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Greipel E, Nagy K, Csákvári E, Dér L, Galajda P, Kutasi J. Chemotactic Interactions of Scenedesmus sp. and Azospirillum brasilense Investigated by Microfluidic Methods. MICROBIAL ECOLOGY 2024; 87:52. [PMID: 38498218 PMCID: PMC10948495 DOI: 10.1007/s00248-024-02366-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 03/08/2024] [Indexed: 03/20/2024]
Abstract
The use of algae for industrial, biotechnological, and agricultural purposes is spreading globally. Scenedesmus species can play an essential role in the food industry and agriculture due to their favorable nutrient content and plant-stimulating properties. Previous research and the development of Scenedesmus-based foliar fertilizers raised several questions about the effectiveness of large-scale algal cultivation and the potential effects of algae on associative rhizobacteria. In the microbiological practice applied in agriculture, bacteria from the genus Azospirillum are one of the most studied plant growth-promoting, associative, nitrogen-fixing bacteria. Co-cultivation with Azospirillum species may be a new way of optimizing Scenedesmus culturing, but the functioning of the co-culture system still needs to be fully understood. It is known that Azospirillum brasilense can produce indole-3-acetic acid, which could stimulate algae growth as a plant hormone. However, the effect of microalgae on Azospirillum bacteria is unclear. In this study, we investigated the behavior of Azospirillum brasilense bacteria in the vicinity of Scenedesmus sp. or its supernatant using a microfluidic device consisting of physically separated but chemically coupled microchambers. Following the spatial distribution of bacteria within the device, we detected a positive chemotactic response toward the microalgae culture. To identify the metabolites responsible for this behavior, we tested the chemoeffector potential of citric acid and oxaloacetic acid, which, according to our HPLC analysis, were present in the algae supernatant in 0.074 mg/ml and 0.116 mg/ml concentrations, respectively. We found that oxaloacetic acid acts as a chemoattractant for Azospirillum brasilense.
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Affiliation(s)
- Erika Greipel
- Albitech Biotechnological Ltd, Berlini Út 47-49, 1045, Budapest, Hungary
- Department of Plant Anatomy, ELTE Eötvös Loránd University, Pázmány Péter Stny 1/C, H-1117, Budapest, Hungary
| | - Krisztina Nagy
- Institute of Biophysics, HUN-REN Biological Research Centre, Szeged, Temesvári Krt. 62, 6726, Szeged, Hungary.
| | - Eszter Csákvári
- Institute of Biophysics, HUN-REN Biological Research Centre, Szeged, Temesvári Krt. 62, 6726, Szeged, Hungary
- Division for Biotechnology, Bay Zoltán Nonprofit Ltd. for Applied Research, Derkovits Fasor 2, 6726, Szeged, Hungary
| | - László Dér
- Institute of Biophysics, HUN-REN Biological Research Centre, Szeged, Temesvári Krt. 62, 6726, Szeged, Hungary
| | - Peter Galajda
- Institute of Biophysics, HUN-REN Biological Research Centre, Szeged, Temesvári Krt. 62, 6726, Szeged, Hungary
| | - József Kutasi
- Albitech Biotechnological Ltd, Berlini Út 47-49, 1045, Budapest, Hungary
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2
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Ly KL, Hu P, Raub CB, Luo X. Programmable Physical Properties of Freestanding Chitosan Membranes Electrofabricated in Microfluidics. MEMBRANES 2023; 13:294. [PMID: 36984680 PMCID: PMC10052736 DOI: 10.3390/membranes13030294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/14/2023] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Microfluidic-integrated freestanding membranes with suitable biocompatibility and tunable physicochemical properties are in high demand for a wide range of life science and biological studies. However, there is a lack of facile and rapid methods to integrate such versatile membranes into microfluidics. A recently invented interfacial electrofabrication of chitosan membranes offers an in-situ membrane integration strategy that is flexible, controllable, simple, and biologically friendly. In this follow-up study, we explored the ability to program the physical properties of these chitosan membranes by varying the electrofabrication conditions (e.g., applied voltage and pH of alginate). We found a strong association between membrane growth rate, properties, and fabrication parameters: high electrical stimuli and pH of alginate resulted in high optical retardance and low permeability, and vice versa. This suggests that the molecular alignment and density of electrofabricated chitosan membranes could be actively tailored according to application needs. Lastly, we demonstrated that this interfacial electrofabrication could easily be expanded to produce chitosan membrane arrays with higher uniformity than the previously well-established flow assembly method. This study demonstrates the tunability of the electrofabricated membranes' properties and functionality, thus expanding the utility of such membranes for broader applications in the future.
