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Ratajczak K, Juzwa W, Piotrowska-Cyplik A. Optimization of the flow cytometry method of detection, quantification and qualification of microorganisms in carrot juice. Food Chem 2024; 460:140606. [PMID: 39089032 DOI: 10.1016/j.foodchem.2024.140606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 07/15/2024] [Accepted: 07/22/2024] [Indexed: 08/03/2024]
Abstract
Fresh, unpasteurized carrot juice is a popular element of the everyday diet of many consumers, and as such the matter of the juice's microbial safety remains an important one. Imaging flow cytometry (FCM) allows a fast enumeration and determination of cells, as well as their further differentiation. However, carrot juice is a difficult food product to analyze with the use of FCM due to interference from autofluorescence and the presence of plant debris. In this research, we aimed to obtain an effective and repeatable protocol for the preparation of carrot juice samples for FCM analysis. Through experimental and software-based means we successfully determined a reliable protocol for the preparation of fresh, unpasteurized carrot juice, which consisted of a sequence of filtering, centrifugation, enzyme treatment, and finally the implementation of the Machine Learning protocol for the best result.
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Affiliation(s)
- Katarzyna Ratajczak
- Department of Food Technology of Plant Origin, Poznan University of Life Sciences, Wojska Polskiego 31, 60-624 Poznań, Poland.
| | - Wojciech Juzwa
- Department of Biotechnology and Food Microbiology, Poznan University of Life Sciences, Wojska Polskiego 48, 60-627 Poznań, Poland.
| | - Agnieszka Piotrowska-Cyplik
- Department of Food Technology of Plant Origin, Poznan University of Life Sciences, Wojska Polskiego 31, 60-624 Poznań, Poland.
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2
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Microfluidic dose-response platform to track the dynamics of drug response in single mycobacterial cells. Sci Rep 2022; 12:19578. [PMID: 36379978 PMCID: PMC9666435 DOI: 10.1038/s41598-022-24175-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022] Open
Abstract
Preclinical analysis of drug efficacy is critical for drug development. However, conventional bulk-cell assays statically assess the mean population behavior, lacking resolution on drug-escaping cells. Inaccurate estimation of efficacy can lead to overestimation of compounds, whose efficacy will not be confirmed in the clinic, or lead to rejection of valuable candidates. Time-lapse microfluidic microscopy is a powerful approach to characterize drugs at high spatiotemporal resolution, but hard to apply on a large scale. Here we report the development of a microfluidic platform based on a pneumatic operating principle, which is scalable and compatible with long-term live-cell imaging and with simultaneous analysis of different drug concentrations. We tested the platform with mycobacterial cells, including the tubercular pathogen, providing the first proof of concept of a single-cell dose-response assay. This dynamic in-vitro model will prove useful to probe the fate of drug-stressed cells, providing improved predictions of drug efficacy in the clinic.
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3
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Jusková P, Schmitt S, Armbrecht L, Dittrich PS. Microbial factories: monitoring vitamin B 2 production by Escherichia coli in microfluidic cultivation chambers. LAB ON A CHIP 2021; 21:4071-4080. [PMID: 34618882 PMCID: PMC8547325 DOI: 10.1039/d1lc00621e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
Microbial cells represent a standard production host for various important biotechnological products. Production yields can be increased by optimising strains and growth conditions and understanding deviations in production rates over time or within the microbial population. We introduce here microfluidic cultivation chambers for highly parallel studies on microbial cultures, enabling continuous biosynthesis monitoring of the industrially relevant product by Escherichia coli cells. The growth chambers are defined by ring-valves that encapsulate a volume of 200 pL when activated. Bacterial cells, labelled with magnetic beads, are inoculated in a small magnetic trap, positioned in the centre of each chamber. Afterwards, the ring-valves are partially activated, allowing for exchange reagents, such as the addition of fresh media or specific inducers of biosynthesis, while the bacterial cells and their progeny are maintained inside. On this platform, we monitor the production of riboflavin (vitamin B2). We used different variants of a riboflavin-overproducing bacterial strain with different riboflavin production levels and could distinguish them on the level of individual micro-colonies. In addition, we could also observe differences in the bacterial morphology with respect to the production. The presented platform represents a flexible microfluidic tool for further studies of microbial cell factories.
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Affiliation(s)
- Petra Jusková
- Department of Biosystems Science and Engineering, Bioanalytics Group, ETH Zürich, Mattenstrasse 26, CH-4058 Basel, Switzerland.
| | - Steven Schmitt
- Department of Biosystems Science and Engineering, Bioprocess Laboratory, ETH Zürich, Mattenstrasse 26, CH-4058 Basel, Switzerland
| | - Lucas Armbrecht
- Department of Biosystems Science and Engineering, Bioanalytics Group, ETH Zürich, Mattenstrasse 26, CH-4058 Basel, Switzerland.
| | - Petra S Dittrich
- Department of Biosystems Science and Engineering, Bioanalytics Group, ETH Zürich, Mattenstrasse 26, CH-4058 Basel, Switzerland.
