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Research Interests: Biosensors and BioSensors
Vytauto Didžiojo universiteta
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This study describes the application of a polypyrrole-based sensor for the determination of SARS-CoV-2-S spike glycoprotein. The SARS-CoV-2-S spike glycoprotein is a spike protein of the coronavirus SARS-CoV-2 that recently caused the... more
This study describes the application of a polypyrrole-based sensor for the determination of SARS-CoV-2-S spike glycoprotein. The SARS-CoV-2-S spike glycoprotein is a spike protein of the coronavirus SARS-CoV-2 that recently caused the worldwide spread of COVID-19 disease. This study is dedicated to the development of an electrochemical determination method based on the application of molecularly imprinted polymer technology. The electrochemical sensor was designed by molecular imprinting of polypyrrole (Ppy) with SARS-CoV-2-S spike glycoprotein (MIP-Ppy). The electrochemical sensors with MIP-Ppy and with polypyrrole without imprints (NIP-Ppy) layers were electrochemically deposited on a platinum electrode surface by a sequence of potential pulses. The performance of polymer layers was evaluated by pulsed amperometric detection. According to the obtained results, a sensor based on MIP-Ppy is more sensitive to the SARS-CoV-2-S spike glycoprotein than a sensor based on NIP-Ppy. Also, the results demonstrate that the MIP-Ppy layer is more selectively interacting with SARS-CoV-2-S glycoprotein than with bovine serum albumin. This proves that molecularly imprinted MIP-Ppy-based sensors can be applied for the detection of SARS-CoV-2 virus proteins.
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In this research the molecular imprinting technology was applied for the formation of glyphosate-sensitive layer. The glyphosate imprinted conducting polymer polypyrrole (MIPpy) was deposited on a gold chip/electrode and used as an... more
In this research the molecular imprinting technology was applied for the formation of glyphosate-sensitive layer. The glyphosate imprinted conducting polymer polypyrrole (MIPpy) was deposited on a gold chip/electrode and used as an electrochemical surface plasmon resonance (ESPR) sensor. The results described in this study disclose some restrictions and challenges, which arise during the development of glyphosate ESPR sensor based on the molecularly imprinted polymer development stage. It was demonstrated, that glyphosate could significantly affect the electrochemical deposition process of molecularly imprinted polymer on the electrode. The results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and surface plasmon resonance (SPR) have demonstrated that glyphosate molecules tend to interact with bare gold electrode and thus hinder the polypyrrole deposition. As a possible solution, the formation of a self-assembled monolayer (SAM) of 11-(1H-Pyrrol-1-yl)undecane-1-thiol (PUT) before electrochemical deposition of MIPpy and NIPpy was applied. Dissociation constant (KD) and free energy of Gibbs (ΔG0) values of glyphosate on MIPpy and Ppy without glyphosate imprints (NIPpy) were calculated. For the interaction of glyphosate with MIPpy the KD was determined as 38.18 ± 2.33⋅10-5 and ΔG0 as -19.51 ± 0.15 kJ/mol.
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Disertacija rengta 2004-2008 metais Vytauto Didžiojo universiteto Gamtos mokslų fakulteto Chemijos katedrojeAut. darbų sąrašas: 104-105 (13 pavad.)Biochemijos katedraVytauto Didžiojo universiteta
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Research Interests: Chemistry, Analytical Chemistry, Chromatography, Morphology, Separation, and 13 morePolymers, Medicine, Polymerization, Separation Science, Porosity, High Performance Liquid Chromatography, Buffers, Monomer, Liquid Chromatography, Hydrogen-Ion Concentration, Size Exclusion Chromatography, Polyacrylamide, and HPLC Chromatography
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Botanikos institutasVytauto Didžiojo universiteta
Disertacija rengta 2004-2008 metais Vytauto Didžiojo universiteto Gamtos mokslų fakulteto Chemijos katedrojeAut. darbų sąrašas: 104-105 (13 pavad.)Biochemijos katedraVytauto Didžiojo universiteta
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This study is dedicated to molecularly imprinted polymer-based sensor development for methylene blue detection. The sensor was designed by molecular imprinting of polypyrrole with phenothiazine derivative methylene blue (MB) as a template... more
This study is dedicated to molecularly imprinted polymer-based sensor development for methylene blue detection. The sensor was designed by molecular imprinting of polypyrrole with phenothiazine derivative methylene blue (MB) as a template molecule. The molecularly imprinted polymer (MIP) was deposited directly on the surface of the indium tin oxide-coated glass electrode by potential cycling. Different deposition conditions, the layer’s durability, and thickness impact were analysed. The working electrodes were coated with molecularly imprinted and non-imprinted polymer layers. Potential pulse chronoamperometry and cyclic voltammetry were used to study these layers. Scanning electron microscopy was used to determine the surface morphology of the polymer layers. The change in optical absorption was used as an analytical tool to evaluate the capability of the MIP layer to adsorb MB. Selectivity was monitored by tracking the optical absorption changes in the presence of Azure A. In the...
