145 results on '"Romas Baronas"'
Search Results
2. Multi-objective optimization and decision visualization of batch stirred tank reactor based on spherical catalyst particles
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Antanas Žilinskas, Romas Baronas, Linas Litvinas, and Linas Petkevičius
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multi-objective optimization ,multi-dimensional scaling ,microreactor ,reaction– diffusion ,Analysis ,QA299.6-433 - Abstract
This paper presents a Bayesian approach rooted algorithm oriented to the properties of multi-objective optimization problems. The performance of the developed algorithm is compared with several other multi-objective optimization algorithms. The approach is applied to the multiobjective optimization of a batch stirred tank reactor based on spherical catalyst microreactors. The microbioreactors are computationally modeled by a two-compartment model based on reaction–diffusion equations containing a nonlinear term related to the Michaelis–Menten enzyme kinetics. A two-stage visualization procedure based on the multi-dimensional scaling is proposed and applied for the visualization of trade-off solutions and for the selection of favorable configurations of the bioreactor.
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- 2019
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3. Modelling the enzyme catalysed substrate conversion in a microbioreactor acting in continuous flow mode
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Romas Baronas, Juozas Kulys, and Linas Petkevičius
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modelling ,diffusion-reaction ,microreactor ,enzyme kinetics ,effectiveness factor ,Analysis ,QA299.6-433 - Abstract
A model for the numerical simulation of the action of microbioreactor acting in the continuous flow mode was developed. The microbioreactor system was mathematically modelled by a two-compartment model based on transient reaction-diffusion equations containing a non-linear term related to the Michaelis–Menten kinetics of the enzymatic reaction. The effectiveness of microbioreactor and the process duration were numerically and partially analytically analysed at transition and steady-state conditions in a wide range of model parameters. The computational simulation was carried out using the finite difference technique. The performed calculations showed nonlinear effects of the internal and external diffusion limitations on the effectiveness and process duration.
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- 2018
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4. The influence of the diffusion module to determination of two substrate concentrations by articial neural network
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Linas Litvinas and Romas Baronas
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Electronic computers. Computer science ,QA75.5-76.95 - Abstract
The essential part of amperometric biosensor is an enzyme. It should be selective, i.e., react only with certain substrate. The selectivity of enzyme reduces the set of possible to use enzymes. This paper demonstrates that non selective enzymes (reacting with two substrates) can be used to determine concentrations of two substrates. For this purpose the steady-state current of two double biosensors was measured. The currents were used as input for an artificial neural network to determine concentrations of the substrates. The proposed approach was approved as the relative error of determined concentrations was relatively small. Paper analyses the influence of biosensor parameters to error values. The recommendations to error values minimisation were obtained.DOI: 10.15181/csat.v3i2.1109
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- 2015
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5. Phoretic interactions and oscillations in active suspensions of growing Escherichia coli
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Remigijus Šimkus, Rita Meškienė, Agota Aučynaitė, Žilvinas Ledas, Romas Baronas, and Rolandas Meškys
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bacterial growth ,bacterial chemotaxis ,biochemical oscillations ,janus particles ,self-phoresis ,Science - Abstract
Bioluminescence imaging experiments were carried out to characterize spatio-temporal patterns of bacterial self-organization in active suspensions (cultures) of bioluminescent Escherichia coli and its mutants. An analysis of the effects of mutations shows that spatio-temporal patterns formed in standard microtitre plates are not related to the chemotaxis system of bacteria. In fact, these patterns are strongly dependent on the properties of mutants that characterize them as self-phoretic (non-flagellar) swimmers. In particular, the observed patterns are essentially dependent on the efficiency of proton translocation across membranes and the smoothness of the cell surface. These characteristics can be associated, respectively, with the surface activity and the phoretic mobility of a colloidal swimmer. An analysis of the experimental data together with mathematical modelling of pattern formation suggests the following: (1) pattern-forming processes can be described by Keller–Segel-type models of chemotaxis with logistic cell kinetics; (2) active cells can be seen as biochemical oscillators that exhibit phoretic drift and alignment; and (3) the spatio-temporal patterns in a suspension of growing E. coli form due to phoretic interactions between oscillating cells of high metabolic activity.
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- 2018
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6. Effect of Diffusion Limitations on Multianalyte Determination from Biased Biosensor Response
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Romas Baronas, Juozas Kulys, Algirdas Lančinskas, and Antanas Žilinskas
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biosensor ,quantitative analysis ,mixture ,modeling ,simulation ,noise ,optimization ,Chemical technology ,TP1-1185 - Abstract
The optimization-based quantitative determination of multianalyte concentrations from biased biosensor responses is investigated under internal and external diffusion-limited conditions. A computational model of a biocatalytic amperometric biosensor utilizing a mono-enzyme-catalyzed (nonspecific) competitive conversion of two substrates was used to generate pseudo-experimental responses to mixtures of compounds. The influence of possible perturbations of the biosensor signal, due to a white noise- and temperature-induced trend, on the precision of the concentration determination has been investigated for different configurations of the biosensor operation. The optimization method was found to be suitable and accurate enough for the quantitative determination of the concentrations of the compounds from a given biosensor transient response. The computational experiments showed a complex dependence of the precision of the concentration estimation on the relative thickness of the outer diffusion layer, as well as on whether the biosensor operates under diffusion- or kinetics-limited conditions. When the biosensor response is affected by the induced exponential trend, the duration of the biosensor action can be optimized for increasing the accuracy of the quantitative analysis.
