectrometer. The system provides a wide spectral range, adjustable spectral resolution, and fast EEM acquisition speed, which allows EEM's to be acquired in 40 seconds at a spectral resolution of 81-cm-1. © 2008 Optical Society of America.
• Peng, L., Motz, J. T., Redmond, R. W., Bouma, B. E., & Tearney, G. J. (2007). Fourier transform emission lifetime spectrometer. OPTICS LETTERS, 32(4), 421-423.
• Peng, L., Motz, J. T., Redmond, R. W., Bouma, B. E., & Tearney, G. J. (2007). Fourier transform emission lifetime spectrometer. Optics Letters, 32(4), 421-423.
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  PMID: 17356673;Abstract: We report a rapid and low cost Fourier transform spectrometer that uses a path length modulated Michelson interferometer to simultaneously measure excitation spectra and excitation wavelength-dependent emission lifetimes. Excitation spectra and lifetimes of excited tris(2,2′-bipyridyl) ruthenium(II) measured using this technique corresponded to values known in the literature. Excitation-dependent lifetimes of porous silicon measured with this technique suggest the influence of quantum confinement effects. This method may be useful for measuring mixtures of emitting species with closely spaced lifetimes as well as studying excitation wavelength-dependent emission phenomena. © 2007 Optical Society of America.
• Peng, L., Varma, M. M., Cho, W., Regnier, F. E., & Nolte, D. D. (2007). Adaptive interferometry of protein on a BioCD. APPLIED OPTICS, 46(22), 5384-5395.
• Peng, L., Varma, M. M., Cho, W., Regnier, F. E., & Nolte, D. D. (2007). Adaptive interferometry of protein on a BioCD. Applied Optics, 46(22), 5384-5395.
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  PMID: 17676154;Abstract: Adaptive spinning-disk interferometry is capable of measuring surface profiles of a thin biolayer with subnanometer longitudinal resolution. High-speed phase modulation in the signal beam arises from the moving surface height profile on the spinning disk and is detected as a homodyne signal via dynamic two-wave mixing. A photorefractive quantum-well device performs as an adaptive mixer that compensates disk wobble and vibration while it phase-locks the signal and reference waves in the phase quadrature condition (π/2 relative phase between the signal and local oscillator). We performed biosensing of immobilized monolayers of antibodies on the disk in both transmission and reflection detection modes. Single- and dual-analyte adaptive spinning-disk immunoassays were demonstrated with good specificity and without observable cross-reactivity. Reflection-mode detection enhances the biosensing sensitivity to one-twentieth of a protein monolayer, creates a topographic map of the protein layer, and can differentiate monolayers of different species by their effective optical thicknesses. © 2007 Optical Society of America.
• Zhao, M., Peng, L., Cho, W., Regnier, F., & Nolte, D. D. (2006). Phase-contrast BioCD: High-speed immunoassays at sub-picogram detection levels - art. no. 60950L. Nanobiophotonics and Biomedical Applications III, 6095, L950-L950.
• Zhao, M., Peng, L., Cho, W., Regnier, F., & Nolte, D. D. (2006). Phase-contrast BioCD: High-speed immunoassays at sub-picogram detection levels. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 6095.
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  Abstract: We previously introduced the biological compact disk (BioCD) as a sensitive detection platform to detect patterned biomolecules immobilized on the surface of a spinning disk. Spinning-disk interferometry allows high speed detection (10 microseconds per spot) of optical path length changes down to sub-nanometer scales with high repeatability. The key to performing stable interferometry on a mechanically spinning disk is self-referencing: locking the phase of the signal and reference beams to quadrature (π/2 phase difference) independent of mechanical vibrations or relative motion. Two quadrature classes of BioCD have been reported previously: the micro-diffraction class (MD-Class) and the adaptive optical class (AO-Class) {Peng, 2004 #565; Varma, 2004 #440}. In this paper, we introduce a third class of BioCD, the Phase-Contrast-Class (PC-Class) BioCD. Protein is immobilized using photolithography on a disk in a 1024 spoke pattern. The edge of the printed protein pattern diffracts a focused laser beam that is detected in the Fourier plane with a split detector. The signal from the split detector is differenced, which plays a role in the electronic domain similar to that of a phase plate in optical phase contrast imaging. The PC-Class BioCD is simple in both theory and implementation, requiring no microstructure fabrication and no complex detection. Its potential in high speed label-free biosensing is demonstrated by a two-analyte immunoassay that shows good rejection of nonspecific binding and low antibody cross-reactivity. Immunoassays were performed against IgG immunoglobulins with detection of bound analyte on pictogram level. To show the potential of scaling up to hundreds or thousands of analytes per disk, an experiment was also performed with small drops of protein solution.