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4
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Identifying extracellular vesicle populations from single cells. Proc Natl Acad Sci U S A 2021; 118:2106630118. [PMID: 34518226 PMCID: PMC8463870 DOI: 10.1073/pnas.2106630118] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2021] [Indexed: 12/13/2022] Open
Abstract
Extracellular vesicles (EVs) are constantly secreted from both eukaryotic and prokaryotic cells. EVs, including those referred to as exosomes, may have an impact on cell signaling and an incidence in diseased cells. In this manuscript, a platform to capture, quantify, and phenotypically classify the EVs secreted from single cells is introduced. Microfluidic chambers of about 300 pL are employed to trap and isolate individual cells. The EVs secreted within these chambers are then captured by surface-immobilized monoclonal antibodies (mAbs), irrespective of their intracellular origin. Immunostaining against both plasma membrane and cytosolic proteins was combined with highly sensitive, multicolor total internal reflection fluorescence microscopy to characterize the immobilized vesicles. The data analysis of high-resolution images allowed the assignment of each detected EV to one of 15 unique populations and demonstrated the presence of highly heterogeneous phenotypes even at the single-cell level. The analysis also revealed that each mAb isolates phenotypically different EVs and that more vesicles were effectively immobilized when CD63 was targeted instead of CD81. Finally, we demonstrate how a heterogeneous suppression in the secreted vesicles is obtained when the enzyme neutral sphingomyelinase is inhibited.
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5
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Yang M, Villarreal JC, Ariyasinghe N, Kruithoff R, Ros R, Ros A. Quantitative Approach for Protein Analysis in Small Cell Ensembles by an Integrated Microfluidic Chip with MALDI Mass Spectrometry. Anal Chem 2021; 93:6053-6061. [PMID: 33819014 PMCID: PMC8128341 DOI: 10.1021/acs.analchem.0c04112] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Increasing evidence has demonstrated that cells are individually heterogeneous. Advancing the technologies for single-cell analysis will improve our ability to characterize cells, study cell biology, design and screen drugs, and aid cancer diagnosis and treatment. Most current single-cell protein analysis approaches are based on fluorescent antibody-binding technology. However, this technology is limited by high background and cross-talk of multiple tags introduced by fluorescent labels. Stable isotope labels used in mass cytometry can overcome the spectral overlap of fluorophores. Nevertheless, the specificity of each antibody and heavy-metal-tagged antibody combination must be carefully validated to ensure detection of the intended target. Thus, novel single-cell protein analysis methods without using labels are urgently needed. Moreover, the labeling approach targets already known motifs, hampering the discovery of new biomarkers relevant to single-cell population variation. Here, we report a combined microfluidic and matrix-assisted laser desorption and ionization (MALDI) mass spectrometric approach for the analysis of protein biomarkers suitable for small cell ensembles. All necessary steps for cell analysis including cell lysis, protein capture, and digestion as well as MALDI matrix deposition are integrated on a microfluidic chip prior to the downstream MALDI-time-of-flight (TOF) detection. For proof of principle, this combined method is used to assess the amount of Bcl-2, an apoptosis regulator, in metastatic breast cancer cells (MCF-7) by using an isotope-labeled peptide as an internal standard. The proposed approach will eventually provide a new means for proteome studies in small cell ensembles with the potential for single-cell analysis and improve our ability in disease diagnosis, drug discovery, and personalized therapy.
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Affiliation(s)
- Mian Yang
- Department of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan City, Hubei Province, 430081, P.R.China
| | - Jorvani Cruz Villarreal
- School of Molecular Sciences, Arizona State University, Tempe AZ, 85287-1604, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe AZ, 85287-7401, USA
| | - Nethmi Ariyasinghe
- Department of Physics and Center for Biological Physics, Arizona State University, Tempe AZ, 85287-1504, USA
- Center for Single Molecule Biophysics, The Biodesign Institute, Arizona State University, Tempe AZ, 85287, USA
| | - Rory Kruithoff
- Department of Physics and Center for Biological Physics, Arizona State University, Tempe AZ, 85287-1504, USA
| | - Robert Ros
- Department of Physics and Center for Biological Physics, Arizona State University, Tempe AZ, 85287-1504, USA
- Center for Single Molecule Biophysics, The Biodesign Institute, Arizona State University, Tempe AZ, 85287, USA
| | - Alexandra Ros
- School of Molecular Sciences, Arizona State University, Tempe AZ, 85287-1604, USA
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe AZ, 85287-7401, USA
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6
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Bucheli OTM, Sigvaldadóttir I, Eyer K. Measuring single-cell protein secretion in immunology: Technologies, advances, and applications. Eur J Immunol 2021; 51:1334-1347. [PMID: 33734428 PMCID: PMC8252417 DOI: 10.1002/eji.202048976] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 01/12/2021] [Accepted: 03/15/2021] [Indexed: 12/19/2022]
Abstract
The dynamics, nature, strength, and ultimately protective capabilities of an active immune response are determined by the extracellular constitution and concentration of various soluble factors. Generated effector cells secrete such mediators, including antibodies, chemo‐ and cytokines to achieve functionality. These secreted factors organize the individual immune cells into functional tissues, initiate, orchestrate, and regulate the immune response. Therefore, a single‐cell resolved analysis of protein secretion is a valuable tool for studying the heterogeneity and functionality of immune cells. This review aims to provide a comparative overview of various methods to characterize immune reactions by measuring single‐cell protein secretion. Spot‐based and cytometry‐based assays, such as ELISpot and flow cytometry, respectively, are well‐established methods applied in basic research and clinical settings. Emerging novel technologies, such as microfluidic platforms, offer new ways to measure and exploit protein secretion in immune reactions. Further technological advances will allow the deciphering of protein secretion in immunological responses with unprecedented detail, linking secretion to functionality. Here, we summarize the development and recent advances of tools that allow the analysis of protein secretion at the single‐cell level, and discuss and contrast their applications within immunology.
