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Zhang T, Di Carlo D, Lim CT, Zhou T, Tian G, Tang T, Shen AQ, Li W, Li M, Yang Y, Goda K, Yan R, Lei C, Hosokawa Y, Yalikun Y. Passive microfluidic devices for cell separation. Biotechnol Adv 2024; 71:108317. [PMID: 38220118 DOI: 10.1016/j.biotechadv.2024.108317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/27/2023] [Accepted: 01/06/2024] [Indexed: 01/16/2024]
Abstract
The separation of specific cell populations is instrumental in gaining insights into cellular processes, elucidating disease mechanisms, and advancing applications in tissue engineering, regenerative medicine, diagnostics, and cell therapies. Microfluidic methods for cell separation have propelled the field forward, benefitting from miniaturization, advanced fabrication technologies, a profound understanding of fluid dynamics governing particle separation mechanisms, and a surge in interdisciplinary investigations focused on diverse applications. Cell separation methodologies can be categorized according to their underlying separation mechanisms. Passive microfluidic separation systems rely on channel structures and fluidic rheology, obviating the necessity for external force fields to facilitate label-free cell separation. These passive approaches offer a compelling combination of cost-effectiveness and scalability when compared to active methods that depend on external fields to manipulate cells. This review delves into the extensive utilization of passive microfluidic techniques for cell separation, encompassing various strategies such as filtration, sedimentation, adhesion-based techniques, pinched flow fractionation (PFF), deterministic lateral displacement (DLD), inertial microfluidics, hydrophoresis, viscoelastic microfluidics, and hybrid microfluidics. Besides, the review provides an in-depth discussion concerning cell types, separation markers, and the commercialization of these technologies. Subsequently, it outlines the current challenges faced in the field and presents a forward-looking perspective on potential future developments. This work hopes to aid in facilitating the dissemination of knowledge in cell separation, guiding future research, and informing practical applications across diverse scientific disciplines.
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Affiliation(s)
- Tianlong Zhang
- College of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China
| | - Dino Di Carlo
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA
| | - Chwee Teck Lim
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Tianyuan Zhou
- College of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China
| | - Guizhong Tian
- College of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China.
| | - Tao Tang
- Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Amy Q Shen
- Micro/Bio/Nanofluidics Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan
| | - Weihua Li
- School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Ming Li
- School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Yang Yang
- Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya, Hainan 572000, China
| | - Keisuke Goda
- Department of Bioengineering, University of California, Los Angeles, CA 90095, USA; Department of Chemistry, University of Tokyo, Tokyo 113-0033, Japan; The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Ruopeng Yan
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Cheng Lei
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Yoichiroh Hosokawa
- Division of Materials Science, Nara Institute of Science and Technology, Nara 630-0192, Japan
| | - Yaxiaer Yalikun
- Division of Materials Science, Nara Institute of Science and Technology, Nara 630-0192, Japan.
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Ozunlu S, Akdogan NG, Bozkurt MN, Doganturk L, Alshammari HA, Le Roy D, Akdogan O. Innovative technique for patterning Nd-Fe-B arrays and development of a microfluidic device with high trapping efficiency. NANOTECHNOLOGY 2021; 32:495501. [PMID: 34399411 DOI: 10.1088/1361-6528/ac1dd6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/16/2021] [Indexed: 06/13/2023]
Abstract
Trapping/separating bio-entities via magnetic field gradients created a vast number of possibilities to develop biosensors for the early detection of diseases without the need for expensive equipment or physician/lab technicians. Thus, opening a window for at-home disposable rapid test kits. In the scope of the current work, an innovative and cost-effective technique to form well-organized arrays of Nd-Fe-B patterns was successfully developed. High aspect ratio Nd-Fe-B flakes were synthesized by surfactant-assisted ball milling technique. Nd-Fe-B flakes were distributed and patterned into a PDMS matrix by the aforementioned technique. A microfluidic channel was integrated on the fabricated Nd-Fe-B/PDMS patch with a high magnetic field gradient to form a microfluidic device. Fe nanoparticles, suspended in hexane, were flowed through the microfluidic channel, and trapping of the magnetic nanoparticles was observed. More experiments would be needed to quantitatively study efficiency. Ergo, the microfluidic device with high trapping efficiency was developed. The established technique has the potential to outperform the precedents in trapping efficiency, cost, and ease of production. The developed device could be integrated into disposable test kits for the early detection of various diseases.