• Jeong, K., Peng, L., Turek, J. J., Melloch, M. R., & Nolte, D. D. (2005). Fourier-domain holographic optical coherence imaging of tumor spheroids and mouse eye. Applied Optics, 44(10), 1798-1805.
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  PMID: 15813515;Abstract: Fourier-domain holography (FDH) has several advantages over image-domain holography for optical coherence imaging of tissue. Writing the hologram in the Fourier plane significantly reduces background arising from reference light scattered from the photorefractive holographic film. The ability to use FDH is enhanced by the use of a diffuse target, such as scattering tissue, rather than specular targets, because the broader angular distribution from diffuse targets is transformed into a relatively uniform distribution in the Fourier plane. We demonstrate significantly improved performance for Fourier-domain optical coherence imaging on rat osteogenic sarcoma tumor spheroids and mouse eye. The sensitivity is documented at -95 dB. © 2005 Optical Society of America.
• Nolte, D. D., & Peng, L. (2005). Detecting molecular recognition with adaptive interferometry: The adaptive-optical BioCD. OSA Trends in Optics and Photonics Series, 99, 650-654.
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  Abstract: We have developed a high-speed interferometric optical assay called the BioCD. It is a spinning disk on which antibody molecules are printed that test for specific proteins in biological samples. The class of the BioCD that I will describe here uses adaptive beam combining in a photorefractive quantum well device to establish interferometric phase quadrature between the signal and reference beams. The interferometer is linearly sensitive to small numbers of captured biological molecules and adaptively compensates for mechanical vibrations and wobble in the optical disk.
• Peng, L., Varma, M. M., & Nolte, D. D. (2005). Adaptive spinning-disk interferometry and the AO-quadrature class of BioCDs. 2005 Conference on Lasers and Electro-Optics, CLEO, 3, 1609-1611.
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  Abstract: Adaptive two-wave mixing is used to quantify index variations in transparent optical media including the phase variations and fluctuations arising from immobilized protein patterns on spinning disks. © 2005 Optical Society of America.
• Peng, L., Varma, M. M., Nolte, D. D., & Regnier, F. E. (2005). Characterizing printed protein biolayers using adaptive spinning-disk interferometry. 2005 Conference on Lasers and Electro-Optics, CLEO, 3, 1763-1765.
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  Abstract: The optical thickness and refractive index of a monolayer of protein, printed using soft lithography on glass, is measured by spinning-disk adaptive homodyne detection, a sensitive new materials characterization tool, and validated by AFM. © 2005 Optical Society of America.
• Peng, L., Varma, M. M., Regnier, F. E., & Nolte, D. D. (2005). Adaptive optical biocompact disk for molecular recognition. Applied Physics Letters, 86(18), 1-3.
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  Abstract: We report the use of adaptive interferometry to detect a monolayer of protein immobilized in a periodic pattern on a spinning glass disk. A photorefractive quantum-well device acting as an adaptive beam mixer in a two-wave mixing geometry stabilizes the interferometric quadrature in the far field. Phase modulation generated by the spinning biolayer pattern in the probe beam is detected as a homodyne signal free of amplitude modulation. Binding between antibodies and immobilized antigens in a two-analyte immunoassay was tested with high specificity and without observable cross reactivity. © 2005 American Institute of Physics.
• Peng, L., Varma, M. M., Regnier, F. E., & Nolte, D. D. (2005). The adaptive BioCD: Interferometric immunoassay on a spinning disk. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 5692, 224-232.
