Flow-through cell
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Rising amounts of antibiotic residues in wastewater cause serious problems including increased bacterial resistance. Wastewater treatment plants (WWTPs) do not, in the case of new, modern pharmaceuticals, ensure their complete removal. Ciprofloxacin (CIP) is one of many micropollutants that partially pass through WWTPs, implying that its monitoring is essential for the assessment of the water quality. In real sewage systems, the determination of CIP needs to be performed under flowing conditions, which calls for the deployment of inexpensive, robust, and easily integrable approaches such as electrochemical techniques. However, to the best of our knowledge, there is no report on the electrochemical determination of CIP in a flowing matrix. To bridge this gap, we perform here cyclic and square-wave voltammetric sensing study of CIP employing boron-doped diamond screen printed electrodes in a custom-made 3D printed flow-through cell to mimic conditions in real sewage systems. An irreversible two-step oxidation of CIP is demonstrated, with the first step providing clear Faradaic response as analytically relevant signal. This response was found to scale with the sample flow rate according to the prediction given by Levich equation. Our work provides an in-depth inspection of the electrochemical response of CIP under controlled-convection conditions, which is an essential prerequisite for monitoring this antibiotic in real flowing sewage systems.
- Klíčová slova
- 3D printed flow-through cell, Antibiotics, Boron-doped diamond electrode, Ciprofloxacin, Electrochemical sensing, Wastewater,
- MeSH
- 3D tisk MeSH
- antibakteriální látky MeSH
- ciprofloxacin * škodlivé účinky chemie MeSH
- diamant chemie MeSH
- elektrochemické techniky MeSH
- elektrody MeSH
- léčivé přípravky chemie MeSH
- odpadní vody * chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antibakteriální látky MeSH
- ciprofloxacin * MeSH
- diamant MeSH
- léčivé přípravky MeSH
- odpadní vody * MeSH
Four-channel flow-through electrochemical cell working in thin-layer regime was designed, fabricated and characterized experimentally and in computational fluid dynamics (CFD) simulations. The new principle of operation allows reproducible splitting of a stream of liquid into multiple flow channels. Systems comprising of 2-, 3-, 4- and 8-channels were tested. The proper function of the cell is given by the ratio of the cross-sections of the fluidic element collecting chamber and the particular flow paths among which the liquid is distributed. Suitable flow rates providing uniform liquid distribution were evaluated and the results were compared to CFD modeling. The flow-through cells designed according to the proposed principle can be simply incorporated in automated routine analysis as only one inlet and one common outlet are required.
There is an agreement in the field that interlaboratory reproducibility of flow cytometry measurements as well as the whole studies might be improved by a consensual use of methodological approach. Typically, a consensus is made on a crucial markers needed in the immunostaining panel, sometimes on the particular fluorochrome conjugates and rarely on a complete set of methods for sample preparation. The term "standardization" is used to describe the complete set of methodical steps, while "harmonization" is used for partial agreement on the method. Standardization can provide a platform for improved reproducibility of cytometry results over prolonged periods of time, across different sites and across different instruments. For the purpose of structured discussion, several desired aims are described: common interpretation of the immunophenotype definition of a target subset, accurate quantification, reproducible pattern of a multicolor immunophenotype, and reproducible intensity of all measured parameters. An overview of how standardization was approached by several large consortia is provided: EuroFlow, The ONE Study, Human Immunology Project Consortium (HIPC), and several other groups. Their particular aims and the tools adopted to reach those aims are noted. How those standardization efforts were adopted in the field and how the resulting outcome was evaluated is reviewed. Multiple challenges in the instrument hardware design, instrument setup tools, reagent design, and quality features need to be addressed to achieve optimal standardization. Furthermore, the aims of different studies vary, and thus, the reasonable requirements for standardization differ. A framework of reference for the reasonable outcomes of different approaches is offered. Finally, it is argued that complete standardization is important not only for the reproducibility of measurements but also for education, for quality assessment and for algorithmic data analysis. The different standardized approaches can and in fact should serve as benchmarking reference tools for the development of future flow cytometry studies. © 2019 International Society for Advancement of Cytometry.