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Affiliation(s)
- S Ozunlu
- Faculty of Engineering and Natural Sciences, Bahçeşehir University, Istanbul, Turkey
| | - N G Akdogan
- Faculty of Engineering, Piri Reis University, Istanbul, Turkey
| | - M N Bozkurt
- Faculty of Engineering and Natural Sciences, Bahçeşehir University, Istanbul, Turkey
| | - L Doganturk
- Faculty of Engineering and Natural Sciences, Bahçeşehir University, Istanbul, Turkey
| | - H A Alshammari
- Faculty of Engineering and Natural Sciences, Bahçeşehir University, Istanbul, Turkey
| | - D Le Roy
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, Campus LyonTech - La Doua, F-69622, Lyon, France
| | - O Akdogan
- Faculty of Engineering and Natural Sciences, Bahçeşehir University, Istanbul, Turkey
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3
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Menon V, Thomas R, Ghale AR, Reinhard C, Pruszak J. Flow cytometry protocols for surface and intracellular antigen analyses of neural cell types. J Vis Exp 2014:52241. [PMID: 25549236 PMCID: PMC4396953 DOI: 10.3791/52241] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Flow cytometry has been extensively used to define cell populations in immunology, hematology and oncology. Here, we provide a detailed description of protocols for flow cytometric analysis of the cluster of differentiation (CD) surface antigens and intracellular antigens in neural cell types. Our step-by-step description of the methodological procedures include: the harvesting of neural in vitro cultures, an optional carboxyfluorescein succinimidyl ester (CFSE)-labeling step, followed by surface antigen staining with conjugated CD antibodies (e.g., CD24, CD54), and subsequent intracellar antigen detection via primary/secondary antibodies or fluorescently labeled Fab fragments (Zenon labeling). The video demonstrates the most critical steps. Moreover, principles of experimental planning, the inclusion of critical controls, and fundamentals of flow cytometric analysis (identification of target population and exclusion of debris; gating strategy; compensation for spectral overlap) are briefly explained in order to enable neurobiologists with limited prior knowledge or specific training in flow cytometry to assess its utility and to better exploit this powerful methodology.
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Affiliation(s)
- Vishal Menon
- Emmy Noether-Group for Stem Cell Biology, Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg
| | - Ria Thomas
- Emmy Noether-Group for Stem Cell Biology, Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg; Spemann Graduate School of Biology and Medicine and Faculty of Biology, University of Freiburg
| | - Arun R Ghale
- Emmy Noether-Group for Stem Cell Biology, Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg; School of Life Sciences, Keele University
| | - Christina Reinhard
- Emmy Noether-Group for Stem Cell Biology, Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg
| | - Jan Pruszak
- Emmy Noether-Group for Stem Cell Biology, Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg; Center for Biological Signaling Studies (BIOSS), University of Freiburg;
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Abstract
Terminal dUTP nick end labeling (TUNEL) is an invaluable technique used in the study of late-stage apoptosis. The technique is based upon detection of fragmented DNA, a well-recognized characteristic of apoptosis, usually with fluorescent markers. Here, we describe the TUNEL technique (1) employing two different detection techniques, fluorescence microscopy and fluorescence-activated cell sorting (2) which can be applied to the analysis of apoptosis in retinal tissues or retinal cell cultures, respectively.
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Klim JR, Fowler AJ, Courtney AH, Wrighton PJ, Sheridan RTC, Wong ML, Kiessling LL. Small-molecule-modified surfaces engage cells through the αvβ3 integrin. ACS Chem Biol 2012; 7:518-25. [PMID: 22201290 DOI: 10.1021/cb2004725] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Integrins play myriad and vital roles in development and disease. They connect a cell with its surroundings and transmit chemical and mechanical signals across the plasma membrane to the cell's interior. Dissecting their roles in cell behavior is complicated by their overlapping ligand specificity and shared downstream signaling components. In principle, immobilized synthetic peptides can mimic extracellular matrix proteins by supporting integrin-mediated adhesion, but most short peptide sequences lack selectivity for one integrin over others. In contrast, synthetic integrin antagonists can be highly selective. We hypothesized that this selectivity could be exploited if antagonists, when immobilized, could support cellular adhesion and activate signaling by engaging specific cell-surface integrins. To investigate this possibility, we designed a bifunctional (RGD)-based peptidomimetic for surface presentation. Our conjugate combines a high affinity integrin ligand with a biotin moiety; the former engages the α(v)β(3) integrin, and the latter allows for presentation on streptavidin-coated surfaces. Surfaces decorated with this ligand promote both cellular adhesion and integrin activation. Moreover, the selectivity of these surfaces for the α(v)β(3) integrin can be exploited to capture a subset of cells from a mixed population. We anticipate that surfaces displaying highly selective small molecule ligands can reveal the contributions of specific integrin heterodimers to cell adhesion and signaling.