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Affiliation(s)
- Khanh L. Ly
- Department of Biomedical Engineering, School of Engineering, Catholic University of America, Washington, DC 20064, USA
| | - Piao Hu
- Department of Mechanical Engineering, School of Engineering, Catholic University of America, Washington, DC 20064, USA
| | - Christopher B. Raub
- Department of Biomedical Engineering, School of Engineering, Catholic University of America, Washington, DC 20064, USA
| | - Xiaolong Luo
- Department of Mechanical Engineering, School of Engineering, Catholic University of America, Washington, DC 20064, USA
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3
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Hu P, Ly KL, Pham LPH, Pottash AE, Sheridan K, Wu HC, Tsao CY, Quan D, Bentley WE, Rubloff GW, Sintim HO, Luo X. Bacterial chemotaxis in static gradients quantified in a biopolymer membrane-integrated microfluidic platform. LAB ON A CHIP 2022; 22:3203-3216. [PMID: 35856590 PMCID: PMC9756273 DOI: 10.1039/d2lc00481j] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Chemotaxis is a fundamental bacterial response mechanism to changes in chemical gradients of specific molecules known as chemoattractant or chemorepellent. The advancement of biological platforms for bacterial chemotaxis research is of significant interest for a wide range of biological and environmental studies. Many microfluidic devices have been developed for its study, but challenges still remain that can obscure analysis. For example, cell migration can be compromised by flow-induced shear stress, and bacterial motility can be impaired by nonspecific cell adhesion to microchannels. Also, devices can be complicated, expensive, and hard to assemble. We address these issues with a three-channel microfluidic platform integrated with natural biopolymer membranes that are assembled in situ. This provides several unique attributes. First, a static, steady and robust chemoattractant gradient was generated and maintained. Second, because the assembly incorporates assembly pillars, the assembled membrane arrays connecting nearby pillars can be created longer than the viewing window, enabling a wide 2D area for study. Third, the in situ assembled biopolymer membranes minimize pressure and/or chemiosmotic gradients that could induce flow and obscure chemotaxis study. Finally, nonspecific cell adhesion is avoided by priming the polydimethylsiloxane (PDMS) microchannel surfaces with Pluronic F-127. We demonstrated chemotactic migration of Escherichia coli as well as Pseudomonas aeruginosa under well-controlled easy-to-assemble glucose gradients. We characterized motility using the chemotaxis partition coefficient (CPC) and chemotaxis migration coefficient (CMC) and found our results consistent with other reports. Further, random walk trajectories of individual cells in simple bright field images were conveniently tracked and presented in rose plots. Velocities were calculated, again in agreement with previous literature. We believe the biopolymer membrane-integrated platform represents a facile and convenient system for robust quantitative assessment of cellular motility in response to various chemical cues.
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Affiliation(s)
- Piao Hu
- Department of Mechanical Engineering, Catholic University of America, Washington, District of Columbia 20064, USA.
| | - Khanh L Ly
- Department of Biomedical Engineering, Catholic University of America, Washington, District of Columbia 20064, USA
| | - Le P H Pham
- Department of Mechanical Engineering, Catholic University of America, Washington, District of Columbia 20064, USA.
| | - Alex E Pottash
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Kathleen Sheridan
- Department of Biomedical Engineering, Catholic University of America, Washington, District of Columbia 20064, USA
| | - Hsuan-Chen Wu
- Institute for Bioscience & Biotechnology Research, University of Maryland, College Park, MD 20742, USA
| | - Chen-Yu Tsao
- Institute for Bioscience & Biotechnology Research, University of Maryland, College Park, MD 20742, USA
| | - David Quan
- Institute for Bioscience & Biotechnology Research, University of Maryland, College Park, MD 20742, USA
| | - William E Bentley
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
- Institute for Bioscience & Biotechnology Research, University of Maryland, College Park, MD 20742, USA
| | - Gary W Rubloff
- Department of Materials Science & Engineering, University of Maryland, College Park, MD 20742, USA
| | - Herman O Sintim
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Xiaolong Luo
- Department of Mechanical Engineering, Catholic University of America, Washington, District of Columbia 20064, USA.
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4
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Das SS, Erez S, Karshalev E, Wu Y, Wang J, Yossifon G. Switching from Chemical to Electrical Micromotor Propulsion across a Gradient of Gastric Fluid via Magnetic Rolling. ACS APPLIED MATERIALS & INTERFACES 2022; 14:30290-30298. [PMID: 35748802 DOI: 10.1021/acsami.2c02605] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
To address and extend the finite lifetime of Mg-based micromotors due to the depletion of the engine (Mg-core), we examine electric fields, along with previously studied magnetic fields, to create a triple-engine hybrid micromotor for driving these micromotors. Electric fields are a facile energy source that is not limited in its operation time and can dynamically tune the micromotor mobility by simply changing the frequency and amplitude of the field. Moreover, the same electrical fields can be used for cell trapping and transport as well as drug delivery. However, the limitations of these propulsion mechanisms are the low pH (and high conductivity) environment required for Mg dissolution, while the electrical propulsion is quenched at these conditions as it requires low conductivity mediums. In order to translate the micromotor between these two extreme medium conditions, we use magnetic rolling as means of self-propulsion along with magnetic steering. Interestingly, electrical propulsion also necessitates at least the partial consumption of the Mg, resulting in a sufficient geometrical asymmetry of the micromotor. We have successfully demonstrated the rapid propulsion switching capability of the micromotor, from chemical to electrical motions, via magnetic rolling within a microfluidic device with the concentration gradient of the simulated gastric fluid. Such triple-engine micromotor propulsion holds considerable promise for in vitro studies mimicking gastric conditions and performing various bioassay tasks.
