| 1. |
- Gustavsson, Robert, 1987-
(författare)
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Development of soft sensors for monitoring and control of bioprocesses
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the manufacture of bio-therapeutics the importance of a well-known process is key for a high product titer and low batch to batch variations. Soft sensors are based on the concept that online sensor signals can be used as inputs to mathematical models to derive new valuable process information. This information could then be used for better monitoring and control of the bioprocess.The aim of the present thesis has been to develop soft sensor solutions for upstream bioprocessing and demonstrate their usefulness in improving robustness and increase the batch-to-batch reproducibility in bioprocesses. The thesis reviews the potential and possibilities with soft sensors for use in production of bio-therapeutics to realize FDA´s process analytical technology (PAT) initiative. Modelling and hardware sensor alternatives which could be used in a soft sensor setup are described and critically analyzed. Different soft sensor approaches to control glucose feeding in fed-batch cultures of Escherichia coli are described. Measurements of metabolic fluxes and specific carbon dioxide production was used as control parameters to increase product yield and decrease the variability of produced recombinant proteins. Metabolic heat signals were used in uninduced cultures to estimate and control the specific growth rate at a desired level and thereby also estimate the biomass concentration online. The introduction of sequential filtering of the signal enabled this method to be used in a down-scaled system. The risk and high impact of contaminations in cell cultures are also described. An in situ microscope (ISM) was used as an online tool to estimate cell concentration and also to determine cell diameter size which enabled the detection of contaminant cells at an early stage.The work presented in this thesis supports the idea that soft sensors can be a useful tool in the strive towards robust and reliable bioprocesses, to ensure high product quality and increased economic profit.
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| 2. |
- Andersson, Henrik, et al.
(författare)
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Assaying cardiac biomarkers for toxicity testing using biosensing and cardiomyocytes derived from human embryonic stem cells
- 2010
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Ingår i: JOURNAL OF BIOTECHNOLOGY. - : Elsevier Science B.V., Amsterdam.. - 0168-1656 .- 1873-4863. ; 150:1, s. 175-181
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Tidskriftsartikel (refereegranskat)abstract
- Human embryonic stem cell (hESC) derived cardiomyocytes are in the present study being used for testing drug-induced cardiotoxicity in a biosensor set-up. The design of an in vitro testing alternative provides a novel opportunity to surpass previous methods based on rodent cells or cell lines due to its significantly higher toxicological relevance. In this report we demonstrate how hESC-derived cardiomyocytes release detectable levels of two clinically decisive cardiac biomarkers, cardiac troponin T and fatty acid binding protein 3, when the cardiac cells are exposed to the well-known cardioactive drug compound. doxorubicin. The release is monitored by the immuno-biosensor technique surface plasmon resonance, particularly appropriate due to its capacity for parallel and high-throughput analysis in complex media.
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| 3. |
- Bachinger, T., et al.
(författare)
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Electronic nose for estimation of product concentration in mammalian cell cultivation
- 2000
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Ingår i: Bioprocess engineering (Berlin. Print). - : Springer Science and Business Media LLC. - 0178-515X .- 1432-0797 .- 1615-7591. ; 23:6, s. 637-642
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Tidskriftsartikel (refereegranskat)abstract
- The off-gas composition from perfusion cultivation of a CHO-cell line producing recombinant human blood coagulation Factor VIII is monitored with an electronic nose. It is shown that the electronic nose in combination with an artificial neural network can be used for on-line estimation of the Factor VIII concentration in production-scale cultivations. The obtained prediction error (1s) for the Factor VIII concentration was 1.1 IU/ml. The potential of the electronic nose for estimation of viable cell count is outlined in laboratory-scale Factor VIII cultivations. The obtained prediction error (1s) for the viable cell count was 0.4 ╫ 106 cells/ml. The results show that this non-invasive method is potentially useful for on-line bioprocess monitoring.
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| 4. |
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| 5. |
- Bachinger, T., et al.
(författare)
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Physiologically motivated monitoring of fermentation processes by means of an electronic nose
- 2001
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Ingår i: Chemical Engineering & Technology. - 0930-7516 .- 1521-4125. ; 24:7, s. 33-42
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Tidskriftsartikel (refereegranskat)abstract
- An on-line approach of non-invasive monitoring of the physiological changes in fermentation processes is presented. In yeast batch and bacterial fed-batch fermentations it is shown that metabolic state changes can be revealed using an electronic nose. The transient responses of the gas sensors to the changes in the composition of the volatiles emitted from the cell cultures during fermentation are used to retrieve a semi-quantitative representation of the physiological state of the cultures. With the sensor responses of the electronic nose it is shown that physiological variables such as rates of growth, substrate uptake and product formation can be depicted. The non-invasive method thus seems as a pertinent alternative to conventional bioreactor monitoring methods.
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| 6. |
- Bachinger, Th, et al.
(författare)
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Searching for process information in the aroma of cell cultures
- 2000
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Ingår i: Trends in Biotechnology. - 0167-7799 .- 1879-3096. ; 18:12, s. 494-500
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Tidskriftsartikel (refereegranskat)abstract
- Aroma emissions from living cells can provide valuable information about the metabolic and physiological condition of those cells. Electronic noses are chemical gas-sensor arrays that use artificial neural network models to evaluate aromas. They can interpret the complex aroma information emitted from cultures of bacteria, yeast cells and animal cells. Potential applications for electronic noses range from medical diagnosis to industrial bioprocessing. Copyright (C) 2000 Elsevier Science Ltd.
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| 7. |
- Bengtsson, Katarina, 1985-, et al.