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Affiliation(s)
- Joseph R. Klim
- Cell
and Molecular Biology Program, ‡Department of Chemistry, and §Department of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Anthony J. Fowler
- Cell
and Molecular Biology Program, ‡Department of Chemistry, and §Department of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Adam H. Courtney
- Cell
and Molecular Biology Program, ‡Department of Chemistry, and §Department of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Paul J. Wrighton
- Cell
and Molecular Biology Program, ‡Department of Chemistry, and §Department of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Rachael T. C. Sheridan
- Cell
and Molecular Biology Program, ‡Department of Chemistry, and §Department of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Margaret L. Wong
- Cell
and Molecular Biology Program, ‡Department of Chemistry, and §Department of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Laura L. Kiessling
- Cell
and Molecular Biology Program, ‡Department of Chemistry, and §Department of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
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Miller MR, Robinson KJ, Cleary MD, Doe CQ. TU-tagging: cell type-specific RNA isolation from intact complex tissues. Nat Methods 2009; 6:439-41. [PMID: 19430475 PMCID: PMC2783170 DOI: 10.1038/nmeth.1329] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 04/10/2009] [Indexed: 11/09/2022]
Abstract
We show that the combination of spatially restricted uracil phosphoribosyltransferase (UPRT) expression with 4-thiouracil (4TU) delivery can be used to label and purify cell type specific RNA from intact complex tissues in Drosophila melanogaster. This method is useful for isolating RNA from cell types that are difficult to isolate by dissection or dissociation methods and should work in many organisms, including mammals and other vertebrates.
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Affiliation(s)
- Michael R Miller
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, Oregon, USA
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7
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Kamihira M, Kumar A. Development of separation technique for stem cells. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2007; 106:173-193. [PMID: 17924081 DOI: 10.1007/10_2006_043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In recent years, human embryonic stem cells have been established, and somatic stem cells derived from various adult organs have been identified and characterized to differentiate into various kinds of functional cells. There have been attempts to use functional cells induced from such stem cells for tissue regeneration and cell therapy. The method is expected to become an important treatment for intractable diseases in the near future. Since tissues and organs generally contain only a small quantity of somatic stem cells, and since it is necessary to separate functional cells generated from stem cells for use in therapy, an effective method for specific cell separation is crucial to the practical application of regenerative medicine. For the specific separation of cells, a fluorescence activated cell sorter using specific antibodies is a powerful tool, but the method is not suitable for large-scale processing and a special device is required. Although a magnetic cell separation system using immuno-magnetic fine particles is also commercially available, the system still needs special apparatus for large-scale processing. We developed a novel method for the separation of specific cells in an aqueous two-phase system using antibodies modified with a temperature-responsive polymer. The method enables the processing of a large quantity of cells without the requirement of a special device.
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Affiliation(s)
- Masamichi Kamihira
- Department of Chemical Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Japan.
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Aldaeus F, Lin Y, Amberg G, Roeraade J. Multi-step dielectrophoresis for separation of particles. J Chromatogr A 2006; 1131:261-6. [PMID: 16884731 DOI: 10.1016/j.chroma.2006.07.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Revised: 06/28/2006] [Accepted: 07/10/2006] [Indexed: 11/24/2022]
Abstract
A new concept for separation of particles based on repetitive dielectrophoretic trapping and release in a flow system is proposed. Calculations using the finite element method have been performed to envision the particle behavior and the separation effectiveness of the proposed method. As a model system, polystyrene beads in deionized water and a micro-flow channel with arrays of interdigited electrodes have been used. Results show that the resolution increases as a direct function of the number of trap-and-release steps, and that a difference in size will have a larger influence on the separation than a difference in other dielectrophoretic properties. About 200 trap-and-release steps would be required to separate particles with a size difference of 0.2%. The enhanced separation power of dielectrophoresis with multiple steps could be of great importance, not only for fractionation of particles with small differences in size, but also for measuring changes in surface conductivity, or for separations based on combinations of difference in size and dielectric properties.