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Affiliation(s)
- Sankha Shuvra Das
- Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion─Israel Institute of Technology, Technion City 3200000, Israel
| | - Shahar Erez
- Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion─Israel Institute of Technology, Technion City 3200000, Israel
- Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, United States
| | - Emil Karshalev
- Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, United States
| | - Yue Wu
- Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion─Israel Institute of Technology, Technion City 3200000, Israel
| | - Joseph Wang
- Department of Nanoengineering, University of California San Diego, La Jolla, California 92093, United States
| | - Gilad Yossifon
- Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion─Israel Institute of Technology, Technion City 3200000, Israel
- School of Mechanical Engineering, Tel Aviv University, Ramat Aviv 6997801, Israel
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5
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Nagy K, Dukic B, Hodula O, Ábrahám Á, Csákvári E, Dér L, Wetherington MT, Noorlag J, Keymer JE, Galajda P. Emergence of Resistant Escherichia coli Mutants in Microfluidic On-Chip Antibiotic Gradients. Front Microbiol 2022; 13:820738. [PMID: 35391738 PMCID: PMC8981919 DOI: 10.3389/fmicb.2022.820738] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/23/2022] [Indexed: 11/13/2022] Open
Abstract
Spatiotemporal structures and heterogeneities are common in natural habitats, yet their role in the evolution of antibiotic resistance is still to be uncovered. We applied a microfluidic gradient generator device to study the emergence of resistant bacteria in spatial ciprofloxacin gradients. We observed biofilm formation in regions with sub-inhibitory concentrations of antibiotics, which quickly expanded into the high antibiotic regions. In the absence of an explicit structure of the habitat, this multicellular formation led to a spatial structure of the population with local competition and limited migration. Therefore, such structures can function as amplifiers of selection and aid the spread of beneficial mutations. We found that the physical environment itself induces stress-related mutations that later prove beneficial when cells are exposed to antibiotics. This shift in function suggests that exaptation occurs in such experimental scenarios. The above two processes pave the way for the subsequent emergence of highly resistant specific mutations.
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Affiliation(s)
- Krisztina Nagy
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
- Department of Biotechnology, University of Szeged, Szeged, Hungary
- *Correspondence: Krisztina Nagy,
| | - Barbara Dukic
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Orsolya Hodula
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Ágnes Ábrahám
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
- Doctoral School of Multidisciplinary Medical Sciences, University of Szeged, Szeged, Hungary
| | - Eszter Csákvári
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - László Dér
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | | | - Janneke Noorlag
- Department of Natural Sciences and Technology, University of Aysén, Coyhaique, Chile
| | - Juan E. Keymer
- Department of Natural Sciences and Technology, University of Aysén, Coyhaique, Chile
| | - Péter Galajda
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
- Péter Galajda,
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Khan A, Smith NM, Tullier MP, Roberts BS, Englert D, Pojman JA, Melvin AT. Development of a Flow-free Gradient Generator Using a Self-Adhesive Thiol-acrylate Microfluidic Resin/Hydrogel (TAMR/H) Hybrid System. ACS APPLIED MATERIALS & INTERFACES 2021; 13:26735-26747. [PMID: 34081856 PMCID: PMC8289190 DOI: 10.1021/acsami.1c04771] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 05/21/2021] [Indexed: 06/12/2023]
Abstract
Microfluidic gradient generators have been used to study cellular migration, growth, and drug response in numerous biological systems. One type of device combines a hydrogel and polydimethylsiloxane (PDMS) to generate "flow-free" gradients; however, their requirements for either negative flow or external clamps to maintain fluid-tight seals between the two layers have restricted their utility among broader applications. In this work, a two-layer, flow-free microfluidic gradient generator was developed using thiol-ene chemistry. Both rigid thiol-acrylate microfluidic resin (TAMR) and diffusive thiol-acrylate hydrogel (H) layers were synthesized from commercially available monomers at room temperature and pressure using a base-catalyzed Michael addition. The device consisted of three parallel microfluidic channels negatively imprinted in TAMR layered on top of the thiol-acrylate hydrogel to facilitate orthogonal diffusion of chemicals to the direction of flow. Upon contact, these two layers formed fluid-tight channels without any external pressure due to a strong adhesive interaction between the two layers. The diffusion of molecules through the TAMR/H system was confirmed both experimentally (using fluorescent microscopy) and computationally (using COMSOL). The performance of the TAMR/H system was compared to a conventional PDMS/agarose device with a similar geometry by studying the chemorepulsive response of a motile strain of GFP-expressing Escherichia coli. Population-based analysis confirmed a similar migratory response of both wild-type and mutant E. coli in both of the microfluidic devices. This confirmed that the TAMR/H hybrid system is a viable alternative to traditional PDMS-based microfluidic gradient generators and can be used for several different applications.
