Elzbieta Malinowska | Warsaw University of Technology (original) (raw)
Papers by Elzbieta Malinowska
Analytica Chimica Acta, 2008
In this work, a new concept of the solid-state sensors free from EMF instabilities is proposed. I... more In this work, a new concept of the solid-state sensors free from EMF instabilities is proposed. In order to prevent the formation of an aqueous layer underneath the ion-selective membrane, instead of improving the hydrophobicity of the monolayer, the moieties terminated with acrylate groups were incorporated within the redox-active monolayer structure. It allowed to "sew" all phases of the sensor (i.e., the transducer, the intermediate layer and the ion-selective membrane) and to obtain a stable and durable ion-selective sensor. It is shown that newly designed monolayer containing both the ferrocene- and the acrylate-terminated molecules does not affect the working parameters of the electrode, such as selectivity or the slope of the calibration curve, although the EMF drift of the sensor is significantly reduced to 0.2 mV per day.
Bioelectrochemistry (Amsterdam, Netherlands), 2016
A simple and cost effective method for the determination of restriction endonuclease activity is ... more A simple and cost effective method for the determination of restriction endonuclease activity is presented. dsDNA immobilized at a gold electrode surface is used as the enzymatic substrate, and an external cationic redox probe is employed in voltammetric measurements for analytical signal generation. The assessment of enzyme activity is based on a decrease of a current signal derived from reduction of methylene blue which is present in the sample solution. For this reason, the covalent attachment of the label molecule is not required which significantly reduces costs of the analysis and simplifies the entire determination procedure. The influence of buffer components on utilized dsDNA/MCH monolayer stability and integrity is also verified. Electrochemical impedance spectroscopy measurements reveal that due to pinhole formation during enzyme activity measurement the presence of any surfactants should be avoided. Additionally, it is shown that the sensitivity of the electrochemical bi...
![Research paper thumbnail of Silver selective electrodes based on thioether functionalized calix[4]arenes as ionophores](https://attachments.academia-assets.com/46667783/thumbnails/1.jpg)
](Analytica Chimica Acta, Nov 1, 1994
Silver selective eiectrodes based on thioether functianaiized calix [ 4j arenes 1 and 2 as ionoph... more Silver selective eiectrodes based on thioether functianaiized calix [ 4j arenes 1 and 2 as ionophores were investigated. For both ionophores the selectivity coefficients (log k,,,) were lower than -2.2 for Hg(II) and lower than -4.6 for other cations tested. The best results were obtained with membranes containing dithioether fimctionalized calix[4]arene (ionophore 2), potassium tetrakis( 4-chlorophenyl)borate (KTpClFB) and bis( l-butylpentyl)adipate (BBPA) as a plasticizer. The Ag( I)response functions exhibited almost theoreticd Nernstian slopes in the activity range 1O-6-1O-1 M of silver ions.
Anal Chim Acta, 2005
The feasibility of using Tecoflex polyurethane as a polymeric matrix for fluoride-selective membr... more The feasibility of using Tecoflex polyurethane as a polymeric matrix for fluoride-selective membranes doped with Zr(IV)-octaethyl-(OEP) or Zr(IV)-tetraphenylporphyrins (TPP) is examined. Membranes containing cationic or anionic additives were prepared, with ionophore working according to neutral or charged carrier mechanism, respectively. Results are compared to those found previously using conventional poly(vinyl chloride) (PVC) as the membrane matrix. It was found that this polymer does not affect significantly the properties of these porphyrins, compared to poly(vinyl chloride) matrix. A dimer–monomer equilibrium determined recently to occur for Zr(IV)-porphyrins in PVC/o-NPOE membranes containing lipophilic anionic additives is also observed to occur (via UV–vis spectrophotometry) in the PU matrix. However, the equilibrium constants for dimer–monomer reactions appear to be lower in PU membranes compared to PVC films, as determined from the degree of super-Nernstian responses towards fluoride as well as the anion concentration ranges required to break the dimer as determined spectroscopically. Due to reduced dimerization of Zr(IV)[OEP]Cl2 it was possible to obtain electrodes with PU/o-NPOE/KTFPB membranes exhibiting only slightly super-Nernstian (−64.6 mV/dec) response towards fluoride and response time (t95 < 120 s) faster than observed for PVC-based membranes. Good working parameters were also obtained for this metalloporphyrin in PU membrane that forces neutral carrier mechanism (PU/DOS/TDMACl): F− calibration slope −58.3 mV/dec and response time t95 < 12 s. Tested membranes were subsequently applied for construction of miniaturized silicon-based sensors. Better fluoride selectivity was observed for sensors with Zr(IV)[OEP]Cl2/PU/o -NPOE/KTFPB membranes (log KF−,J−pot: ClO4− 0.7; Br− −1.9; NO3− −1.9; Cl− −3.1), compared to Zr(IV)[OEP]Cl2/PU/DOS/TDMACl matrix (log KF−,J−pot: ClO4− −0.8; Br− −1.3; NO3− −1.5; Cl− −2.1). However, latter composition was chosen to be better for flow measurement mode, as dimer formation can be totally prevented within this membrane. Sensors with Zr(IV)[OEP]Cl2/PU/DOS/TDMACl maintained their characteristics at least for 2 months.
