Anna Nowicka

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Papers by Anna Nowicka

Electrografting of carboxyphenyl thin layer onto gold for DNA and enzyme immobilization

by Anna Nowicka and Zbigniew Stojek

ABSTRACT The convenient functionalization of metal surfaces by carboxyphenyl groups in aprotic me... more ABSTRACT The convenient functionalization of metal surfaces by carboxyphenyl groups in aprotic media is not possible for two reasons. First, carboxy derivatives of diazonium salts are very unstable and, second, the electroreduction product is soluble in the solvent. So, the optimization of the conditions of the electrografting of the metal surfaces by applying aqueous solutions is much needed. Compared to earlier cyclic voltammetry approaches we have shown that the chronoamperometric deposition is more convenient. The constant potential equal to the voltammetric peak potential and the molar ratio 1:1 for the substrates: 4-aminobenzoic acid and NaNO2 as the diazotization agent, in 0.5 M HCl, appeared to be very satisfying conditions for the deposition of a thin layer of deposit of perpendicularly oriented carboxyphenyl groups at the Au surface and for maximal elimination of the influence of the side-reactions products. Under the determined conditions the immobilization of DNA strands was optimal and the deposited laccase layer was tightly packed and very efficient toward the electroreduction of oxygen. Electrochemical impedance spectroscopy, electrochemical quartz crystal microbalance, cyclic voltammetry, chronocoulometry, atomic force microscopy, contact angle measurements and UV-Vis spectroscopy of the solution were used to characterize the electrografted carboxyphenyl layers and subsequent oligonucleotide and enzyme immobilization process.

Repeated rearrangements of oligonucleotides immobilized on gold surface caused by UV irradiation in presence of dissolved oxygen

by Anna Nowicka and Zbigniew Stojek

A layer of either synthetic or natural DNA deposited on the gold electrode surface can be specifi... more A layer of either synthetic or natural DNA deposited on the gold electrode surface can be specifically excited by UV irradiation under conditions of the presence of dissolved oxygen in the solution. Apparently such irradiation leads to the reversible changes in the rigidity of the DNA layer and the corresponding extent of hydration of the strands. This can be monitored with an electrochemical quartz crystal microbalance, since the regular oscillations appear in the microbalance readout. It was found that the presence of dissolved oxygen is necessary for the start and the continuation of the oscillations, while the UV light is necessary only for the triggering of this phenomenon. The oxygen reactive species formed during the UV irradiation must take part in the cycling process, as the oscillation continues after turning the UV light off. Some voltammetric and CD spectroscopic experiments were also done with the DNA layers to monitor the action of UV radiation. The PAH polymer, that contains no easily oxidized components, was examined for the comparison purpose.

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A dual DNA biosensor based on two redox couples with a hydrogel sensing platform functionalized with carboxyl groups and gold nanoparticles

by Anna Nowicka and Marcin Karbarz

Sensors and Actuators B: Chemical, 2015

ABSTRACT Poly(N-isopropylacrylamide-co-acrylic acid) hydrogels containing COOH groups and gold na... more ABSTRACT Poly(N-isopropylacrylamide-co-acrylic acid) hydrogels containing COOH groups and gold nanoparticles were used to propose a new dual-target hybridization assay that involves a dual hybridization event. The target DNA strands were labeled with two different redox probes: ferrocene and anthraquinone derivatives. The targets were simultaneously detected by obtaining two well separated voltammetric peaks. Such good stability of the biosensor can be attributed to the strong covalent bond between Au nanoparticles and the thiolated probe DNA. Also the bond between carboxyl group of the gel and amine-terminated capture-probe DNA is strong in pH ca. 7. The sensor response increased linearly with the logarithm of the target DNA concentration in the range from: 2 × 10−12 to 1 × 10−6 M and 2 × 10−13 to 2 × 10−6 M for target DNA labeled by antraquinone and ferrocene derivative respectively. The determined detection limit was approx. 8 × 10−13 M and 7 × 10−14 M for target DNA labeled with antraquinone and with ferrocene, respectively, which corresponded to the presence of ∼2 × 108 copies of DNA in the solution (0.5 mL). The proposed biosensor can be used for the detection of DNA at the fM level. This achievement is very important for biosensors that use DNA labeled with redox probes, as here we have shown that the sensitivity improved by at least two orders of magnitude compared to the traditional biosensors.

