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Müller DH, Börger M, Thien J, Koß HJ. The Good pH probe: non-invasive pH in-line monitoring using Good buffers and Raman spectroscopy. Anal Bioanal Chem 2023; 415:7247-7258. [PMID: 37982845 PMCID: PMC10684429 DOI: 10.1007/s00216-023-04993-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/04/2023] [Accepted: 10/09/2023] [Indexed: 11/21/2023]
Abstract
In bioprocesses, the pH value is a critical process parameter that requires monitoring and control. For pH monitoring, potentiometric methods such as pH electrodes are state of the art. However, they are invasive and show measurement value drift. Spectroscopic pH monitoring is a non-invasive alternative to potentiometric methods avoiding this measurement value drift. In this study, we developed the Good pH probe, which is an approach for spectroscopic pH monitoring in bioprocesses with an effective working range between pH 6 and pH 8 that does not require the estimation of activity coefficients. The Good pH probe combines for the first time the Good buffer 3-(N-morpholino)propanesulfonic acid (MOPS) as pH indicator with Raman spectroscopy as spectroscopic technique, and Indirect Hard Modeling (IHM) for the spectral evaluation. During a detailed characterization, we proved that the Good pH probe is reversible, exhibits no temperature dependence between 15 and 40 °C, has low sensitivity to the ionic strength up to 1100 mM, and is applicable in more complex systems, in which other components significantly superimpose the spectral features of MOPS. Finally, the Good pH probe was successfully used for non-invasive pH in-line monitoring during an industrially relevant enzyme-catalyzed reaction with a root mean square error of prediction (RMSEP) of 0.04 pH levels. Thus, the Good pH probe extends the list of critical process parameters monitorable using Raman spectroscopy and IHM by the pH value.
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Affiliation(s)
- David Heinrich Müller
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062, Aachen, Germany
| | - Marieke Börger
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062, Aachen, Germany
| | - Julia Thien
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062, Aachen, Germany
| | - Hans-Jürgen Koß
- Institute of Technical Thermodynamics, RWTH Aachen University, Schinkelstraße 8, 52062, Aachen, Germany.
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2
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Viebrock K, Rabl D, Meinen S, Wunder P, Meyer JA, Frey LJ, Rasch D, Dietzel A, Mayr T, Krull R. Microsensor in Microbioreactors: Full Bioprocess Characterization in a Novel Capillary-Wave Microbioreactor. BIOSENSORS 2022; 12:bios12070512. [PMID: 35884315 PMCID: PMC9312480 DOI: 10.3390/bios12070512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/27/2022] [Accepted: 07/05/2022] [Indexed: 11/17/2022]
Abstract
Microbioreactors (MBRs) with a volume below 1 mL are promising alternatives to established cultivation platforms such as shake flasks, lab-scale bioreactors and microtiter plates. Their main advantages are simple automatization and parallelization and the saving of expensive media components and test substances. These advantages are particularly pronounced in small-scale MBRs with a volume below 10 µL. However, most described small-scale MBRs are lacking in process information from integrated sensors due to limited space and sensor technology. Therefore, a novel capillary-wave microbioreactor (cwMBR) with a volume of only 7 µL has the potential to close this gap, as it combines a small volume with integrated sensors for biomass, pH, dissolved oxygen (DO) and glucose concentration. In the cwMBR, pH and DO are measured by established luminescent optical sensors on the bottom of the cwMBR. The novel glucose sensor is based on a modified oxygen sensor, which measures the oxygen uptake of glucose oxidase (GOx) in the presence of glucose up to a concentration of 15 mM. Furthermore, absorbance measurement allows biomass determination. The optical sensors enabled the characterization of an Escherichia coli batch cultivation over 8 h in the cwMBR as proof of concept for further bioprocesses. Hence, the cwMBR with integrated optical sensors has the potential for a wide range of microscale bioprocesses, including cell-based assays, screening applications and process development.
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Affiliation(s)
- Kevin Viebrock
- Institute of Biochemical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (K.V.); (P.W.); (J.-A.M.); (L.J.F.); (D.R.)