Analytica Chimica Acta, Feb 9, 2009
In this work, complexes of Zr(IV) and Al(III) cations with 2,7,12,17-tetra-tert-butyl-5,10,15,20t... more In this work, complexes of Zr(IV) and Al(III) cations with 2,7,12,17-tetra-tert-butyl-5,10,15,20tetraazaporphine (TAP) were tested as ionophores in plasticized PVC membranes of ion-selective electrodes. It was found that both tested ionophores show enhanced affinity towards fluoride anion. High fluoride selectivity was observed in the presence of anionic or cationic additives in the membrane, which indicates that proposed compounds work according to charged or neutral carrier mechanism, depending on membrane composition and pretreatment.
Anal Chim Acta, 2002
The feasibility of using Zr(IV)-porphyrins as novel ionophores for preparing anion-selective poly... more The feasibility of using Zr(IV)-porphyrins as novel ionophores for preparing anion-selective polymeric membrane electrodes is examined. Electrodes constructed using o-nitrophenyl octyl ether plasticized poly(vinyl chloride) membranes containing Zr(IV)-octaethylporphyrin (OEP) dichloride (Zr(IV)[OEP]Cl2) or Zr(IV)-tetraphenylporphyrin (TPP) dichloride (Zr(IV)[TPP]Cl2) were found to exhibit enhanced potentiometric selectivity toward fluoride compared to electrodes based on a typical anion-exchanger (e.g. tridodecylmethylammonium chloride). At pH 5.5, the electrodes displayed the following selectivity sequences: ClO4− > SCN− > I− > F− > NO3− > Br− > NO2− > Cl− and F− > ClO4− > SCN− > I− > NO2− > NO3− > Br− > Cl− for membranes doped with Zr(IV)[OEP]Cl2) and Zr(IV)[TPP]Cl2, respectively. Both ionophores are shown to operate via a charged carrier mechanism, with 10 mol% of lipophilic tetraphenylborate derivative in the membrane phase required to achieve optimal selectivity. Electrodes prepared with both metalloporphyrin species display super-Nernstian response toward fluoride with slopes typically greater than −100 mV per decade. It is shown, via UV–VIS spectroscopy of the membrane phase, that this behavior occurs due to spontaneous formation of hydroxide ion bridged porphyrin dimers in the membrane in the presence of the lipophilic anionic additive. The dimers are easily converted to monomeric species upon increasing the concentration of fluoride in the sample solution. Decreasing the pH of sample buffer background solution (from pH 5.5 to pH 3) decreases the lower detection limit (DL) of the electrode response toward fluoride (by two-order of magnitude) and improves the electrodes’ selectivity.