(författare)
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A clip-on electroosmotic pump for oscillating flow in microfluidic cell culture devices
- 2018
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Ingår i: Microfluidics and Nanofluidics. - : Springer Berlin/Heidelberg. - 1613-4982 .- 1613-4990. ; 22:3
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in microfluidic devices put a high demand on small, robust and reliable pumps suitable for high-throughput applications. Here we demonstrate a compact, low-cost, directly attachable (clip-on) electroosmotic pump that couples with standard Luer connectors on a microfluidic device. The pump is easy to make and consists of a porous polycarbonate membrane and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) electrodes. The soft electrode and membrane materials make it possible to incorporate the pump into a standard syringe filter holder, which in turn can be attached to commercial chips. The pump is less than half the size of the microscope slide used for many commercial lab-on-a-chip devices, meaning that these pumps can be used to control fluid flow in individual reactors in highly parallelized chemistry and biology experiments. Flow rates at various electric current and device dimensions are reported. We demonstrate the feasibility and safety of the pump for biological experiments by exposing endothelial cells to oscillating shear stress (up to 5 dyn/cm2) and by controlling the movement of both micro- and macroparticles, generating steady or oscillatory flow rates up to ± 400 μL/min.
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| 8. |
- Brandgård, J., et al.
(författare)
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Monitoring growth of the methanogenic archaea Methanobacterium formicicum using an electronic nose
- 2001
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Ingår i: Biotechnology letters. - 0141-5492 .- 1573-6776. ; 23:4, s. 241-248
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Tidskriftsartikel (refereegranskat)abstract
- Growth of the methanogenic archaea, Methanobacterium formicicum, in pure culture was monitored by analysing samples from the gas phase with an array of chemical gas sensors (an 'electronic nose'). Analyses of the methane and protein formation rates were used as independent parameters of growth, and the data obtained from the electronic nose were evaluated using principal component analysis (PCA). We found that different growth phases can be distinguished with the electronic nose followed by PCA evaluation. The fast response of the sensors in combination with the high correlations with other parameters measuring growth show that the electronic nose can be a useful tool to rapidly determine methanogenic growth.
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| 9. |
- Christoffersson, Jonas, 1986-, et al.
(författare)
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A Cardiac Cell Outgrowth Assay for Evaluating Drug Compounds Using a Cardiac Spheroid-on-a-Chip Device
- 2018
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Ingår i: Bioengineering. - : MDPI AG. - 2306-5354. ; 5:2, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional (3D) models with cells arranged in clusters or spheroids have emerged as valuable tools to improve physiological relevance in drug screening. One of the challenges with cells cultured in 3D, especially for high-throughput applications, is to quickly and non-invasively assess the cellular state in vitro. In this article, we show that the number of cells growing out from human induced pluripotent stem cell (hiPSC)-derived cardiac spheroids can be quantified to serve as an indicator of a drug’s effect on spheroids captured in a microfluidic device. Combining this spheroid-on-a-chip with confocal high content imaging reveals easily accessible, quantitative outgrowth data. We found that effects on outgrowing cell numbers correlate to the concentrations of relevant pharmacological compounds and could thus serve as a practical readout to monitor drug effects. Here, we demonstrate the potential of this semi-high-throughput “cardiac cell outgrowth assay” with six compounds at three concentrations applied to spheroids for 48 h. The image-based readout complements end-point assays or may be used as a non-invasive assay for quality control during long-term culture.
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| 10. |
- Christoffersson, Jonas, 1986-, et al.
(författare)
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Fabrication of modular hyaluronan-PEG hydrogels to support 3D cultures of hepatocytes in a perfused liver-on-a-chip device
- 2019
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Ingår i: Biofabrication. - : Institute of Physics (IOP). - 1758-5082 .- 1758-5090. ; 11:1, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Liver cell culture models are attractive in both tissue engineering and for development of assays for drug toxicology research. To retain liver specific cell functions, the use of adequate cell types and culture conditions, such as a 3D orientation of the cells and a proper supply of nutrients and oxygen, are critical. In this article, we show how extracellular matrix mimetic hydrogels can support hepatocyte viability and functionality in a perfused liver-on-a-chip device. A modular hydrogel system based on hyaluronan and poly(ethylene glycol) (HA-PEG), modified with cyclooctyne moieties for bioorthogonal strain-promoted alkyne-azide 1, 3-dipolar cycloaddition (SPAAC), was developed, characterized, and compared for cell compatibility to hydrogels based on agarose and alginate. Hepatoma cells (HepG2) formed spheroids with viable cells in all hydrogels with the highest expression of albumin and urea in alginate hydrogels. By including an excess of cyclooctyne in the HA backbone, azide-modified cell adhesion motifs (linear and cyclic RGD peptides) could be introduced in order to enhance viability and functionality of human induced pluripotent stem cell derived hepatocytes (hiPS-HEPs). In the HA-PEG hydrogels modified with cyclic RGD peptides hiPS-HEPs migrated and grew in 3D and showed an increased viability and higher albumin production compared to when cultured in the other hydrogels. This flexible SPAAC crosslinked hydrogel system enabled fabrication of perfused 3D cell culture of hiPS-HEPs and is a promising material for further development and optimization of liver-on-a-chip devices.
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| 11. |
- Christoffersson, Jonas, 1986-
(författare)
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Organs-on-chips for the pharmaceutical development process : design perspectives and implementations
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organs-on-chips are dynamic cell culture devices created with the intention to mimic organ function in vitro. Their purpose is to assess the toxicity and efficacy of drugs and, as early as possible in the pharmaceutical development process, predict the outcome of clinical trials. The aim of this thesis is to explain and discuss these cell culture devices from a design perspective and to experimentally exemplify some of the specific functions that characterize organs-on-chips.The cells in our body reside in complex environments with chemical and mechanical cues that affect their function and purpose. Such a complex environment is difficult to recreate in the laboratory and has therefore been overlooked in favor of more simple models, i.e. static twodimensional (2D) cell cultures. Numerous recent reports have shown cell culture systems that can resemble the cell’s natural habitat and enhance cell functionality and thereby potentially provide results that better reflects animal and human trials. The way these organs-on-chips improve in vitro cell culture assays is to include e.g. a three-dimensional cell architecture (3D), mechanical stimuli, gradients of oxygen or nutrients, or by combining several relevant cell types that affect each other in close proximity.The research conducted for this thesis shows how cells in 3D spheroids or in 3D hydrogels can be cultured in perfused microbioreactors. Furthermore, a pump based on electroosmosis, and a method for an objective conceptual design process, is introduced to the field of organs-on-chips.