- Center of Pharmaceutical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.M.); (A.D.)
| | - Dominik Rabl
- Institute of Analytical Chemistry and Food Chemistry, Technische Universität Graz, 8010 Graz, Austria; (D.R.); (T.M.)
| | - Sven Meinen
- Center of Pharmaceutical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.M.); (A.D.)
- Institute of Microtechnology, Technische Universität Braunschweig, 38124 Braunschweig, Germany
| | - Paul Wunder
- Institute of Biochemical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (K.V.); (P.W.); (J.-A.M.); (L.J.F.); (D.R.)
- Center of Pharmaceutical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.M.); (A.D.)
| | - Jan-Angelus Meyer
- Institute of Biochemical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (K.V.); (P.W.); (J.-A.M.); (L.J.F.); (D.R.)
- Center of Pharmaceutical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.M.); (A.D.)
| | - Lasse Jannis Frey
- Institute of Biochemical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (K.V.); (P.W.); (J.-A.M.); (L.J.F.); (D.R.)
- Center of Pharmaceutical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.M.); (A.D.)
| | - Detlev Rasch
- Institute of Biochemical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (K.V.); (P.W.); (J.-A.M.); (L.J.F.); (D.R.)
- Center of Pharmaceutical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.M.); (A.D.)
| | - Andreas Dietzel
- Center of Pharmaceutical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.M.); (A.D.)
- Institute of Microtechnology, Technische Universität Braunschweig, 38124 Braunschweig, Germany
| | - Torsten Mayr
- Institute of Analytical Chemistry and Food Chemistry, Technische Universität Graz, 8010 Graz, Austria; (D.R.); (T.M.)
| | - Rainer Krull
- Institute of Biochemical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (K.V.); (P.W.); (J.-A.M.); (L.J.F.); (D.R.)
- Center of Pharmaceutical Engineering, Technische Universität Braunschweig, 38106 Braunschweig, Germany; (S.M.); (A.D.)
- Correspondence:
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3
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Dutta B, Halder S. Schiff base compounds as fluorimetric pH sensor: a review. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2022; 14:2132-2146. [PMID: 35638380 DOI: 10.1039/d2ay00552b] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
With the recent progress of biological and environmental research, detection of pH values has become one of the most indispensable requirements. To determine the pH values of a certain medium, organic Schiff base compounds and their derivatives have been observed to play pivotal roles because of their smooth synthetic roots, easily tuneable structural architecture, non-destructive signals of emission, visually differentiable colour generation and capability of real sample analysis. Therefore with the revolutionary upgradation of wavelength radiometric techniques, the construction of molecular structures which can exhibit dual emission and absorption characteristics and which can be regulated by the change in pH values, has been a stimulating challenge. Generally a pH sensor molecule has a chromophoric or fluorophoric portion. Normally heteroatoms attached to these chromophore units either get protonated or deprotonated in acidic or basic media which gives rise to changes in absorption and emission properties of the molecule.
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Affiliation(s)
- Basudeb Dutta
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741246, India
| | - Shibashis Halder
- Department of Chemistry, Tej Narayan Banaili College, Bhagalpur, Bihar 812007, India.
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4
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A camphor-based Schiff base fluorescent probe for detection of alkaline pH and its applications in living cells. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2021.132038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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5
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Fuchs S, Johansson S, Tjell AØ, Werr G, Mayr T, Tenje M. In-Line Analysis of Organ-on-Chip Systems with Sensors: Integration, Fabrication, Challenges, and Potential. ACS Biomater Sci Eng 2021; 7:2926-2948. [PMID: 34133114 PMCID: PMC8278381 DOI: 10.1021/acsbiomaterials.0c01110] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 05/27/2021] [Indexed: 12/31/2022]
Abstract
Organ-on-chip systems are promising new in vitro research tools in medical, pharmaceutical, and biological research. Their main benefit, compared to standard cell culture platforms, lies in the improved in vivo resemblance of the cell culture environment. A critical aspect of these systems is the ability to monitor both the cell culture conditions and biological responses of the cultured cells, such as proliferation and differentiation rates, release of signaling molecules, and metabolic activity. Today, this is mostly done using microscopy techniques and off-chip analytical techniques and assays. Integrating in situ analysis methods on-chip enables improved time resolution, continuous measurements, and a faster read-out; hence, more information can be obtained from the developed organ and disease models. Integrated electrical, electrochemical, and optical sensors have been developed and used for chemical analysis in lab-on-a-chip systems for many years, and recently some of these sensing principles have started to find use in organ-on-chip systems as well. This perspective review describes the basic sensing principles, sensor fabrication, and sensor integration in organ-on-chip systems. The review also presents the current state of the art of integrated sensors and discusses future potential. We bring a technological perspective, with the aim of introducing in-line sensing and its promise to advance organ-on-chip systems and the challenges that lie in the integration to researchers without expertise in sensor technology.
