Vera Mansfeldova

Bio: Vera Mansfeldova is an academic researcher from Charles University in Prague. The author has contributed to research in topics: Work function & Standard hydrogen electrode. The author has an hindex of 2, co-authored 3 publications receiving 46 citations.

Work Function of TiO2 (Anatase, Rutile, and Brookite) Single Crystals: Effects of the Environment

Abstract: Electrochemical impedance spectroscopy, photoelectron spectroscopy, and Kelvin probe measurements on various TiO2 single-crystal surfaces show that the position of the Fermi level and the conductio...

Crystallic silver amalgam--a novel electrode material.

Abstract: A crystallic silver amalgam was found to be a suitable working electrode material for voltammetric determination of electrochemically reducible organic nitro-compounds. Optimum conditions for crystal growth were found, the crystal surface was investigated by atomic force microscopy in tapping mode and single crystals were used for the preparation of quasi-cylindrical single crystal silver amalgam electrode (CAgAE). An electrochemical behavior of this alternative electrode material was investigated in aqueous media by direct current voltammetry, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and adsorptive stripping voltammetry (AdSV) using 4-nitrophenol as a model compound. Applicable potential windows of the CAgAE were found comparable with those obtained at a hanging mercury drop electrode, providing high hydrogen overpotential, and polished silver solid amalgam electrode. Thanks to the smooth single crystal electrode surface, the effect of the passivation is not too pronounced, direct DPV determination of 100 μmol l−1 of 4-nitrophenol at CAgAEs in 0.2 mol l−1 acetate buffer pH 4.8 provides a RSD around 1.5% (n = 15). DPV calibration curves of 4-nitrophenol are linear in the whole concentration range 1–100 μmol l−1 with a limit of quantification of 1.5 μmol l−1. The attempt to increase sensitivity by application of AdSV was not successful. The mechanism of 4-nitrophenol reduction at CAgAE was investigated by CV.

Recent Applications of Mercury Electrodes for Monitoring of Pesticides: A Critical Review

Abstract: This critical review deals with possibilities and limitations of mercury electrodes in the field of voltammetric and amperometric determination of submicromolar concentrations of various electrochemically reducible pesticides. Attention is mostly focused on the last 10 years to show that even now mercury based electrodes are unsurpassed sensors for this purpose.

Screen-Printed Disposable Sensors Modified with Bismuth Precursors for Rapid Voltammetric Determination of 3 Ecotoxic Nitrophenols

Abstract: This work reports the application of screen-printed electrodes bulk-modified with bismuth precursors to the voltammetric determination of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP) in water samples. A bismuth film was formed at the electrode surface via in situ reduction of the precursor compound contained in the electrode matrix by cathodic polarization at −1.20 V. The formation of bismuth layer at the precursor-modified electrodes was assessed by cyclic voltammetric (CV) at different pH values and by optical techniques. The target nitrophenols were voltammetrically determined by recording their reduction peaks in the differential pulse (DP) mode. The composition and content of the precursor compounds in the printed ink and the effect of the pH of the supporting electrolyte on the DP reduction currents of the 3 target nitrophenols were studied. The limits of quantification (LOQs) in three water matrices (distilled water, tap water and surface water) were in the range 1.1–2.2 µmol L−1. Using a simple solid-phase extraction (SPE) procedure with Lichrolut EN cartridges and elution with methanol, a preconcentration factor of 100 was achieved; the LOQs were 0.021, 0.027 and 0.025 µmol L−1 for 2-NP, 4-NP and 2,4-DNP, respectively. The recoveries of samples spiked with the 3 target nitrophenols at two concentration levels (0.04 and 0.1 µmol L−1) were always >87 %.

Platinum-Titania Schottky Junction as Nanosonosensitizer, Glucose Scavenger, and Tumor Microenvironment-Modulator for Promoted Cancer Treatment.

Abstract: To date, the construction of heterogeneous interfaces between sonosensitizers and other semiconductors or noble metals has aroused increasing attention, owing to an enhanced interface charge transfer, augmented spin-flip, and attenuated activation energy of oxygen. Here, a smart therapeutic nanoplatform is constructed by surface immobilization of glucose oxidase (GOx) onto a TiO2@Pt Schottky junction. The sonodynamic therapy (SDT) and starvation therapy (ST) mediated by TiO2@Pt/GOx (TPG) promote systemic tumor suppression upon hypoxia alleviation in tumor microenvironment. The band gap of TiO2@Pt is outstandingly decreased to 2.9 eV, in contrast to that of pristine TiO2. The energy structure optimization enables a more rapid generation of singlet oxygen (1O2) and hydroxyl radicals (•OH) by TiO2@Pt under ultrasound irradiation, resulting from an enhanced separation of hole-electron pair for redox utilization. The tumorous reactive oxygen species (ROS) accumulation and GOx-mediated glucose depletion facilitate oxidative damage and energy exhaustion of cancer cells, both of which can be tremendously amplified by Pt-catalyzed oxygen self-supply. Importantly, the combinatorial therapy triggers intense immunogenetic cell death, which favors a follow-up suppression of distant tumor and metastasis by evoking antitumor immunity. Collectively, this proof-of-concept paradigm provides an insightful strategy for highly efficient SDT/ST, which possesses good clinical potential for tackling cancer.