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Affiliation(s)
- Anowar
H. Khan
- Department
of Chemistry, Louisiana State University, Baton Rouge 70803, Louisiana, United States
| | - Noah Mulherin Smith
- Cain
Department of Chemical Engineering, Louisiana
State University, Baton Rouge 70803, Louisiana, United States
| | - Michael P. Tullier
- Department
of Chemistry, Louisiana State University, Baton Rouge 70803, Louisiana, United States
| | - B. Seth Roberts
- Cain
Department of Chemical Engineering, Louisiana
State University, Baton Rouge 70803, Louisiana, United States
| | - Derek Englert
- Chemical
and Materials Engineering, University of
Kentucky, Paducah 42002, Kentucky, United States
| | - John A. Pojman
- Department
of Chemistry, Louisiana State University, Baton Rouge 70803, Louisiana, United States
| | - Adam T. Melvin
- Cain
Department of Chemical Engineering, Louisiana
State University, Baton Rouge 70803, Louisiana, United States
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7
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Ly KL, Hu P, Pham LHP, Luo X. Flow-assembled chitosan membranes in microfluidics: recent advances and applications. J Mater Chem B 2021; 9:3258-3283. [PMID: 33725061 PMCID: PMC8369861 DOI: 10.1039/d1tb00045d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The integration of membranes in microfluidic devices has been extensively exploited for various chemical engineering and bioengineering applications over the past few decades. To augment the applicability of membrane-integrated microfluidic platforms for biomedical and tissue engineering studies, a biologically friendly fabrication process with naturally occurring materials is highly desired. The in situ preparation of membranes involving interfacial reactions between parallel laminar flows in microfluidic networks, known as the flow-assembly technique, is one of the most biocompatible approaches. Membranes of many types with flexible geometries have been successfully assembled inside complex microchannels using this facile and versatile flow-assembly approach. Chitosan is a naturally abundant polysaccharide known for its pronounced biocompatibility, biodegradability, good mechanical stability, ease of modification and processing, and film-forming ability under near-physiological conditions. Chitosan membranes assembled by flows in microfluidics are freestanding, robust, semipermeable, and well-aligned in microstructure, and show high affinity to bioactive reagents and biological components (e.g. biomolecules, nanoparticles, or cells) that provide facile biological functionalization of microdevices. Here, we discuss the recent developments and optimizations in the flow-assembly of chitosan membranes and chitosan-based membranes in microfluidics. Furthermore, we recapitulate the applications of the chitosan membrane-integrated microfluidic platforms dedicated to biology, biochemistry, and drug release fields, and envision the future developments of this important platform with versatile functions.
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Affiliation(s)
- Khanh L Ly
- Department of Biomedical Engineering, The Catholic University of America, Washington, DC 20064, USA
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8
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Garcia-Seyda N, Aoun L, Tishkova V, Seveau V, Biarnes-Pelicot M, Bajénoff M, Valignat MP, Theodoly O. Microfluidic device to study flow-free chemotaxis of swimming cells. LAB ON A CHIP 2020; 20:1639-1647. [PMID: 32249280 DOI: 10.1039/d0lc00045k] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Microfluidic devices have been used in the last two decades to study in vitro cell chemotaxis, but few existing devices generate gradients in flow-free conditions. Flow can bias cell directionality of adherent cells and precludes the study of swimming cells like naïve T lymphocytes, which only migrate in a non-adherent fashion. We developed two devices that create stable, flow-free, diffusion-based gradients and are adapted for adherent and swimming cells. The flow-free environment is achieved by using agarose gel barriers between a central channel with cells and side channels with chemoattractants. These barriers insulate cells from injection/rinsing cycles of chemoattractants, they dampen residual drift across the device, and they allow co-culture of cells without physical interaction, to study contactless paracrine communication. Our devices were used here to investigate neutrophil and naïve T lymphocyte chemotaxis.
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Affiliation(s)
- Nicolas Garcia-Seyda
- Aix Marseille Univ, Inserm, CNRS, Turing Center for Living Systems, LAI, Marseille, France.
| | - Laurene Aoun
- Aix Marseille Univ, Inserm, CNRS, Turing Center for Living Systems, LAI, Marseille, France.
| | | | - Valentine Seveau
- Aix Marseille Univ, Inserm, CNRS, Turing Center for Living Systems, LAI, Marseille, France.
| | | | - Marc Bajénoff
- Aix Marseille Univ, Inserm, CNRS, CIML, Marseille, France
| | - Marie-Pierre Valignat
- Aix Marseille Univ, Inserm, CNRS, Turing Center for Living Systems, LAI, Marseille, France.
| | - Olivier Theodoly
- Aix Marseille Univ, Inserm, CNRS, Turing Center for Living Systems, LAI, Marseille, France.
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Chemotactic Responses of Jurkat Cells in Microfluidic Flow-Free Gradient Chambers. MICROMACHINES 2020; 11:mi11040384. [PMID: 32260431 PMCID: PMC7231302 DOI: 10.3390/mi11040384] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/02/2020] [Accepted: 04/02/2020] [Indexed: 12/29/2022]
Abstract
Gradients of soluble molecules coordinate cellular communication in a diverse range of multicellular systems. Chemokine-driven chemotaxis is a key orchestrator of cell movement during organ development, immune response and cancer progression. Chemotaxis assays capable of examining cell responses to different chemokines in the context of various extracellular matrices will be crucial to characterize directed cell motion in conditions which mimic whole tissue conditions. Here, a microfluidic device which can generate different chemokine patterns in flow-free gradient chambers while controlling surface extracellular matrix (ECM) to study chemotaxis either at the population level or at the single cell level with high resolution imaging is presented. The device is produced by combining additive manufacturing (AM) and soft lithography. Generation of concentration gradients in the device were simulated and experimentally validated. Then, stable gradients were applied to modulate chemotaxis and chemokinetic response of Jurkat cells as a model for T lymphocyte motility. Live imaging of the gradient chambers allowed to track and quantify Jurkat cell migration patterns. Using this system, it has been found that the strength of the chemotactic response of Jurkat cells to CXCL12 gradient was reduced by increasing surface fibronectin in a dose-dependent manner. The chemotaxis of the Jurkat cells was also found to be governed not only by the CXCL12 gradient but also by the average CXCL12 concentration. Distinct migratory behaviors in response to chemokine gradients in different contexts may be physiologically relevant for shaping the host immune response and may serve to optimize the targeting and accumulation of immune cells to the inflammation site. Our approach demonstrates the feasibility of using a flow-free gradient chamber for evaluating cross-regulation of cell motility by multiple factors in different biologic processes.