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Affiliation(s)
- Olivia T M Bucheli
- ETH Laboratory for Functional Immune Repertoire Analysis, Institute of Pharmaceutical Sciences, D-CHAB, ETH Zürich, Zürich, Switzerland
| | - Ingibjörg Sigvaldadóttir
- ETH Laboratory for Functional Immune Repertoire Analysis, Institute of Pharmaceutical Sciences, D-CHAB, ETH Zürich, Zürich, Switzerland
| | - Klaus Eyer
- ETH Laboratory for Functional Immune Repertoire Analysis, Institute of Pharmaceutical Sciences, D-CHAB, ETH Zürich, Zürich, Switzerland
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7
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Haidas D, Napiorkowska M, Schmitt S, Dittrich PS. Parallel Sampling of Nanoliter Droplet Arrays for Noninvasive Protein Analysis in Discrete Yeast Cultivations by MALDI-MS. Anal Chem 2020; 92:3810-3818. [DOI: 10.1021/acs.analchem.9b05235] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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8
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Microfluidic Single-Cell Analytics. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2020; 179:159-189. [PMID: 32737554 DOI: 10.1007/10_2020_134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
What is the impact of cellular heterogeneity on process performance? How do individual cells contribute to averaged process productivity? Single-cell analysis is a key technology for answering such key questions of biotechnology, beyond bulky measurements with populations. The analysis of cellular individuality, its origins, and the dependency of process performance on cellular heterogeneity has tremendous potential for optimizing biotechnological processes in terms of metabolic, reaction, and process engineering. Microfluidics offer unmatched environmental control of the cellular environment and allow massively parallelized cultivation of single cells. However, the analytical accessibility to a cell's physiology is of crucial importance for obtaining the desired information on the single-cell production phenotype. Highly sensitive analytics are required to detect and quantify the minute amounts of target analytes and small physiological changes in a single cell. For their application to biotechnological questions, single-cell analytics must evolve toward the measurement of kinetics and specific rates of the smallest catalytic unit, the single cell. In this chapter, we focus on an introduction to the latest single-cell analytics and their application for obtaining physiological parameters in a biotechnological context from single cells. We present and discuss recent advancements in single-cell analytics that enable the analysis of cell-specific growth, uptake, and production kinetics, as well as the gene expression and regulatory mechanisms at a single-cell level.
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9
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He S, Hong X, Zhang M, Wu L, Yan X. Label-Free Detection of Bacteria in Fruit Juice by Nano-Flow Cytometry. Anal Chem 2019; 92:2393-2400. [PMID: 31820949 DOI: 10.1021/acs.analchem.9b01869] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Rapid quantification of microbial contamination in fruit juice is highly desired for food safety control. Yet, the complex sample matrix and the diversity of bacterial contaminants present a great challenge. Employing a laboratory-built nano-flow cytometer (nFCM), here we report the development of a label-free approach for the detection of bacteria population in fruit juice. The weak autofluorescence of bacterial cells was used as a hallmark for the identification of bacteria. The sample pretreatment protocol was optimized to reduce fluorescence background, lyse residual plant cells and debris, and attain a good recovery of bacteria from juice samples. It was demonstrated that the nFCM was able to enumerate individual bacteria of very weak autofluorescence, and a clear differentiation from residual juice particulates was achieved. For bacteria spiked in the orange juice, the recovery rate was around 95% and a linear correlation between nFCM analysis and plate counting was acquired in the range of 3 × 104 to 3 × 108 cfu/mL. The assay, including sample pretreatment and instrument analysis, can be accomplished within 1 h, which is far more efficient than plate counting. Using a 40 mL sample volume, the detection limit in apple juice was ∼102 cells/mL. The as-developed method was successfully applied to bacterial measurement of freshly made orange juice and apple juice purchased from grocery stores. We believe it could also have potential practical application in microbial control analysis of other juices and water.