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The appearance of biological molecules, so-called biomarkers in body fluids at abnormal concentrations, is considered a good tool for detecting disease. Biomarkers are usually looked for in the most common body fluids, such as blood,... more
The appearance of biological molecules, so-called biomarkers in body fluids at abnormal concentrations, is considered a good tool for detecting disease. Biomarkers are usually looked for in the most common body fluids, such as blood, nasopharyngeal fluids, urine, tears, sweat, etc. Even with significant advances in diagnostic technology, many patients with suspected infections receive empiric antimicrobial therapy rather than appropriate treatment, which is driven by rapid identification of the infectious agent, leading to increased antimicrobial resistance. To positively impact healthcare, new tests are needed that are pathogen-specific, easy to use, and produce results quickly. Molecularly imprinted polymer (MIP)-based biosensors can achieve these general goals and have enormous potential for disease detection. This article aimed to overview recent articles dedicated to electrochemical sensors modified with MIP to detect protein-based biomarkers of certain infectious diseases in h...
Research Interests: Biosensors and BioSensors
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Detecting bacteria—Listeria monocytogenes—is an essential healthcare and food industry issue. The objective of the current study was to apply platinum (Pt) and screen-printed carbon (SPCE) electrodes modified by molecularly imprinted... more
Detecting bacteria—Listeria monocytogenes—is an essential healthcare and food industry issue. The objective of the current study was to apply platinum (Pt) and screen-printed carbon (SPCE) electrodes modified by molecularly imprinted polymer (MIP) in the design of an electrochemical sensor for the detection of Listeria monocytogenes. A sequence of potential pulses was used to perform the electrochemical deposition of the non-imprinted polypyrrole (NIP-Ppy) layer and Listeria monocytogenes-imprinted polypyrrole (MIP-Ppy) layer over SPCE and Pt electrodes. The bacteria were removed by incubating Ppy-modified electrodes in different extraction solutions (sulphuric acid, acetic acid, L-lysine, and trypsin) to determine the most efficient solution for extraction and to obtain a more sensitive and repeatable design of the sensor. The performance of MIP-Ppy- and NIP-Ppy-modified electrodes was evaluated by pulsed amperometric detection (PAD). According to the results of this research, it c...
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In this research the molecular imprinting technology was applied for the formation of glyphosate-sensitive layer. The glyphosate imprinted conducting polymer polypyrrole (MIPpy) was deposited on a gold chip/electrode and used as an... more
In this research the molecular imprinting technology was applied for the formation of glyphosate-sensitive layer. The glyphosate imprinted conducting polymer polypyrrole (MIPpy) was deposited on a gold chip/electrode and used as an electrochemical surface plasmon resonance (ESPR) sensor. The results described in this study disclose some restrictions and challenges, which arise during the development of glyphosate ESPR sensor based on the molecularly imprinted polymer development stage. It was demonstrated, that glyphosate could significantly affect the electrochemical deposition process of molecularly imprinted polymer on the electrode. The results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and surface plasmon resonance (SPR) have demonstrated that glyphosate molecules tend to interact with bare gold electrode and thus hinder the polypyrrole deposition. As a possible solution, the formation of a self-assembled monolayer (SAM) of 11-(1H-Pyrrol-1-yl)undecane-1-thiol (PUT) before electrochemical deposition of MIPpy and NIPpy was applied. Dissociation constant (KD) and free energy of Gibbs (ΔG0) values of glyphosate on MIPpy and Ppy without glyphosate imprints (NIPpy) were calculated. For the interaction of glyphosate with MIPpy the KD was determined as 38.18 ± 2.33⋅10-5 and ΔG0 as -19.51 ± 0.15 kJ/mol.