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| 12. |
- Cimander, C., et al.
(författare)
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Assessment of the performance of a fed-batch cultivation from the preculture quality using an electronic nose
- 2002
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Ingår i: Biotechnology progress (Print). - : Wiley. - 8756-7938 .- 1520-6033. ; 18:2, s. 380-386
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Tidskriftsartikel (refereegranskat)abstract
- An electronic nose, a gas-phase multisensor system, was used to monitor precultivations of a recombinant tryptophan-producing Escherichia coli strain. The electronic nose signals showed a high correlation toward the main stages of the precultivations, namely, exponential growth, oxygen-limited growth, and glucose depletion. Principal component analysis (PCA) of the electronic nose signals was performed and shown to be useful for monitoring preculture progression. More importantly, PCA also allowed a qualitative assessment of the preculture performance during subsequent fed-batch cultivations. The electronic nose signals from the precultures showed, furthermore, a high correlation to the time of phosphate limitation and the tryptophan yield coefficient of the subsequent fed-batch cultivations, which allowed an accurate prediction of these process variables using partial least squares (PLS). The results demonstrate on data from 12 cultivations how the electronic nose can be a useful tool for the assessment of inoculum quality, thereby providing means of reducing batch-to-batch variation and increasing the productivity of bioprocesses.
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| 13. |
- Cimander, Christian, et al.
(författare)
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Bioprocess control from a multivariate process trajectory.
- 2004
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Ingår i: Bioprocess and biosystems engineering (Print). - : Springer Science and Business Media LLC. - 1615-7591 .- 1615-7605. ; 26:6, s. 401-411
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Tidskriftsartikel (refereegranskat)abstract
- A multivariate bioprocess control approach, capable of tracking a pre-set process trajectory correlated to the biomass or product concentration in the bioprocess is described. The trajectory was either a latent variable derived from multivariate statistical process monitoring (MSPC) based on partial least squares (PLS) modeling, or the absolute value of the process variable. In the control algorithm the substrate feed pump rate was calculated from on-line analyzer data. The only parameters needed were the substrate feed concentration and the substrate yield of the growth-limiting substrate. On-line near-infrared spectroscopy data were used to demonstrate the performance of the control algorithm on an Escherichia coli fed-batch cultivation for tryptophan production. The controller showed good ability to track a defined biomass trajectory during varying process dynamics. The robustness of the control was high, despite significant external disturbances on the cultivation and control parameters.
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| 14. |
- Cimander, C., et al.
(författare)
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Online monitoring of a bioprocess based on a multi-analyser system and multivariate statistical process modelling
- 2002
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Ingår i: Journal of chemical technology and biotechnology (1986). - : Wiley. - 0268-2575 .- 1097-4660. ; 77:10, s. 1157-1168
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Tidskriftsartikel (refereegranskat)abstract
- Multivariate statistical process control (MSPC) was for the first time applied to analyse data from a bioprocess on-line multi-analyser system consisting of an electronic nose (EN), a near-infrared spectroscope (NIRS), a mass spectrometer (MS) and standard bioreactor probes. One hundred and fifty sensor signals from the electronic nose, 1050 wavelength signals from the NIRS, carbon dioxide evolution rate calculated from mass spectrometer signals and standard bioreactor data (eg amount of substrate fed) were interrogated for their ability to model a bioprocess using MSPC. The models obtained were validated on a recombinant Escherichia coli fed-batch process for tryptophan production. Limiting trajectories were defined in the MSPC models for warning, action, and process experience with respect to biomass and tryptophan concentrations. The results showed the capacity and robustness of MSPC models for monitoring with multi-analysers and allowed a comparison of the different analysers' suitability for this kind of data processing. Furthermore, the results demonstrate that MSPC models provide a functional and versatile framework for coping with large information flows and are also suited to a variety of other bioprocessing monitoring and control tasks. ⌐ 2002 Society of Chemical Industry.
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| 15. |
- Cimander, C., et al.
(författare)
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Sensor fusion for on-line monitoring of yoghurt fermentation
- 2002
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Ingår i: Journal of Biotechnology. - 0168-1656 .- 1873-4863. ; 99:3, s. 237-248
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Tidskriftsartikel (refereegranskat)abstract
- Measurement data from an electronic nose (EN), a near-infrared spectrometer (NIRS) and standard bioreactor probes were used to follow the course of lab-scale yoghurt fermentation. The sensor signals were fused using a cascade neural network: a primary network predicted quantitative process variables, including lactose, galactose and lactate, a secondary network predicted a qualitative process state variable describing critical process phases, such as the onset of coagulation or the harvest time. Although the accuracy of the neural network prediction was acceptable and comparable with the off-line reference assay, its stability and performance were significantly improved by correction of faulty data. The results demonstrate that on-line sensor fusion with the chosen analyzers improves monitoring and quality control of yoghurt fermentation with implications to other fermentation processes. ⌐ 2002 Elsevier Science B.V. All rights reserved.
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| 16. |
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| 17. |
- Ivansson, D., et al.