Tetrahedron, 2005
The synthesis and binding properties of resorcinarene-based cavitands functionalized with N-acylt... more The synthesis and binding properties of resorcinarene-based cavitands functionalized with N-acylthiourea moieties towards different cations are described. Extraction studies with metal (Pb2+, Cu2+, Ag+, Hg2+, Cd2+, Eu3+, Fe3+, K+, Na+, and Ca2+) picrates and the incorporation in ion selective electrodes (ISEs), show that there is more than a 40% increase of the Ag+ extraction for N-acylthiourea ionophores (2, 3, and
Analytical Chemistry, May 1, 1998
The effect of the nonionic surfactants Brij 35 and Triton X-100 on the selectivity of neutral car... more The effect of the nonionic surfactants Brij 35 and Triton X-100 on the selectivity of neutral carrier-based ionselective electrodes (ISEs) commonly used for measurements of electrolytes in whole blood is investigated. Studies are conducted with plasticized PVC membranes doped with several neutral ionophores commonly employed to prepare clinically useful potassium, calcium, and sodium ISEs. An observed increase in the electrodes' EMF values upon the addition of surfactant to the test solution suggests a change in the ion selectivity of the polymeric membranes in the presence of Brij 35 or Triton X-100. For membranes doped with K + -selective valinomycin, the effect of nonionic surfactants is relatively small. However, in the case of calcium-selective membranes prepared with ETH 1001 and ETH 129, nonionic surfactants, especially Triton X-100, decrease the selectivity for calcium over potassium cations by nearly 1 order of magnitude. Such behavior is even more dramatic for sodium-selective membranes, with the degree of surfactant-induced loss of ion selectivity dependent on the specific sodium ionophore employed, the lipophilic tetraphenylborate derivative content of the membrane, and the surfactant type. A detailed theoretical model is presented to explain the effect of nonionic surfactants on the EMF response function of cation-selective polymeric membrane electrodes. Experimental results are in good agreement with theoretical predictions based on known binding constants for ionophores and surfactants with given cations.
Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95, 1995
Silicon-based chips with vacuum deposited gold electrode were tested as transducers for the devel... more Silicon-based chips with vacuum deposited gold electrode were tested as transducers for the development of DNA-modified biosensors. It was found that these structures are superior over commercially available transducers, mainly due to perfectly smooth surface of gold working electrode. This was confirmed with microscopic and electrochemical experiments. Obtained transducers were modified with oligonucleotide self-assembled monolayer. These sensors were shown to detect chosen DNA sequence with the employment of methylene blue as a redox marker. The same sensors were used to determine UO 2 2+ cation, however these efforts were unsuccessful.
ELECTROPHORESIS, 2015
The presented work aimed at systematic investigation of biological activity of CdSex S1- x /ZnS a... more The presented work aimed at systematic investigation of biological activity of CdSex S1- x /ZnS and CdSe/ZnS quantum dots (QDs), whose surface was modified with different ligands. For these studies, we used a microfluidic system combined with fluorescence microscopy techniques, which enabled analysis of cells&amp;amp;amp;amp;amp;#39; morphology, viability, and QDs uptake. PDMS and glass-based microfluidic system enabled the precise control of the cell environment, allowed to examine five replications of each tested QDs concentrations (statistically significant number), monitor multiple cellular events, and avoid manual preparation of QDs dilutions. We investigated the influence of the core composition and the type of surface modifiers on QDs toxicity. We also determined whether the examined nanoparticles penetrate into the cells. For all tested nanoparticles, the decrease of cells&amp;amp;amp;amp;amp;#39; viability was observed when increasing nanoparticles concentration. The decrease of live cells&amp;amp;amp;amp;amp;#39; number in microchambers and the accumulation of the nanoparticles around cultured cells were observed. The effect of hydrocarbon chain length of surface modifiers and QDs core composition on the cell viability was confirmed in our tests.