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10
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Ly KL, Raub CB, Luo X. Tuning the porosity of biofabricated chitosan membranes in microfluidics with co-assembled nanoparticles as templates. MATERIALS ADVANCES 2020; 1:34-44. [PMID: 33073238 PMCID: PMC7518516 DOI: 10.1039/d0ma00073f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 05/04/2023]
Abstract
Biopolymer membranes assembled in microfluidic devices offer many biological process- and analysis-related applications. One of the key characteristics of bio-fabricated membranes is their porosity, which regulates the transport of molecules, ions, or particles and contributes to their semi-permeability and selectivity. This study aims to tune the porosity of biofabricated chitosan membranes (CM) using incorporated nanoparticles as templates. CM with polystyrene nanoparticles (CM-np) were assembled by flow in microchannel networks. The membranes with incorporated nanoparticles were crosslinked with glutaraldehyde, and then the nanoparticles were dissolved with dimethyl sulfoxide. The in situ synthesized porous CM (pCM) were characterized with scanning electron microscopy and polarized light microscopy. Permeability tests confirmed the increased pore sizes of the pCM and enhanced permeability to macromolecules. Sharper static gradients in three-channel microfluidic devices were demonstrated with the pCM as compared to those with the original CM. The capability to customize the porosity of flow-assembled, freestanding and robust biopolymer membranes inside a microfluidic network is attractive and broadens the applications of these membranes in biomolecular and cellular studies.
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Affiliation(s)
- Khanh L Ly
- Department of Biomedical Engineering , Catholic University of America , Washington , DC 20064 , USA
| | - Christopher B Raub
- Department of Biomedical Engineering , Catholic University of America , Washington , DC 20064 , USA
| | - Xiaolong Luo
- Department of Mechanical Engineering , Catholic University of America , Washington , DC 20064 , USA .
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11
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Gurung JP, Gel M, Baker MAB. Microfluidic techniques for separation of bacterial cells via taxis. MICROBIAL CELL (GRAZ, AUSTRIA) 2020; 7:66-79. [PMID: 32161767 PMCID: PMC7052948 DOI: 10.15698/mic2020.03.710] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/24/2019] [Accepted: 01/10/2020] [Indexed: 12/22/2022]
Abstract
The microbial environment is typically within a fluid and the key processes happen at the microscopic scale where viscosity dominates over inertial forces. Microfluidic tools are thus well suited to study microbial motility because they offer precise control of spatial structures and are ideal for the generation of laminar fluid flows with low Reynolds numbers at microbial lengthscales. These tools have been used in combination with microscopy platforms to visualise and study various microbial taxes. These include establishing concentration and temperature gradients to influence motility via chemotaxis and thermotaxis, or controlling the surrounding microenvironment to influence rheotaxis, magnetotaxis, and phototaxis. Improvements in microfluidic technology have allowed fine separation of cells based on subtle differences in motility traits and have applications in synthetic biology, directed evolution, and applied medical microbiology.
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Affiliation(s)
- Jyoti P. Gurung
- School of Biotechnology and Biomolecular Science, UNSW Sydney
| | - Murat Gel
- CSIRO Manufacturing, Clayton
- CSIRO Future Science Platform for Synthetic Biology
| | - Matthew A. B. Baker
- School of Biotechnology and Biomolecular Science, UNSW Sydney
- CSIRO Future Science Platform for Synthetic Biology
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12
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Karbalaei A, Cho HJ. Microfluidic Devices Developed for and Inspired by Thermotaxis and Chemotaxis. MICROMACHINES 2018; 9:E149. [PMID: 30424083 PMCID: PMC6187570 DOI: 10.3390/mi9040149] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/07/2018] [Accepted: 03/22/2018] [Indexed: 01/08/2023]
Abstract
Taxis has been reported in many cells and microorganisms, due to their tendency to migrate toward favorable physical situations and avoid damage and death. Thermotaxis and chemotaxis are two of the major types of taxis that naturally occur on a daily basis. Understanding the details of the thermo- and chemotactic behavioral response of cells and microorganisms is necessary to reveal the body function, diagnosing diseases and developing therapeutic treatments. Considering the length-scale and range of effectiveness of these phenomena, advances in microfluidics have facilitated taxis experiments and enhanced the precision of controlling and capturing microscale samples. Microfabrication of fluidic chips could bridge the gap between in vitro and in situ biological assays, specifically in taxis experiments. Numerous efforts have been made to develop, fabricate and implement novel microchips to conduct taxis experiments and increase the accuracy of the results. The concepts originated from thermo- and chemotaxis, inspired novel ideas applicable to microfluidics as well, more specifically, thermocapillarity and chemocapillarity (or solutocapillarity) for the manipulation of single- and multi-phase fluid flows in microscale and fluidic control elements such as valves, pumps, mixers, traps, etc. This paper starts with a brief biological overview of the concept of thermo- and chemotaxis followed by the most recent developments in microchips used for thermo- and chemotaxis experiments. The last section of this review focuses on the microfluidic devices inspired by the concept of thermo- and chemotaxis. Various microfluidic devices that have either been used for, or inspired by thermo- and chemotaxis are reviewed categorically.
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Affiliation(s)
- Alireza Karbalaei
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA.
| | - Hyoung Jin Cho
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA.