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Affiliation(s)
- Stefanie Fuchs
- Institute
for Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Sofia Johansson
- Department
of Materials Science and Engineering, Science for Life Laboratory, Uppsala University, Box 35, 751 03 Uppsala, Sweden
| | - Anders Ø. Tjell
- Institute
for Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Gabriel Werr
- Department
of Materials Science and Engineering, Science for Life Laboratory, Uppsala University, Box 35, 751 03 Uppsala, Sweden
| | - Torsten Mayr
- Institute
for Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Maria Tenje
- Department
of Materials Science and Engineering, Science for Life Laboratory, Uppsala University, Box 35, 751 03 Uppsala, Sweden
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6
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Biocatalysis in Continuous-Flow Microfluidic Reactors. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2021; 179:211-246. [DOI: 10.1007/10_2020_160] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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7
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Steinegger A, Wolfbeis OS, Borisov SM. Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications. Chem Rev 2020; 120:12357-12489. [PMID: 33147405 PMCID: PMC7705895 DOI: 10.1021/acs.chemrev.0c00451] [Citation(s) in RCA: 173] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Indexed: 12/13/2022]
Abstract
This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and pKa values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.
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Affiliation(s)
- Andreas Steinegger
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
| | - Otto S. Wolfbeis
- Institute
of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, D-93040 Regensburg, Germany
| | - Sergey M. Borisov
- Institute
of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
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8
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Bolivar JM, Nidetzky B. The Microenvironment in Immobilized Enzymes: Methods of Characterization and Its Role in Determining Enzyme Performance. Molecules 2019; 24:molecules24193460. [PMID: 31554193 PMCID: PMC6803829 DOI: 10.3390/molecules24193460] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/17/2019] [Accepted: 09/19/2019] [Indexed: 12/11/2022] Open
Abstract
The liquid milieu in which enzymes operate when they are immobilized in solid materials can be quite different from the milieu in bulk solution. Important differences are in the substrate and product concentration but also in pH and ionic strength. The internal milieu for immobilized enzymes is affected by the chemical properties of the solid material and by the interplay of reaction and diffusion. Enzyme performance is influenced by the internal milieu in terms of catalytic rate (“activity”) and stability. Elucidation, through direct measurement of differences in the internal as compared to the bulk milieu is, therefore, fundamentally important in the mechanistic characterization of immobilized enzymes. The deepened understanding thus acquired is critical for the rational development of immobilized enzyme preparations with optimized properties. Herein we review approaches by opto-chemical sensing to determine the internal milieu of enzymes immobilized in porous particles. We describe analytical principles applied to immobilized enzymes and focus on the determination of pH and the O2 concentration. We show measurements of pH and [O2] with spatiotemporal resolution, using in operando analysis for immobilized preparations of industrially important enzymes. The effect of concentration gradients between solid particle and liquid bulk on enzyme performance is made evident and quantified. Besides its use in enzyme characterization, the method can be applied to the development of process control strategies.
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Affiliation(s)
- Juan M Bolivar
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, A-8010 Graz, Austria.
- Chemical and Materials Engineering Department, Complutense University of Madrid, 28040 Madrid, Spain.
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, A-8010 Graz, Austria.
- Austrian Centre of Industrial Biotechnology (acib), Petersgasse 14, A-8010 Graz, Austria.