- Klíčová slova
- EuroFlow, data analysis, flow cytometry, standardization,
- MeSH
- imunofenotypizace MeSH
- indikátory a reagencie MeSH
- lidé MeSH
- průtoková cytometrie * MeSH
- referenční standardy MeSH
- reprodukovatelnost výsledků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- indikátory a reagencie MeSH
We present results of experiments focused on emergent and cooperative dynamics in a system of two coupled flow-through stirred reaction cells with diffusion-like mass exchange and a strongly nonlinear chemical reaction between hydrogen peroxide and thiosulphate catalysed by cupric ions in diluted solution of sulphuric acid. Due to complex mechanism, in which a crucial role is played by hydrogen and/or hydroxide ions, dynamics in a single cell entail multiple stationary states, excitability and oscillations conveniently indicated by measuring pH. When coupled, the system shows a plethora of dynamical regimes depending on the coupling strength and flow rate. Under certain conditions both cells display dynamics close to that in the absence of coupling, but majority of the regimes are emergent and cannot be deduced from dynamics of decoupled reactors. The most prominent is a stationary state maintaining highly acidic values of pH in one of the reactors and weakly acidic in the other. When each cell is set to display excitability and the coupled system is externally perturbed, the cells may cooperate and transmit excitations elicited by pulsed perturbations in one cell to the other. Periodic pulses induce firing patterns marked by a various degree of propagated excitations and by being periodic or irregular.
- Publikační typ
- časopisecké články MeSH
Cyanobacteria are prokaryotic organisms characterised by their complex structures and a wide range of pigments. With their ability to fix CO2, cyanobacteria are interesting for white biotechnology as cell factories to produce various high-value metabolites such as polyhydroxyalkanoates, pigments, or proteins. White biotechnology is the industrial production and processing of chemicals, materials, and energy using microorganisms. It is known that exposing cyanobacteria to low levels of stressors can induce the production of secondary metabolites. Understanding of this phenomenon, known as hormesis, can involve the strategic application of controlled stressors to enhance the production of specific metabolites. Consequently, precise measurement of cyanobacterial viability becomes crucial for process control. However, there is no established reliable and quick viability assay protocol for cyanobacteria since the task is challenging due to strong interferences of autofluorescence signals of intercellular pigments and fluorescent viability probes when flow cytometry is used. We performed the screening of selected fluorescent viability probes used frequently in bacteria viability assays. The results of our investigation demonstrated the efficacy and reliability of three widely utilised types of viability probes for the assessment of the viability of Synechocystis strains. The developed technique can be possibly utilised for the evaluation of the importance of polyhydroxyalkanoates for cyanobacterial cultures with respect to selected stressor-repeated freezing and thawing. The results indicated that the presence of polyhydroxyalkanoate granules in cyanobacterial cells could hypothetically contribute to the survival of repeated freezing and thawing.
- Klíčová slova
- Biotechnology, Cyanobacteria, Flow cytometry, Fluorescent viability probes, Stress resistance, Viability assessment,
- MeSH
- fluorescenční barviva * MeSH
- fyziologický stres * MeSH
- mikrobiální viabilita * MeSH
- polyhydroxyalkanoáty metabolismus MeSH
- průtoková cytometrie * metody MeSH
- sinice * fyziologie MeSH
- Synechocystis * fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fluorescenční barviva * MeSH
- polyhydroxyalkanoáty MeSH
Peptide-peptide interactions are crucial in the living cell as they lead to the formation of the numerous types of complexes. In this study, synthetic peptides containing 11 of cysteines (α-domain of metallothionein (MT)) and sialic acid binding region (130-loop of hemagglutinin (HA)) were employed. The aim of the experiment was studying the interactions between MT and HA-derived peptides. For this purpose, fragments were tagged with cysteines at C-terminal part to serve as ligand sites for PbS and CuS quantum dots (QDs), and therefore these conjugates can be traced and quantified during wide spectrum of methods. As a platform for interaction, γ-Fe2O3 paramagnetic particles modified with tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane (hydrodynamic diameter 30-40 nm) were utilized and MT/HA interactions were examined using multi-instrumental approach including electrochemistry, electrophoretic methods, and MALDI-TOF/TOF mass spectrometry. It was found that peptides enter mutual creation of complexes, which are based on some of nonbonded interactions. The higher willingness to interact was observed in MT-derived peptides toward immobilized HA. Finally, we designed and manufactured flow-through electrochemical 3D printed device (reservoir volume 150 μL) and utilized it for automated analysis of the HA/MT metal labels. Under the optimal conditions, (deposition time and flow rate 80 s and 1.6 mL/min for CuS and 120 s and 1.6 mL/min PbS, respectively), the results of peptide-conjugated QDs were comparable with atomic absorption spectrometry.
- Klíčová slova
- 3D printing, Advanced materials, Influenza, Lab-On-a-Chip, Magnetic particle,
- MeSH
- 3D tisk * MeSH
- magnetické nanočástice chemie MeSH
- mikrofluidní analytické techniky přístrojové vybavení MeSH
- peptidy analýza chemie metabolismus MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- magnetické nanočástice MeSH
- peptidy MeSH
The review focuses on the design of detection cells, the use of microcontrollers for processing and evaluation of the detection signal, and the development of multi-detection systems for electromigration, liquid chromatography, flow-through and microfluidic techniques. A separate section is the introduction of modern 3D printing techniques and the use of new printing materials for the design of multidetection systems. In addition to traditional utilisation in separation techniques, new versions of contactless conductivity detectors are finding applications in FIA, SIA, portable and paper based analytical systems or as independent sensors. Applicationwise, C4Ds find new use in gas detection, segmented flow monitoring, as part of point of care devices, and in many other biomedical, environmental, agricultural and industrial applications.