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Colin R, Sourjik V. Emergent properties of bacterial chemotaxis pathway. Curr Opin Microbiol 2017; 39:24-33. [PMID: 28822274 DOI: 10.1016/j.mib.2017.07.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Accepted: 07/27/2017] [Indexed: 11/17/2022]
Abstract
The chemotaxis pathway of Escherichia coli is the most studied sensory system in prokaryotes. The highly conserved general architecture of this pathway consists of two modules which mediate signal transduction and adaptation. The signal transduction module detects and amplifies changes in environmental conditions and rapidly transmits these signals to control bacterial swimming behavior. The adaptation module gradually resets the activity and sensitivity of the first module after initial stimulation and thereby enables the temporal comparisons necessary for bacterial chemotaxis. Recent experimental and theoretical work has unraveled multiple quantitative features emerging from the interplay between these two modules. This has laid the groundwork for rationalization of these emerging properties in the context of the evolutionary optimization of the chemotactic behavior.
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Affiliation(s)
- Remy Colin
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology, Karl-von-Frisch-strasse 16, 35043 Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology, Karl-von-Frisch-strasse 16, 35043 Marburg, Germany.
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14
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Nyúl-Tóth Á, Kozma M, Nagyőszi P, Nagy K, Fazakas C, Haskó J, Molnár K, Farkas AE, Végh AG, Váró G, Galajda P, Wilhelm I, Krizbai IA. Expression of pattern recognition receptors and activation of the non-canonical inflammasome pathway in brain pericytes. Brain Behav Immun 2017; 64:220-231. [PMID: 28432035 DOI: 10.1016/j.bbi.2017.04.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/31/2017] [Accepted: 04/12/2017] [Indexed: 12/27/2022] Open
Abstract
Cerebral pericytes are mural cells embedded in the basement membrane of capillaries. Increasing evidence suggests that they play important role in controlling neurovascular functions, i.e. cerebral blood flow, angiogenesis and permeability of the blood-brain barrier. These cells can also influence neuroinflammation which is highly regulated by the innate immune system. Therefore, we systematically tested the pattern recognition receptor expression of brain pericytes. We detected expression of NOD1, NOD2, NLRC5, NLRP1-3, NLRP5, NLRP9, NLRP10 and NLRX mRNA in non-treated cells. Among the ten known human TLRs, TLR2, TLR4, TLR5, TLR6 and TLR10 were found to be expressed. Inflammatory mediators induced the expression of NLRA, NLRC4 and TLR9 and increased the levels of NOD2, TLR2, inflammasome-forming caspases and inflammasome-cleaved interleukins. Oxidative stress, on the other hand, upregulated expression of TLR10 and NLRP9. Activation of selected pattern recognition receptors can lead to inflammasome assembly and caspase-dependent secretion of IL-1β. TNF-α and IFN-γ increased the levels of pro-IL-1β and pro-caspase-1 proteins; however, no canonical activation of NLRP1, NLRP2, NLRP3 or NLRC4 inflammasomes could be observed in human brain vascular pericytes. On the other hand, we could demonstrate secretion of active IL-1β in response to non-canonical inflammasome activation, i.e. intracellular LPS or infection with E. coli bacteria. Our in vitro results indicate that pericytes might have an important regulatory role in neuroinflammation.
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Affiliation(s)
- Ádám Nyúl-Tóth
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Mihály Kozma
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Péter Nagyőszi
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Krisztina Nagy
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Csilla Fazakas
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - János Haskó
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Kinga Molnár
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Attila E Farkas
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Attila G Végh
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - György Váró
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Péter Galajda
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary.
| | - Imola Wilhelm
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary; Institute of Life Sciences, Vasile Goldiş Western University of Arad, Str. Liviu Rebreanu 86, 310414 Arad, Romania.
| | - István A Krizbai
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, 6726 Szeged, Hungary; Institute of Life Sciences, Vasile Goldiş Western University of Arad, Str. Liviu Rebreanu 86, 310414 Arad, Romania.
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15
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Murugesan N, Dhar P, Panda T, Das SK. Interplay of chemical and thermal gradient on bacterial migration in a diffusive microfluidic device. BIOMICROFLUIDICS 2017; 11:024108. [PMID: 28396712 PMCID: PMC5367144 DOI: 10.1063/1.4979103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 03/13/2017] [Indexed: 05/09/2023]
Abstract
Living systems are constantly under different combinations of competing gradients of chemical, thermal, pH, and mechanical stresses allied. The present work is about competing chemical and thermal gradients imposed on E. coli in a diffusive stagnant microfluidic environment. The bacterial cells were exposed to opposing and aligned gradients of an attractant (1 mM sorbitol) or a repellant (1 mM NiSO4) and temperature. The effects of the repellant/attractant and temperature on migration behavior, migration rate, and initiation time for migration have been reported. It has been observed that under competing gradients of an attractant and temperature, the nutrient gradient (gradient generated by cells itself) initiates directed migration, which, in turn, is influenced by temperature through the metabolic rate. Exposure to competing gradients of an inhibitor and temperature leads to the imposed chemical gradient governing the directed cell migration. The cells under opposing gradients of the repellant and temperature have experienced the longest decision time (∼60 min). The conclusion is that in a competing chemical and thermal gradient environment in the range of experimental conditions used in the present work, the migration of E. coli is always initiated and governed by chemical gradients (either generated by the cells in situ or imposed upon externally), but the migration rate and percentage of migration of cells are influenced by temperature, shedding insights into the importance of such gradients in deciding collective dynamics of such cells in physiological conditions.