(författare)
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Quantitation of intracellular recombinant human superoxide dismutase using surface plasmon resonance
- 2002
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Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 456:2, s. 193-200
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Tidskriftsartikel (refereegranskat)abstract
- An immunosensor assay for the quantitation of intracellular recombinant human superoxide dismutase (rhSOD) in Escherichia coli cultivations based on detection with surface plasmon resoance (SPR) is described. A monoclonal antibody for rhSOD was immobilized on a SPR dextran gold chip. Bacterial samples were sonicated and centrifugated prior to injection over the antibody chip for SPR detection. The assay time was 7min and allowed quantitation in the range of 1-64nM SOD in lysate samples with a precision of 1.1-3.4%. The assay was applied to monitor the concentration of rhSOD during E. coli bioreactor cultivations where the rhSOD production was induced by iso-propyl-b-D-thiogalactoside (IPTG). The assay allowed accurate monitoring of the production of rhSOD where the important phases in the product formation were possible to see. The report also discusses influence from sample preparation, SPR selectivity and sensitivity and quantitation limits. The assay proved to be fast, sensitive and accurate with low background effects from the dextran matrix of the SPR chip. ⌐ 2002 Published by Elsevier Science B.V.
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| 18. |
- Jungar, Christina, et al.
(författare)
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Analysis of carbohydrates using liquid chromatography-surface plasmon resonance immunosensing systems
- 2000
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 281:2, s. 151-158
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Tidskriftsartikel (refereegranskat)abstract
- An immunosensing system based on surface plasmon resonance (SPR) was used for on-line detection and characterization of carbohydrate molecules separated by high-performance liquid chromatography. These analytes, with or without serum, were continuously separated and analyzed in the combined liquid chromatography-surface plasmon resonance (LC-SPR) system. By using weak and readily reversible monoclonal antibodies, the SPR system allowed specific on-line monitoring of the substances. To increase the specificity of the immunosensor, nonrelevant antibodies were used as reference in a serial flow cell. The sensitivity of the LC-SPR system was dependent on molecular weight of the carbohydrate, affinity of binding, and design of the sensor. (C) 2000 Academic Press.
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| 19. |
- Jungar, Christina, et al.
(författare)
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Neoglycoconjugates as affinity ligands in surface plasmon resonance analysis
- 2001
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Ingår i: Analytica Chimica Acta. - 0003-2670 .- 1873-4324. ; 449:1-2, s. 51-58
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Tidskriftsartikel (refereegranskat)abstract
- Neoglycoconjugates, i.e. de novo synthesized conjugates of glycosides and carrier molecules such as proteins or polylipids, were used as affinity ligands in a surface plasmon resonance (SPR) biosensor assay. The affinity of the glycoconjugates, normally in the lower affinity range, was influenced by increasing the number of glycosides bound per carrier protein, the coupling chemistry, and the assay temperature. As a model system, albumin-conjugated A- and B-active blood group oligosaccharides with suitable linker molecules were chosen. Specific monoclonal antibodies were used as analytes to verify the interactive performance. Affinity kinetics of the systems were evaluated from the SPR biosensor data. The results demonstrate that neoglycoconjugates are a good alternative in presenting affinity ligands of small, specific molecules in SPR-based assays with retained specificity and bioavailability. ⌐ 2001 Elsevier Science B.V. All rights reserved.
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| 20. |
- Komaraiah, P., et al.
(författare)
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Enhancement of anthraquinone accumulation in Morinda citrifolia suspension cultures
- 2005
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Ingår i: Plant Science. - : Elsevier BV. - 0168-9452 .- 1873-2259. ; 168:5, s. 1337-1344
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Tidskriftsartikel (refereegranskat)abstract
- Enhancement of accumulation of anthraquinones in Morinda citrifolia (Noni fruit) suspension cultures was accomplished by treatment with elicitors, by ultrasonication and by controlled feeding of the carbon source in the growth medium. The elicitation was attained by additions of polyunsaturated fatty acids (linoleic acid, α-linolenic acid, arachidonic acid), methyl jasmonate, salicylate and nitric oxide (by addition of sodium nitroprusside to the medium) at different concentrations. The accumulation of anthraquinones in the elicited cultures ranged from 5 to 12 mg/g dry weight of cells, which was two to three-fold of what was attained in control cultures. Treatment by short pulses of ultrasonication enhanced the accumulation up to 2.5-fold after 16 s of sonication. A synergistic effect was achieved by simultaneously applying elicitation and controlled addition of sucrose, that increased the anthraquinone production to 16.74 mg/g of dry weight, which was more than a four-fold increase above the control cultures. The accumulation of the anthraquinones in the M. citrifolia cells was confirmed by confocal laser fluorescence microscopy. Minor fluorescence was observed from the cells in the lag phase (1-3 days), while substantially higher fluorescence was observed at late exponential and stationary phase (10-14 days). Rounder spherical cells emitted less fluorescence than elongated slender cells. The fluorescence was assumed to be a result of autofluorescent properties of the aromatic anthraquinone molecules. © 2005 Elsevier Ireland Ltd. All rights reserved.
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| 21. |
- Kreij, Karl, 1975-, et al.
(författare)
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On-line detection of microbial contaminations in animal cell reactor cultures using an electronic nose device
- 2005
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Ingår i: Cytotechnology (Dordrecht). - : Springer Science and Business Media LLC. - 0920-9069 .- 1573-0778. ; 48:1-3, s. 41-58
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Tidskriftsartikel (refereegranskat)abstract
- An electronic nose (EN) device was used to detect microbial and viral contaminations in a variety of animal cell culture systems. The emission of volatile components from the cultures accumulated in the bioreactor headspace, was sampled and subsequently analysed by the EN device. The EN, which was equipped with an array of 17 chemical gas sensors of varying selectivity towards the sampled volatile molecules, generated response patterns of up to 85 computed signals. Each 15 or 20 min a new gas sample was taken generating a new response pattern. A software evaluation tool visualised the data mainly by using principal component analysis. The EN was first used to detect microbial contaminations in a Chinese hamster ovary (CHO) cell line producing a recombinant human macrophage colony stimulating factor (rhM-CSF). The CHO cell culture was contaminated by Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida utilis which all were detected. The response patterns from the CHO cell culture were compared with monoculture references of the microorganisms. Second, contaminations were studied in an Sf-9 insect cell culture producing another recombinant protein (VP2 protein). Contaminants were detected from E. coli, a filamentous fungus and a baculovirus. Third, contamination of a human cell line, HEK-293, infected with E. coli exhibited comparable results. Fourth, bacterial contaminations could also be detected in cultures of a MLV vector producer cell line. Based on the overall experiences in this study it is concluded that the EN method has in a number of cases the potential to be developed into a useful on-line contamination alarm in order to support safety and economical operation for industrial cultivation. © Springer 2005.