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9
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Žnidaršič‐Plazl P. The Promises and the Challenges of Biotransformations in Microflow. Biotechnol J 2019; 14:e1800580. [DOI: 10.1002/biot.201800580] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/11/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Polona Žnidaršič‐Plazl
- Faculty of Chemistry and Chemical TechnologyUniversity of LjubljanaVečna pot 113, SI‐1000 Ljubljana Slovenia
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10
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Staudinger C, Breininger J, Klimant I, Borisov SM. Near-infrared fluorescent aza-BODIPY dyes for sensing and imaging of pH from the neutral to highly alkaline range. Analyst 2019; 144:2393-2402. [PMID: 30801584 DOI: 10.1039/c9an00118b] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
New aza-BODIPY pH indicators with spectral properties modulated solely by photoinduced electron transfer (PET) are presented. The pH sensitive hydroxyl group is located in the meta-position of a phenyl substituent with respect to the aza-BODIPY core, which eliminates the conjugation to the chromophore. The new dyes show reversible "on"-"off" fluorescence response upon deprotonation of the receptor but no changes in the absorption spectrum, which is in contrast to state-of-the-art indicators of the aza-BODIPY family. This eliminates potential changes in the efficiency of the inner filter effect and Förster resonance energy transfer (FRET) and makes the new dyes suitable acceptors in light harvesting systems used for ratiometric pH imaging. The introduction of electron-withdrawing or electron-donating groups into the receptor results in a set of indicators suitable for measurements from physiological (pH 7) to very alkaline (pH 13) conditions. The new sensors are particularly promising for monitoring of pH changes in concrete, as was recently shown elsewhere.
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Affiliation(s)
- Christoph Staudinger
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, 8010, Graz, Austria.
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11
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Dalfen I, Dmitriev RI, Holst G, Klimant I, Borisov SM. Background-Free Fluorescence-Decay-Time Sensing and Imaging of pH with Highly Photostable Diazaoxotriangulenium Dyes. Anal Chem 2018; 91:808-816. [PMID: 30518209 DOI: 10.1021/acs.analchem.8b02534] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Novel fluorescent diazaoxatriangulenium (DAOTA) pH indicators for lifetime-based self-referenced pH sensing are reported. The DAOTA dyes were decorated with phenolic-receptor groups inducing fluorescence quenching via a photoinduced-electron-transfer mechanism. Electron-withdrawing chlorine substituents ensure response in the most relevant pH range (apparent p Ka' values of ∼5 and 7.5 for the p, p-dichlorophenol- and p-chlorophenol-substituted dyes, respectively). The dyes feature long fluorescence lifetimes (17-20 ns), high quantum yields (∼60%), and high photostabilities. Planar optodes are prepared upon immobilization of the dyes into polyurethane hydrogel D4. Apart from the response in the fluorescence intensity, the optodes show pH-dependent lifetime behavior, which makes them suitable for studying 2D pH distributions with the help of fluorescence-lifetime-imaging techniques. The lifetime response is particularly pronounced for the sensors with high dye concentrations (0.5-1 wt % with respect to the polymer) and is attributed to the efficient homo-FRET mechanism.