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  Abstract: The speed of interferometric detection is at least 1000 times faster than the fluorometric detection used in the vast majority of clinical diagnostic systems. This opens the possibility to perform thousands of assays in the time it takes fluorescence to perform only one. Molecules immobilized on a spinning disk, like a CD, present the fastest and simplest means of interrogating thousands of micron-scale interferometer elements per second. However, the challenge of interferometry on a spinning disk is to maintain stable phase in the presence of mechanical vibration. In this paper, we demonstrate the first use of adaptive optics in an adaptive optical homodyne mixer to perform interferometry on a multi-analyte BioCD. The BioCD is a 4, diameter glass disk printed with a spoke pattern of protein. When the disk spins, the periodic protein pattern is transferred into a high-speed optical phase modulation by spinning the disk at 3000 rpm in the path of a probe laser. A nonlinear optical film mixes the signal beam with a stable reference beam in a two-wave mixing configuration that adaptively phase-locks the two beams to create stable phase in spite of mechanical vibration. Specific binding of antibody to printed antigen is detected as an increased homodyne signal. Multi-analyte detection on Anti Mouse and Anti Rabbit IgG is performed in which Mouse IgG and Rabbit IgG act as the non-specific reagent to each other. Detection is made on circular tracks. The technique has the potential of fast screening for large numbers of protein interactions.
• Varma, M. M., Peng, L., Regnier, F. E., & Nolte, D. D. (2005). Label-free multi-analyte detection using a BioCD. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 5699, 503-510.
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  Abstract: We previously reported the application of spinning-disk interferometry, implemented in a compact optical sensor format called the BioCD, in the detection of antigen-antibody recognition. The BioCD consists of interferometers micro-fabricated on the surface of a 2" laser mirror disk, which can spin up to 6000 rpm resulting in high data acquisition rates. The interferometric elements are fabricated by evaporating gold ridges on the mirror substrate operating in the linear sensitivity regime of the interferometer defined as quadrature. Antibodies or proteins are immobilized on the gold interferometric structures through alkanethiols, and the target molecules are immobilized by application of reagents or samples to the disk while it is spinning. The centrifugal force distributes the sample over the sensor surface, causing a change in the optical phase of the interferometric elements, which is detected in real time using a lock-in amplifier with small detection bandwidth. We detected the binding of Mouse IgG by immobilized Anti-Mouse IgG using the BioCD with a detection limit of 1 ng/ml and low non-specific binding. Furthermore, the selectivity of specific binding was found to be greater than 1 in 10000, determined using the response curve of the BioCD to exposures of specific and non-specific analytes of varying concentrations. This opens up the possibility of simultaneous detection of several analytes with the same sensor while maintaining high selectivity. In this paper we demonstrate simultaneous detection of Rabbit and Mouse IgG on the same disk. The sensitivity limit for multi-analyte detection remains the same as that for a single analyte. In addition to the ability to do simultaneous detection, the current detection scheme presents a way to reference the results of one track with respect to others, thus increasing the reliability of the data. Used in conjunction with high-density protein patterning techniques, the BioCD has the potential to be a highly multiplexed label-free high-speed sensor.
• Jeong, K., Peng, L., Nolte, D. D., & Melloch, M. R. (2004). Fourier-domain holography in photorefractive quantum-well films. Applied Optics, 43(19), 3802-3811.
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  PMID: 15250546;Abstract: Fourier-domain holography (FDH) is investigated as a candidate for holographic optical coherence imaging to produce real-time images of structure inside living tissue and turbid media. The effects of spatial filtering, the background intensity distributions, and the role of background noise in determining dynamic range are evaluated for both FDH and image-domain holography (IDH). The grating washout effect in FDH (edge enhancement) is removed by use of a vibrating diffuser that consequently improves the image quality. By comparing holographic images and background images of FDH and IDH we show that FDH provides a higher dynamic range and a higher image quality than IDH for this specific application of imaging diffuse volumetric objects. © 2004 Optical Society of America.
• Nolte, D. D., Varma, M., Peng, L., Inierowicz, D., & Regnier, F. (2004). Spinning-disk laser interferometers for immuno-assays and proteomics: The BioCD. Proceedings of SPIE - The International Society for Optical Engineering, 5328, 41-48.
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  Abstract: Spinning-disk self-referencing laser interferometers are being developed as high-speed high-sensitivity platforms for immunoassay and proteomics applications. Their compact disc (CD) formats have the potential for ultra-high-throughput multianalyte assays as well as for binding kinetics and quantitative analysis. Self-referencing interferometers are immune to mechanical variations, enabling interferometric sensitivities and speeds that are several orders of magnitude larger than for their counterpart fluorometric techniques. This paper defines for the first time three classes of the BioCD that differ in their method of self-referencing and reviews their relative merits and sensitivities. Each uses a near-field probe with far-field detection. The three classes are: microdiffraction, adaptive optical, and photonic cavity.