- Klíčová slova
- 3D printing, Capillary electrophoresis, Contactless conductivity detection, Microcontroller, Microfluidics, Sensor,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
In oxygenic phototrophs, chlorophylls, hemes, and bilins are synthesized by a common branched pathway. Given the phototoxic nature of tetrapyrroles, this pathway must be tightly regulated, and an important regulatory role is attributed to magnesium chelatase enzyme at the branching between the heme and chlorophyll pathway. Gun4 is a porphyrin-binding protein known to stimulate in vitro the magnesium chelatase activity, but how the Gun4-porphyrin complex acts in the cell was unknown. To address this issue, we first performed simulations to determine the porphyrin-docking mechanism to the cyanobacterial Gun4 structure. After correcting crystallographic loop contacts, we determined the binding site for magnesium protoporphyrin IX. Molecular modeling revealed that the orientation of α6/α7 loop is critical for the binding, and the magnesium ion held within the porphyrin is coordinated by Asn-211 residue. We also identified the basis for stronger binding in the Gun4-1 variant and for weaker binding in the W192A mutant. The W192A-Gun4 was further characterized in magnesium chelatase assay showing that tight porphyrin binding in Gun4 facilitates its interaction with the magnesium chelatase ChlH subunit. Finally, we introduced the W192A mutation into cells and show that the Gun4-porphyrin complex is important for the accumulation of ChlH and for channeling metabolites into the chlorophyll biosynthetic pathway.
- Klíčová slova
- Gun4, Mgprotoporphyrin IX, Synechocystis 6803, chlorophyll, cyanobacteria, docking, molecular modeling, porphyrin,
- MeSH
- bakteriální proteiny chemie metabolismus MeSH
- chlorofyl biosyntéza MeSH
- cirkulární dichroismus MeSH
- konformace proteinů MeSH
- krystalografie rentgenová MeSH
- mutace MeSH
- porfyriny metabolismus MeSH
- simulace molekulární dynamiky MeSH
- Synechocystis genetika růst a vývoj metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bakteriální proteiny MeSH
- chlorofyl MeSH
- porfyriny MeSH
Instrumentation for flow cytometry and sorting is designed around the assumption that samples are single-cell suspensions. However, with few exceptions, higher plants comprise complex multicellular tissues and organs, in which the individual cells are held together by shared cell walls. Single-cell suspensions can be obtained through digestion of the cells walls and release of the so-called protoplasts (plants without their cell wall). Here we describe best practices for protoplast preparation, and for analysis through flow cytometry and cell sorting. Finally, the numerous downstream applications involving sorted protoplasts are discussed.
- Klíčová slova
- autofluorescence, best practices, plant flow cytometry and sorting, protoplasts, viability and integrity,
- MeSH
- protoplasty * MeSH
- průtoková cytometrie MeSH
- separace buněk MeSH
- suspenze MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Názvy látek
- suspenze MeSH
A microfluidic device made of polydimethylsiloxane was developed for continuous evaluation of natural migration mobility of many eukaryotic cells in relaxed and deformed state. The device was fabricated by standard photolithography and soft lithography techniques using the SU-8 3010 negative photoresist on a glass wafer as the master mold. The simple flow-free device exploits the chemotactic movement of cells through a set of mechanical barriers in the direction of concentration gradients of attractants. The barriers are formed by arrays of circular cross-section pillars with decreasing spacing 7, 5, and 3 μm. To pass through the obstacles, the cells are deformed and change their cytoskeletal architecture. The instantaneous migration velocities of cells are monitored in a time-lapse setup of the scanning confocal microscope. Thus, the cellular deformability and migratory activity can easily be evaluated. The functionality of the device was tested with model HeLa cells stably transfected with fluorescent Premo FUCCI Cell Cycle Sensor. The designed device has the potential to be implemented for testing the tendency of patients' tumors to metastasis.
- Klíčová slova
- Cell deformability, Cell mobility, Confocal microscopy, Metastasis, Microfluidics,
- MeSH
- buněčné kultury přístrojové vybavení MeSH
- design vybavení MeSH
- dimethylpolysiloxany chemie MeSH
- HeLa buňky MeSH
- konfokální mikroskopie MeSH
- lidé MeSH
- mikrofluidní analytické techniky přístrojové vybavení MeSH
- pohyb buněk fyziologie MeSH
- tvar buňky fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- baysilon MeSH Prohlížeč
- dimethylpolysiloxany MeSH