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Affiliation(s)
- Irene Dalfen
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
| | - Ruslan I Dmitriev
- School of Biochemistry and Cell Biology , University College Cork , T12 K8AF Cork , Ireland.,Institute for Regenerative Medicine , I.M. Sechenov First Moscow State University , 119146 Moscow , Russian Federation
| | | | - Ingo Klimant
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
| | - Sergey M Borisov
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
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12
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Lladó Maldonado S, Panjan P, Sun S, Rasch D, Sesay AM, Mayr T, Krull R. A fully online sensor-equipped, disposable multiphase microbioreactor as a screening platform for biotechnological applications. Biotechnol Bioeng 2018; 116:65-75. [DOI: 10.1002/bit.26831] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 08/08/2018] [Accepted: 09/05/2018] [Indexed: 01/09/2023]
Affiliation(s)
- Susanna Lladó Maldonado
- Institute of Biochemical Engineering, Technische Universität Braunschweig; Braunschweig Germany
- Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig; Braunschweig Germany
| | - Peter Panjan
- Unit of Measurement Technologies, University of Oulu; Kajaani Finland
| | - Shiwen Sun
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology; Graz Austria
| | - Detlev Rasch
- Institute of Biochemical Engineering, Technische Universität Braunschweig; Braunschweig Germany
- Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig; Braunschweig Germany
| | - Adama M. Sesay
- Unit of Measurement Technologies, University of Oulu; Kajaani Finland
| | - Torsten Mayr
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology; Graz Austria
| | - Rainer Krull
- Institute of Biochemical Engineering, Technische Universität Braunschweig; Braunschweig Germany
- Center of Pharmaceutical Engineering (PVZ), Technische Universität Braunschweig; Braunschweig Germany
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13
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Bolivar JM, Valikhani D, Nidetzky B. Demystifying the Flow: Biocatalytic Reaction Intensification in Microstructured Enzyme Reactors. Biotechnol J 2018; 14:e1800244. [PMID: 30091533 DOI: 10.1002/biot.201800244] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/18/2018] [Indexed: 12/27/2022]
Abstract
Continuous (flow) reactors have drawn a wave of renewed interest in biocatalysis. Many studies find that the flow reactor offers enhanced conversion efficiency. What the reported reaction intensification actually consists in, however, often remains obscure. Here, a canonical microreactor design for heterogeneously catalyzed continuous biotransformations, featuring flow microchannels that contain the enzyme immobilized on their wall surface are examined. Glycosylations by sucrose phosphorylase are used to assess the potential for reaction intensification due to microscale effects. Key variables are identified, and their corresponding relationship equations, to describe, and optimize, the interplay between reaction characteristics, microchannel geometry and reactor operation. The maximum space-time-yield (STY_max) scales directly with the enzyme activity immobilized on the available wall surface. Timescale analysis, comparing the characteristic times of reaction (τreac ) and diffusion (τdiff ) to the mean residence time (τres ), reveals operational conditions for optimum reactor output. Theoretical insight into determinants of microreactor performance is applied to biocatalytic syntheses of α-d-glucose 1-phosphate and α-glucosyl glycerol. Process boundaries for enzyme showing, respectively, high (80 U mg-1 ) and low (4 U mg-1 ) specific activities are thus established and options for process design revealed. Opportunities, and limitations, of the application of principles of microscale flow chemistry to biocatalytic transformations are made evident.
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Affiliation(s)
- Juan M Bolivar
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, Graz, Austria.,Austrian Centre of Industrial Biotechnology, Petersgasse 14, Graz, Austria
| | - Donya Valikhani
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, Graz, Austria.,Austrian Centre of Industrial Biotechnology, Petersgasse 14, Graz, Austria
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14
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Mariani F, Gualandi I, Tessarolo M, Fraboni B, Scavetta E. PEDOT: Dye-Based, Flexible Organic Electrochemical Transistor for Highly Sensitive pH Monitoring. ACS APPLIED MATERIALS & INTERFACES 2018; 10:22474-22484. [PMID: 29883081 DOI: 10.1021/acsami.8b04970] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Organic electrochemical transistors (OECTs) are bioelectronic devices able to bridge electronic and biological domains with especially high amplification and configurational versatility and thus stand out as promising platforms for healthcare applications and portable sensing technologies. Here, we have optimized the synthesis of two pH-sensitive composites of PEDOT (poly(3,4-ethylenedioxythiophene)) doped with pH dyes (BTB and MO, i.e., Bromothymol Blue and Methyl Orange, respectively), showing their ability to successfully convert the pH into an electrical signal. The PEDOT:BTB composite, which exhibited the best performance, was used as the gate electrode to develop an OECT sensor for pH monitoring that can reliably operate in a two-fold transduction mode with super-Nernstian sensitivity. When the OECT transconductance is employed as analytical signal, a sensitivity of 93 ± 8 mV pH unit-1 is achieved by successive sampling in aqueous electrolytes. When the detection is carried out by dynamically changing the pH of the same medium, the offset gate voltage of the OECT shifts by (1.1 ± 0.3) × 102 mV pH unit-1. As a further step, the optimized configuration was realized on a PET substrate, and the performance of the resulting flexible OECT was assessed in artificial sweat within a medically relevant pH range.
