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Tovar M, Hengoju S, Weber T, Mahler L, Choudhary M, Becker T, Roth M. One Sensor for Multiple Colors: Fluorescence Analysis of Microdroplets in Microbiological Screenings by Frequency-Division Multiplexing. Anal Chem 2019; 91:3055-3061. [PMID: 30689354 DOI: 10.1021/acs.analchem.8b05451] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
High-speed multiwavelength fluorescence measurements are of paramount importance in microfluidic analytics. However, multicolor detection requires an intricate arrangement of multiple detectors and meticulously aligned filters and dichroic beamsplitters that counteract the simplicity, versatility, and low cost of microfluidic approaches. To break free from the restrictions of optical setup complexity, we introduce a simpler single-sensor setup based on laser-frequency modulation and frequency-division multiplexing (FDM). We modulate lasers to excite the sample with four non-overlapping frequency signals. A single photomultiplier tube detects all the modulated emitted light collected by an optical fiber in the microfluidic chip. Signal demodulation is performed with a lock-in amplifier separating the emitted light into four color channels in real time. This approach not only reduces complexity and provides setup flexibility but also results in improved signal quality and, thus, higher signal-to-noise ratios that translate into increased sensitivity. To validate the setup for high-throughput biological applications, we measured multiple signals from different microorganisms and fluorescently encoded droplet populations for exploring beneficial or antagonistic roles in microbial cocultivation systems, as is the case for antibiotic screening assays.
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Affiliation(s)
- Miguel Tovar
- Bio Pilot Plant , Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute , 07745 Jena , Germany.,Faculty of Biology and Pharmacy , Friedrich Schiller University , 07743 Jena , Germany
| | - Sundar Hengoju
- Bio Pilot Plant , Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute , 07745 Jena , Germany.,Faculty of Biology and Pharmacy , Friedrich Schiller University , 07743 Jena , Germany
| | - Thomas Weber
- Bio Pilot Plant , Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute , 07745 Jena , Germany.,Ilmenau University of Technology , 98693 Ilmenau , Germany
| | - Lisa Mahler
- Bio Pilot Plant , Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute , 07745 Jena , Germany.,Faculty of Biology and Pharmacy , Friedrich Schiller University , 07743 Jena , Germany
| | - Mahipal Choudhary
- Bio Pilot Plant , Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute , 07745 Jena , Germany
| | | | - Martin Roth
- Bio Pilot Plant , Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute , 07745 Jena , Germany
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Tsyboulski D, Orlova N, Saggau P. Amplitude modulation of femtosecond laser pulses in the megahertz range for frequency-multiplexed two-photon imaging. Opt Express 2017; 25:9435-9442. [PMID: 28437905 DOI: 10.1364/oe.25.009435] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We present a frequency-multiplexed multi-site two-photon imaging method utilizing amplitude modulation of femtosecond laser pulses in the MHz range to tag each excitation beam and the corresponding fluorescence signals with specific frequencies. The frequency tags are generated with an interferometric scheme employing acousto-optic deflectors (AODs) to achieve precise spatial overlap of femtosecond laser pulses with periodically varying phase shift. Creating matching excitation beam patterns in each interferometer arm using multiple AOD driving frequencies, and subsequently overlapping these matching patterns, results in multiple encoded excitation beams with unique beat frequencies available for scanning. As a proof-of-concept, we demonstrate multiplexed two-photon image acquisition using test samples, and compare the performance of this approach to conventional two-photon laser scanning microscopy.
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