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- 2014
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7. Computational Modeling of Mediator Oxidation by Oxygen in an Amperometric Glucose Biosensor
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Dainius Šimelevičius, Karolis Petrauskas, Romas Baronas, and Julija Razumienė
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modeling ,reaction-diffusion ,biosensor ,oxygen ,aerobic ,anaerobic ,Chemical technology ,TP1-1185 - Abstract
In this paper, an amperometric glucose biosensor is modeled numerically. The model is based on non-stationary reaction-diffusion type equations. The model consists of four layers. An enzyme layer lies directly on a working electrode surface. The enzyme layer is attached to an electrode by a polyvinyl alcohol (PVA) coated terylene membrane. This membrane is modeled as a PVA layer and a terylene layer, which have different diffusivities. The fourth layer of the model is the diffusion layer, which is modeled using the Nernst approach. The system of partial differential equations is solved numerically using the finite difference technique. The operation of the biosensor was analyzed computationally with special emphasis on the biosensor response sensitivity to oxygen when the experiment was carried out in aerobic conditions. Particularly, numerical experiments show that the overall biosensor response sensitivity to oxygen is insignificant. The simulation results qualitatively explain and confirm the experimentally observed biosensor behavior.
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- 2014
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8. Computational modeling of luminous bacteria self-organization on the cylindrical container side surface
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Žilvinas Ledas, Romas Baronas, and Remigijus Šimkus
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Electronic computers. Computer science ,QA75.5-76.95 - Abstract
This paper deals with the computational modeling of the pattern formation of luminous bacteria. Two bacterial self-organization models are investigated – Keller-Segel diffusion-advection-reaction type equations and the model with additional oxygen equation. These models were applied for the modeling of fluid cultures of lux-gene engineered Escherichia coli in the cylindrical container as seen from the side in 2 dimensions and in quasi-1 dimension along the top three phase contact line. The spatiotemporal patterns were simulated by using the finite difference technique. By applying these models the influence of the cylindrical container depth on the pattern formation was investigated.
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- 2013
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9. Modelling Carbon Nanotubes-Based Mediatorless Biosensor
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Julija Razumiene, Karolis Petrauskas, Juozas Kulys, and Romas Baronas
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modelling ,simulation ,reaction-diffusion ,biosensor ,mediatorless ,SWCNT ,Chemical technology ,TP1-1185 - Abstract
This paper presents a mathematical model of carbon nanotubes-based mediatorless biosensor. The developed model is based on nonlinear non-stationary reaction-diffusion equations. The model involves four layers (compartments): a layer of enzyme solution entrapped on a terylene membrane, a layer of the single walled carbon nanotubes deposited on a perforated membrane, and an outer diffusion layer. The biosensor response and sensitivity are investigated by changing the model parameters with a special emphasis on the mediatorless transfer of the electrons in the layer of the enzyme-loaded carbon nanotubes. The numerical simulation at transient and steady state conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate.
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- 2012
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10. Modelling of Amperometric Biosensor Used for Synergistic Substrates Determination
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Dainius Simelevicius, Juozas Kulys, and Romas Baronas
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modelling ,simulation ,reaction-diffusion ,biosensor ,synergistic substrates ,Chemical technology ,TP1-1185 - Abstract
In this paper the operation of an amperometric biosensor producing a chemically amplified signal is modelled numerically. The chemical amplification is achieved by using synergistic substrates. The model is based on non-stationary reaction-diffusion equations. The model involves three layers (compartments): a layer of enzyme solution entrapped on the electrode surface, a dialysis membrane covering the enzyme layer and an outer diffusion layer which is modelled by the Nernst approach. The equation system is solved numerically by using the finite difference technique. The biosensor response and sensitivity are investigated by altering the model parameters influencing the enzyme kinetics as well as the mass transport by diffusion. The biosensor action was analyzed with a special emphasis to the effect of the chemical amplification. The simulation results qualitatively explain and confirm the experimentally observed effect of the synergistic substrates conversion on the biosensor response.
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- 2012
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11. Computational modeling of the bacterial self-organization in a rounded container: The effect of dimensionality
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Romas Baronas, Žilvinas Ledas, and Remigijus Šimkus
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chemotaxis ,reaction-diffusion ,pattern formation ,mathematical modelling ,Analysis ,QA299.6-433 - Abstract
A bacterial self-organization in a rounded container as detected by bioluminescence imaging is mathematically modeled by applying the the Keller–Segel approach with logistic growth. The pattern formation in a colony of luminous Escherichia coli is numerically simulated by the nonlinear reaction-advection-diffusion equations. In this work, the pattern formation is studied in 3D and the results are compared with previous and new 2D and 1D simulations. The numerical simulation at transition conditions was carried out using the finite difference technique. The simulation results showed that the developed 3D model captures fairly well the sophisticated patterns observed in the experiments. Since the numerical simulation based on the 3D model is very time-consuming, the reduction of spatial dimension of the model for simulating 1D spatiotemporal patterns is discussed. Due to the accumulation of luminous cells near the top three-phase contact line the experimental patterns of the bioluminescence can be qualitatively described by 1D and 2D models by adjusting values of the diffusion coefficient and/or chemotactic sensitivity.
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- 2015
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12. Modelling Amperometric Biosensors Based on Chemically Modified Electrodes
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Juozas Kulys and Romas Baronas
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chemically modified electrode ,biosensor ,modelling ,simulation. ,Chemical technology ,TP1-1185 - Abstract
The response of an amperometric biosensor based on a chemically modified electrode was modelled numerically. A mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments: an enzyme layer and an outer diffusion layer. In order to define the main governing parameters the corresponding dimensionless mathematical model was derived. The digital simulation was carried out using the finite difference technique. The adequacy of the model was evaluated using analytical solutions known for very specific cases of the model parameters. By changing model parameters the output results were numerically analyzed at transition and steady state conditions. The influence of the substrate and mediator concentrations as well as of the thicknesses of the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially when the biosensor acts under a mixed limitation of the diffusion and the enzyme interaction with the substrate.
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- 2008
13. Modelling a Peroxidase-based Optical Biosensor
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Juozas Kulys, Evelina Gaidamauskait˙e, and Romas Baronas
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optical biosensor ,peroxidase ,modelling ,simulation. ,Chemical technology ,TP1-1185 - Abstract
The response of a peroxidase-based optical biosensor was modelled digitally.A mathematical model of the optical biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments, an enzyme layerand an outer diffusion layer. The digital simulation was carried out using finite differencetechnique. The influence of the substrate concentration as well as of the thickness of both theenzyme and diffusion layers on the biosensor response was investigated. Calculations showedcomplex kinetics of the biosensor response, especially at low concentrations of the peroxidaseand of the hydrogen peroxide.