Circuit World, 2015
Purpose -The aim of this paper was to verify applicability of graphene-based sensors for voltamme... more Purpose -The aim of this paper was to verify applicability of graphene-based sensors for voltammetric and amperometric measurements of low-concentration compounds in biological fluids. Design/methodology/approach -Using the screen printing method, electrochemical sensors were manufactured on polymethylmetacrylate foil using a paste consisting of organic solvents and graphene nanopetals. As the model of a biological fluid tear film was chosen, the compound chosen as the analyte was H 2 O 2 , which is produced in oxidation of biological compounds. Tear film analog was prepared, in which, the measurements were carried out in a wide range of concentrations to determine the oxidation potential of H 2 O 2 through square-wave voltammetry. The second series of amperometric measurements was carried out for concentrations between 0 and 30 M/L, which is the lower range of physiological glucose concentration in tear films. Findings -The sensors presented linearity for concentrations from 0 to 3.5 per cent. Mean linear correlation coefficient between the peak current and the concentration for the examined sensors was 0.9764. Mean sensitivity was 434.4 mA·M Ϫ1 ·L Ϫ1 . Research limitations/implications -Results indicate a need for optimization of the sensors' performance. Main parameters to be improved are surface area of electrodes and purity of the graphene layer, as well as uniformity of the manufacturing process to improve accuracy and repeatability of measurements. Practical implications -Technology and materials used present an opportunity for creating low-cost, miniaturized and biocompatible sensors to be used in medical monitoring. Originality/value -Printed electronics technology described was not investigated previously in the field of biological sensors and could contribute to the solving of vital medicine problems.
Inzynieria Chemiczna i Procesowa
Biochemical Oxygen Demand (BOD) is an important factor used to measure water pollution. This arti... more Biochemical Oxygen Demand (BOD) is an important factor used to measure water pollution. This article reviews recent developments of microbial biosensors with respect to their applications for low BOD estimation. Four main methods to measure BOD using a biosensor are described: microbial fuel cells, optical methods, oxygen electrode based methods and mediator-based methods. Each of them is based on different principles, thus a different approach is required to improve the limit of detection. A proper choice of microorganisms used in the biosensor construction and/or sample pre-treatment processes is also essential to improve the BOD lower detection limit.
ECS Transactions, 2013
The feasibility of using gold electrodes modified with short-chain, thymine-rich, ss-DNA oligonuc... more The feasibility of using gold electrodes modified with short-chain, thymine-rich, ss-DNA oligonucleotides for determination of mercury cation is examined. The methylene blue was used as a redox marker for analytical signal generation. Biosensor response was based on the difference in electrochemical signal before and after subjecting it to sample containing Hg 2+ ion. The lower detection limit of 3 nmol L -1 for Hg 2+ was observed, together with good selectivity against common metal cations.
2007 14th International Conference on Mixed Design of Integrated Circuits and Systems, 2007
Preparation of pH-sensors and structures ready for ion-sensitive coating for in-line water pollut... more Preparation of pH-sensors and structures ready for ion-sensitive coating for in-line water pollution monitoring was the aim of the paper. Au and AgCl electrodes with Au backside contacts were developed using mono-Si substrates. Sequence of manufacturing process was presented. Device series resistance and potentiometric response were positively tested. ISFET pH sensors were manufactured and fully characterized. They were suitable for
The sensors for determination of potassium in soil are examined: i) medium-size ion-selective ele... more The sensors for determination of potassium in soil are examined: i) medium-size ion-selective electrodes with plasticized PVC-based ion-selective membranes, hydroxyethylenecelulose-based gel as inner electrolyte and silver/ silver chloride inner electrode and ii) back-side contact miniaturized sensors with gold inner electrode, polyacrylate-based ionselective membrane and redox-active Self-Assembled Monolayer as an intermediate phase. The selectivity of sensors to potassium ion was achieved by introduction of valinomycin as ionophore into the membrane phase. Preliminary potentiometric characterization of the examined sensors confirmed their good working parameters. The sensors were applied for the analysis of soil extracts. Results revealed good reproducibility and accuracy of proposed sensors, indicating their successful usage for this purpose.
Sensors and Actuators B: Chemical, 2005
Newly designed miniaturized potentiometric ion-selective sensors consisting of silicon-based tran... more Newly designed miniaturized potentiometric ion-selective sensors consisting of silicon-based transducers with Au contact, monolayers of redox-active organothiols and ion-selective polymeric membranes are presented. The purpose of incorporation of self-assembled monolayers is to improve sensors’ EMF stability. The influence of the chemical structure of intermediate layer on the electrochemical characteristics of sensors and the resistance to O2 and CO2 interferences of
Journal of Inclusion Phenomena, 2004
16-Membered azothia-and azoxythiacrown ethers have been studied as ion carriers in ion-selective ... more 16-Membered azothia-and azoxythiacrown ethers have been studied as ion carriers in ion-selective membranes. Their selectivities towards alkali, alkaline earth, transition and heavy metal cations were evaluated. The complex formation constants for these compounds with chosen cations have been determined using segmented sandwich membranes method.