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| 22. |
- Lidén, H., et al.
(författare)
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On-line determination of non-volatile or low-concentration metabolites in a yeast cultivation using an electronic nose
- 2000
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Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 125:6, s. 1123-1128
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Tidskriftsartikel (refereegranskat)abstract
- An electronic nose was used for on-line gas phase monitoring of key metabolites in a Saccharomyces cerevisiae cultivation. The metabolites were either non-volatile or present at very low concentrations and therefore not detectable in the gas phase by the sensors in the electronic nose. It was found that it is still possible to make a prediction based on the off-gas emission. Artificial neural networks (ANNs) were trained using data acquired by the gas sensors and reference data obtained from on-line HPLC analyses, from a total of six cultivations to estimate concentrations of the metabolites glucose, glycerol, acetate and acetaldehyde. The ANNs were subsequently validated on an independent set of cultivation data resulting in a prediction accuracy described by the root mean square error (RMSE) of 0.13 (in the range 0-7.33), 0.015 (0.08-0.15), 0.012 (0-0.20) and 0.004 (0-0.11) g L-1, respectively. Data from a cultivation with higher initial glucose concentration were added to the original data and the extended set was used for training an ANN to determine concentration variables at higher concentration ranges than in the first study. The RMSE was 1.2 (0-9.31), 0.016 (0.09-0.20), 0.026 (0-0.19) and 0.010 (0-0.15) g L-1, respectively, when validating the ANNs.
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| 23. |
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| 24. |
- Mandenius, Carl-Fredrik, 1954-, et al.
(författare)
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Monitoring of influenza virus hemagglutinin in process samples using weak affinity ligands and surface plasmon resonance
- 2008
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Ingår i: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 623, s. 66-75
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Tidskriftsartikel (refereegranskat)abstract
- Surface plasmon resonance (SPR) was used to screen the interaction between a variety of affinity ligands and hemagglutinin (HA) from human influenza virus, with the aim of identifying low affinity ligands useful for the development of a rapid bioanalytical sensor. Three sialic acid-based structures and four lectins were evaluated as sensor ligands. The sialic acid-based ligands included a natural sialic acid-containing glycoprotein, human α1-acid glycoprotein (α1-AGP), and two synthetic 6′-sialyllactose-conjugates, with varying degree of substitution. The interaction of HA with the four lectin-based ligands, concanavalin A (Con A), wheat germ agglutinin (WGA), Maackia amurensis lectin (MAL), and Sambucus nigra agglutinin (SNA), showed a wide variation of affinity strengths. Affinity and kinetics data were estimated. Strong affinities were observed for Con A, WGA, α1-AGP, and a 6′-sialyllactose-conjugate with a high substitution degree, and low affinities were observed for MAL and a 6′-sialyllactose-conjugate with low substitution. The main objective, to identify a low affinity ligand which could be used for on-line monitoring and product quantification, was met by a 6′-sialyllactose–ovalbumin conjugate that had 0.6 mol ligand per mol carrier protein. The apparent affinity of this ligand was estimated to be 1.5 ± 0.03 μM (KD) on the SPR surface. Vaccine process samples containing HA were analyzed in the range 10–100 μg HA mL−1 and correlated with single-radial immunodiffusion. The coefficient of variation on the same chip was between 0.010 and 0.091.
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| 25. |
- Mandenius, Carl-Fredrik, 1954-
(författare)
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The role of PAT in Biotechnology
- 2006
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Ingår i: European pharmaceutical review. - 1360-8606. ; 3, s. 69-76
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Tidskriftsartikel (refereegranskat)
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| 26. |
- Navratil, M., et al.
(författare)
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On-line multi-analyzer monitoring of biomass, glucose and acetate for growth rate control of a Vibrio cholerae fed-batch cultivation
- 2005
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 115:1, s. 67-79
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Tidskriftsartikel (refereegranskat)abstract
- In situ near-infrared (NIR) spectroscopy and in-line electronic nose (EN) mapping were used to monitor and control a cholera-toxin producing Vibrio cholerae fed-batch cultivation carried out with a laboratory method as well as with a production method. Prediction models for biomass, glucose and acetate using NIR spectroscopy were developed based on spectral identification and partial-least squares (PLS) regression resulting in high correlation to reference data (standard errors of prediction for biomass, glucose and acetate were 0.20 g l-1, 0.26 g l-1 and 0.28 g l-1). A compensation algorithm for aerated bioreactor disturbances was integrated in the model computation, which in particular improved the prediction by the biomass model. First, the NIR data were applied together with EN in-line data selected by principal component analysis (PCA) for generating a trajectory representation of the fed-batch cultivation. A correlation between the culture progression and EN signals was demonstrated, which proved to be beneficial in monitoring the culture quality. It was shown that a deviation from a normal cultivation behavior could easily be recognized and that the trajectory was able to alarm a bacterial contamination. Second, the NIR data indicated the potential of predicting the concentration of formed cholera toxin with a model prediction error of 0.020 g l-1. Third, the on-line biomass prediction based on the NIR model was used to control the overflow metabolism acetate formation of the V. cholerae culture. The controller compared actual specific growth rate as estimated from the prediction with the critical acetate formation growth rate, and from that difference adjusted the glucose feed rate. © 2004 Elsevier B.V. All rights reserved.