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- 2007
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14. Modelling of Amperometric Biosensors in the Case of Substrate Inhibition
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Romas Baronas and Juozas Kulys
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biosensor ,enzyme inhibition ,diffusion ,modelling ,Chemical technology ,TP1-1185 - Abstract
The response of an amperometric biosensor at mixed enzyme kinetics anddiffusion limitations was modelled digitally in the case of substrate inhibition. Digitalsimulations were carried out using a finite difference technique. Calculations showedcomplex kinetics of biosensor response. At low enzyme activity and substrate concentration(S0), the response of the sensor looks like it is limited by a simple substrate diffusion. Atsubstrate concentration comparable to the Michaelis-Menten constant (KM), the responsechange shows a maximal value. A sharp response change was indicated at high enzymeactivity and high (4.9 > S0/KM > 4.5) substrate concentration. This was explained by multiconcentrationof substrate generation inside the enzyme layer. This conclusion wasconfirmed by the analytical solution of the simplified biosensor model with externaldiffusion limitation at steady-state conditions. The complex kinetics of response changeproduces different calibration graphs for biosensor response at transition and steady state.
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- 2006
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15. Mathematical Modeling of Plate−gap Biosensors with an Outer Porous Membrane
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Valdas Laurinavicius, Irmantas Kaunietis, Feliksas Ivanauskas, and Romas Baronas
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modeling ,reaction−diffusion ,simulation ,biosensor. ,Chemical technology ,TP1-1185 - Abstract
A plate−gap model of a porous enzyme doped electrode covered by a porousinert membrane has been proposed and analyzed. The two−dimensional−in−spacemathematical model of the plate−gap biosensors is based on the reaction−diffusionequations containing a nonlinear term related to the Michaelis−Menten kinetics. Usingnumerical simulation of the biosensor action, the influence of the geometry of the outermembrane on the biosensor response was investigated at wide range of analyteconcentrations as well as of the reaction rates. The numerical simulation was carried outusing finite−difference technique. The behavior of the plate−gap biosensors was comparedwith that of a flat electrode deposited with a layer of enzyme and covered with the sameouter membrane.
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- 2006
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16. Mathematical Modeling of Biosensors Based on an Array of Enzyme Microreactors
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Juozas Kulys, Feliksas Ivanauskas, and Romas Baronas
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Reaction-diffusion ,modeling ,biosensor ,microreactor. ,Chemical technology ,TP1-1185 - Abstract
This paper presents a two-dimensional-in-space mathematical model ofbiosensors based on an array of enzyme microreactors immobilised on a single electrode.The modeling system acts under amperometric conditions. The microreactors were modeledby particles and by strips. The model is based on the diffusion equations containing a non-linear term related to the Michaelis-Menten kinetics of the enzymatic reaction. The modelinvolves three regions: an array of enzyme microreactors where enzyme reaction as well asmass transport by diffusion takes place, a diffusion limiting region where only the diffusiontakes place, and a convective region, where the analyte concentration is maintained constant.Using computer simulation, the influence of the geometry of the microreactors and of thediffusion region on the biosensor response was investigated. The digital simulation wascarried out using the finite difference technique.
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- 2006
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17. Application of artificial neural networks and biosensors to determine concentrations of mixture
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Linas Litvinas and Romas Baronas
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biosensor ,artificial neural networks ,principal component analysis ,Mathematics ,QA1-939 - Abstract
Biosensor response, in case of multi-substrate mixture, has nonlinear dependence on substrate concentrations. This work investigates the possibility to approximate this dependency with artificial neural network. Also the influence of external diffusion layer to results of multi-substrate determination was investigated. The numerically modelled biosensor response was used as experimental data. The principal components analysis was used to reduce the dimension of biosensor response. Prefered method gives acceptable acuratnes on multi-substrate determination and it can be improved by relatively large external diffusion layer.
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- 2014
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18. Mathematical Model of the Biosensors Acting in a Trigger Mode
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Feliksas Ivanauskas, Juozas Kulys, and Romas Baronas
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Biosensor ,amperometry ,modelling ,simulation ,amplification ,Chemical technology ,TP1-1185 - Abstract
Abstract: A mathematical model of biosensors acting in a trigger mode has been developed. One type of the biosensors utilized a trigger enzymatic reaction followed by the cyclic enzymatic and electrochemical conversion of the product (CCE scheme). Other biosensors used the enzymatic trigger reaction followed by the electrochemical and enzymatic product cyclic conversion (CEC scheme). The models were based on diffusion equations containing a non-linear term related to Michaelis-Menten kinetics of the enzymatic reactions. The digital simulation was carried out using the finite difference technique. The influence of the substrate concentration, the maximal enzymatic rate as well as the membrane thickness on the biosensor response was investigated. The numerical experiments demonstrated a significant gain (up to dozens of times) in biosensor sensitivity when the biosensor response was under diffusion control. In the case of significant signal amplification, the response time with triggering was up to several times longer than that of the biosensor without triggering.
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- 2004
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19. The Influence of the Enzyme Membrane Thickness on the Response of Amperometric Biosensors
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Juozas Kulys, Feliksas Ivanauskas, and Romas Baronas
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Amperometric biosensor ,enzyme membrane ,diffusion ,modelling ,simulation ,Chemical technology ,TP1-1185 - Abstract
A mathematical model of amperometric biosensors has been developed. The model is based on non-stationary diffusion equations containing a non-linear term related to Michaelis-Menten kinetics of the enzymatic reaction. Using digital simulation, the influence of the thickness of enzyme membrane on the biosensor response was investigated. The digital simulation of the biosensor operation showed the non-monotonous change of the maximal biosensor current versus the membrane thickness at the various maximal enzymatic rates. Digital simulation was carried out using the finite difference technique. Results of the numerical simulation was compared with known analytical solutions. This paper presents a framework for selection of the membrane thickness, ensuring the sufficiently stable sensitivity of a biosensor in a required range of the maximal enzymatic rate.