Analytica Chimica Acta, 2008
In this work, a new concept of the solid-state sensors free from EMF instabilities is proposed. I... more In this work, a new concept of the solid-state sensors free from EMF instabilities is proposed. In order to prevent the formation of an aqueous layer underneath the ion-selective membrane, instead of improving the hydrophobicity of the monolayer, the moieties terminated with acrylate groups were incorporated within the redox-active monolayer structure. It allowed to &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;sew&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; all phases of the sensor (i.e., the transducer, the intermediate layer and the ion-selective membrane) and to obtain a stable and durable ion-selective sensor. It is shown that newly designed monolayer containing both the ferrocene- and the acrylate-terminated molecules does not affect the working parameters of the electrode, such as selectivity or the slope of the calibration curve, although the EMF drift of the sensor is significantly reduced to 0.2 mV per day.
Bioelectrochemistry (Amsterdam, Netherlands), 2016
A simple and cost effective method for the determination of restriction endonuclease activity is ... more A simple and cost effective method for the determination of restriction endonuclease activity is presented. dsDNA immobilized at a gold electrode surface is used as the enzymatic substrate, and an external cationic redox probe is employed in voltammetric measurements for analytical signal generation. The assessment of enzyme activity is based on a decrease of a current signal derived from reduction of methylene blue which is present in the sample solution. For this reason, the covalent attachment of the label molecule is not required which significantly reduces costs of the analysis and simplifies the entire determination procedure. The influence of buffer components on utilized dsDNA/MCH monolayer stability and integrity is also verified. Electrochemical impedance spectroscopy measurements reveal that due to pinhole formation during enzyme activity measurement the presence of any surfactants should be avoided. Additionally, it is shown that the sensitivity of the electrochemical bi...
Analytica Chimica Acta, Nov 1, 1994
Silver selective eiectrodes based on thioether functianaiized calix [ 4j arenes 1 and 2 as ionoph... more Silver selective eiectrodes based on thioether functianaiized calix [ 4j arenes 1 and 2 as ionophores were investigated. For both ionophores the selectivity coefficients (log k,,,) were lower than -2.2 for Hg(II) and lower than -4.6 for other cations tested. The best results were obtained with membranes containing dithioether fimctionalized calix[4]arene (ionophore 2), potassium tetrakis( 4-chlorophenyl)borate (KTpClFB) and bis( l-butylpentyl)adipate (BBPA) as a plasticizer. The Ag( I)response functions exhibited almost theoreticd Nernstian slopes in the activity range 1O-6-1O-1 M of silver ions.
Anal Chim Acta, 2005
The feasibility of using Tecoflex polyurethane as a polymeric matrix for fluoride-selective membr... more The feasibility of using Tecoflex polyurethane as a polymeric matrix for fluoride-selective membranes doped with Zr(IV)-octaethyl-(OEP) or Zr(IV)-tetraphenylporphyrins (TPP) is examined. Membranes containing cationic or anionic additives were prepared, with ionophore working according to neutral or charged carrier mechanism, respectively. Results are compared to those found previously using conventional poly(vinyl chloride) (PVC) as the membrane matrix. It was found that this polymer does not affect significantly the properties of these porphyrins, compared to poly(vinyl chloride) matrix. A dimer–monomer equilibrium determined recently to occur for Zr(IV)-porphyrins in PVC/o-NPOE membranes containing lipophilic anionic additives is also observed to occur (via UV–vis spectrophotometry) in the PU matrix. However, the equilibrium constants for dimer–monomer reactions appear to be lower in PU membranes compared to PVC films, as determined from the degree of super-Nernstian responses towards fluoride as well as the anion concentration ranges required to break the dimer as determined spectroscopically. Due to reduced dimerization of Zr(IV)[OEP]Cl2 it was possible to obtain electrodes with PU/o-NPOE/KTFPB membranes exhibiting only slightly super-Nernstian (−64.6 mV/dec) response towards fluoride and response time (t95 < 120 s) faster than observed for PVC-based membranes. Good working parameters were also obtained for this metalloporphyrin in PU membrane that forces neutral carrier mechanism (PU/DOS/TDMACl): F− calibration slope −58.3 mV/dec and response time t95 < 12 s. Tested membranes were subsequently applied for construction of miniaturized silicon-based sensors. Better fluoride selectivity was observed for sensors with Zr(IV)[OEP]Cl2/PU/o -NPOE/KTFPB membranes (log KF−,J−pot: ClO4− 0.7; Br− −1.9; NO3− −1.9; Cl− −3.1), compared to Zr(IV)[OEP]Cl2/PU/DOS/TDMACl matrix (log KF−,J−pot: ClO4− −0.8; Br− −1.3; NO3− −1.5; Cl− −2.1). However, latter composition was chosen to be better for flow measurement mode, as dimer formation can be totally prevented within this membrane. Sensors with Zr(IV)[OEP]Cl2/PU/DOS/TDMACl maintained their characteristics at least for 2 months.