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The development of microbial fuel cells based on electro-catalytic processes is among the novel topics, which are recently emerging in the sustainable development of energetic systems. Microbial fuel cells have emerged as unique... more
The development of microbial fuel cells based on electro-catalytic processes is among the novel topics, which are recently emerging in the sustainable development of energetic systems. Microbial fuel cells have emerged as unique biocatalytic systems, which transform the chemical energy accumulated in renewable organic fuels and at the same time reduce pollution from hazardous organic compounds. However, not all microorganisms involved in metabolic/catalytic processes generate sufficient redox potential. In this research, we have assessed the applicability of the microorganism Rhizobium anhuiense as a catalyst suitable for the design of microbial fuel cells. To improve the charge transfer, several redox mediators were tested, namely menadione, riboflavin, and 9,10-phenanthrenequinone (PQ). The best performance was determined for a Rhizobium anhuiense-based bio-anode mediated by menadione with a 0.385 mV open circuit potential and 5.5 μW/cm2 maximal power density at 0.35 mV, which gen...
Research Interests: Biosensors and BioSensors
This review is dedicated to the development of molecularly imprinted polymers (MIPs) and the application of MIPs in sensor design. MIP-based biological recognition parts can replace receptors or antibodies, which are rather expensive.... more
This review is dedicated to the development of molecularly imprinted polymers (MIPs) and the application of MIPs in sensor design. MIP-based biological recognition parts can replace receptors or antibodies, which are rather expensive. Conducting polymers show unique properties that are applicable in sensor design. Therefore, MIP-based conducting polymers, including polypyrrole, polythiophene, poly(3,4-ethylenedioxythiophene), polyaniline and ortho-phenylenediamine are frequently applied in sensor design. Some other materials that can be molecularly imprinted are also overviewed in this review. Among many imprintable materials conducting polymer, polypyrrole is one of the most suitable for molecular imprinting of various targets ranging from small organics up to rather large proteins. Some attention in this review is dedicated to overview methods applied to design MIP-based sensing structures. Some attention is dedicated to the physicochemical methods applied for the transduction of ...
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The serologic diagnosis of coronavirus disease 2019 (COVID-19) and the evaluation of vaccination effectiveness are identified by the presence of antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this... more
The serologic diagnosis of coronavirus disease 2019 (COVID-19) and the evaluation of vaccination effectiveness are identified by the presence of antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this paper, we present the electrochemical-based biosensing technique for the detection of antibodies specific to the SARS-CoV-2 proteins. Recombinant SARS-CoV-2 spike proteins (rSpike) were immobilised on the surface of a gold electrode modified by a self-assembled monolayer (SAM). This modified electrode was used as a sensitive element for the detection of polyclonal mouse antibodies against the rSpike (anti-rSpike). Electrochemical impedance spectroscopy (EIS) was used to observe the formation of immunocomplexes while cyclic voltammetry (CV) was used for additional analysis of the surface modifications. It was revealed that the impedimetric method and the elaborate experimental conditions are appropriate for the further development of electrochemical ...
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Analysis of pharmaceuticals and biologically active materials recently can be performed by biosensors, which can be based on conducting polymers. Therefore, in this Mini Review some achievements in the synthesis and application of... more
Analysis of pharmaceuticals and biologically active materials recently can be performed by biosensors, which can be based on conducting polymers. Therefore, in this Mini Review some achievements in the synthesis and application of conducting polymer—polypyrrole (Ppy), which is often used in the design of sensors and biosensors, are overviewed. Some perspective methods of conducting polymer synthesis are outlined. Significant attention has been paid to electrochemical, chemical and biochemical synthesis of conducting polymers (CPs) , which were developed by authors. The applicability of polypyrrole based functional layers in the design of electrochemical biosensors is overviewed. The adaptability of enzyme—glucose oxidase (GOx), which can be applied as (i) biological recognition element—in the design of glucose biosensors, (ii) a biocatalyst—in the synthesis of some above mentioned conducting polymers, is discussed. Part of biocompatibility related aspects of some conducting polymers...
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This paper provides an overview of the application of conducting polymers (CPs) used in the design of tactile sensors. While conducting polymers can be used as a base in a variety of forms, such as films, particles, matrices, and fillers,... more
This paper provides an overview of the application of conducting polymers (CPs) used in the design of tactile sensors. While conducting polymers can be used as a base in a variety of forms, such as films, particles, matrices, and fillers, the CPs generally remain the same. This paper, first, discusses the chemical and physical properties of conducting polymers. Next, it discusses how these polymers might be involved in the conversion of mechanical effects (such as pressure, force, tension, mass, displacement, deformation, torque, crack, creep, and others) into a change in electrical resistance through a charge transfer mechanism for tactile sensing. Polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene), polydimethylsiloxane, and polyacetylene, as well as application examples of conducting polymers in tactile sensors, are overviewed. Attention is paid to the additives used in tactile sensor development, together with conducting polymers. There is a long list of additives and com...