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- 2003
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20. Modeling the bacterial self-organization in a circular container along the contact line as detected by bioluminescence imaging
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Romas Baronas and Remigijus Šimkus
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reaction-diffusion ,chemotaxis ,pattern formation ,mathematical modeling ,whole-cell biosensor ,Analysis ,QA299.6-433 - Abstract
This paper presents a one-dimensional-in-space mathematical model of a bacterial selforganization in a circular container along the contact line as detected by quasi-one-dimensional bioluminescence imaging. The pattern formation in a luminous Escherichia coli colony was modeled by the nonlinear reaction-diffusion-chemotaxis equations in which the reaction term for the cells is a logistic (autocatalytic) growth function. By varying the input parameters the output results were analyzed with a special emphasis on the influence of the model parameters on the pattern formation. The numerical simulation at transition conditions was carried out using the finite difference technique. The mathematical model and the numerical solution were validated by experimental data.
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- 2011
21. Sudėtinės geometrinės struktūros biojutiklių kompiuterinis modeliavimas
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Romas Baronas and Karolis Petrauskas
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Communication. Mass media ,P87-96 - Abstract
Biojutikliai yra analitiniai įrenginiai, skirti medžiagų koncentracijoms matuoti. Kuriant naujus biojutiklius reikia atlikti daug eksperimentų. Siekiant sumažinti atliekamų fizinių eksperimentų skaičių taikomas kompiuterinis biojutiklių veiksmo odeliavimas, kai įprastai kiekvienam struktūriškai naujam biojutikliui yra sudaromas matematinis modelis, tuomet jis keičiamas skirtuminiu, o jo lygčių sistemos sprendimas įgyvendinamas sudarant kompiuterinį modelį. Kiekvienas žingsnis reikalauja atidos ir turėtų būti automatizuotas. Straipsnyje yra pateikiamas biojutiklio metamodelis, leidžiantis formuluoti biojutiklių modelius dalykinės srities sąvokomis. Pasiūlytasis metamodelis aprašo biojutiklių modelius, formuluojamus dvimatėje erdvėje, apimančius biojutiklio struktūros, jo geometrinių savybių, biojutikliuose vykstančių reakcijų ir difuzijos procesų aprašus. Sudarius metamodelį, buvo sukurta programinė įranga, automatiškai sukonstruojanti kompiuterinį biojutiklio modelį pagal metamodelio sąvokomis išreikšto biojutiklio aprašą. Metamodelis ir programinė įranga buvo taikoma realiam biojutiklio modeliui sudaryti ir jo veiksmui modeliuoti kompiuteriniu būdu.", t. y. ištrinti žodžius "biojutiklių veiksmo. Computer-Aided Modeling of Biosensors with a Complex Geometrical Structure Romas Baronas, Karolis Petrauskas Summary Biosensors are analytical devices used to measure the concentration of substances. When developing new biosensors, a lot of experiments are needed to be performed. Mathematical modeling of biosensors is used to decrease the number of physical experiments. Models of biosensors are usually created for each structurally unique biosensor by defining its mathematical model and the corresponding numerical approximation. Equations of the numerical model are then solved using computer programs, usually created for a particular model of the biosensor. Each of these steps requires a great attention and should be automated. The article presents a metamodel for a biosensor, enabling one to define models of biosensors in domain-specific terms. The proposed metamodel describes biosensor models, defined in the two-dimensional space and including definitions of the structure of a biosensor, its geometrical properties, reactions and diffusion processes taking place in it. Upon defining the metamodel, we compiled the computer software able to create computer models for biosensors from the models formulated according to the proposed metamodel. The metamodel was practically used to define a model for a real biosensor, and the biosensor modeling software was used to simulate its operation.
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- 2011
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22. Amperometrinių biojutiklių su sinerginių substratų stiprinimu kompiuterinis modeliavimas
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Dainius Šimelevičius and Romas Baronas
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Communication. Mass media ,P87-96 - Abstract
Šiame straipsnyje yra tiriamas amperometrinis biojutiklis, kuriame biojutiklio atsakas yra stiprinamas chemiškai – sinerginiais substratais. Tokiuose biojutikliuose, be substrato, kurio koncentracija matuojama, naudojamas ir pagalbinis substratas, reikalingas substratų sinergetikai. Biojutiklis yra modeliuojamas naudojant nestacionarias netiesines reakcijos-difuzijos lygtis. Modeliuojami keturi biojutiklio sluoksniai: fermento sluoksnis, kuriame vyksta visos biocheminės reakcijos ir difuzija, dializės membrana ir difuzijos sluoksnis, kuriuose vyksta tik difuzija ir reakcijos, kuriose nedalyvauja fermentas, o ketvirtasis sluoksnis yra tirpalo dalis, kurioje palaikoma vienoda medžiagų koncentracija. Lygčių sistema sprendžiama skaitiškai, naudojant baigtinių skirtumų metodą. Tiriama biojutiklio atsako bei jautrio priklausomybė nuo substratų koncentracijų ir nuo difuzijos sluoksnio storio. Modelling Amperometric Biosensors with Synergistic Substrate Amplification Dainius Šimelevičius, Romas Baronas Summary Computational modelling of a biosensor in which chemical amplification by synergistic substrates takes place was investigated in this study. In the biosensors of this type, in addition to the substrate (analyte), another auxiliary substrate is used. It is necessary to achieve the substrates synergy. The operation of the biosensor is modelled using non-stationary reactiondiffusion equations. The model involves four regions: the enzyme layer where the enzymatic reactions as well as the mass transport by diffusion take place, the dialysis membrane and the diffusion limiting region where the mass transport by diffusion and non-enzymatic reactions take place, and the convective region in which the analyte concentration is maintained constant. The equation system is solved numerically using the finite difference technique. The biosensor response dependency on substrate concentrations and the diffusion layer thickness, as well as the biosensor sensitivity dependence on the same parameters have been studied. "line-height: 18px;">