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Affiliation(s)
- Fredrik Aldaeus
- Royal Institute of Technology, KTH, School of Chemical Science and Engineering, Analytical chemistry, SE-100 44 Stockholm, Sweden
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9
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Lien S, Szyda J, Leeflang EP, Hubert R, Zhang L, Schmitt K, Arnheim N. Single‐Sperm Typing. ACTA ACUST UNITED AC 2002; Chapter 1:Unit 1.6. [DOI: 10.1002/0471142905.hg0106s32] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | | | - Rene Hubert
- University of Southern California Los Angeles California
| | - Lin Zhang
- University of Southern California Los Angeles California
| | - Karin Schmitt
- University of Southern California Los Angeles California
| | - Norman Arnheim
- University of Southern California Los Angeles California
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10
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Boeck G. Current status of flow cytometry in cell and molecular biology. INTERNATIONAL REVIEW OF CYTOLOGY 2001; 204:239-98. [PMID: 11243596 DOI: 10.1016/s0074-7696(01)04006-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This review summarizes recent developments in flow cytometry (FC). It gives an overview of techniques currently available, in terms of apparatus and sample handling, a guide to evaluating applications, an overview of dyes and staining methods, an introduction to internet resources, and a broad listing of classic references and reviews in various fields of interest, as well as some recent interesting articles.
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Affiliation(s)
- G Boeck
- Institute for General and Experimental Pathology, University Innsbruck, Medical School, Austria
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11
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Fluorescence-Based Selection of Gene-Corrected Hematopoietic Stem and Progenitor Cells From Acid Sphingomyelinase-Deficient Mice: Implications for Niemann-Pick Disease Gene Therapy and the Development of Improved Stem Cell Gene Transfer Procedures. Blood 1999. [DOI: 10.1182/blood.v93.1.80.401k28_80_86] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The general utility of a novel, fluorescence-based procedure for assessing gene transfer and expression has been demonstrated using hematopoietic stem and progenitor cells. Lineage-depleted hematopoietic cells were isolated from the bone marrow or fetal livers of acid sphingomyelinase–deficient mice, and retrovirally transduced with amphotropic or ecotropic vectors encoding a normal acid sphingomyelinase (ASM) cDNA. Anti–c-Kit antibodies were then used to label stem- and progenitor-enriched cell populations, and the Bodipy fluorescence was analyzed in each group after incubation with a Bodipy-conjugated sphingomyelin. Only cells expressing the functional ASM (ie, transduced) could degrade the sphingomyelin, thereby reducing their Bodipy fluorescence as compared with nontransduced cells. The usefulness of this procedure for the in vitro assessment of gene transfer into hematopoietic stem cells was evaluated, as well as its ability to provide an enrichment of transduced stem cells in vivo. To show the value of this method for in vitro analysis, the effects of retroviral transduction using ecotropic versus amphotropic vectors, various growth factor combinations, and adult bone marrow versus fetal liver stem cells were assessed. The results of these studies confirmed the fact that ecotropic vectors were much more efficient at transducing murine stem cells than amphotropic vectors, and that among the three most commonly used growth factors (stem cell factor [SCF] and interleukins 3 and 6 [IL-3 and IL-6]), SCF had the most significant effect on the transduction of stem cells, whereas IL-6 had the most significant effect on progenitor cells. In addition, it was determined that fetal liver stem cells were only approximately twofold more “transducible” than stem cells from adult bone marrow. Transplantation of Bodipy-selected bone marrow cells into lethally irradiated mice showed that the number of spleen colony-forming units that were positive for the retroviral vector (as determined by polymerase chain reaction) was 76%, as compared with 32% in animals that were transplanted with cells that were nonselected. The methods described within this manuscript are particularly useful for evaluating hematopoietic stem cell gene transfer in vivo because the marker gene used in the procedure (ASM) encodes a naturally occurring mammalian enzyme that has no known adverse effects, and the fluorescent compound used for selection (Bodipy sphingomyelin) is removed from the cells before transplantation.