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ABSTRACT h i g h l i g h t s Electrochemical synthesis of polypyrrole (Ppy) film was performed on the gold electrode. Stability of Ppy films during elec-trochemical treatment was investi-gated. Cyclic voltammetry as electrochemi-cal... more
ABSTRACT h i g h l i g h t s Electrochemical synthesis of polypyrrole (Ppy) film was performed on the gold electrode. Stability of Ppy films during elec-trochemical treatment was investi-gated. Cyclic voltammetry as electrochemi-cal repulsion method was applied. Electrochemical repulsion condi-tions of Ppy from the electrode surface were evaluated. g r a p h i c a l a b s t r a c t a b s t r a c t This study reports the electrochemical synthesis of polypyrrole (Ppy) film on the gold surface and the evaluation of this film repulsion conditions from the electrode surface. It is known that overall stability of the conducting polymer layer on the electrode is critical for many applications including biosensors. It can be affected by many factors however electrochemical treatment of electrode is mostly well-known among them. This work was mainly based on the preparation of the polymeric layer and the investigation of its stability. Overoxidised polypyrrole film was synthesized on the gold electrode. Later this layer was treated by potential cycling in wide potential intervals. The stability of Ppy layers deposited on electrode was evaluated. It was determined that Ppy layer was stable within 0–0.9 V potential range, scan rate was 20 mV/s, vs. Ag/AgCl/KCl sat. while it was repulsed from the gold electrode by 10 potential cycles within 0.0–1.0 V potential range at the same scan rate. Some possible future applications of repulsed Ppy films are predicted.
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Monitoring and tracking infection is required in order to reduce the spread of the coronavirus disease 2019 (COVID-19), induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To achieve this goal, the development and... more
Monitoring and tracking infection is required in order to reduce the spread of the coronavirus disease 2019 (COVID-19), induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To achieve this goal, the development and deployment of quick, accurate, and sensitive diagnostic methods are necessary. The determination of the SARS-CoV-2 virus is performed by biosensing devices, which vary according to detection methods and the biomarkers which are inducing/providing an analytical signal. RNA hybridisation, antigen-antibody affinity interaction, and a variety of other biological reactions are commonly used to generate analytical signals that can be precisely detected using electrochemical, electrochemiluminescence, optical, and other methodologies and transducers. Electrochemical biosensors, in particular, correspond to the current trend of bioanalytical process acceleration and simplification. Immunosensors are based on the determination of antigen-antibody interaction, w...
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Polypyrrole (Ppy) and poly(methylene blue) (PMB) heterostructure (Ppy-PMB) was electrochemically formed on the indium tin oxide (ITO) coated glass slides, which served as working electrodes. For electropolymerization, a solution... more
Polypyrrole (Ppy) and poly(methylene blue) (PMB) heterostructure (Ppy-PMB) was electrochemically formed on the indium tin oxide (ITO) coated glass slides, which served as working electrodes. For electropolymerization, a solution containing pyrrole, methylene blue, and a saccharide (lactose, sucrose, or heparin) that served as dopant was used. The aim of this study was to compare the effect of the saccharides (lactose, sucrose, and heparin) on the electrochromic properties of the Ppy-PMB layer. AFM and SEM have been used for the analysis of the surface dominant features of the Ppy-PMB layers. From these images, it was concluded that the saccharides used in this study have a moderate effect on the surface morphology. Electrochromic properties were analyzed with respect to the changes of absorbance of the layer at two wavelengths (668 nm and 750 nm) by changing the pH of the surrounding solution and the potential between +0.8 V and −0.8 V. It was demonstrated that the highest absorbanc...