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Affiliation(s)
- Shengbin He
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen , Fujian 361005 , P. R. China
| | - Xinyi Hong
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen , Fujian 361005 , P. R. China
| | - Miaomiao Zhang
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen , Fujian 361005 , P. R. China
| | - Lina Wu
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen , Fujian 361005 , P. R. China
| | - Xiaomei Yan
- MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, Key Laboratory for Chemical Biology of Fujian Province, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical Biology, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen , Fujian 361005 , P. R. China
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10
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Alves IP, Reis NM. Microfluidic smartphone quantitation of Escherichia coli in synthetic urine. Biosens Bioelectron 2019; 145:111624. [PMID: 31546201 DOI: 10.1016/j.bios.2019.111624] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/20/2019] [Accepted: 08/21/2019] [Indexed: 10/26/2022]
Abstract
In spite of the clinical need, there is a major gap in rapid diagnostics for identification and quantitation of E. coli and other pathogens, also regarded as the biggest bottleneck in the fight against the spread of antimicrobial resistant bacterial strains. This study reports for the first time an optical, smartphone-based microfluidic fluorescence sandwich immunoassay capable of quantifying E. coli in buffer and synthetic urine in less than 25 min without sample preparation nor concentration. A limit of detection (LoD) up to 240 CFU/mL, comensurate with cut-off for UTIs (103-105 CFUs/mL) was achieved. Replicas of full response curves performed with 100-107 CFUs/mL of E. coli K12 in synthetic urine yielded recovery values in the range 80-120%, assay reproducibility below 30% and precision below 20%, therefore similar to high-performance automated immunoassays. The unrivalled LoD was mainly linked to the 'open fluidics' nature of the 10-bore microfluidic strips used that enabled passing a large volume of sample through the microcapillaries coated with capture antibody. The new smartphone based test has the potential of being as a rapid, point-of-care test for rule-in of E. coli infections that are responsible for around 80% of UTIs, helping to stop the over-prescription of antibiotics and the monitoring of patients with other symptomatic communicable diseases caused by E. coli at global scale.
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Affiliation(s)
- Isabel P Alves
- Department of Chemical Engineering, Loughborough University, Leicestershire, LE11 3TU, UK
| | - Nuno M Reis
- Centre for Biosensors, Bioelectronics and Biodevices (C3Bio), Department of Chemical Engineering, University of Bath, Bath, BA2 7AY, UK.
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11
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Armbrecht L, Müller RS, Nikoloff J, Dittrich PS. Single-cell protein profiling in microchambers with barcoded beads. MICROSYSTEMS & NANOENGINEERING 2019; 5:55. [PMID: 31700673 PMCID: PMC6826046 DOI: 10.1038/s41378-019-0099-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 05/21/2023]
Abstract
Single-cell profiling provides insights into cellular behaviour that macroscale cell cultures and bulk measurements cannot reveal. In the context of personalized cancer treatment, the profiling of individual tumour cells may lead to higher success rates for therapies by rapidly selecting the most efficacious drugs. Currently, genomic analysis at the single-cell level is available through highly sensitive sequencing approaches. However, the identification and quantification of intracellular or secreted proteins or metabolites remains challenging. Here, we introduce a microfluidic method that facilitates capture, automated data acquisition and the multiplexed quantification of proteins from individual cells. The microfluidic platform comprises 1026 chambers with a volume of 152 pL each, in which single cells and barcoded beads are co-immobilized. We demonstrated multiplexed single-cell protein quantification with three different mammalian cell lines, including two model breast cancer cell lines. We established on-chip immunoassays for glyceraldehyde-3-phosphate dehydrogenase (GAPDH), galectin-3 (Gal-3) and galectin-3 binding protein (Gal-3bp) with detection limits as low as 7.0 × 104, 2.3 × 105 and 1.8 × 103 molecules per cell, respectively. The three investigated cell types had high cytosolic levels of GAPDH and could be clearly differentiated by their expression levels of Gal-3 and Gal-3bp, which are important factors that contribute to cancer metastasis. Because it employed commercially available barcoded beads for this study, our platform could be easily used for the single-cell protein profiling of several hundred different targets. Moreover, this versatile method is applicable to the analysis of bacteria, yeast and mammalian cells and nanometre-sized lipid vesicles.
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Affiliation(s)
- Lucas Armbrecht
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Rafael Sebastian Müller
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Jonas Nikoloff
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Petra Stephanie Dittrich
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
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12
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Immunocapture of Escherichia coli in a fluoropolymer microcapillary array. J Chromatogr A 2019; 1585:46-55. [DOI: 10.1016/j.chroma.2018.11.067] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 11/21/2018] [Accepted: 11/24/2018] [Indexed: 11/16/2022]
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13
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Blocking electrochemical collisions of single E. coli and B. subtilis bacteria at ultramicroelectrodes elucidated using simultaneous fluorescence microscopy. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.05.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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14
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Alizadeh N, Hallaj R, Salimi A. Dual Amplified Electrochemical Immunosensor for Hepatitis B Virus Surface Antigen Detection Using Hemin/G-Quadruplex Immobilized onto Fe3
O4
-AuNPs or (Hemin-Amino-rGO-Au) Nanohybrid. ELECTROANAL 2017. [DOI: 10.1002/elan.201700727] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Negar Alizadeh
- Department of Chemistry; University of Kurdistan; 66177-15175 Sanandaj- Iran
| | - Rahman Hallaj
- Department of Chemistry; University of Kurdistan; 66177-15175 Sanandaj- Iran
- Research Center for Nanotechnology; University of Kurdistan; 66177-15175 Sanandaj- Iran
| | - Abdollah Salimi
- Department of Chemistry; University of Kurdistan; 66177-15175 Sanandaj- Iran
- Research Center for Nanotechnology; University of Kurdistan; 66177-15175 Sanandaj- Iran
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15
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Rosenthal K, Oehling V, Dusny C, Schmid A. Beyond the bulk: disclosing the life of single microbial cells. FEMS Microbiol Rev 2017; 41:751-780. [PMID: 29029257 PMCID: PMC5812503 DOI: 10.1093/femsre/fux044] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 09/08/2017] [Indexed: 01/08/2023] Open
Abstract
Microbial single cell analysis has led to discoveries that are beyond what can be resolved with population-based studies. It provides a pristine view of the mechanisms that organize cellular physiology, unbiased by population heterogeneity or uncontrollable environmental impacts. A holistic description of cellular functions at the single cell level requires analytical concepts beyond the miniaturization of existing technologies, defined but uncontrolled by the biological system itself. This review provides an overview of the latest advances in single cell technologies and demonstrates their potential. Opportunities and limitations of single cell microbiology are discussed using selected application-related examples.