Analytica Chimica Acta, Feb 9, 2009
In this work, complexes of Zr(IV) and Al(III) cations with 2,7,12,17-tetra-tert-butyl-5,10,15,20t... more In this work, complexes of Zr(IV) and Al(III) cations with 2,7,12,17-tetra-tert-butyl-5,10,15,20tetraazaporphine (TAP) were tested as ionophores in plasticized PVC membranes of ion-selective electrodes. It was found that both tested ionophores show enhanced affinity towards fluoride anion. High fluoride selectivity was observed in the presence of anionic or cationic additives in the membrane, which indicates that proposed compounds work according to charged or neutral carrier mechanism, depending on membrane composition and pretreatment.
Anal Chim Acta, 2002
The feasibility of using Zr(IV)-porphyrins as novel ionophores for preparing anion-selective poly... more The feasibility of using Zr(IV)-porphyrins as novel ionophores for preparing anion-selective polymeric membrane electrodes is examined. Electrodes constructed using o-nitrophenyl octyl ether plasticized poly(vinyl chloride) membranes containing Zr(IV)-octaethylporphyrin (OEP) dichloride (Zr(IV)[OEP]Cl2) or Zr(IV)-tetraphenylporphyrin (TPP) dichloride (Zr(IV)[TPP]Cl2) were found to exhibit enhanced potentiometric selectivity toward fluoride compared to electrodes based on a typical anion-exchanger (e.g. tridodecylmethylammonium chloride). At pH 5.5, the electrodes displayed the following selectivity sequences: ClO4− > SCN− > I− > F− > NO3− > Br− > NO2− > Cl− and F− > ClO4− > SCN− > I− > NO2− > NO3− > Br− > Cl− for membranes doped with Zr(IV)[OEP]Cl2) and Zr(IV)[TPP]Cl2, respectively. Both ionophores are shown to operate via a charged carrier mechanism, with 10 mol% of lipophilic tetraphenylborate derivative in the membrane phase required to achieve optimal selectivity. Electrodes prepared with both metalloporphyrin species display super-Nernstian response toward fluoride with slopes typically greater than −100 mV per decade. It is shown, via UV–VIS spectroscopy of the membrane phase, that this behavior occurs due to spontaneous formation of hydroxide ion bridged porphyrin dimers in the membrane in the presence of the lipophilic anionic additive. The dimers are easily converted to monomeric species upon increasing the concentration of fluoride in the sample solution. Decreasing the pH of sample buffer background solution (from pH 5.5 to pH 3) decreases the lower detection limit (DL) of the electrode response toward fluoride (by two-order of magnitude) and improves the electrodes’ selectivity.