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- 2011
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23. Kompiuterinis optinio biojutiklio savybių tyrimas taikant bedimensį modelį
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Evelina Gaidamauskaitė and Romas Baronas
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Communication. Mass media ,P87-96 - Abstract
Šiame darbe, siekiant nustatyti pagrindinius kinetinius peroksidazinio optinio biojutiklio matematinio modelio parametrus, buvo sudarytas bedimensis modelis. Biojutikliui taikomos reakcijos-difuzijos lygtys su netiesiniu nariu, aprašančiu fermentinę reakciją. Biojutiklio veikimas modeliuojamas fermento ir difuzijos sluoksniuose. Ištirta biojutiklio atsako ir jautrio priklausomybė nuo bedimensio biojutiklio modulio. Suformuluotas uždavinys sprendžiamas baigtinių skirtumų metodu. Gauti rezultatai pagrindžia šio modelio pritaikomumą. Atliekami peroksidazinio optinio biojutiklio eksperimentiniai tyrimai leis nustatyti modelio taikymo ribas. A Computational Investigation of the Optical Biosensor by a Dimensionless Model Evelina Gaidamauskaitė, Romas Baronas Summary In order to determine the main governing parameters, a dimensionless mathematical model of a peroxidase-based optical biosensor is derived. The mathematical model of the biosensor is based on a system of non-linear reaction-diffusion equations. The modelled biosensor comprises two compartments, an enzyme layer and an outer diffusion layer. The influence of the dimensionless diffusion modulus on the biosensor response and the sensitivity is investigated. The digital simulation was carried out using a finite difference method.
- Published
- 2009
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24. Biojutiklių, modeliuojamų dvimatėje erdvėje, kompiuterinių modelių automatizuotas sudarymas
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Karolis Petrauskas and Romas Baronas
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Communication. Mass media ,P87-96 - Abstract
Biojutikliai yra plačiai naudojami tirti medžiagų koncentracijai tirpaluose. Viena pagrindinių biojutiklio sudedamųjų dalių yra fermentas. Fermentai yra gana brangios medžiagos, dėl to ir vykdyti eksperimentus yra brangu. Kuriant naujus biojutiklius tenka atlikti daug eksperimentų. Kad būtų sumažintas reikiamų eksperimentų skaičius, taikomas kompiuterinis biojutiklių veiksmo modeliavimas. Dažniausiai konkrečios geometrijos biojutikliui kuriamas konkretus jo kompiuterinis modelis. Šiame straipsnyje pristatoma sistema, kuri gali prisitaikyti prie konkrečios geometrijos biojutiklio. Sistema gali būti taikoma biojutikliams, kurių veiksmas aprašomas matematiniais modeliais, formuluojamais dvimatėje stačiakampėje srityje. Konkretaus biojutiklio matematinio modelio sprendinys komponuojamas parenkant konkrečius algoritmus. Computer aided model composition for biosensors modelled in two-dimensional space Karolis Petrauskas, Romas Baronas Summary Biosensors are analytical devices that use biological components, usually enzymes, which catalyse the interaction with a target analyte. Biosensors are widely used in clinical, environment and industrial applications for the determination of species concentrations. In some applications of biosensors, enzymes are very expensive and only available in very limited quantity. In design of novel highly sensitive biosensors a lot of experiments are required. Computer simulation of the biosensor action is an effective way to decrease a number of physical experiments. This paper presents a system adaptive to a concrete geometry of the biosensor. The system may be applied for biosensors, the action of which can be described by a mathematical model formulated in a two dimensional space. A simulator for a concrete biosensor is generated from the detailed description of the biosensor action. eight: 18px;">
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- 2008
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25. Modelling biosensors with perforated membrane
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Romas Baronas, Feliksas Ivanauskas, and Juozas Kulys
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reaction-diffusion ,mathematical modelling ,biosensor ,perforated membrane ,Mathematics ,QA1-939 - Abstract
This paper presents a two-dimensional-in-space mathematical model of amperometric biosensors with perforated membrane. The model is based on the diffusion equations containing a non-linear term related to the Michaelis–Menten kinetics of the enzymatic reaction. The digital simulation was carried out using the finite difference technique. Using computer simulation of the biosensors action, the influence of the geometry of the perforated membrane on the biosensor response was investigated.
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- 2005
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26. The classification of concentration of mixture of analytes using total principal component regression
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Romas Baronas, Feliksas Ivanauskas, Robertas Paulauskas, and Pranas Vaitkus
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total principal component regression ,pseudo inversematrix ,Mathematics ,QA1-939 - Abstract
In this paper total principal component regression is used for biosensors response to mixtures of compounds classification. The results are compared with the results obtained using artificial neural networks.
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- 2005
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27. Modeling of an array of amperometric microbiosensors
- Author
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Feliksas Ivanauskas, Romas Baronas, Juozas Kulys, and Mifodijus Sapagovas
- Subjects
reaction-diffusion ,mathematical modelling ,biosensor ,microreactor ,Mathematics ,QA1-939 - Abstract
This paper presents a two-dimensional-in-space mathematical model of a sensor system based on an array of enzyme microreactors immobilised on a single electrode. The model is based on the diffussion equations containing a non-linear term related to the Michaelis–Menten kinetics of the enzymatic reaction. Using computer simulation the influence of the geometry of the enzyme microreactors on the biosensor response was investigated. The digital simulation was carried out using the finite difference technique.