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| 27. |
- Randek, Judit, 1990-
(författare)
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Advancement of sensor technology for monitoring and control of upstream bioprocesses
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In bioprocesses, the upstream process part with cultivation and harvesting steps has decisive influence on the final process outcome, including the quality of the product, the productivity and the yield. To ensure stable product quality of biopharmaceuticals, the U.S. Food and Drug Administration (FDA) encourages the industry to apply the process analytical technology (PAT) guidelines. These guidelines strongly recommend advancements in sensor monitoring and control technology as the important means for improving performance of pharmaceutical manufacturing.The aim of this thesis is to contribute to this advancement of sensor technology, by proposing alternative ways to apply existing sensors for monitoring and control of upstream bioprocesses. Cutting-edge sensor technologies are evaluated with respect to their suitability for process monitoring of critical process parameters. The sensor technologies are compared with other analytical techniques, mainly based on their performance and applicability for monitoring as well as control of common bioprocesses.To cover diverse bioprocess conditions and requirements, a range of organisms, including bacteria, yeast and mammalian cells, have been used in the thesis. Through this, different needs, obstacles and challenges have been unraveled when culturing these organisms. One of these challenges is the wide span of growth rates of the cells used in production, which limits the number of the sensor technologies that are suitable for accomplishing efficient process monitoring and control. The mammalian cells for example, grow at a low rate, and may therefore allow the use of an at-line measurement technology as the presented screen-printed single-use enzyme biosensor for monitoring of metabolite formation. On the contrary, rapidly growing microorganisms, for example bacteria and yeasts, require faster analytical techniques, such as the in-line capacitance and near-infrared sensors used in the presented studies.This thesis emphasizes the current needs and the importance of providing new and more advanced sensor technology for upstream bioprocess monitoring. The parallel advancements of bioreactor designs, with both stainless steel and disposable bioreactors, further emphasizes the need for a high degree of adaptability of the sensors. As highlighted in the thesis, the advancement of the sensors should also contribute to improve process stability and quality of the product by applying process control methods that efficiently can handle unexpected variations in biological production systems.
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| 28. |
- Randek, Judit, 1990-, et al.
(författare)
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In situ scanning capacitance sensor with spectral analysis reveals morphological states in cultures for production of biopharmaceuticals
- 2020
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 313
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Tidskriftsartikel (refereegranskat)abstract
- In situ capacitance sensing is shown to be capable of monitoring critical morphological changes in industrial cultures by analyzing the sensor’s frequency spectrum. Scanning the frequency of an alternating current between the electrodes of a capacitance sensor, placed in a cell culture, allowed detection of the size change of microbial cells from shifts in the spectra. The frequency was scanned between 0.1–15 MHz and cell size was measured from 1 to 20 μm. The analysis of the spectra was verified with two recombinant strains, one producing human insulin and another Green Fluorescence Protein (GFP). Both the insulin and GFP cultivations were carried out in 6 L fed-batch bioreactors using typical industrial procedures. The spectral analysis provided critical information about the changes in the size of the cells. It is suggested that this information may have high relevance for a better assessment of the state of cultivations producing proteins, for optimization and for improving the economy of large-scale biopharmaceutical production.
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| 29. |
- Randek, Judit, 1990-, et al.
(författare)
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On-line soft sensing in upstream bioprocessing
- 2018
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Ingår i: Critical reviews in biotechnology. - : TAYLOR & FRANCIS LTD. - 0738-8551 .- 1549-7801. ; 38:1, s. 106-121
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Forskningsöversikt (refereegranskat)abstract
- This review provides an overview and a critical discussion of novel possibilities of applying soft sensors for on-line monitoring and control of industrial bioprocesses. Focus is on bio-product formation in the upstream process but also the integration with other parts of the process is addressed. The term soft sensor is used for the combination of analytical hardware data (from sensors, analytical devices, instruments and actuators) with mathematical models that create new real-time information about the process. In particular, the review assesses these possibilities from an industrial perspective, including sensor performance, information value and production economy. The capabilities of existing analytical on-line techniques are scrutinized in view of their usefulness in soft sensor setups and in relation to typical needs in bioprocessing in general. The review concludes with specific recommendations for further development of soft sensors for the monitoring and control of upstream bioprocessing.
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| 30. |
- Roch, Patricia, 1988-
(författare)
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Monitoring of product variants in biopharmaceutical downstream processing : Mechanistic and data-driven modeling approaches
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the manufacturing of biopharmaceuticals, a multistep purification strategy is employed to remove process-related impurities and product variants, to achieve high product quality, assuring patients’ safety. To guarantee that biopharmaceuticals are safe and to accomplish quality, strict policies were established by regulatory agencies as well as guiding principles, such as Quality by Design and process analytical technology. To make the manufacturing process economical, relatively high product yield and productivity are also desirable.The removal of product variants often poses a challenge in downstream processing due to their structural similarity to the product resulting in similar behavior. One way of overcoming this issue is to employ additional monitoring tools capable to distinguish between the product and product variants.This thesis demonstrates the development of novel monitoring tools, based on existing monitoring and modeling approaches, to facilitate downstream processing.Existing techniques are evaluated and critically compared toward meeting the requirements on monitoring quality attributes in downstream processing.A mechanistic model-based monitoring tool was established for a reversed phase chromatography polishing step of insulin to predict the elution profile of insulin and two insulin variants. By relying on model-based monitoring a significant increase in product yield was achieved.Further, multi-wavelength fluorescence spectroscopy coupled with the multi-way algorithm parallel factor analysis was utilized to monitor product variants of biopharmaceuticals in downstream processing. This monitoring tool capitalizes on a shift in fluorescence emission between the product and its variant. Developed for monitoring aggregates during antibody purification, the transferability of the approach to other relevant biopharmaceuticals, such as factor VIII and erythropoietin, has been confirmed.The monitoring tools developed in this thesis, extend existing monitoring tools for downstream processing of biopharmaceuticals. When implementing these monitoring tools into the different phases of biopharmaceuticals’ lifespan, their potential could range from optimizing downstream processes during purification strategy development to supporting manufacturing by facilitating process decisions.