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Affiliation(s)
- Federica Mariani
- Dipartimento di Chimica Industriale "Toso Montanari" , Università di Bologna , Viale Risorgimento 4 , 40136 Bologna , Italy
| | - Isacco Gualandi
- Dipartimento di Chimica Industriale "Toso Montanari" , Università di Bologna , Viale Risorgimento 4 , 40136 Bologna , Italy
| | - Marta Tessarolo
- Dipartimento di Fisica e Astronomia , Università di Bologna , Viale Berti Pichat 6/2 , 40127 Bologna , Italy
| | - Beatrice Fraboni
- Dipartimento di Fisica e Astronomia , Università di Bologna , Viale Berti Pichat 6/2 , 40127 Bologna , Italy
| | - Erika Scavetta
- Dipartimento di Chimica Industriale "Toso Montanari" , Università di Bologna , Viale Risorgimento 4 , 40136 Bologna , Italy
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15
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Wohlgemuth R. Horizons of Systems Biocatalysis and Renaissance of Metabolite Synthesis. Biotechnol J 2018; 13:e1700620. [DOI: 10.1002/biot.201700620] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/26/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Roland Wohlgemuth
- European Federation of Biotechnology; Section on Applied Biocatalysis (ESAB); Theodor-Heuss-Allee 25,Frankfurt am Main 60486 Germany
- Sigma-Aldrich; Member of Merck Group; Industriestrasse 25,Buchs 9470 Switzerland
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16
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P Radhakrishnan AN, Marques MPC, Davies MJ, O'Sullivan B, Bracewell DG, Szita N. Flocculation on a chip: a novel screening approach to determine floc growth rates and select flocculating agents. LAB ON A CHIP 2018; 18:585-594. [PMID: 29345271 DOI: 10.1039/c7lc00793k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Flocculation is a key purification step in cell-based processes for the food and pharmaceutical industry where the removal of cells and cellular debris is aided by adding flocculating agents. However, finding the best suited flocculating agent and optimal conditions to achieve rapid and effective flocculation is a non-trivial task. In conventional analytical systems, turbulent mixing creates a dynamic equilibrium between floc growth and breakage, constraining the determination of floc formation rates. Furthermore, these systems typically rely on end-point measurements only. We have successfully developed for the first time a microfluidic system for the study of flocculation under well controlled conditions. In our microfluidic device (μFLOC), floc sizes and growth rates were monitored in real time using high-speed imaging and computational image analysis. The on-line and in situ detection allowed quantification of floc sizes and their growth kinetics. This eliminated the issues of sample handling, sample dispersion, and end-point measurements. We demonstrated the power of this approach by quantifying the growth rates of floc formation under forty different growth conditions by varying industrially relevant flocculating agents (pDADMAC, PEI, PEG), their concentration and dosage. Growth rates between 12.2 μm s-1 for a strongly cationic flocculant (pDADMAC) and 0.6 μm s-1 for a non-ionic flocculant (PEG) were observed, demonstrating the potential to rank flocculating conditions in a quantitative way. We have therefore created a screening tool to efficiently compare flocculating agents and rapidly find the best flocculating condition, which will significantly accelerate early bioprocess development.
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Affiliation(s)
- Anand N P Radhakrishnan
- Department of Biochemical Engineering, University College London, Bernard Katz Building, Gordon Street, London WC1H 0AH, UK.