Orientation of Laccase on Charged Surfaces. Mediatorless Oxygen Reduction on Amino- and Carboxyl-Ended Ethylphenyl Groups

by Anna Nowicka and unauthorised use remove this profile

The Journal of Physical Chemistry C, 2012

ABSTRACT The gold electrode surface has been functionalized by phenyl groups ending with aminoeth... more ABSTRACT The gold electrode surface has been functionalized by phenyl groups ending with aminoethyl or carboxyethyl entities. The functionalization was achieved by the electrochemical reduction of 4-aminoethylbenzene- or 4-carboxyethylbenzenediazonium salts. The laccase layers were studied by polarization modulation infrared spectroscopy (PMIRRAS), linear sweep voltammetry, and electrochemical quartz microbalance. The kind of surface groups controlling the orientation of the enzyme on the surface was revealed by PMIRRAS. The orientation influenced the enzyme activity on its turn. The direct, mediatorless electrocatalytic current due to the oxygen reduction was observed starting from +0.60 V versus Ag/AgCl at pH 4.5 for laccase immobilized on the amine-ended layer. The observed potential value is close to the redox potential of the laccase T1 center. The electrocatalytic current values were equal to 4 mA/cm. Immobilization of laccase on the carboxyethyl groups leads to smaller electrocatalytic current values. The onset of the electrocatalytic current was down-shifted to +0.56 V.

Chromium(VI) but Not Chromium(III) Species Decrease Mitoxantrone Affinity to DNA

by Anna Nowicka, Zbigniew Stojek, and Maria R Hepel

The Journal of Physical Chemistry B, 2013

Binding of mitoxantrone (MXT) to double-stranded DNA has been investigated as a model drug-DNA bi... more Binding of mitoxantrone (MXT) to double-stranded DNA has been investigated as a model drug-DNA binding system to evaluate the effects of various forms of chromium on the binding properties. We have found that Cr(III), which binds strongly to DNA, does not affect the MXT affinity to DNA. In contrast, Cr(VI), in the form of chromate ions CrO(4)(2-), decreases the MXT affinity to DNA despite electrostatic repulsions with phosphate-deoxyribose chains of DNA. The MXT-DNA binding constant was found to decrease from (1.96 ± 0.005) × 10(5) to (0.77 ± 0.018) × 10(5) M(-1) for Cr(VI) concentration changing from 0 to 30 μM. The influence of Cr(VI) on MXT-DNA binding has been attributed to the oxidation of guanine residue, thus interrupting the intercalation of MXT into the DNA double helix at the preferential CpG intercalation site. This supposition is corroborated by the observed increase in the MXT binding site size from 2 bp (base pairs) to 4-6 bp in the presence of Cr(VI). The measurements of the MXT-DNA binding constant and the MXT binding site size on a DNA molecule have been carried out using spectroscopic, voltammetric, and nanogravimetric techniques, providing useful information on the mechanism of the interactions.

Substantial difference between temperature dependencies of dsDNA predenaturation process obtained by voltammetry and spectroscopy

by Anna Nowicka, Zbigniew Stojek, and Ewelina Zabost

Physical Chemistry Chemical Physics, 2009

The electrooxidation of double stranded DNA has been studied in a wide temperature range by cycli... more The electrooxidation of double stranded DNA has been studied in a wide temperature range by cyclic and square wave voltammetries and the results were compared with UV-Vis and CD spectroscopies. A twofold increase of dsDNA voltammetric peaks related to the conformation changes preceding the denaturation process was found to begin at a temperature lower than the well known increase of dsDNA absorbance upon denaturation (the melting point) by circa 20 degrees C. Since the dsDNA voltammetric peaks are related directly to the electrooxidation of guanine and adenine, early conformational changes in guanine-cytosine (G-C) and adenine-thymine (A-T) pairs in dsDNA are possible reasons for the increase of the voltammetric peaks. The above observations prove that the voltammetric methods are much more sensitive to the changes in guanine and adenine base-pairs conformations and indicate increased exposition of guanine and adenine in the reversible stages that precede the denaturation process of dsDNA. Interestingly, two distinct ranges of change in ellipticity in CD spectra correlate well to the changes obtained by voltammetry and UV spectroscopy, respectively. We also checked the influence of an intercalator on the dsDNA denaturation (temperature) plots. The spectroscopic measurements indicated an increase in the stability of the structure of the double stranded helix upon the addition of the intercalator, while voltammetry showed also that the exposition of guanine and adenine for the electrooxidation drops substantially in the region preceding the denaturation process.