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| 31. |
- Skoglund, A., et al.
(författare)
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Applying process monitoring with multivariate analysis through a knowledge-based systems approach to a paperboard machine
- 2005
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Ingår i: Computers in industry (Print). - : Elsevier BV. - 0166-3615 .- 1872-6194. ; 56:5, s. 472-478
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Tidskriftsartikel (refereegranskat)abstract
- The utility of multivariate statistical process control (MSPC) in the process industry can be further improved by applying knowledge-based systems (KBS) principles. First, the extensive volumes of process data generated in a production process can be pre-assessed by the KBS according to set rules. Second, the KBS can make a selection between various MSPC model alternatives. Third, the KBS may support the plant operators when evaluating the MSPC output results. This is shown in this preliminary study where a KBS was applied to an existing MSPC application on a paperboard machine. It is suggested that these experiences may also successfully be applied with other continuous processes in the manufacturing industry. © 2005 Published by Elsevier B.V.
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| 32. |
- Skoglund, A., et al.
(författare)
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Comparison between linear and nonlinear prediction models for monitoring of a paperboard machine
- 2002
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Ingår i: Chemical Engineering & Technology. - 0930-7516 .- 1521-4125. ; 25:2, s. 197-202
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Tidskriftsartikel (refereegranskat)abstract
- Data from a paperboard machine were used to compare the performance of linear partial least squares (PLS) and nonlinear feed-forward neural network (FFNN) modeling of a continuous process. Fifteen selected variables were used as input parameters to the models, while the quality class of the manufactured product was the output response. The models were validated with external data different to those used in the design of the models. Evaluation with root mean square error of prediction (RMSEP) showed that the FFNN models were better for prediction than the PLS models. For monitoring, however, the PLS models detected deviations from normal settings in the paperboard machine more sensitively than the FFNN models. It is suggested that these findings have general relevance to other continuous processes in manufacturing industries too.
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| 33. |
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| 34. |
- Skoglund, A., et al.
(författare)
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Multivariate process model for grade change in a paperboard machine
- 2000
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 15:3, s. 183-188
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a practical approach to making stable multivariate models for on-line applications, which is illustrated with data from paperboard manufacturing. A partial least squares regression model was designed for two products and the grade change between them in a paperboard machine. The model was set up from historical data that covered the process from stock preparation to calendering. Validation of the model was performed with grade changes that was not in the model, which resulted in good predictions. An example is also given that describes the ability of the model to detect process disturbances.
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| 35. |
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| 36. |
- Theuer, Lorentz, et al.
(författare)
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Single-use printed biosensor for l-lactate and its application in bioprocess monitoring
- 2020
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Ingår i: Processes. - : MDPI AG. - 2227-9717. ; 8:3
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Tidskriftsartikel (refereegranskat)abstract
- There is a profound need in bioprocess manufacturing for low-cost single-use sensors that allow timely monitoring of critical product and production attributes. One such opportunity is screen-printed enzyme-based electrochemical sensors, which have the potential to enable low-cost online and/or off-line monitoring of specific parameters in bioprocesses. In this study, such a singleuse electrochemical biosensor for lactate monitoring is designed and evaluated. Several aspects of its fabrication and use are addressed, including enzyme immobilization, stability, shelf-life and reproducibility. Applicability of the biosensor to off-line monitoring of bioprocesses was shown by testing in two common industrial bioprocesses in which lactate is a critical quality attribute (Corynebacterium fermentation and mammalian Chinese hamster ovary (CHO) cell cultivation). The specific response to lactate of the screen-printed biosensor was characterized by amperometric measurements. The usability of the sensor at typical industrial culture conditions was favorably evaluated and benchmarked with commonly used standard methods (HPLC and enzymatic kits). The single-use biosensor allowed fast and accurate detection of lactate in prediluted culture media used in industrial practice. The design and fabrication of the biosensor could most likely be adapted to several other critical bioprocess analytes using other specific enzymes. This makes this single-use screen-printed biosensor concept a potentially interesting and versatile tool for further applications in bioprocess monitoring. © 2020 by the authors.
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| 37. |
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| 38. |
- Tran, Thuy, 1980-, et al.
(författare)
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Nanoplasmonic Avidity-Based Detection and Quantification of IgG Aggregates
- 2022
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Ingår i: Analytical Chemistry. - : AMER CHEMICAL SOC. - 0003-2700 .- 1520-6882. ; 94:45, s. 15754-15762
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Tidskriftsartikel (refereegranskat)abstract
- Production of therapeutic monoclonal antibodies (mAbs) is a complex process that requires extensive analytical and bioanalytical characterization to ensure high and consistent product quality. Aggregation of mAbs is common and very problematic and can result in products with altered pharmacodynamics and pharmacokinetics and potentially increased immunogenicity. Rapid detection of aggregates, however, remains very challenging using existing analytical techniques. Here, we show a real-time and label-free fiber optical nanoplasmonic biosensor system for specific detection and quantification of immunoglobulin G (IgG) aggregates exploiting Protein A mediated avidity effects. Compared to monomers, IgG aggregates were found to have substantially higher apparent affinity when binding to Protein Afunctionalized sensor chips in a specific pH range (pH 3.8-4.0). Under these conditions, aggregates and monomers showed significantly different binding and dissociation kinetics. Reliable and rapid aggregate quantification was demonstrated with a limit of detection (LOD) and limit of quantification (LOQ) of about 9 and 30 mu g/mL, respectively. Using neural network-based curve fitting, it was further possible to simultaneously quantify monomers and aggregates for aggregate concentrations lower than 30 mu g/mL. Our work demonstrates a unique avidity-based biosensor approach for fast aggregate analysis that can be used for rapid at-line quality control, including lot/batch release testing. This technology can also likely be further optimized for real-time in-line monitoring of product titers and quality, facilitating process intensification and automation.