- Published
- 2004
- Full Text
- View/download PDF
28. The classification of concentration of mixture of analytes
- Author
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Romas Baronas, Feliksas Ivanauskas, Romualdas Maslovskis, and Pranas Vaitkus
- Subjects
neutral networks ,principal components analysis ,independent components analysis ,Mathematics ,QA1-939 - Abstract
This paper presents a system which is used for the classification of biosensor signals. The proposed system is applied to the the synthesized and experimental data. The developed system showed good prediction perfomance.
- Published
- 2004
- Full Text
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29. Modelling surface roughness of enzyme layer of amperometric biosensors
- Author
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Feliksas Ivanauskas, Romas Baronas, Juozas Kulys, and Mifodijus Sapagovas
- Subjects
Mathematics ,QA1-939 - Abstract
A mathematical model of amperometric biosensors is presented. The model is based on the diffusion equations containing a non-linear term related to the Michaelis-Menten kinetics of the enzyme reaction. The model takes into concideration surface roughness of the enzyme layer. Using digital simulation, the influence of the geometry of the roughness on the biosensor response was investigated. The digital simulation was carried out using the finite difference technique.
- Published
- 2003
- Full Text
- View/download PDF
30. Modeling And Simulation Of Porous Multi Layer Microbioreactors.
- Author
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Linas Petkevicius and Romas Baronas
- Published
- 2019
- Full Text
- View/download PDF
31. Asynchronous Client-Side Coordination of Cluster Service Sessions.
- Author
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Karolis Petrauskas and Romas Baronas
- Published
- 2018
- Full Text
- View/download PDF
32. Effectiveness of the Asynchronous Client-Side Coordination of Cluster Service Sessions.
- Author
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Karolis Petrauskas and Romas Baronas
- Published
- 2018
- Full Text
- View/download PDF
33. Application Of Two Phase Multi-Objective Optimization To Design Of Biosensors Utilizing Cyclic Substrate Conversion.
- Author
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Linas Litvinas, Romas Baronas, and Antanas Zilinskas
- Published
- 2017
- Full Text
- View/download PDF
34. One-Dimensional Modelling Of A Carbon Nanotube-Based Biosensor.
- Author
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Karolis Petrauskas and Romas Baronas
- Published
- 2012
- Full Text
- View/download PDF
35. Modeling carbohydrates oxidation by oxygen catalyzed by bienzyme glucose dehydrogenase/laccase system immobilized into microreactor with carbon nanotubes
- Author
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Juozas Kulys, Linas Petkevicius, and Romas Baronas
- Subjects
010304 chemical physics ,Applied Mathematics ,Diffusion ,010102 general mathematics ,Kinetics ,Continuous stirred-tank reactor ,chemistry.chemical_element ,General Chemistry ,01 natural sciences ,Oxygen ,Enzyme catalysis ,Chemical engineering ,chemistry ,Glucose dehydrogenase ,0103 physical sciences ,Limiting oxygen concentration ,0101 mathematics ,Microreactor - Abstract
This paper presents a mathematical model of a batch stirred tank reactor based on an array of identical spherical porous microbioreactors loaded with non specific glucose dehydrogenase and oxygen reducing enzyme, i.e. laccase. The model was validated by experimental data. The microreactors (MR) are mathematically modeled by a two-compartment model, based on reaction–diffusion equations containing nonlinear terms related to the Michaelis–Menten kinetics of two enzymatic reactions with addition of the mass transport. The dynamics of oxygen concentration change is analysed numerically using the finite difference technique. The transient effectiveness factor and the process duration are investigated at different initial concentration of carbohydate (lactose) as well as at internal and external diffusion resistances. The simulation results show a non-monotonic effect of the initial concentration of lactose and nonlinear effects of the internal and external diffusion limitations on the transient effectiveness.
- Published
- 2020
36. Computational Modeling of Bienzyme Biosensor with Different Initial and Boundary Conditions.
- Author
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Vytautas Aseris, Romas Baronas, and Juozas Kulys
- Published
- 2013
37. Modelling Carbon Nanotubes-Based Mediatorless Biosensor.
- Author
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Romas Baronas, Juozas Kulys, Karolis Petrauskas, and Julija Razumiene
- Published
- 2012
- Full Text
- View/download PDF
38. Numerical simulation of a plate-gap biosensor with an outer porous membrane.
- Author
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Feliksas Ivanauskas and Romas Baronas
- Published
- 2008
- Full Text
- View/download PDF
39. COMPUTATIONAL MODELING OF SELF-ORGANIZATION OF BACTERIAL POPULATION CONSISTING OF SUBPOPULATIONS OF ACTIVE AND PASSIVE CELLS
- Author
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Remigijus Šimkus, Romas Baronas, and Žilvinas Ledas
- Subjects
Ecology ,biology ,Chemistry ,Applied Mathematics ,010102 general mathematics ,Chemotaxis ,Bacterial population ,General Medicine ,medicine.disease_cause ,biology.organism_classification ,01 natural sciences ,Agricultural and Biological Sciences (miscellaneous) ,010305 fluids & plasmas ,0103 physical sciences ,medicine ,Biophysics ,Bioluminescence ,0101 mathematics ,Escherichia coli ,Bacteria - Abstract
This paper deals with the computational modeling of the bioluminescence pattern formation in suspensions of Escherichia coli bacteria. The aim was to develop a computational model for simulating the bacterial populations consisting of two subpopulations of active and passive cells. A suitable model based on Keller–Segel and Fisher equations was proposed and the spatiotemporal patterns were simulated using the finite difference technique. The influence of cell activation, deactivation, chemotactic sensitivity, growth rate and saturating signal production parameter values on the pattern formation was investigated. The proposed model can be used to effectively simulate quasi-one-dimensional spatiotemporal patterns. We provide a simple qualitative explanation of the experimental results and estimated model parameters. In particular, it is argued that the effective model simulates patterns of evaporation-driven convection in open-to-air suspensions of cells that can be either active or passive.