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Abstract Various nanotechnological methods and high number of nanostructured materials including polymer nanocomposites (PNCs) become extremely important in sensor and biosensor technology. Conducting polymers as artificial versatile... more
Abstract Various nanotechnological methods and high number of nanostructured materials including polymer nanocomposites (PNCs) become extremely important in sensor and biosensor technology. Conducting polymers as artificial versatile materials seem very suitable for the development of various analyte-recognizing parts of sensors and biosensors. This contribution is reviewing major fabrication methods of conducting polymer-based nanocomposites for biosensorics. Experience of authors in application of various electrochemically generated polymers in design of biosensors is presented. The influence of fabrication method on sensor characteristics is overviewed. Major types of biosensors based on conducting polymers including catalytic biosensors, DNA-sensors, immunosensors and molecularly imprinted polymer-based affinity sensors is discussed. Conducting and electrochemically generated polymers that are mostly used in sensor design are presented.
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In this research, scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS) were applied for the evaluation of surface characteristics of electrochemical (amperometric) biosensor based on two composite... more
In this research, scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS) were applied for the evaluation of surface characteristics of electrochemical (amperometric) biosensor based on two composite structures consisting of perforated polycarbonate membrane modified by carbon-nanomaterials and glucose oxidase. The first structure consisted of the polycarbonate filter membrane, punctured by 400 nm holes (PCM) consequently modified with single walled carbon nanotubes (SWCNT) and graphene oxide (GO) layer (PCM/SWCNT/GO); and the other structure consisted of the same PCM, consequently modified with SWCNT and reduced graphene oxide (rGO) layer (PCM/SWCNT/rGO). These two composite structures were developed and applied in biosensor design. In order to form a biosensing surfaces the PCM/SWCNT/GO and PCM/SWCNT/rGO composite structures were modified by immobilized glucose oxidase (GOx). The surface of GOx modified PCM/SWCNT/GO composite structure (PCM/SWCN...
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The indium tin oxide (ITO)-coated glass was used as a working electrode for electrochemical deposition of conducting polymer polypyrrole (Ppy). Before polymerization, the electrode surface was additionally modified with... more
The indium tin oxide (ITO)-coated glass was used as a working electrode for electrochemical deposition of conducting polymer polypyrrole (Ppy). Before polymerization, the electrode surface was additionally modified with triethoxymethylsilane (TEMS) to provide better adhesion of polypyrrole to the surface of ITO. The polymerization of Ppy was performed electrochemically, regarding the previous studies. The ionic strength of the solution was supported by LiClO4. Since the dissolved CO2 in the solution forms weak acid and, thus, the pH of a solution can be slightly changed, the electrochromic response to the pH changes was evaluated. Britton–Robinson buffer (BRB) was used as the model system for an evaluation of the electrochromic response of polypyrrole at different pH values and concentrations of NaHCO3, which was a source of CO2 in the solution. For the evaluation of the electrochromic response in the presence of CO2, the double potential step chronoamperometry method was applied an...
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The review focuses on the overview of electrochemical sensors based on molecularly imprinted polymers (MIPs) for the determination of uric acid. The importance of robust and precise determination of uric acid is highlighted, a short... more
The review focuses on the overview of electrochemical sensors based on molecularly imprinted polymers (MIPs) for the determination of uric acid. The importance of robust and precise determination of uric acid is highlighted, a short description of the principles of molecular imprinting technology is presented, and advantages over the others affinity-based analytical methods are discussed. The review is mainly concerned with the electro-analytical methods like cyclic voltammetry, electrochemical impedance spectroscopy, amperometry, etc. Moreover, there are some scattered notes to the other electrochemistry-related analytical methods, which are capable of providing additional information and to solve some challenges that are not achievable using standard electrochemical methods. The significance of these overviewed methods is highlighted. The overview of the research that is employing MIPs imprinted with uric acid is mainly targeted to address these topics: (i) type of polymers, which...
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In this research we report the gas-sensing properties of TiO2-x/TiO2-based hetero-structure, which was ‘self-heated’ by current that at constant potential passed through the structure. Amperometric measurements were applied for the... more
In this research we report the gas-sensing properties of TiO2-x/TiO2-based hetero-structure, which was ‘self-heated’ by current that at constant potential passed through the structure. Amperometric measurements were applied for the evaluation of sensor response towards ethanol, methanol, n-propanol and acetone gases/vapours. The sensitivity towards these gases was based on electrical resistance changes, which were determined by amperometric measurements of current at fixed voltage applied between Pt-based contacts/electrodes deposited on the TiO2-x/TiO2-based layer. X-ray diffraction (XRD) analysis revealed the formation of TiO2-x/TiO2-based hetero-structure, which is mainly based on Ti3O5/TiO2 formed during the hydro-thermal oxidation-based sensing-layer preparation process. Additionally, photoluminescence and time-resolved photoluminescence decay kinetics-based signals of this sensing structure revealed the presence of TiO2 mainly in the anatase phase in the TiO2-x/TiO2-based hete...