• Peng, L., Nolte, D. D., Ping, Y. u., & Melloch, M. R. (2004). Adaptive optical coherence-domain reflectometry using photorefractive quantum wells. Journal of the Optical Society of America B: Optical Physics, 21(11), 1953-1963.
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  Abstract: Adaptive optical-coherence-domain reflectometry (OCDR) is performed by use of an adaptive interferometer and homodyne detection. The adaptive element of the interferometer is a photorefractive quantum-well device in a two-wave mixing geometry. The mixing self-adaptively maintains constant relative phase between the signal and reference waves and dynamically compensates gross movements of the sample or optical components as well as image speckle. The application described here is used for laser ranging into and through turbid media. Adaptive OCDR is a bridge between conventional optical coherence tomography and adaptive holographic optical coherence imaging. The insertion loss for the adaptive performance is -15 dB, but adaptive OCDR has potential applications for coherence tomography under conditions of large target motion and low background. We also demonstrate its potential application for optoacoustics and laser-based ultrasound detection. © 2004 Optical Society of America.
• Peng, L., Varma, M. M., & Nolte, D. D. (2004). Adaptive spinning-disk interferometry for biosensing. OSA Trends in Optics and Photonics Series, 96 A, 423-424.
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  Abstract: We have implemented the first adaptive interferometry for biosensing on a spinning disk by two-wave mixing homodyne detection using photorefractive quantum wells. Binding between specific antigen and antibody has been observed using this technique. © 2003 Optical Society of America.
• Ping, Y. u., Mustata, M., Peng, L., Turek, J. J., Melloch, M. R., French, P. M., & Nolte, D. D. (2004). Holographic optical coherence imaging of rat osteogenic sarcoma tumor spheroids. Applied Optics, 43(25), 4862-4873.
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  PMID: 15449473;Abstract: Holographic optical coherence imaging is a full-frame variant of coherence-domain imaging. An optoelectronic semiconductor holographic film functions as a coherence filter placed before a conventional digital video camera that passes coherent (structure-bearing) light to the camera during holographic readout while preferentially rejecting scattered light. The data are acquired as a succession of en face images at increasing depth inside the sample in a fly-through acquisition. The samples of living tissue were rat osteogenic sarcoma multicellular tumor spheroids that were grown from a single osteoblast cell line in a bioreaotor. Tumor spheroids are nearly spherical and have radial symmetry, presenting a simple geometry for analysis. The tumors investigated ranged in diameter from several hundred micrometers to over 1 mm. Holographic features from the tumors were observed in reflection to depths of 500-600 μm with a total tissue path length of approximately 14 mean free paths. The volumetric data from the tumor spheroids reveal heterogeneous structure, presumably caused by necrosis and microcalcifications characteristic of some human avascular tumors. © 2004 Optical Society of America.
• Yu, P., Peng, L., Mustata, M., Turek, J. J., Melloch, M. R., & Nolte, D. D. (2004). Time-dependent speckle in holographic optical coherence imaging and the health of tumor tissue. Optics Letters, 29(1), 68-70.
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  PMID: 14719663;Abstract: Holographic optical coherence imaging acquires en face images from successive depths inside scattering tissue. In a study of multicellular tumor spheroids the holographic features recorded from a fixed depth are observed to be time dependent, and they may be classified as variable or persistent. The ratio of variable to persistent features, as well as speckle correlation times, provides quantitative measures of the health of the tissue. Studies of rat osteogenic sarcoma tumor spheroids that have been subjected to metabolic and cross-polymerizing poisons provide quantitative differentiation among healthy, necrotic, and poisoned tissue. Organelle motility in healthy tissue appears as super-Brownian laser speckle, whereas chemically fixed tissue exhibits static speckle.
• Dunsby, C., Gu, Y., Ansari, Z., French, P. M., Peng, L., Yu, P., Melloch, M. R., & Nolte, D. D. (2003). High-speed depth-sectioned wide-field imaging using low-coherence photorefractive holographic microscopy. Optics Communications, 219(1-6), 87-99.