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Gruber P, Carvalho F, Marques MPC, O'Sullivan B, Subrizi F, Dobrijevic D, Ward J, Hailes HC, Fernandes P, Wohlgemuth R, Baganz F, Szita N. Enzymatic synthesis of chiral amino-alcohols by coupling transketolase and transaminase-catalyzed reactions in a cascading continuous-flow microreactor system. Biotechnol Bioeng 2017; 115:586-596. [PMID: 28986983 PMCID: PMC5813273 DOI: 10.1002/bit.26470] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/03/2017] [Accepted: 10/04/2017] [Indexed: 11/12/2022]
Abstract
Rapid biocatalytic process development and intensification continues to be challenging with currently available methods. Chiral amino‐alcohols are of particular interest as they represent key industrial synthons for the production of complex molecules and optically pure pharmaceuticals. (2S,3R)‐2‐amino‐1,3,4‐butanetriol (ABT), a building block for the synthesis of protease inhibitors and detoxifying agents, can be synthesized from simple, non‐chiral starting materials, by coupling a transketolase‐ and a transaminase‐catalyzed reaction. However, until today, full conversion has not been shown and, typically, long reaction times are reported, making process modifications and improvement challenging. In this contribution, we present a novel microreactor‐based approach based on free enzymes, and we report for the first time full conversion of ABT in a coupled enzyme cascade for both batch and continuous‐flow systems. Using the compartmentalization of the reactions afforded by the microreactor cascade, we overcame inhibitory effects, increased the activity per unit volume, and optimized individual reaction conditions. The transketolase‐catalyzed reaction was completed in under 10 min with a volumetric activity of 3.25 U ml−1. Following optimization of the transaminase‐catalyzed reaction, a volumetric activity of 10.8 U ml−1 was attained which led to full conversion of the coupled reaction in 2 hr. The presented approach illustrates how continuous‐flow microreactors can be applied for the design and optimization of biocatalytic processes.
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Affiliation(s)
- Pia Gruber
- Department of Biochemical Engineering, University College London, London, United Kingdom
| | - Filipe Carvalho
- Department of Bioengineering and IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Marco P C Marques
- Department of Biochemical Engineering, University College London, London, United Kingdom
| | - Brian O'Sullivan
- Department of Biochemical Engineering, University College London, London, United Kingdom
| | - Fabiana Subrizi
- Department of Chemistry, University College London, London, United Kingdom
| | - Dragana Dobrijevic
- Department of Biochemical Engineering, University College London, London, United Kingdom
| | - John Ward
- Department of Biochemical Engineering, University College London, London, United Kingdom
| | - Helen C Hailes
- Department of Chemistry, University College London, London, United Kingdom
| | - Pedro Fernandes
- Department of Bioengineering and IBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,Faculty of Engineering, Universidade Lusófona de Humanidades e Tecnologias, Lisboa, Portugal
| | | | - Frank Baganz
- Department of Biochemical Engineering, University College London, London, United Kingdom
| | - Nicolas Szita
- Department of Biochemical Engineering, University College London, London, United Kingdom
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18
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Marques MP, Szita N. Bioprocess microfluidics: applying microfluidic devices for bioprocessing. Curr Opin Chem Eng 2017; 18:61-68. [PMID: 29276669 PMCID: PMC5727670 DOI: 10.1016/j.coche.2017.09.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Microfluidic devices as novel bioprocess development tools. Processes with stem cells, microbes and enzymes are viable in microfluidic devices. Microfluidic devices with integrated sensors provide high quality data. Laminar flow enables spatial and temporal control over transport phenomena. Standardization of devices required for automation and industrial uptake.
Scale-down approaches have long been applied in bioprocessing to resolve scale-up problems. Miniaturized bioreactors have thrived as a tool to obtain process relevant data during early-stage process development. Microfluidic devices are an attractive alternative in bioprocessing development due to the high degree of control over process variables afforded by the laminar flow, and the possibility to reduce time and cost factors. Data quality obtained with these devices is high when integrated with sensing technology and is invaluable for scale-translation and to assess the economical viability of bioprocesses. Microfluidic devices as upstream process development tools have been developed in the area of small molecules, therapeutic proteins, and cellular therapies. More recently, they have also been applied to mimic downstream unit operations.
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Affiliation(s)
- Marco Pc Marques
- Department of Biochemical Engineering, University College London, Bernard Katz Building, Gordon Street, London WC1H 0AH, United Kingdom
| | - Nicolas Szita
- Department of Biochemical Engineering, University College London, Bernard Katz Building, Gordon Street, London WC1H 0AH, United Kingdom
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19
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Flow Bioreactors as Complementary Tools for Biocatalytic Process Intensification. Trends Biotechnol 2017; 36:73-88. [PMID: 29054312 DOI: 10.1016/j.tibtech.2017.09.005] [Citation(s) in RCA: 187] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 12/21/2022]
Abstract
Biocatalysis has widened its scope and relevance since new molecular tools, including improved expression systems for proteins, protein and metabolic engineering, and rational techniques for immobilization, have become available. However, applications are still sometimes hampered by low productivity and difficulties in scaling up. A practical and reasonable step to improve the performances of biocatalysts (including both enzymes and whole-cell systems) is to use them in flow reactors. This review describes the state of the art on the design and use of biocatalysis in flow reactors. The encouraging successes of this enabling technology are critically discussed, highlighting new opportunities, problems to be solved and technological advances.