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ABSTRACT In this study some affinity and dielectric properties of molecularly imprinted (MIP) conducting polymer – polypyrrole (Ppy) based thin films were evaluated. Films of polypyrrole molecularly imprinted with theophylline (MIP-Ppy)... more
ABSTRACT In this study some affinity and dielectric properties of molecularly imprinted (MIP) conducting polymer – polypyrrole (Ppy) based thin films were evaluated. Films of polypyrrole molecularly imprinted with theophylline (MIP-Ppy) and non-imprinted polypyrrole (NIP-Ppy) were formed on boron doped silicon (Si) substrates in order to evaluate the efficiency of Ppy to bind theophylline. The substrates were modified with boron-doped oxygen terminated nanocrystalline diamond (B:NCD:O) The dielectric properties of B:NCD:O/Ppy-based multi-layered structures were analyzed using spectroscopic ellipsometry and spectrophotometric techniques. Electrochemical impedance spectroscopy was applied for the investigation of kinetics of theophylline interaction with MIP-Ppy and NIP-Ppy. The sensitivity of molecularly imprinted and non-imprinted polymer films was analyzed by injection of different theophylline concentrations. Assuming that Ppy film electrical capacitance change is a result of Ppy dielectric constant change induced by absorbed theophylline molecules, the electrical capacitance change (ΔC) kinetics at different concentrations of theophylline was analyzed using first pseudo order kinetic equation. The dissociation equilibrium constant KD of MIP-Ppy/theophylline complex at room temperature was calculated as 1.7·10-8 M, and Gibbs free energy change (ΔG) of MIP-Ppy/theophylline complex formation was calculated as-43.5 kJ/mol. It was concluded that molecularly imprinted polypyrrole thin film could be used for the detection of theophylline.
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The aim of this study was to assess the impact of nanocrystalline diamond (NCD) thin coatings on neural cell adhesion and proliferation. NCD was fabricated on fused silica substrates by microwave plasma chemical vapor deposition (MPCVD)... more
The aim of this study was to assess the impact of nanocrystalline diamond (NCD) thin coatings on neural cell adhesion and proliferation. NCD was fabricated on fused silica substrates by microwave plasma chemical vapor deposition (MPCVD) method. Different surface terminations were performed through exposure to reactive hydrogen and by UV induced oxidation during ozone treatment. Boron doped NCD coatings were also prepared and investigated. NCD surface wettability was determined by contact angle measurement. To assess biocompatibility of the NCD coatings, the neuroblastoma SH-SY5Y cell line was used. Cells were plated directly onto diamond surfaces and cultured in medium with or without fetal bovine serum (FBS), in order to evaluate the ability of cells to adhere and to proliferate. The obtained results showed that these cells adhered and proliferated better on NCD surfaces than on the bare fused silica. The cell proliferation on NCD in medium with and without FBS after 48h from plati...
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Diamond nanoparticles (DNPs) are very attractive for biomedical applications, particularly for bioimaging. The aim of this study was to evaluate the impact of DNPs on neural cancer cells and thus to assess the possible application of DNPs... more
Diamond nanoparticles (DNPs) are very attractive for biomedical applications, particularly for bioimaging. The aim of this study was to evaluate the impact of DNPs on neural cancer cells and thus to assess the possible application of DNPs for these cells imaging. For this purpose, the neuroblastoma SH-SY5Y cell line was chosen. Cells were cultured in medium with different concentrations (15, 50, 100 and 150 μg/ml) of DNPs. After 48 h of incubation, cell metabolic activity was evaluated by the XTT assay. For assessment of cellular metabolic activity, cells were also cultured on differently terminated nanocrystalline diamond (NCD) coatings in medium with 150 μg/ml of DNPs. Cell adhesion and morphology were evaluated by brightfield microscopy. Diamond nanoparticle internalization was determined by confocal microscopy. The obtained results showed that low concentrations (15, 50 and 100 μg/ml) of nanoparticles did not significantly affect the SH-SY5Y cell metabolic activity. However, a higher concentration (150 μg/ml) of DNPs statistically significantly reduced SH-SY5Y cell metabolic activity. After 48 h incubation with 150 μg/ml DNPs, cell metabolic activity was 23% lower than in medium without DNPs on standard tissue culture polystyrene.