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Affiliation(s)
- Nithya Murugesan
- Department of Chemical Engineering, Indian Institute of Technology Madras , Chennai 600 036, India
| | - Purbarun Dhar
- Department of Mechanical Engineering, Indian Institute of Technology Ropar , Rupnagar 140001, India
| | - Tapobrata Panda
- Department of Chemical Engineering, Indian Institute of Technology Madras , Chennai 600 036, India
| | - Sarit K Das
- Department of Mechanical Engineering, Indian Institute of Technology Madras , Chennai 600 036, India
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16
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Pham P, Vo T, Luo X. Steering air bubbles with an add-on vacuum layer for biopolymer membrane biofabrication in PDMS microfluidics. LAB ON A CHIP 2017; 17:248-255. [PMID: 27942655 DOI: 10.1039/c6lc01362g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Membrane functionality is crucial in microfluidics for realizing operations such as filtration, separation, concentration, signaling among cells and gradient generation. Currently, common methods often sandwich commercially available membranes in multi-layer devices, or use photopolymerization or temperature-induced gelation to fabricate membrane structures in one-layer devices. Biofabrication offers an alternative to forming membrane structures with biomimetic materials and mechanisms in mild conditions. We have recently developed a biofabrication strategy to form parallel biopolymer membranes in gas-permeable polydimethylsiloxane (PDMS) microfluidic devices, which used positive pressure to dissipate air bubbles through PDMS to initiate membrane formation but required careful pressure balancing between two flows. Here, we report a technical innovation by simply placing as needed an add-on PDMS vacuum layer on PDMS microfluidic devices to dissipate air bubbles and guide the biofabrication of biopolymer membranes. Vacuuming through PDMS was simply achieved by either withdrawing a syringe or releasing a squeezed nasal aspirator. Upon vacuuming, air bubbles dissipated within minutes, membranes were effortlessly formed, and the add-on vacuum layer can be removed. Subsequent membrane growth could be robustly controlled with the flows and pH of solutions. This new process is user-friendly and has achieved a 100% success rate in more than 200 trials in membrane biofabrication.
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Affiliation(s)
- Phu Pham
- Department of Mechanical Engineering, The Catholic University of America, Washington, D.C. 20064, USA.
| | - Thanh Vo
- Department of Mechanical Engineering, The Catholic University of America, Washington, D.C. 20064, USA.
| | - Xiaolong Luo
- Department of Mechanical Engineering, The Catholic University of America, Washington, D.C. 20064, USA.
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17
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Wolfram CJ, Rubloff GW, Luo X. Perspectives in flow-based microfluidic gradient generators for characterizing bacterial chemotaxis. BIOMICROFLUIDICS 2016; 10:061301. [PMID: 27917249 PMCID: PMC5106431 DOI: 10.1063/1.4967777] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 10/31/2016] [Indexed: 05/08/2023]
Abstract
Chemotaxis is a phenomenon which enables cells to sense concentrations of certain chemical species in their microenvironment and move towards chemically favorable regions. Recent advances in microbiology have engineered the chemotactic properties of bacteria to perform novel functions, but traditional methods of characterizing chemotaxis do not fully capture the associated cell motion, making it difficult to infer mechanisms that link the motion to the microbiology which induces it. Microfluidics offers a potential solution in the form of gradient generators. Many of the gradient generators studied to date for this application are flow-based, where a chemical species diffuses across the laminar flow interface between two solutions moving through a microchannel. Despite significant research efforts, flow-based gradient generators have achieved mixed success at accurately capturing the highly subtle chemotactic responses exhibited by bacteria. Here we present an analysis encompassing previously published versions of flow-based gradient generators, the theories that govern their gradient-generating properties, and new, more practical considerations that result from experimental factors. We conclude that flow-based gradient generators present a challenge inherent to their design in that the residence time and gradient decay must be finely balanced, and that this significantly narrows the window for reliable observation and quantification of chemotactic motion. This challenge is compounded by the effects of shear on an ellipsoidal bacterium that causes it to preferentially align with the direction of flow and subsequently suppresses the cross-flow chemotactic response. These problems suggest that a static, non-flowing gradient generator may be a more suitable platform for chemotaxis studies in the long run, despite posing greater difficulties in design and fabrication.
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Affiliation(s)
- Christopher J Wolfram
- Department of Materials Science and Engineering, University of Maryland , College Park, Maryland 20742, USA
| | - Gary W Rubloff
- Department of Materials Science and Engineering, University of Maryland , College Park, Maryland 20742, USA
| | - Xiaolong Luo
- Department of Mechanical Engineering, The Catholic University of America , Washington, DC 20064, USA
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Luo X, Vo T, Jambi F, Pham P, Choy JS. Microfluidic partition with in situ biofabricated semipermeable biopolymer membranes for static gradient generation. LAB ON A CHIP 2016; 16:3815-3823. [PMID: 27713976 DOI: 10.1039/c6lc00742b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We report an in situ biofabrication strategy that conveniently partitions microfluidic networks into physically separated while chemically communicating microchannels with semipermeable biopolymer membranes, which enable the facile generation of static gradients for biomedical applications. The biofabrication of parallel biopolymer membranes was initiated with the dissipation of trapped air bubbles in parallel apertures in polydimethylsiloxane (PDMS) microfluidic devices, followed by tunable membrane growth with precise temporal and spatial control to the desired thickness. Static gradients were generated within minutes and well maintained over time by pure diffusion of molecules through the biofabricated semipermeable membranes. As an example application, the static gradient of alpha factor was generated to study the development of the "shmoo" morphology of yeast over time. The in situ biofabrication provides a simple approach to generate static gradients and an ideal platform for biological applications where flow-free static gradients are indispensable.