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  Abstract: Low-coherence photorefractive holography has the potential to acquire wide-field coherence-gated images at frame rates approaching 1000 frames/s, including through scattering media. We present a quantitative analysis of the system optimization and limits of performance for coherence-gated imaging through scattering media using photorefractive holography and compare this performance to direct CCD detection. We show that, for high optical quality recording photorefractive multiple quantum well devices, photorefractive holography has the potential to provide a higher dynamic range than is possible with direct CCD-based detection. © 2003 Elsevier Science B.V. All rights reserved.
• Peng, L., Yu, P., Nolte, D. D., & Melloch, M. R. (2003). High-speed adaptive interferometer for optical coherence-domain reflectometry through turbid media. Optics Letters, 28(6), 396-398.
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  PMID: 12659258;Abstract: Two-wave mixing in a dynamic holographic film acts as the adaptive beam combiner in a short-coherence interferometer that performs optical coherence-domain reflectometry (OCDR) through turbid media. This approach combines the high spatial resolution and sensitivity of coherence-domain reflectometry with photorefractive quantum-well-based adaptive homodyne detection. A depth resolution of 28 μm and penetration through 16 mean free paths in a turbid medium have been obtained in this adaptive OCDR application. © 2003 Optical Society of America.
• Yu, P., Peng, L. L., Mustata, M., Nolte, D. D., Turek, J. J., Melloch, M. R., Dunsby, C., Gu, Y., & French, P. M. (2003). Imaging of tumor necroses using full-frame optical coherence imaging. Proceedings of SPIE - The International Society for Optical Engineering, 4956, 34-41.
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  Abstract: Holographic optical coherence imaging (OCI) has been used to acquire depth resolved images in tumor spheroids. OCI is a coherence-domain imaging technique that uses dynamic holography as the coherence gate. The technique is full-frame (en face) and background free, allowing real-time acquisition to a digital camera without motional reconstruction artifacts. We describe the method of operation of the holographic OCI on highly scattering specimens of tumor spheroids. Because of the sub-resolution structure in the sample, the holograms consist primarily of speckle fields. We present two kinds of volumetric data acquisition. One is uses fly-throughs with a stepping reference delay. Another is static holograms at a fixed reference delay with the coherence gate inside the tumor spheroids. At a fixed reference delay, the holograms consist of time-dependent speckle patterns. The method can be used to study cell motility inside tumor spheroids when metabolic or cross-linking poisons are delivered to the specimens.
• Yu, P., Peng, L., Nolte, D. D., & Melloch, M. R. (2003). Ultrasound detection through turbid media. Optics Letters, 28(10), 819-821.
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  PMID: 12779157;Abstract: Optical coherence-domain reflectometry and laser-based ultrasound detection have been combined with the use of adaptive optics to detect ultrasound through turbid media. The dynamic hologram in a photorefractive quantum-well device performs as a coherence gate that eliminates multiply scattered background. Quadrature homodyne detection conditions are selected by the choice of center wavelength of the pulse spectrum, requiring no active stabilization or feedback. A depth resolution of 30 μm was achieved, with a pulse duration of nominally 120 fs for ultrasound detection through turbid media up to optical thicknesses of 11 mean free scattering lengths. © 2003 Optical Society of America.
• Peng, L., Mustata, M., Jarvis, J. D., Yu, P., & Nolte, D. D. (2002). Adaptive optical coherence tomography using photorefractive quantum wells. Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 103-104.
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  Abstract: Adaptive optical coherence tomography (OCT) using photorefractive quantum wells was discussed. The coherent light was detected as an adaptive homodyne signal. Depth information was retrieved by using a short-coherence light source and scanning a delay line. The scheme is robust and sensitive to mechanical vibrations and laser speckle.
• Chen, X. J., Jia, C. C., Xu, C. K., Ouyang, G., Peng, L. L., Tian, S. X., & Xu, K. Z. (2000). An electron momentum spectroscopy study of the highest occupied molecular orbital of chlorotrifluoromethane. Chemical Physics Letters, 319(1-2), 76-80.