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Affiliation(s)
- Katrin Rosenthal
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
- Laboratory of Chemical Biotechnology, Department of Biochemical & Chemical Engineering, TU Dortmund University, Dortmund, Germany
| | - Verena Oehling
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
- Laboratory of Chemical Biotechnology, Department of Biochemical & Chemical Engineering, TU Dortmund University, Dortmund, Germany
| | - Christian Dusny
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
| | - Andreas Schmid
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
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16
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Stratz S, Verboket PE, Hasler K, Dittrich PS. Cultivation and quantitative single-cell analysis of Saccharomyces cerevisiae on a multifunctional microfluidic device. Electrophoresis 2017; 39:540-547. [PMID: 28880404 DOI: 10.1002/elps.201700253] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/29/2017] [Accepted: 08/29/2017] [Indexed: 11/06/2022]
Abstract
Here, we present a multifunctional microfluidic device whose integrative design enables to combine cell culture studies and quantitative single cell biomolecule analysis. The platform consists of 32 analysis units providing two key features; first, a micrometer-sized trap for hydrodynamic capture of a single Saccharomyces cerevisiae (S. cerevisiae) yeast cell; second, a convenient double-valve configuration surrounding the trap. Actuating of the outer valve with integrated opening results in a partial isolation in a volume of 11.8 nL, i.e. the cell surrounding fluid can be exchanged diffusion-based without causing shear stress or cell loss. Actuation of the inner ring-shaped valve isolates the trapped cell completely in a small analysis volume of 230 pL. The device was used to determine the growth rate of yeast cells (S. cerevisiae) under under optimum and oxidative stress conditions. In addition, we successfully quantified the cofactor beta-nicotinamide adenine dinucleotide phosphate (NAD(P)H) in single and few cells exposed to the different microenvironments. In conclusion, the microdevice enables to analyze the influence of an external stress factor on the cellular fitness in a fast and more comprehensive way as cell growth and intracellular biomolecule levels can be investigated.
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Affiliation(s)
- Simone Stratz
- ETH Zurich, Department of Chemistry and Applied Biosciences, Zurich, Switzerland.,ETH Zurich, Department of Biosystems Science and Engineering, Basel, Switzerland
| | - Pascal Emilio Verboket
- ETH Zurich, Department of Chemistry and Applied Biosciences, Zurich, Switzerland.,ETH Zurich, Department of Biosystems Science and Engineering, Basel, Switzerland
| | - Karina Hasler
- ETH Zurich, Department of Chemistry and Applied Biosciences, Zurich, Switzerland
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17
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Armbrecht L, Gabernet G, Kurth F, Hiss JA, Schneider G, Dittrich PS. Characterisation of anticancer peptides at the single-cell level. LAB ON A CHIP 2017; 17:2933-2940. [PMID: 28736788 PMCID: PMC6440648 DOI: 10.1039/c7lc00505a] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The development of efficacious anticancer therapeutics is difficult due to the heterogeneity of the cellular response to chemotherapy. Anticancer peptides (ACPs) are promising drug candidates that have been shown to be active against a range of cancer cells. However, few ACP studies focus on tumour single-cell heterogeneities. In order to address this need, we developed a microfluidic device and an imaging procedure that enable the capture, monitoring, and analysis of several hundred single cells for the study of drug response. MCF-7 human breast adenocarcinoma cells were captured in hydrodynamic traps and isolated in individual microchambers of less than 100 pL volume. With pneumatic valves, different sets of microchambers were actuated to expose the cells to various drugs. Here, the effect of three membranolytic ACPs - melittin, aurein 1.2 and aurein 2.2 - was investigated by monitoring the efflux of calcein from single MCF-7 cells. The loss of membrane integrity was observed with two different strategies that allow either focusing on one cell for mechanistic studies or parallel analysis of hundreds of individual cells. In general, the device is applicable to the analysis of the effect of various drugs on a large number of different cell types. The platform will enable us in the future to determine the origin of heterogeneous responses on pharmacological substances like ACPs within cell populations by combining it with other on-chip analytical methods.
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Affiliation(s)
- L Armbrecht
- Department of Biosystems Science and Engineering, ETH Zurich, Switzerland.