- Published
- 2019
40. Locally weighted neural networks for an analysis of the biosensor response.
- Author
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Romas Baronas, Feliksas Ivanauskas, Romualdas Maslovskis, Marijus Radavicius, and Pranas Vaitkus
- Published
- 2007
41. Reliability of One Dimensional Model of Moisture Diffusion in Wood.
- Author
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Romas Baronas, Feliksas Ivanauskas, and Mifodijus Sapagovas
- Published
- 2002
- Full Text
- View/download PDF
42. Mathematical Modeling of Biosensors
- Author
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Romas Baronas, Juozas Kulys, and Feliksas Ivanauskas
- Subjects
Materials science ,Nanotechnology ,Biosensor - Published
- 2021
43. Biosensors Utilizing Consecutive and Parallel Substrates Conversion
- Author
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Juozas Kulys, Feliksas Ivanauskas, and Romas Baronas
- Subjects
Analyte ,chemistry.chemical_compound ,Stationary conditions ,chemistry ,Electrode ,technology, industry, and agriculture ,macromolecular substances ,Ferrocyanide ,Selectivity ,Biological system ,Biosensor ,Amperometry ,Internal diffusion - Abstract
Coupling different enzymes either in sequence or in competition pathway is a way to enhance the range of analyte species accessible to measurement, the selectivity and the sensitivity of biosensors. In this chapter, mathematical models of several types of amperometric multi-enzyme biosensors utilizing consecutive or parallel substrates conversion are modeled and analysed at stationary and transient conditions. A biosensor based on bienzyme electrode with co-immobilized D-glucose oxidase and peroxidase is considered under stationary conditions at excess concentrations of oxygen and ferrocyanide. A trienzyme biosensor utilizing consecutive substrates conversion with three enzymes is modeled at internal diffusion limitation. A biosensor with dual catalase-peroxidase bioelectrode is mathematically modeled by nonlinear reaction–diffusion equations. Finally, multi-enzyme biosensors utilizing parallel and competitive multi-substrate conversion are analysed.
- Published
- 2020
44. Biosensors with Porous and Perforated Membranes
- Author
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Romas Baronas, Juozas Kulys, and Feliksas Ivanauskas
- Subjects
Nonlinear system ,Membrane ,Materials science ,Transducer ,Linear range ,Chemical engineering ,Calibration curve ,Perforation (oil well) ,Kinetics ,technology, industry, and agriculture ,macromolecular substances ,Biosensor - Abstract
The additional application of catalytically inactive membranes can solve some drawbacks of biosensors, such as a relatively short linear range of the calibration graph, an instability and a low specificity. The selective membranes are usually used to increase the biosensors specificity. In this chapter, amperometric biosensors with inert and selective membranes are mathematically modeled by nonlinear reaction–diffusion equations containing a nonlinear term related to the Michaelis–Menten kinetics of an enzymatic reaction. At first, a biosensor, containing enzymatic and outer inert membranes, is mathematically and numerically modeled by a three-compartment model in one-dimensional space at transient conditions. Then, the model is extended to cover a transducer with an additional selective membrane permeable for the product of the enzymatic reaction, and the output results are numerically analysed with a special emphasis on the influence of the selective membrane to the biosensor response. And finally, the biosensor with selective and outer perforated membranes is modeled in two-dimensions. The biosensor response is analysed with a special focus on the geometry of the membrane perforation
- Published
- 2020
45. Biosensors Utilizing Non-Michaelis–Menten Kinetics
- Author
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Juozas Kulys, Feliksas Ivanauskas, and Romas Baronas
- Subjects
biology ,Chemistry ,Diffusion ,Substrate (chemistry) ,Thermodynamics ,Michaelis–Menten kinetics ,Diffusion layer ,symbols.namesake ,Allosteric enzyme ,biology.protein ,symbols ,Nernst equation ,Enzyme kinetics ,Steady state (chemistry) - Abstract
The action of biosensors utilizing non-Michaelis–Menten kinetics is modeled at mixed enzyme kinetics and diffusion limitation in the cases of substrate and reaction product inhibition as well as of allostery at steady state and transient conditions. Computational modeling of the substrate inhibition at steady state shows multi-steady state concentrations of the substrate at the surface of the enzyme layer (membrane) when the diffusion module is much larger than one and the substrate bulk concentration is much higher than Michaelis–Menten constant. The multi-steady state concentration generates multi-response of the biosensor. At transient conditions, analytical systems are modeled by a two-compartment model comprising a mono-enzyme layer and an external Nernst diffusion layer. The complex enzyme kinetics produces different calibration curves for the response at the transition and the steady state. The cooperative phenomena of allosteric enzymes are modeled by applying the substrate uptake and the Hill equations. The positive cooperativity leads to a steady state current less than that when the biosensor action obeys the Michaelis–Menten kinetics, while negative cooperativity leads to increasing the biosensor response. The substrate concentration, at which the saturation curves of allosteric biosensors intersect, increases with increasing the external diffusion limitation.
- Published
- 2020
46. Introduction to Modeling of Biosensors
- Author
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Feliksas Ivanauskas, Romas Baronas, and Juozas Kulys
- Subjects
Nonlinear system ,Transducer ,Materials science ,Computer simulation ,Kinetics ,Potentiometric titration ,Substrate (chemistry) ,Nanotechnology ,Steady state (chemistry) ,Biosensor - Abstract
This chapter introduces mathematical modeling of catalytic biosensors. After a brief tutorial consideration of kinetics of biocatalytic reactions, transducer function of biosensors and a general scheme of biosensor action, a detail mathematical model is then presented for an amperometric biosensor based on a mono-layer of an enzyme immobilized onto the surface of the electrode. The biosensor is modeled by two-component (substrate and product) reaction–diffusion equations containing a nonlinear term related to the Michaelis–Menten kinetics of an enzyme reaction. A few modifications of the mathematical model describing the action of potentiometric, optical and fluorescence biosensors are discussed, too. A special emphasis is placed on the modeling biosensors at steady state and internal or external diffusion limitation with a contribution to the modeling biosensors at non-stationary state at some critical concentrations of the substrate when analytical solution of the governing equations is performed. Using numerical simulation, the influence of the model parameters on the biosensor response is investigated. The simulation of the biosensor operation particularly showed a non-monotonous change of the steady state biosensor current versus the membrane thickness at the various maximal enzymatic rates.