Tetrahedron, 2005
The synthesis and binding properties of resorcinarene-based cavitands functionalized with N-acylt... more The synthesis and binding properties of resorcinarene-based cavitands functionalized with N-acylthiourea moieties towards different cations are described. Extraction studies with metal (Pb2+, Cu2+, Ag+, Hg2+, Cd2+, Eu3+, Fe3+, K+, Na+, and Ca2+) picrates and the incorporation in ion selective electrodes (ISEs), show that there is more than a 40% increase of the Ag+ extraction for N-acylthiourea ionophores (2, 3, and
Analytical Chemistry, May 1, 1998
The effect of the nonionic surfactants Brij 35 and Triton X-100 on the selectivity of neutral car... more The effect of the nonionic surfactants Brij 35 and Triton X-100 on the selectivity of neutral carrier-based ionselective electrodes (ISEs) commonly used for measurements of electrolytes in whole blood is investigated. Studies are conducted with plasticized PVC membranes doped with several neutral ionophores commonly employed to prepare clinically useful potassium, calcium, and sodium ISEs. An observed increase in the electrodes' EMF values upon the addition of surfactant to the test solution suggests a change in the ion selectivity of the polymeric membranes in the presence of Brij 35 or Triton X-100. For membranes doped with K + -selective valinomycin, the effect of nonionic surfactants is relatively small. However, in the case of calcium-selective membranes prepared with ETH 1001 and ETH 129, nonionic surfactants, especially Triton X-100, decrease the selectivity for calcium over potassium cations by nearly 1 order of magnitude. Such behavior is even more dramatic for sodium-selective membranes, with the degree of surfactant-induced loss of ion selectivity dependent on the specific sodium ionophore employed, the lipophilic tetraphenylborate derivative content of the membrane, and the surfactant type. A detailed theoretical model is presented to explain the effect of nonionic surfactants on the EMF response function of cation-selective polymeric membrane electrodes. Experimental results are in good agreement with theoretical predictions based on known binding constants for ionophores and surfactants with given cations.
Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95, 1995
Silicon-based chips with vacuum deposited gold electrode were tested as transducers for the devel... more Silicon-based chips with vacuum deposited gold electrode were tested as transducers for the development of DNA-modified biosensors. It was found that these structures are superior over commercially available transducers, mainly due to perfectly smooth surface of gold working electrode. This was confirmed with microscopic and electrochemical experiments. Obtained transducers were modified with oligonucleotide self-assembled monolayer. These sensors were shown to detect chosen DNA sequence with the employment of methylene blue as a redox marker. The same sensors were used to determine UO 2 2+ cation, however these efforts were unsuccessful.
ELECTROPHORESIS, 2015
The presented work aimed at systematic investigation of biological activity of CdSex S1- x /ZnS a... more The presented work aimed at systematic investigation of biological activity of CdSex S1- x /ZnS and CdSe/ZnS quantum dots (QDs), whose surface was modified with different ligands. For these studies, we used a microfluidic system combined with fluorescence microscopy techniques, which enabled analysis of cells&amp;amp;amp;amp;amp;#39; morphology, viability, and QDs uptake. PDMS and glass-based microfluidic system enabled the precise control of the cell environment, allowed to examine five replications of each tested QDs concentrations (statistically significant number), monitor multiple cellular events, and avoid manual preparation of QDs dilutions. We investigated the influence of the core composition and the type of surface modifiers on QDs toxicity. We also determined whether the examined nanoparticles penetrate into the cells. For all tested nanoparticles, the decrease of cells&amp;amp;amp;amp;amp;#39; viability was observed when increasing nanoparticles concentration. The decrease of live cells&amp;amp;amp;amp;amp;#39; number in microchambers and the accumulation of the nanoparticles around cultured cells were observed. The effect of hydrocarbon chain length of surface modifiers and QDs core composition on the cell viability was confirmed in our tests.
Circuit World, 2015
Purpose -The aim of this paper was to verify applicability of graphene-based sensors for voltamme... more Purpose -The aim of this paper was to verify applicability of graphene-based sensors for voltammetric and amperometric measurements of low-concentration compounds in biological fluids. Design/methodology/approach -Using the screen printing method, electrochemical sensors were manufactured on polymethylmetacrylate foil using a paste consisting of organic solvents and graphene nanopetals. As the model of a biological fluid tear film was chosen, the compound chosen as the analyte was H 2 O 2 , which is produced in oxidation of biological compounds. Tear film analog was prepared, in which, the measurements were carried out in a wide range of concentrations to determine the oxidation potential of H 2 O 2 through square-wave voltammetry. The second series of amperometric measurements was carried out for concentrations between 0 and 30 M/L, which is the lower range of physiological glucose concentration in tear films. Findings -The sensors presented linearity for concentrations from 0 to 3.5 per cent. Mean linear correlation coefficient between the peak current and the concentration for the examined sensors was 0.9764. Mean sensitivity was 434.4 mA·M Ϫ1 ·L Ϫ1 . Research limitations/implications -Results indicate a need for optimization of the sensors' performance. Main parameters to be improved are surface area of electrodes and purity of the graphene layer, as well as uniformity of the manufacturing process to improve accuracy and repeatability of measurements. Practical implications -Technology and materials used present an opportunity for creating low-cost, miniaturized and biocompatible sensors to be used in medical monitoring. Originality/value -Printed electronics technology described was not investigated previously in the field of biological sensors and could contribute to the solving of vital medicine problems.