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18
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Affiliation(s)
- Lucas Armbrecht
- Department of Biosystems Science and Engineering, ETH Zurich, CH-8093 Zurich, Switzerland
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19
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Stratz S, Dittrich PS. A Microfluidic Device for Immunoassay-Based Protein Analysis of Single E. coli Bacteria. Methods Mol Biol 2016; 1346:11-25. [PMID: 26542712 DOI: 10.1007/978-1-4939-2987-0_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
We present a method suitable for quantitative analysis of intracellular proteins, metabolites and secondary messengers of single bacterial cells. The method integrates the concept of immunoassays on a microfluidic device that facilitates single cell trapping and isolating in a small volume of a few tens of picoliters. Combination of the benefits of microfluidic systems for single cell analysis with the high analytical selectivity and sensitivity of immunoassays enables the detection of even low abundant intracellular analytes which occur only at a few hundred copies per bacterium.
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Affiliation(s)
- Simone Stratz
- Department of Biosystems Science and Engineering, ETH Zurich, Vladimir-Prelog-Weg 3, Zurich, 8091, Switzerland
| | - Petra S Dittrich
- Department of Biosystems Science and Engineering, ETH Zurich, Vladimir-Prelog-Weg 3, Zurich, 8091, Switzerland.
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20
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Yang M, Nelson R, Ros A. Toward Analysis of Proteins in Single Cells: A Quantitative Approach Employing Isobaric Tags with MALDI Mass Spectrometry Realized with a Microfluidic Platform. Anal Chem 2016; 88:6672-9. [PMID: 27257853 DOI: 10.1021/acs.analchem.5b03419] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Protein identification and quantification in individual cells is essential to understand biological processes such as those involved in cell apoptosis, cancer, biomarker discovery, disease diagnostics, pathology, or therapy. Compared with present single cell genome analysis, probing the protein content of single cells has been hampered by the lack of a protein amplification technique. Here, we report the development of a quantitative mass spectrometric approach combined with microfluidic technology reaching the detection sensitivity of high abundant proteins in single cells. A microfluidic platform with a series of chambers and valves, ensuring a set of defined wells for absolute quantification of targeted proteins, was developed and combined with isotopic labeling strategies employing isobaric tags for relative and absolute quantitation (iTRAQ)-labels. To this aim, we adapted iTRAQ labeling to an on-chip protocol. Simultaneous protein digestion and labeling performed on the microfluidic platform rendered the labeling strategy compatible with all necessary manipulation steps on-chip, including the matrix delivery for MALDI-TOF analysis. We demonstrate this approach with the apoptosis related protein Bcl-2 and quantitatively assess the number of Bcl-2 molecules detected. We anticipate that this approach will eventually allow quantification of protein expression on the single cell level.
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Affiliation(s)
- Mian Yang
- School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.,Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States
| | - Randall Nelson
- Molecular Biomarkers Laboratory, The Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States
| | - Alexandra Ros
- School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.,Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University , Tempe, Arizona 85287, United States
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21
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Krone KM, Warias R, Ritter C, Li A, Acevedo-Rocha CG, Reetz MT, Belder D. Analysis of Enantioselective Biotransformations Using a Few Hundred Cells on an Integrated Microfluidic Chip. J Am Chem Soc 2016; 138:2102-5. [DOI: 10.1021/jacs.5b12443] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Karin M. Krone
- Institute
of Analytical Chemistry, University of Leipzig, Linnéstrasse 3, 04103 Leipzig, Germany
| | - Rico Warias
- Institute
of Analytical Chemistry, University of Leipzig, Linnéstrasse 3, 04103 Leipzig, Germany
| | - Cornelia Ritter
- Faculty
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Aitao Li
- Faculty
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim/Ruhr, Germany
| | - Carlos G. Acevedo-Rocha
- Faculty
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim/Ruhr, Germany
| | - Manfred T. Reetz
- Faculty
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim/Ruhr, Germany
| | - Detlev Belder
- Institute
of Analytical Chemistry, University of Leipzig, Linnéstrasse 3, 04103 Leipzig, Germany
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22
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Abstract
The combination of microbial engineering and microfluidics is synergistic in nature. For example, microfluidics is benefiting from the outcome of microbial engineering and many reported point-of-care microfluidic devices employ engineered microbes as functional parts for the microsystems. In addition, microbial engineering is facilitated by various microfluidic techniques, due to their inherent strength in high-throughput screening and miniaturization. In this review article, we firstly examine the applications of engineered microbes for toxicity detection, biosensing, and motion generation in microfluidic platforms. Secondly, we look into how microfluidic technologies facilitate the upstream and downstream processes of microbial engineering, including DNA recombination, transformation, target microbe selection, mutant characterization, and microbial function analysis. Thirdly, we highlight an emerging concept in microbial engineering, namely, microbial consortium engineering, where the behavior of a multicultural microbial community rather than that of a single cell/species is delineated. Integrating the disciplines of microfluidics and microbial engineering opens up many new opportunities, for example in diagnostics, engineering of microbial motors, development of portable devices for genetics, high throughput characterization of genetic mutants, isolation and identification of rare/unculturable microbial species, single-cell analysis with high spatio-temporal resolution, and exploration of natural microbial communities.