Subjective contour illusion: sex-related effect of unilateral brain damage

by Iwona Szatkowska and Anna Nowicka

Neuroreport, 2001

The aim of the study was to investigate the effect of unilateral brain lesions on the perception ... more The aim of the study was to investigate the effect of unilateral brain lesions on the perception of subjective contours. Brain damage resulted in a reduced ability to perceive the illusion. The effect, however, was hemisphere and sex dependent. In women an illusion decrement due to either the left or right hemisphere damage was observed, while in men only right hemisphere damage caused a decrement. No specific effect of intrahemispheric localisation of lesion was found. We conclude that mechanisms contributing to subjective contour perception are right hemisphere dependent in males whereas in females they are bilaterally represented.

The extreme migrational enhancement of faradaic current at microelectrodes: experimental studies on sodium (6,8-diferrocenylmethylthio)octanoate electrooxidation

by Anna Nowicka and Zbigniew Stojek

Journal of Electroanalytical Chemistry, 2005

The unusual electrochemical behavior of sodium (6,8-diferrocenylmethylthio)octanoate in aqueous s... more The unusual electrochemical behavior of sodium (6,8-diferrocenylmethylthio)octanoate in aqueous solutions is reported. This diferrocene derivative forms an anion, gives a two-electron oxidation voltammetric wave and, correspondingly, changes its charge from −1 to +1. The electrode reaction belongs to the class of sign-reversal processes for which the theory predicts a very high ratio of the faradaic currents obtained in the absence

Voltammetric Studies of Parallel Electrode Processes Under Low Ionic Strength Conditions. Influence of Convection

by Anna Nowicka and Zbigniew Stojek

Electroanalysis, 2006

Abstract It is known that either a very strong enhancement or an almost complete depression of th... more

Interactions of Dissolved dsDNA with Intercalating Drug by Anodic Voltammetry and Spectroscopy. Influence of pH

by Anna Nowicka, Zbigniew Stojek, and Ewelina Zabost

Electroanalysis, 2009

The interactions of C-1305 (5-dimethylaminopropylamino-8-hydroxy-6H-v-triazolo[4,5,1-de]acridin-6... more The interactions of C-1305 (5-dimethylaminopropylamino-8-hydroxy-6H-v-triazolo[4,5,1-de]acridin-6-one) with DNA were studied using differential pulse voltammetry and UV-vis spectroscopy. C-1305 interacts with dsDNA in two ways: by intercalation and by binding to the minor-groove. For the intercalation at physiological pH (7.4) the values of the binding constant, K 1 , and the binding-site size, n 1 , equal 3.36 Â 10 5 M À1 and 2.5, respectively. For the weak interactions the K 2 and n 2 parameters equal 0.18 Â 10 5 M À1 and 4. In the presence of excess NaCl the weak interactions do not vanish, therefore they are assigned to the minor groove binding. Substantial and complex is the influence of pH.

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Enzyme-Amplified Amperometric Detection of DNA Using Redox Mediating Films on Gold Microelectrodes

by Zbigniew Stojek and Anna Nowicka

Electroanalysis, 2009

This report describes a simple methodology for preparation of an enzyme-amplified amperometric DN... more This report describes a simple methodology for preparation of an enzyme-amplified amperometric DNA hybridisation assay using solution-phase ferrocenemethanol mediation of glucose oxidase oxidation of glucose. The recognition layer consists of amine-terminated ssDNA (designed for binding of the sequence ssrA gene of Listeria monocytogenes) bound within a carboxymethylated dextran film that is anchored to a graphite electrode. Anchoring sites are provided by electrochemical grafting of an arylamine to the carbon surface following in situ diazotisation of p-phenylenediamine. Hybridisation between the immobilised probe ssDNA and a biotin-labelled target ssDNA sequence is detected by following the oxidation of glucose upon addition of a glucose oxidase-avidinD conjugate and ferrocenemethanol. The stability of the anchored film permits washing and blocking steps to discriminate between hybridisation and non-specific binding. The signal current, measured by cyclic voltammetry and constant potential amperometry, scales with biotin-complementary DNA concentration, from 2.5 × 10 −6 M to 3 × 10 −7 M and a detection limit of 0.2 nmol in the 500 L sample at the 3-mm diameter graphite electrode is estimated. Approaches to improve upon the analytical performance of this simple assay are highlighted.