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  Abstract: The highest occupied molecular orbital (HOMO) of chlorotrifluoromethane (CF3Cl) has been studied by binary (e, 2e) electron momentum spectroscopy (EMS) for the first time. Impact energy of 1200 eV plus binding energy and symmetric non-coplanar geometry are employed. The experimental momentum profile of HOMO is compared with Hartree-Fock (HF) and density functional theory (DFT-B3LYP) calculations. An outer-valence Green's function (OVGF) calculation of ionization potentials of outer-valence orbitals has also been carried out and compared with previous MS Xα calculations and photoelectron spectroscopy (PES) measurements.
• Chen, X. J., Ouyang, G., Jia, C. C., Peng, L. L., Xu, C. K., Tian, S. X., & Xu, K. Z. (2000). Study of outer valence orbitals of carbon dioxide by (e, 2e) spectroscopy. Journal of Electron Spectroscopy and Related Phenomena, 107(3), 273-282.
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  Abstract: By using symmetric non-coplanar electron momentum spectroscopy at impact energy of 1200 eV plus binding energy, valence shell binding energy spectra of carbon dioxide have been obtained. The experimental momentum profiles of four outer valence orbitals: 1πg, 1πu, 3σu, 4σg are compared with theoretical profiles calculated by Hartree-Fock and density functional theory (DFT-B3LYP) methods using both 6-311++G* and double-zeta basis sets. The experimental results are in good agreement with the calculated results. A minimum at p≈1.2 a.u. for the 3σu orbital is found. The experimental momentum profiles generally agree better with the profiles calculated by the DFT method than those by the HF method. The position and momentum space density maps for four outer valence orbitals of CO2 are also presented.
• Jia, C., Chen, X., Ouyang, G., Chunkai, X. u., Peng, L., Tian, S., & Kezun, X. u. (2000). Measurement of electron momentum profile of 3σ_u orbital of carbon dioxide. Chinese Journal of Chemical Physics, 13(4), 387-.
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  Abstract: The electron momentum distribution of 3σu orbital of carbon dioxide has been measured at high momentum resolution. Through comparation between experimental and theoretical results, the calculation by DFT-B3LYP method using 6-311 + +G* basis set is more agreement with the experimental data than other calculations.
• Jia, C. C., Chen, X. J., Tian, S. X., Oy, G., Peng, L. L., Yang, B. X., Xu, K. Z., Yuan, L. F., & Yang, J. L. (1999). Investigation of propane using electron momentum spectroscopy. Journal of Physics B: Atomic, Molecular and Optical Physics, 32(6), 1515-1522.
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  Abstract: The valence shell binding energy spectra and three inner valence orbitals electron momentum distributions for propane (C3H8) are measured by symmetric non-coplanar electron momentum spectroscopy at an impact energy of 1200 eV. The measured binding energy spectrum is compared with previously published results. The experimental momentum profiles of three inner valence orbitals are compared with calculated momentum profiles by Hartree-Fock and density functional theory (DFT-B3LYP) methods using double-zeta and 6-311++G** basis sets. Agreement is found between experimental and calculated results. The position and momentum space density maps for three inner valence orbitals of oriented C3H8 molecule are presented.

Proceedings Publications

• Zhang, H., Zhao, M., Peng, L., Enderlein, J., Gregor, ., Gryczynski, Z., Erdmann, R., & Koberling, F. (2014, 2013). Nonlinear Structured Illumination Microscopy with Surface Plasmon Resonance Enhanced Stimulated Emission Depletion. In SINGLE MOLECULE SPECTROSCOPY AND SUPERRESOLUTION IMAGING VI, 8590.

Presentations

• Peng, L. (2022, February). Rapid random z-access two-photon light-sheet microscope for neural imaging. SPIE Photonics West, Neural Imaging and Sensing 2022.
• Peng, L. (2021). Deep tissue Two-Photon light sheet imaging. OSA Imaging and Applied Optics Congress.
• Peng, L. (2021). Deep tissue light sheet imaging with structured illumination. SPIE Photonics West.
• Peng, L. (2020, July). 3D Light Sheet Imaging with Structured Illumination. OSA Optical Sensors and Sensing Congress.
• Xu, D., Peng, L., & Ding, J. (2020, March). Two-photon Bessel beam scanning microscope for neural activities. SPIE Photonics West, Neural Imaging and Sensing 2020.
• Xu, D., Ding, J., & Peng, L. (2019, February). Multi-modality two-photon Bessel beam scanning microscope for neural imaging. SPIE Photonics West, Neural Imaging and Sensing 2019.