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12
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Fluorescence-Based Selection of Gene-Corrected Hematopoietic Stem and Progenitor Cells From Acid Sphingomyelinase-Deficient Mice: Implications for Niemann-Pick Disease Gene Therapy and the Development of Improved Stem Cell Gene Transfer Procedures. Blood 1999. [DOI: 10.1182/blood.v93.1.80] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
The general utility of a novel, fluorescence-based procedure for assessing gene transfer and expression has been demonstrated using hematopoietic stem and progenitor cells. Lineage-depleted hematopoietic cells were isolated from the bone marrow or fetal livers of acid sphingomyelinase–deficient mice, and retrovirally transduced with amphotropic or ecotropic vectors encoding a normal acid sphingomyelinase (ASM) cDNA. Anti–c-Kit antibodies were then used to label stem- and progenitor-enriched cell populations, and the Bodipy fluorescence was analyzed in each group after incubation with a Bodipy-conjugated sphingomyelin. Only cells expressing the functional ASM (ie, transduced) could degrade the sphingomyelin, thereby reducing their Bodipy fluorescence as compared with nontransduced cells. The usefulness of this procedure for the in vitro assessment of gene transfer into hematopoietic stem cells was evaluated, as well as its ability to provide an enrichment of transduced stem cells in vivo. To show the value of this method for in vitro analysis, the effects of retroviral transduction using ecotropic versus amphotropic vectors, various growth factor combinations, and adult bone marrow versus fetal liver stem cells were assessed. The results of these studies confirmed the fact that ecotropic vectors were much more efficient at transducing murine stem cells than amphotropic vectors, and that among the three most commonly used growth factors (stem cell factor [SCF] and interleukins 3 and 6 [IL-3 and IL-6]), SCF had the most significant effect on the transduction of stem cells, whereas IL-6 had the most significant effect on progenitor cells. In addition, it was determined that fetal liver stem cells were only approximately twofold more “transducible” than stem cells from adult bone marrow. Transplantation of Bodipy-selected bone marrow cells into lethally irradiated mice showed that the number of spleen colony-forming units that were positive for the retroviral vector (as determined by polymerase chain reaction) was 76%, as compared with 32% in animals that were transplanted with cells that were nonselected. The methods described within this manuscript are particularly useful for evaluating hematopoietic stem cell gene transfer in vivo because the marker gene used in the procedure (ASM) encodes a naturally occurring mammalian enzyme that has no known adverse effects, and the fluorescent compound used for selection (Bodipy sphingomyelin) is removed from the cells before transplantation.
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13
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Lee LG, Woo SL, Head DF, Dubrow RS, Baer TM. Near-IR dyes in three-color volumetric capillary cytometry: cell analysis with 633- and 785-nm laser excitation. CYTOMETRY 1995; 21:120-8. [PMID: 8582231 DOI: 10.1002/cyto.990210203] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Several fluorescent dyes that absorb in the near-infrared are described. The photostability and aggregation properties of the dyes were examined. Two of the dyes, BHMP and BHDMAP, emit at 805 nm and were useful dyes for protein labeling. A dual-laser, three-color scanning instrument was constructed. CD3+CD4+ and CD3+CD8+ populations were enumerated in undiluted, whole blood based on the fluorescence of Cy5, Cy5.5 and BHMP.
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Affiliation(s)
- L G Lee
- Biometric Imaging, Mountain View, CA 94043, USA
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14
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Francisco JA, Georgiou G. The expression of recombinant proteins on the external surface of Escherichia coli. Biotechnological applications. Ann N Y Acad Sci 1994; 745:372-82. [PMID: 7832524 DOI: 10.1111/j.1749-6632.1994.tb44389.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The expression of recombinant proteins on the external surface of Gram-negative bacteria is expected to open the way for a number of significant biotechnological applications, including the development of live bacterial vaccines, the production of whole cell adsorbents, the preparation of whole cell catalysts, and the display and selection of peptide and antibody libraries. We have developed a fusion protein system for the production of active recombinant proteins on the surface of Escherichia coli. Using this system we have expressed beta-lactamase, the Cellulomonas fimi exoglucanase Cex as well as its cellulose binding domain, and an antidigoxin single chain Fv antibody fragment on the cell surface. Recently we have begun to explore some of the potential applications for cell-surface expression.
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Affiliation(s)
- J A Francisco
- Department of Chemical Engineering, University of Texas at Austin 78712
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15
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Francisco JA, Campbell R, Iverson BL, Georgiou G. Production and fluorescence-activated cell sorting of Escherichia coli expressing a functional antibody fragment on the external surface. Proc Natl Acad Sci U S A 1993; 90:10444-8. [PMID: 8248129 PMCID: PMC47793 DOI: 10.1073/pnas.90.22.10444] [Citation(s) in RCA: 158] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We have expressed a single chain Fv (scFv) antibody fragment, consisting of the variable heavy and variable light domains from two separate anti-digoxin monoclonal antibodies, on the external surface of Escherichia coli by fusing it to an Lpp-OmpA hybrid previously shown to direct heterologous proteins to the cell surface. This scFv fusion was expressed at a high level and was shown to bind the hapten with high affinity and specificity. Whole cell ELISAs, fluorescence microscopy, protease sensitivity, and flow cytometry all confirmed that the scFv was anchored on the outer membrane and was accessible on the surface. Utilizing fluorescence-activated cell sorting, we were able to specifically enrich scFv-producing cells from a 10(5)-fold excess of control cells in only two steps. The expression of antibody fragments on the surface of E. coli is being evaluated as an attractive method for the in vitro production and selection of useful antibody fragments.
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Affiliation(s)
- J A Francisco
- Department of Chemical Engineering, University of Texas, Austin 78712
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