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| 39. |
- Tran, Thuy, et al.
(författare)
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Process integrated biosensors for real-time monitoring of antibodies for automated affinity purification
- 2022
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Ingår i: Analytical Methods. - : Royal Society of Chemistry. - 1759-9660 .- 1759-9679. ; 14:44, s. 4555-4562
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Tidskriftsartikel (refereegranskat)abstract
- Therapeutic monoclonal antibodies (mAbs) provide new means for treatments of a wide range of diseases and comprise a large fraction of all new approved drugs. Production of mAbs is expensive compared to conventional drug production, primarily due to the complex processes involved. The affinity purification step is dominating the cost of goods in mAb manufacturing. Process intensification and automation could reduce costs, but the lack of real-time process analytical technologies (PAT) complicates this development. We show a specific and robust fiber optical localized surface plasmon resonance (LSPR) sensor technology that is optimized for in-line product detection in the effluent in affinity capture steps. The sensor system comprises a flow cell and a replaceable sensor chip functionalized with biorecognition elements for specific analyte detection. The high selectivity of the sensor enable detection of mAbs in complex sample matrices at concentrations below 2.5 mu g mL(-1). In place regeneration of the sensor chips allowed for continuous monitoring of multiple consecutive chromatographic separation cycles. Excellent performance was obtained at different purification scales with flow rates up to 200 mL min(-1). This sensor technology facilitates efficient column loading, optimization, and control of chromatography systems, which can pave the way for continuous operation and automation of protein purification steps.
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| 40. |
- van Noort, D., et al.
(författare)
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Porous gold surfaces for biosensor applications
- 2000
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 15:3-4, s. 203-209
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Tidskriftsartikel (refereegranskat)abstract
- The sensitivity of optical biosensors where the detection takes place on a planar gold surface can be improved by making the surface porous. The porosity allows a larger number of ligands per surface area resulting in larger optical shifts when interacting with specifically binding analyte molecules. The porous gold was deposited as a thin layer on a planar gold surface by electrochemical deposition in a solution of tetrachloroaurate and lead acetate. A protein, streptavidin, was adsorbed into the formed porous layer and the time course of the adsorption was monitored by in-situ ellipsometry. When the porous layer was 500 nm in thickness a six-fold increase of the ellipsometric response was obtained compared with a planar gold surface. The dependency of porosity and layer thickness was explained with a mathematical model of the gold/porous gold/protein/solution system. Copyright (C) 2000 Elsevier Science S.A.The sensitivity of optical biosensors where the detection takes place on a planar gold surface can be improved by making the surface porous. The porosity allows a larger number of ligands per surface area resulting in larger optical shifts when interacting with specifically binding analyte molecules. The porous gold was deposited as a thin layer on a planar gold surface by electrochemical deposition in a solution of tetrachloroaurate and lead acetate. A protein, streptavidin, was adsorbed into the formed porous layer and the time course of the adsorption was monitored by in-situ ellipsometry. When the porous layer was 500 nm in thickness a six-fold increase of the ellipsometric response was obtained compared with a planar gold surface. The dependency of porosity and layer thickness was explained with a mathematical model of the gold/porous gold/protein/solution system.
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| 41. |
- Vostiar, I., et al.
(författare)
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Intracellular monitoring of superoxide dismutase expression in an Escherichia coli fed-batch cultivation using on-line disruption with at-line surface plasmon resonance detection
- 2005
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 342:1, s. 152-159
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Tidskriftsartikel (refereegranskat)abstract
- An on-line cell disruption system for at-line monitoring of the intracellular concentration of recombinant human superoxide dismutase (rhSOD) in a genetically modified Escherichia coli strain, HMS174(DE3) (pET11a/rhSOD), in bioreactor cultivations is described. The sampled bacteria were disrupted on-line by rapid mixing with a nonionic detergent. The recombinant protein content of the lysed bacterial sample was quantitated by a subsequent surface plasmon resonance biosensor with a specific monoclonal antibody. Extraction efficiency of the monitoring system was optimized with respect to the flow rate ratio of the cell suspension and the detergent at relevant cell densities with the aim to attain rapid monitoring. Monitoring was demonstrated for a shake flask culture and a glucose-limited fed-batch cultivation. The results are compared with a traditional enzyme-linked immunosorbent assay method showing a correlation coefficient of R2 = 0.97. Extraction efficiency of rhSOD reached 95-99% at a total processing time of 1.8-2.6 min and a contact time of 0.8-1.4 min. The possibility of extending the monitoring system to other intracellular proteins is discussed. © 2005 Elsevier Inc. All rights reserved.
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| 42. |
- Vostiar, Igor, et al.
(författare)
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Off-line monitoring of bacterial stress response during recombinant protein production using an optical biosensor
- 2004
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 0168-1656 .- 1873-4863. ; 111:2, s. 191-201
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Tidskriftsartikel (refereegranskat)abstract
- A surface plasmon resonance (SPR) biosensor was used to monitor the profiles of the heat-shock protein (DnaK) and the expression of a heterologous protein to map the dynamics of the cellular stress response in Escherichia coli. As expression system was used an E. coli strain overproducing human recombinant superoxide dismutase (rhSOD). Expression of DnaK showed complex patterns differing with strength of induction. The strong up-regulation of DnaK expression was observed in all cultivations which over-produced of rhSOD. Similar patterns were not observed in non-induced reference cultures. Differences in DnaK concentration profiles were correlated with induction strength. Presented data, carried out in shake flask and glucose limited fed-batch cultivation, show a good consistency with previously published transcriptional profiling results and provide complementary information to understand stress response related to overproduction of recombinant protein. The study also demonstrates the feasibility of using the SPR as a two channel protein array for monitoring of intracellular components. © 2004 Elsevier B.V. All rights reserved.
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