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Gruber P, Marques MPC, Szita N, Mayr T. Integration and application of optical chemical sensors in microbioreactors. LAB ON A CHIP 2017; 17:2693-2712. [PMID: 28725897 DOI: 10.1039/c7lc00538e] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The quantification of key variables such as oxygen, pH, carbon dioxide, glucose, and temperature provides essential information for biological and biotechnological applications and their development. Microfluidic devices offer an opportunity to accelerate research and development in these areas due to their small scale, and the fine control over the microenvironment, provided that these key variables can be measured. Optical sensors are well-suited for this task. They offer non-invasive and non-destructive monitoring of the mentioned variables, and the establishment of time-course profiles without the need for sampling from the microfluidic devices. They can also be implemented in larger systems, facilitating cross-scale comparison of analytical data. This tutorial review presents an overview of the optical sensors and their technology, with a view to support current and potential new users in microfluidics and biotechnology in the implementation of such sensors. It introduces the benefits and challenges of sensor integration, including, their application for microbioreactors. Sensor formats, integration methods, device bonding options, and monitoring options are explained. Luminescent sensors for oxygen, pH, carbon dioxide, glucose and temperature are showcased. Areas where further development is needed are highlighted with the intent to guide future development efforts towards analytes for which reliable, stable, or easily integrated detection methods are not yet available.
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Affiliation(s)
- Pia Gruber
- Department of Biochemical Engineering, University College London, Gower Street, WC1E 6BT, London, UK.
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21
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Nagl S. Micro free-flow isoelectric focusing with integrated optical pH sensors. Eng Life Sci 2017; 18:114-123. [PMID: 32624893 DOI: 10.1002/elsc.201700035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 02/07/2017] [Accepted: 07/13/2017] [Indexed: 01/12/2023] Open
Abstract
Recently, a new observation method for monitoring of pH gradients in microfluidic free-flow electrophoresis has emerged. It is based on the use of chip-integrated fluorescent or luminescent micro sensor layers. These are able to monitor pH gradients in miniaturized separations in real time and spatially resolved; this is particularly useful in isoelectric focusing. Here these multifunctional microdevices that feature continuous separation, monitoring, and in some instances other functionalities, are reviewed. The employed microfabrication procedures to produce these devices are discussed and the different pH sensor matrices that were integrated and their applications in the separation of different types of biomolecules. The procedures for obtaining spatially resolved information about the separated molecules and the pH at the same time and different detection modalities to achieve this such as deep UV fluorescence as well as time-resolved referenced pH sensing and the integration of a precolumn labeling step into these platforms are also highlighted.
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Affiliation(s)
- Stefan Nagl
- Department of Chemistry The Hong Kong University of Science and Technology Kowloon Hong Kong SAR P. R. China
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Gruber P, Marques MPC, O'Sullivan B, Baganz F, Wohlgemuth R, Szita N. Conscious coupling: The challenges and opportunities of cascading enzymatic microreactors. Biotechnol J 2017; 12. [DOI: 10.1002/biot.201700030] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 03/24/2017] [Accepted: 04/05/2017] [Indexed: 12/14/2022]
Affiliation(s)
- Pia Gruber
- Department of Biochemical Engineering; University College London; WC1H 0AH United Kingdom
| | - Marco P. C. Marques
- Department of Biochemical Engineering; University College London; WC1H 0AH United Kingdom
| | - Brian O'Sullivan
- Department of Biochemical Engineering; University College London; WC1H 0AH United Kingdom
| | - Frank Baganz
- Department of Biochemical Engineering; University College London; WC1H 0AH United Kingdom
| | | | - Nicolas Szita
- Department of Biochemical Engineering; University College London; WC1H 0AH United Kingdom
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