- Published
- 2020
47. Modeling Carbon Nanotube Based Biosensors
- Author
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Romas Baronas, Feliksas Ivanauskas, and Juozas Kulys
- Subjects
Nonlinear system ,Materials science ,Mathematical model ,Computer simulation ,Chemical physics ,Glucose dehydrogenase ,law ,Finite difference ,Carbon nanotube ,Diffusion (business) ,Biosensor ,law.invention - Abstract
This chapter presents two-dimensional and one-dimensional-in-space mathematical models of mediated and unmediated (mediatorless) amperometric biosensors based on an enzyme-loaded carbon nanotube (CNT) layer deposited on the perforated membrane. The models are based on nonlinear reaction–diffusion equations and involve four regions: the enzyme and the CNT regions where enzymatic reactions as well as the mass transport by diffusion take place, a diffusion limiting layer where only the mass transport by diffusion takes place and a convective region where the analyte concentration is maintained constant. By changing input parameters the output results are numerically analysed with an emphasis to the influence of the geometry and the catalytic activity of the biosensors to their response and sensitivity. The mediatorless transfer of the electrons in the region of enzyme-loaded carbon nanotubes is especially investigated. The numerical simulation at transient conditions was carried out using the finite difference technique. The mathematical models and the numerical solutions were validated by experimental data. The obtained agreement between the simulation results and the experimental data was admissible at different concentrations of the substrate.
- Published
- 2020
48. Biosensors Response Amplification with Cyclic Substrates Conversion
- Author
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Romas Baronas, Juozas Kulys, and Feliksas Ivanauskas
- Subjects
Chemical kinetics ,Analyte ,Chemistry ,Diffusion ,Kinetics ,technology, industry, and agriculture ,Substrate (chemistry) ,macromolecular substances ,Conjugated system ,Electrochemistry ,Biosensor ,Combinatorial chemistry - Abstract
The sensitivity of biosensors can be notably increased by a cyclic conversion of substrates or reaction products. In this chapter, mathematical models of different types of amperometric biosensors utilizing the cyclic conversion are modeled and analysed at transient conditions assuming an absence of outer diffusion limitations. A specific type of highly sensitive biosensors utilizing the substrate cyclic conversion in single enzyme membrane has been analytically modeled assuming the first-order reaction kinetics. The amplification of biosensor response by conjugated electrochemical and enzymatic substrate conversions is modeled by reaction–diffusion equations containing a nonlinear term related to Michaelis–Menten kinetic of the enzymatic reaction. The trigger of the response of biosensors utilizing substrate (analyte) conversion following the cyclic product conversion has been modeled and analysed computationally, too. The simulated response of the biosensors acting in two trigger schemes is compared with the response of a single enzyme biosensor utilizing Michaelis–Menten kinetics. The numerical experiments demonstrated significant gain in the biosensor sensitivity when the biosensor response was under diffusion control.
- Published
- 2020
49. Biosensors Acting in Injection Mode
- Author
-
Romas Baronas, Feliksas Ivanauskas, and Juozas Kulys
- Subjects
Diffusion layer ,Nonlinear system ,Analyte ,Materials science ,Calibration curve ,technology, industry, and agriculture ,macromolecular substances ,Sensitivity (control systems) ,Diffusion (business) ,Biological system ,Michaelis–Menten kinetics ,Biosensor - Abstract
This chapter numerically investigates the sensitivity of an amperometric biosensor acting in the flow injection mode when the biosensor contacts an analyte for a short time. The analytical system is modeled by non-stationary reaction–diffusion equations containing a nonlinear term related to the Michaelis–Menten kinetics of an enzymatic reaction. At first, the biosensor action is modeled by a mono-layer mono-enzyme model assuming no external diffusion limitation. Then, the model is extended to a two-compartment model by adding an outer diffusion layer. The biosensor operation is analysed with a special emphasis to the conditions at which the biosensor sensitivity can be increased and the calibration curve can be prolonged by changing the injection duration, the permeability of the external diffusion layer, the thickness of the enzyme layer and the catalytic activity of the enzyme. The apparent Michaelis constant is used as a main characteristic of the sensitivity and the calibration curve of the biosensor. The numerical simulation was carried out using the finite difference technique.
- Published
- 2020
50. Biosensors Utilizing Synergistic Substrates Conversion
- Author
-
Romas Baronas, Feliksas Ivanauskas, and Juozas Kulys
- Subjects
chemistry.chemical_compound ,chemistry ,biology ,Glucose dehydrogenase ,Reagent ,biology.protein ,Glucose oxidase ,Ferricyanide ,Steady state (chemistry) ,Ferrocyanide ,Combinatorial chemistry ,Biosensor ,Phenoxazine - Abstract
Biosensors containing glucose oxidase, carbohydrate oxidase and laccase and utilizing a few synergistic schemes of substrates conversion are modeled at steady state and transient conditions. A glucose dehydrogenase-based bioelectrocatalytical system, where ferricyanide is converted to ferrocyanide in the presence of highly reactive organic electron transfer compounds, and a laccase-based bioelectrode utilizing synergistic N-substituted phenothiazine and phenoxazine oxidation in the presence of hexacyanoferrate (II) are modeled mathematically by nonlinear reaction–diffusion equations. The modeling biosensors comprise three compartments, an enzyme layer, a dialysis membrane and an outer diffusion layer. The digital simulation was carried out using the finite difference technique. By changing the input parameters, the action of biosensors was analysed with a special emphasis to the influence of the kinetic constants and reagents concentrations on the synergy of the simultaneous substrates conversion. The digital simulation of the system confirmed that the high sensitivity of the bioelectrode achieved in the presence of organic mediators is due to the synergistic substrates conversion demonstrated experimentally.
- Published
- 2020
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