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Affiliation(s)
- Songzi Kou
- Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
| | - Danhui Cheng
- Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Fei Sun
- Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
| | - I-Ming Hsing
- Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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23
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Hümmer D, Kurth F, Naredi-Rainer N, Dittrich PS. Single cells in confined volumes: microchambers and microdroplets. LAB ON A CHIP 2016; 16:447-58. [PMID: 26758781 DOI: 10.1039/c5lc01314c] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Microfluidic devices capable of manipulating and guiding small fluid volumes open new methodical approaches in the fields of biology, pharmacy, and medicine. They have already proven their extraordinary value for cell analysis. The emergence of microfluidic platforms has paved the way to novel analytical strategies for the positioning, treatment and observation of living cells, for the creation of chemically defined liquid environments, and for tailoring biomechanical or physical conditions in small volumes. In this article, we particularly focus on two complementary approaches: (i) the isolation of cells in small chambers defined by microchannels and integrated valves and (ii) the encapsulation of cells in microdroplets. We review the advantages and limitations of both approaches and discuss their potential for single-cell analysis and related fields. Our intention is also to give a recommendation on which platform is most appropriate for a new question, i.e., a guideline to choose the most suitable platform.
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Affiliation(s)
- D Hümmer
- ETH Zurich - Department of Biosystems Science Engineering, Vladimir-Prelog-Weg 3, CH-8093 Zürich, Switzerland.
| | - F Kurth
- ETH Zurich - Department of Biosystems Science Engineering, Vladimir-Prelog-Weg 3, CH-8093 Zürich, Switzerland.
| | - N Naredi-Rainer
- ETH Zurich - Department of Biosystems Science Engineering, Vladimir-Prelog-Weg 3, CH-8093 Zürich, Switzerland.
| | - P S Dittrich
- ETH Zurich - Department of Biosystems Science Engineering, Vladimir-Prelog-Weg 3, CH-8093 Zürich, Switzerland.
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24
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Konopińska K, Pietrzak M, Mazur R, Malinowska E. Analytical characterization of IgG–cTpp and IgG–Mn-cTpp conjugates. J PORPHYR PHTHALOCYA 2016. [DOI: 10.1142/s1088424615500984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Herein, the conjugation of carboxylated tetraphenylporphyrin or its derivative containing manganese cation and model protein — immunoglobulin G is presented. The obtained IgG–cTpp and IgG–Mn-cTpp conjugates were subsequently used for model immunoassays construction. The IgG–cTpp formation was confirmed using size-exclusion chromatography. Thanks to the unique properties of applied labels the assay analysis was carried out with both spectrophotometric and spectrofluorimetric detection. The assays were performed creating semi-quantitative detection system using 96-well plates. The incubation time, ensuring full saturation of the surface with secondary antibodies was also optimized. Moreover, in the case of IgG–Mn-cTpp conjugates we present the possibility of both direct and indirect determination of the label, the latter based on the catalytic activity of Mn-cTpp, which allows for amplification of the measured signal. We proved that both cTpp and Mn-cTpp may be successfully used for protein labeling and serve as universal tracers for various formats of affinity assays and sensors.
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Affiliation(s)
- Kamila Konopińska
- Department of Microbioanalytics, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Mariusz Pietrzak
- Department of Microbioanalytics, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Radosław Mazur
- Department of Metabolic Regulation, Institute of Biochemistry, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Elżbieta Malinowska
- Department of Microbioanalytics, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
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25
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26
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Phenotypic Heterogeneity, a Phenomenon That May Explain Why Quorum Sensing Does Not Always Result in Truly Homogenous Cell Behavior. Appl Environ Microbiol 2015. [PMID: 26025903 DOI: 10.1128/aem.00900-15/format/epub] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023] Open
Abstract
Phenotypic heterogeneity describes the occurrence of "nonconformist" cells within an isogenic population. The nonconformists show an expression profile partially different from that of the remainder of the population. Phenotypic heterogeneity affects many aspects of the different bacterial lifestyles, and it is assumed that it increases bacterial fitness and the chances for survival of the whole population or smaller subpopulations in unfavorable environments. Well-known examples for phenotypic heterogeneity have been associated with antibiotic resistance and frequently occurring persister cells. Other examples include heterogeneous behavior within biofilms, DNA uptake and bacterial competence, motility (i.e., the synthesis of additional flagella), onset of spore formation, lysis of phages within a small subpopulation, and others. Interestingly, phenotypic heterogeneity was recently also observed with respect to quorum-sensing (QS)-dependent processes, and the expression of autoinducer (AI) synthase genes and other QS-dependent genes was found to be highly heterogeneous at a single-cell level. This phenomenon was observed in several Gram-negative bacteria affiliated with the genera Vibrio, Dinoroseobacter, Pseudomonas, Sinorhizobium, and Mesorhizobium. A similar observation was made for the Gram-positive bacterium Listeria monocytogenes. Since AI molecules have historically been thought to be the keys to homogeneous behavior within isogenic populations, the observation of heterogeneous expression is quite intriguing and adds a new level of complexity to the QS-dependent regulatory networks. All together, the many examples of phenotypic heterogeneity imply that we may have to partially revise the concept of homogeneous and coordinated gene expression in isogenic bacterial populations.