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Substantial Influence of Temperature on Anchoring of Gold-Nanoparticle Monolayer for Performance of DNA Biosensors

by Anna Nowicka, Zbigniew Stojek, Maria R Hepel, and Mikołaj Donten

Electroanalysis, 2010

This paper presents a way of modification of crystalline gold surface with a high quality layer o... more This paper presents a way of modification of crystalline gold surface with a high quality layer of gold nanoparticles (Au NPs) via self-assembled dithiol. The application of additional Au NPs monolayer prepared at various temperatures was tested with three types of biosensors previously described in the literature. The examined DNA biosensors differed by the detection method and the way of the immobilization of DNA probe at the modified gold electrode surface. For the immobilization of DNA probe in the sensing layer either the formation of SAM or the affinity binding (biotin -sterptavidin) or covalent attachment were used. The necessary condition of successful preparation of a perfect such monolayer is the preparation temperature of 4 8C. The preparation of Au NPs layers at higher than 4 8C temperatures leads to poor repeatability and unsatisfactory precision of the measurements. The application of the perfect Au monolayer lowers the detection limit (circa by 10 to 100 times) for all tested DNA biosensors.

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Voltammetry of Undiluted Red-Ox Systems. Electrochemical ESR- and Electrochemical Impedance Spectroscopy Evidence for Formation of Ionic Liquid at Microelectrode Surface

by Zbigniew Stojek and Anna Nowicka

Electroanalysis, 2008

ABSTRACT It is believed that voltammetry of undiluted red-ox liquids can lead to the formation of... more ABSTRACT It is believed that voltammetry of undiluted red-ox liquids can lead to the formation of stable thin layers of ionic liquids at the microelectrode surface. Such situation was postulated for several liquids (solvents), however, so far no hard evidence supporting this expectation was obtained. By using electron spin resonance in combination with voltammetric experiments and electrochemical impedance spectroscopy we have shown that the concentration of the cation radicals at the microelectrode surface may be high (nitrobenzene) and the overall resistance of the solution abruptly drops (methanol) when the potential at the microelectrode corresponds to the wave plateau of the undiluted organic liquid. Both facts constitute a good evidence for the formation of microlayers of ionic liquids at the microelectrode surface during electrolysis of undiluted red-ox systems.

New Anthraquinone Derivatives as Electrochemical Redox Indicators for the Visualization of the DNA Hybridization Process

by Anna Nowicka, Zbigniew Stojek, and Rafał Jurczakowski

Electroanalysis, 2010

Interactions of dsDNA and ssDNA, at the surface of gold and silver electrodes, with three novel a... more Interactions of dsDNA and ssDNA, at the surface of gold and silver electrodes, with three novel anthraquinone derivatives: 3-(9',10'-dioxo-9',10'-dihydro-anthracen-1-yl)-7,11-di(carboxymethyl)-3,7,11-triazatridecanedioic acid, (AQ-1); 1-(9',10'-dioxo-9',10'-dihydro-anthracen-1yl)-9-carboxymethyl-5-methyl-1,5,9-triazaundecanoicacid, (AQ-2); and N-(2-(9,10-dioxo-9,10-dihydro-anthracen-1-ylamino)ethyl)-2-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecan-7-yl) acetamide, (AQ-3) are studied. These derivatives are well soluble in water and phosphate buffer solutions. The square wave voltammetric behavior of these redox indicators is described and the parameters of interactions with DNA are reported. It is also pointed out that these compounds can be employed as the hybridization indicators. The difference in the binding ability of the particular redox indicator to single and double stranded DNA can be used for the detection of the complementary nucleic acids.