Inzynieria Chemiczna i Procesowa
Biochemical Oxygen Demand (BOD) is an important factor used to measure water pollution. This arti... more Biochemical Oxygen Demand (BOD) is an important factor used to measure water pollution. This article reviews recent developments of microbial biosensors with respect to their applications for low BOD estimation. Four main methods to measure BOD using a biosensor are described: microbial fuel cells, optical methods, oxygen electrode based methods and mediator-based methods. Each of them is based on different principles, thus a different approach is required to improve the limit of detection. A proper choice of microorganisms used in the biosensor construction and/or sample pre-treatment processes is also essential to improve the BOD lower detection limit.
ECS Transactions, 2013
The feasibility of using gold electrodes modified with short-chain, thymine-rich, ss-DNA oligonuc... more The feasibility of using gold electrodes modified with short-chain, thymine-rich, ss-DNA oligonucleotides for determination of mercury cation is examined. The methylene blue was used as a redox marker for analytical signal generation. Biosensor response was based on the difference in electrochemical signal before and after subjecting it to sample containing Hg 2+ ion. The lower detection limit of 3 nmol L -1 for Hg 2+ was observed, together with good selectivity against common metal cations.
2007 14th International Conference on Mixed Design of Integrated Circuits and Systems, 2007
Preparation of pH-sensors and structures ready for ion-sensitive coating for in-line water pollut... more Preparation of pH-sensors and structures ready for ion-sensitive coating for in-line water pollution monitoring was the aim of the paper. Au and AgCl electrodes with Au backside contacts were developed using mono-Si substrates. Sequence of manufacturing process was presented. Device series resistance and potentiometric response were positively tested. ISFET pH sensors were manufactured and fully characterized. They were suitable for
The sensors for determination of potassium in soil are examined: i) medium-size ion-selective ele... more The sensors for determination of potassium in soil are examined: i) medium-size ion-selective electrodes with plasticized PVC-based ion-selective membranes, hydroxyethylenecelulose-based gel as inner electrolyte and silver/ silver chloride inner electrode and ii) back-side contact miniaturized sensors with gold inner electrode, polyacrylate-based ionselective membrane and redox-active Self-Assembled Monolayer as an intermediate phase. The selectivity of sensors to potassium ion was achieved by introduction of valinomycin as ionophore into the membrane phase. Preliminary potentiometric characterization of the examined sensors confirmed their good working parameters. The sensors were applied for the analysis of soil extracts. Results revealed good reproducibility and accuracy of proposed sensors, indicating their successful usage for this purpose.
Sensors and Actuators B: Chemical, 2005
Newly designed miniaturized potentiometric ion-selective sensors consisting of silicon-based tran... more Newly designed miniaturized potentiometric ion-selective sensors consisting of silicon-based transducers with Au contact, monolayers of redox-active organothiols and ion-selective polymeric membranes are presented. The purpose of incorporation of self-assembled monolayers is to improve sensors’ EMF stability. The influence of the chemical structure of intermediate layer on the electrochemical characteristics of sensors and the resistance to O2 and CO2 interferences of
Journal of Inclusion Phenomena, 2004
16-Membered azothia-and azoxythiacrown ethers have been studied as ion carriers in ion-selective ... more 16-Membered azothia-and azoxythiacrown ethers have been studied as ion carriers in ion-selective membranes. Their selectivities towards alkali, alkaline earth, transition and heavy metal cations were evaluated. The complex formation constants for these compounds with chosen cations have been determined using segmented sandwich membranes method.