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27
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Lin Y, Zhou Q, Lin Y, Tang D, Niessner R, Knopp D. Enzymatic Hydrolysate-Induced Displacement Reaction with Multifunctional Silica Beads Doped with Horseradish Peroxidase–Thionine Conjugate for Ultrasensitive Electrochemical Immunoassay. Anal Chem 2015; 87:8531-40. [DOI: 10.1021/acs.analchem.5b02253] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Youxiu Lin
- Key
Laboratory of Analysis and Detection for Food Safety (Ministry of
Education and Fujian Province), Institute of Nanomedicine and Nanobiosensing,
Department of Chemistry, Fuzhou University, Fuzhou 350108, People’s Republic of China
| | - Qian Zhou
- Key
Laboratory of Analysis and Detection for Food Safety (Ministry of
Education and Fujian Province), Institute of Nanomedicine and Nanobiosensing,
Department of Chemistry, Fuzhou University, Fuzhou 350108, People’s Republic of China
| | - Yuping Lin
- Key
Laboratory of Analysis and Detection for Food Safety (Ministry of
Education and Fujian Province), Institute of Nanomedicine and Nanobiosensing,
Department of Chemistry, Fuzhou University, Fuzhou 350108, People’s Republic of China
| | - Dianping Tang
- Key
Laboratory of Analysis and Detection for Food Safety (Ministry of
Education and Fujian Province), Institute of Nanomedicine and Nanobiosensing,
Department of Chemistry, Fuzhou University, Fuzhou 350108, People’s Republic of China
| | - Reinhard Niessner
- Chair
for Analytical Chemistry, Institute of Hydrochemistry, Technische Universität München, Marchioninistrasse 17, D-81377 München, Germany
| | - Dietmar Knopp
- Chair
for Analytical Chemistry, Institute of Hydrochemistry, Technische Universität München, Marchioninistrasse 17, D-81377 München, Germany
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28
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Dittrich P, Ibáñez AJ. Analysis of metabolites in single cells-what is the best micro-platform? Electrophoresis 2015; 36:2196-2206. [PMID: 25929796 DOI: 10.1002/elps.201500045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 04/04/2015] [Accepted: 04/04/2015] [Indexed: 11/11/2022]
Abstract
This review covers new innovations and developments in the field of single-cell level analysis of metabolites, involving the role of microfluidic and microarray platforms to manipulate and handle the cells prior their detection. Microfluidic and microarray platforms have shown great promise. The latest developments demonstrate their potential to identify a particular cell or even an ensemble of cells (sharing a common property or phenotype) that co-exist in a much larger cell population. The reason for this is the capability of these platforms to perform several complex analytical processes, such as: cleanup, sorting, derivatization, separation, and detection, with great robustness, speed, and reduced sample/reagent consumption. Here, we present several examples that illustrate the rapid strides that have been made for the routine analysis of metabolites by coupling different microfluidics and microarrays devices to a wide range of analytical detectors (e.g. fluorescent microscopy, electrochemical, and mass spectrometry). Herein, we also present selected examples detailing the use of microfluidics and microarrays in the visualization of the natural occurring cell-to-cell heterogeneity in isogenic populations, in particular during the response to external cues. The possibility to accurate monitor the cell-to-cell heterogeneity based on different levels of key metabolites is of clinical relevance, since cell-to-cell heterogeneity can influence, for example, the outcome of a drug treatment.
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Affiliation(s)
- Petra Dittrich
- ETH Zurich - Chemie und Angewandte Biowissenschaften, Wolfgang-Pauli-Str. 10, Zurich, 8093, Switzerland
| | - Alfredo J Ibáñez
- ETH Zurich - Department of Chemistry and Applied Biosciences, Vladimir-Prelog-weg 3, Zurich, 8093, Switzerland
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29
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Phenotypic Heterogeneity, a Phenomenon That May Explain Why Quorum Sensing Does Not Always Result in Truly Homogenous Cell Behavior. Appl Environ Microbiol 2015; 81:5280-9. [PMID: 26025903 DOI: 10.1128/aem.00900-15] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Phenotypic heterogeneity describes the occurrence of "nonconformist" cells within an isogenic population. The nonconformists show an expression profile partially different from that of the remainder of the population. Phenotypic heterogeneity affects many aspects of the different bacterial lifestyles, and it is assumed that it increases bacterial fitness and the chances for survival of the whole population or smaller subpopulations in unfavorable environments. Well-known examples for phenotypic heterogeneity have been associated with antibiotic resistance and frequently occurring persister cells. Other examples include heterogeneous behavior within biofilms, DNA uptake and bacterial competence, motility (i.e., the synthesis of additional flagella), onset of spore formation, lysis of phages within a small subpopulation, and others. Interestingly, phenotypic heterogeneity was recently also observed with respect to quorum-sensing (QS)-dependent processes, and the expression of autoinducer (AI) synthase genes and other QS-dependent genes was found to be highly heterogeneous at a single-cell level. This phenomenon was observed in several Gram-negative bacteria affiliated with the genera Vibrio, Dinoroseobacter, Pseudomonas, Sinorhizobium, and Mesorhizobium. A similar observation was made for the Gram-positive bacterium Listeria monocytogenes. Since AI molecules have historically been thought to be the keys to homogeneous behavior within isogenic populations, the observation of heterogeneous expression is quite intriguing and adds a new level of complexity to the QS-dependent regulatory networks. All together, the many examples of phenotypic heterogeneity imply that we may have to partially revise the concept of homogeneous and coordinated gene expression in isogenic bacterial populations.
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