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Affiliation(s)
- Xiaolong Luo
- Department of Mechanical Engineering, The Catholic University of America, Washington, D.C. 20064, USA.
| | - Thanh Vo
- Department of Mechanical Engineering, The Catholic University of America, Washington, D.C. 20064, USA.
| | - Fahad Jambi
- Department of Mechanical Engineering, The Catholic University of America, Washington, D.C. 20064, USA.
| | - Phu Pham
- Department of Mechanical Engineering, The Catholic University of America, Washington, D.C. 20064, USA.
| | - John S Choy
- Department of Biology, The Catholic University of America, Washington, D.C. 20064, USA
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Kundu S. Stochastic modelling suggests that an elevated superoxide anion - hydrogen peroxide ratio can drive extravascular phagocyte transmigration by lamellipodium formation. J Theor Biol 2016; 407:143-154. [PMID: 27380944 DOI: 10.1016/j.jtbi.2016.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 07/01/2016] [Indexed: 11/24/2022]
Abstract
Chemotaxis, integrates diverse intra- and inter-cellular molecular processes into a purposeful patho-physiological response; the operatic rules of which, remain speculative. Here, I surmise, that superoxide anion induced directional motility, in a responding cell, results from a quasi pathway between the stimulus, surrounding interstitium, and its biochemical repertoire. The epochal event in the mounting of an inflammatory response, is the extravascular transmigration of a phagocyte competent cell towards the site of injury, secondary to the development of a lamellipodium. This stochastic-to-markovian process conversion, is initiated by the cytosolic-ROS of the damaged cell, but is maintained by the inverse association of a de novo generated pool of self-sustaining superoxide anions and sub-critical hydrogen peroxide levels. Whilst, the exponential rise of O2(.-) is secondary to the focal accumulation of higher order lipid raft-Rac1/2-actin oligomers; O2(.-) mediated inactivation and redistribution of ECSOD, accounts for the minimal concentration of H2O2 that the phagocyte experiences. The net result of this reciprocal association between ROS/ RNS members, is the prolonged perturbation and remodeling of the cytoskeleton and plasma membrane, a prelude to chemotactic migration. The manuscript also describes the significance of stochastic modeling, in the testing of plausible molecular hypotheses of observable phenomena in complex biological systems.
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Affiliation(s)
- Siddhartha Kundu
- Department of Biochemistry, Dr. Baba Saheb Ambedkar Medical College & Hospital, Government of NCT Delhi, Sector - 6, Rohini, Delhi 110085, India; Mathematical and Computational Biology, Information Technology Research Academy (ITRA), Media Lab Asia, 2nd Floor, Block 2, C-DOT Campus, Mehrauli, New Delhi 110030, India; School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Mehrauli Road, New Delhi 110067, India.
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20
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Choi HI, Kim JYH, Kwak HS, Sung YJ, Sim SJ. Quantitative analysis of the chemotaxis of a green alga, Chlamydomonas reinhardtii, to bicarbonate using diffusion-based microfluidic device. BIOMICROFLUIDICS 2016; 10:014121. [PMID: 26958101 PMCID: PMC4769253 DOI: 10.1063/1.4942756] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 02/12/2016] [Indexed: 05/24/2023]
Abstract
There is a growing interest in the photosynthetic carbon fixation by microalgae for the production of valuable products from carbon dioxide (CO2). Microalgae are capable of transporting bicarbonate (HCO3 (-)), the most abundant form of inorganic carbon species in the water, as a source of CO2 for photosynthesis. Despite the importance of HCO3 (-) as the carbon source, little is known about the chemotactic response of microalgae to HCO3 (-). Here, we showed the chemotaxis of a model alga, Chlamydomonas reinhardtii, towards HCO3 (-) using an agarose gel-based microfluidic device with a flow-free and stable chemical gradient during the entire assay period. The device was validated by analyzing the chemotactic responses of C. reinhardtii to the previously known chemoattractants (NH4Cl and CoCl2) and chemotactically neutral molecule (NaCl). We found that C. reinhardtii exhibited the strongest chemotactic response to bicarbonate at the concentration of 26 mM in a microfluidic device. The chemotactic response to bicarbonate showed a circadian rhythm with a peak during the dark period and a valley during the light period. We also observed the changes in the chemotaxis to bicarbonate by an inhibitor of bicarbonate transporters and a mutation in CIA5, a transcriptional regulator of carbon concentrating mechanism, indicating the relationship between chemotaxis to bicarbonate and inorganic carbon metabolism in C. reinhardtii. To the best of our knowledge, this is the first report of the chemotaxis of C. reinhardtii towards HCO3 (-), which contributes to the understanding of the physiological role of the chemotaxis to bicarbonate and its relevance to inorganic carbon utilization.
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Affiliation(s)
- Hong Il Choi
- Department of Chemical and Biological Engineering, Korea University , Seoul 136-713, South Korea
| | - Jaoon Young Hwan Kim
- Department of Chemical and Biological Engineering, Korea University , Seoul 136-713, South Korea
| | - Ho Seok Kwak
- Department of Chemical and Biological Engineering, Korea University , Seoul 136-713, South Korea
| | - Young Joon Sung
- Department of Chemical and Biological Engineering, Korea University , Seoul 136-713, South Korea
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