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Electrochemical quartz crystal microbalance (EQCM) was used for the evaluation of conducting polymer polypyrrole (Ppy), which was formed by a sequence of potential pulses on a Au-plated EQCM disc. The Ppy layer was obtained from freshly... more
Electrochemical quartz crystal microbalance (EQCM) was used for the evaluation of conducting polymer polypyrrole (Ppy), which was formed by a sequence of potential pulses on a Au-plated EQCM disc. The Ppy layer was obtained from freshly prepared polymerization solution consisting of pyrrole that was dissolved in phosphate buffer. The main aim of the study was to determine some aspects of the Ppy layer formation process. The polymerization process was estimated by EQCM and chronoamperometry. The Cottrell equation was used for the integration of total charge that was passing through the electrochemical cell during the formation of the Ppy-based layer. It was found that the charge of the electrical double layer, which was estimated while applying an Anson plot, is negative. From this observation, it could be assumed that the pyrrole oxidation process could be well described by principles of heterogeneous kinetics. The negative value of the electrical double layer was the result of a charge-transfer restriction. This restriction of charge transfer could occur due to partial blocking of the electrode surface by an aggregated Ppy particle-based layer. Quartz crystal motional resistance (R) was taken into account during this research. Ppy layer formation is represented schematically on the basis of the obtained experimental results and analytical data.
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Abbreviations: AFM-atomic force microscopy; Cd-capacitance of electrical double layer; c-concentration of analyte; CPE-constant phase element of electrical double layer; EIS-electrochemical impedance spectroscopy; ka-constant of... more
Abbreviations: AFM-atomic force microscopy; Cd-capacitance of electrical double layer; c-concentration of analyte; CPE-constant phase element of electrical double layer; EIS-electrochemical impedance spectroscopy; ka-constant of association rate; kd-constant of dissociation rate; KA-association equilibrium constant (KA= ka/kd); KD-dissociation equilibrium constant (KD = 1/KA); KD_theoph-dissociation equilibrium constant of theophylline interaction with MIP-Ppy; KD_caffeine-dissociation equilibrium constant of caffeine interaction with MIP-Ppy; MIP-molecularly-imprinted polymer; MIP-Ppy-molecularly-imprinted polypyrrole; PBS-phosphate buffered saline solution; Ppy-polypyrrole; QCM-quartz crystal microbalance; R-resistance of MIP-Ppy layer; Rs-resistance of the electrolyte; Δf-resonance frequency; ΔG°-standard state Gibbs free energy. Abstract The synthesis and some properties of polypyrrole layer molecularly-imprinted by caffeine (MIP-Ppy), which was formed on gold covered quartz crystal, were evaluated by quartz crystal microbalance (QCM). Electrochemical polymerization was applied for the formation of this MIP-Ppy. In the study unique home-made flow-through QCM cell was used for the formation of MIP-Ppy and QCM measurements. The main advantages of the applied flow-through cell design were (i) reduced volume of the cell and (ii) the possibility to perform continuous association/dissociation processes. The performed QCM measurement data proved that the QCM sensor modified with MIP-Ppy is more sensitive to caffeine than to the theophylline. Evaluation of association/dissociation kinetics between caffeine imprinted MIP-Ppy and both xanthine derivatives (caffeine and theophylline) and some parameters of thermodynamics calculated for this interaction demonstrated significant differences, which showed that the MIP-Ppy tends to interact with caffeine more strongly than with theophylline. Electrochemical impedance spectroscopy was applied for the evaluation of MIP-Ppy degradation.
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ABSTRACT This study describes the evaluation of histamine imprinted polypyrrole deposited on boron doped nanocrystalline diamond (NCD). Boron doped oxygen terminated NCD (B : NCD) was used as a conducting substrate for the design of here... more
ABSTRACT This study describes the evaluation of histamine imprinted polypyrrole deposited on boron doped nanocrystalline diamond (NCD). Boron doped oxygen terminated NCD (B : NCD) was used as a conducting substrate for the design of here reported electrochemical sensor. Some peculiarities of B : NCD were evaluated and oxidation kinetics of both NCD and B : NCD was investigated. Both the NCD and B : NCD were modified by molecularly imprinted polypyrrole and not-imprinted polypyrrole. Histamine was used as a template for molecular imprinting of polypyrrole. Electrochemical impedance spectroscopy was applied for the evaluation of formed MIP and NIP layers.