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Guo B, Lei C, Kobayashi H, Ito T, Yalikun Y, Jiang Y, Tanaka Y, Ozeki Y, Goda K. High-throughput, label-free, single-cell, microalgal lipid screening by machine-learning-equipped optofluidic time-stretch quantitative phase microscopy. Cytometry A 2017; 91:494-502. [PMID: 28399328 DOI: 10.1002/cyto.a.23084] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 01/19/2017] [Accepted: 01/23/2017] [Indexed: 12/16/2022]
Abstract
The development of reliable, sustainable, and economical sources of alternative fuels to petroleum is required to tackle the global energy crisis. One such alternative is microalgal biofuel, which is expected to play a key role in reducing the detrimental effects of global warming as microalgae absorb atmospheric CO2 via photosynthesis. Unfortunately, conventional analytical methods only provide population-averaged lipid amounts and fail to characterize a diverse population of microalgal cells with single-cell resolution in a non-invasive and interference-free manner. Here high-throughput label-free single-cell screening of lipid-producing microalgal cells with optofluidic time-stretch quantitative phase microscopy was demonstrated. In particular, Euglena gracilis, an attractive microalgal species that produces wax esters (suitable for biodiesel and aviation fuel after refinement), within lipid droplets was investigated. The optofluidic time-stretch quantitative phase microscope is based on an integration of a hydrodynamic-focusing microfluidic chip, an optical time-stretch quantitative phase microscope, and a digital image processor equipped with machine learning. As a result, it provides both the opacity and phase maps of every single cell at a high throughput of 10,000 cells/s, enabling accurate cell classification without the need for fluorescent staining. Specifically, the dataset was used to characterize heterogeneous populations of E. gracilis cells under two different culture conditions (nitrogen-sufficient and nitrogen-deficient) and achieve the cell classification with an error rate of only 2.15%. The method holds promise as an effective analytical tool for microalgae-based biofuel production. © 2017 International Society for Advancement of Cytometry.
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Affiliation(s)
- Baoshan Guo
- Department of Chemistry, University of Tokyo, Tokyo, 113-0033, Japan
| | - Cheng Lei
- Department of Chemistry, University of Tokyo, Tokyo, 113-0033, Japan.,Department of Electronic Engineering, Tsinghua University, Beijing, 100084, China
| | | | - Takuro Ito
- Japan Science and Technology Agency, Kawaguchi, 332-0012, Japan
| | - Yaxiaer Yalikun
- Laboratory for Integrated Biodevices, Quantitative Biology Center, RIKEN, Osaka, 565-0871, Japan
| | - Yiyue Jiang
- Department of Chemistry, University of Tokyo, Tokyo, 113-0033, Japan
| | - Yo Tanaka
- Laboratory for Integrated Biodevices, Quantitative Biology Center, RIKEN, Osaka, 565-0871, Japan
| | - Yasuyuki Ozeki
- Department of Electrical Engineering and Information Systems, University of Tokyo, Tokyo, 113-8656, Japan
| | - Keisuke Goda
- Department of Chemistry, University of Tokyo, Tokyo, 113-0033, Japan.,Japan Science and Technology Agency, Kawaguchi, 332-0012, Japan.,Department of Electrical Engineering, University of California, Los Angeles, California, 90095
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Lau AKS, Wong TTW, Ho KKY, Tang MTH, Chan ACS, Wei X, Lam EY, Shum HC, Wong KKY, Tsia KK. Interferometric time-stretch microscopy for ultrafast quantitative cellular and tissue imaging at 1 μm. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:76001. [PMID: 24983913 DOI: 10.1117/1.jbo.19.7.076001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 05/29/2014] [Indexed: 05/20/2023]
Abstract
Quantitative phase imaging (QPI) has been proven to be a powerful tool for label-free characterization of biological specimens. However, the imaging speed, largely limited by the image sensor technology, impedes its utility in applications where high-throughput screening and efficient big-data analysis are mandated. We here demonstrate interferometric time-stretch (iTS) microscopy for delivering ultrafast quantitative phase cellular and tissue imaging at an imaging line-scan rate >20 MHz—orders-of-magnitude faster than conventional QPI. Enabling an efficient time-stretch operation in the 1-μm wavelength window, we present an iTS microscope system for practical ultrafast QPI of fixed cells and tissue sections, as well as ultrafast flowing cells (at a flow speed of up to 8 m∕s). To the best of our knowledge, this is the first time that time-stretch imaging could reveal quantitative morphological information of cells and tissues with nanometer precision. As many parameters can be further extracted from the phase and can serve as the intrinsic biomarkers for disease diagnosis, iTS microscopy could find its niche in high-throughput and high-content cellular assays (e.g., imaging flow cytometry) as well as tissue refractometric imaging (e.g., whole-slide imaging for digital pathology).
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Affiliation(s)
- Andy K S Lau
- University of Hong Kong, Faculty of Engineering, Department of Electrical and Electronic Engineering, Pokfulam Road, Hong Kong, China
| | - Terence T W Wong
- University of Hong Kong, Faculty of Engineering, Department of Electrical and Electronic Engineering, Pokfulam Road, Hong Kong, China
| | - Kenneth K Y Ho
- University of Hong Kong, Faculty of Engineering, Department of Mechanical Engineering, Pokfulam Road, Hong Kong, China
| | - Matthew T H Tang
- University of Hong Kong, Faculty of Engineering, Department of Mechanical Engineering, Pokfulam Road, Hong Kong, China
| | - Antony C S Chan
- University of Hong Kong, Faculty of Engineering, Department of Electrical and Electronic Engineering, Pokfulam Road, Hong Kong, China
| | - Xiaoming Wei
- University of Hong Kong, Faculty of Engineering, Department of Electrical and Electronic Engineering, Pokfulam Road, Hong Kong, China
| | - Edmund Y Lam
- University of Hong Kong, Faculty of Engineering, Department of Electrical and Electronic Engineering, Pokfulam Road, Hong Kong, China
| | - Ho Cheung Shum
- University of Hong Kong, Faculty of Engineering, Department of Mechanical Engineering, Pokfulam Road, Hong Kong, ChinacUniversity of Hong Kong-Shenzhen Institute of Research and Innovation, Shenzhen Software Park, Shenzhen, China
| | - Kenneth K Y Wong
- University of Hong Kong, Faculty of Engineering, Department of Electrical and Electronic Engineering, Pokfulam Road, Hong Kong, China
| | - Kevin K Tsia
- University of Hong Kong, Faculty of Engineering, Department of Electrical and Electronic Engineering, Pokfulam Road, Hong Kong, China
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