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Construction of DNA biosensor at glassy carbon surface modified with 4-aminoethylbenzenediazonium salt

by Anna Nowicka and Zbigniew Stojek

Biosensors and Bioelectronics, 2011

A simple, label-free electrochemical impedance-spectroscopy method for sequence-specific detectio... more A simple, label-free electrochemical impedance-spectroscopy method for sequence-specific detection of DNA using a 4-aminoethylbenzenediazonium (AEBD) salt as a binder for amino-modified probe DNA is reported. This novel method simplifies the anchoring of DNA at the GC surface and opens new ways for the detection of hybridization. The hybridization of target DNA, without and with mismatches, with the probe DNA anchored at the GC surface modified with AEBD, greatly increases the interfacial electron transfer resistance at the double-stranded DNA modified electrodes for the redox couple Fe(CN) 6 3−/4− . The resistance was measured using electrochemical impedance spectroscopy. The sensor response increased linearly with logarithm of concentration of target DNA in the range 2 × 10 −12 ÷ 2 × 10 −6 M. The obtained quantification limit was circa 6.5 × 10 −17 mole in a 7 L droplet and corresponded to a concentration of 9.2 × 10 −12 M of target DNA in the sample. This limit is equivalent to the detection of circa 4 × 10 7 copies of DNA in a 7 L droplet or circa 5.7 × 10 12 DNA copies in one litre of sample.

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Nanogravimetric and voltammetric DNA-hybridization biosensors for studies of DNA damage by common toxicants and pollutants

by Anna Nowicka, Zbigniew Stojek, and Maria R Hepel

Biophysical Chemistry, 2010

Electrochemical and nanogravimetric DNA-hybridization biosensors have been developed for sensing ... more Electrochemical and nanogravimetric DNA-hybridization biosensors have been developed for sensing single mismatches in the probe-target ssDNA sequences. The voltammetric transduction was achieved by coupling ferrocene moiety to streptavidin linked to biotinylated tDNA. The mass-related frequency transduction was implemented by immobilizing the sensory pDNA on a gold-coated quartz crystal piezoresonators oscillating in the 10MHz band. The high sensitivity of these sensors enabled us to study DNA damage caused by representative toxicants and environmental pollutants, including Cr(VI) species, common pesticides and herbicides. We have found that the sensor responds rapidly to any damage caused by Cr(VI) species, with more severe DNA damage observed for Cr(2)O(7)(2-) and for CrO(4)(2-) in the presence of H(2)O(2) as compared to CrO(4)(2-) alone. All herbicides and pesticides examined caused DNA damage or structural alterations leading to the double-helix unwinding. Among these compounds, paraoxon-ethyl and atrazine caused the fastest and most severe damage to DNA. The physico-chemical mechanism of damaging interactions between toxicants and DNA has been proposed. The methodology of testing voltammetric and nanogravimetric DNA-hybridization biosensors developed in this work can be employed as a simple protocol to obtain rapid comparative data concerning DNA damage caused by herbicide, pesticides and other toxic pollutants. The DNA-hybridization biosensor can, therefore, be utilized as a rapid screening device for classifying environmental pollutants and to evaluate DNA damage induced by these compounds.

Electrooxidation of dissolved dsDNA backed by in situ UV–Vis spectroscopy

by Zbigniew Stojek, Anna Nowicka, Ewelina Zabost, and Mikołaj Donten

Bioelectrochemistry, 2007

The electrooxidation of double-stranded DNA (dsDNA) from calf thymus was carried by using cyclic ... more The electrooxidation of double-stranded DNA (dsDNA) from calf thymus was carried by using cyclic voltammetry. A glassy carbon disk-, a platinum disk-, a platinum mesh-and a carbon vapor-deposited platinum mesh electrodes were used. It is shown that the appropriate chemical and biological (steam treatment) purification of the complete cell allows, for the graphite electrode, formation of a wide anodic dsDNA signal with two visible anodic peaks. There was no necessity of preaccumulation of dsDNA on the electrode surface and of use of mediators to get well defined voltammetric signals. These peaks apparently reflect electrooxidation of the DNA's guanine and adenine. The spectrophotometric data obtained during the electrooxidation indicate that the absorbance increases with an increase in potential and electrooxidation current of dsDNA. However, the absorption band maximum either does or does not change its position depending on the mesh material. This different spectroscopic behavior may mean that the changes in the dsDNA structure upon electrooxidation are different in the case of Pt and C electrodes.

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