Huczynski A.,Adam Mickiewicz University
Chemical Biology and Drug Design | Year: 2012
Very recently, it has been shown that it is possible to selectively kill breast cancer stem cells using the ionophore antibiotic, salinomycin. Its ability to kill cancer stem cells and apoptosis-resistant cancer cells may define salinomycin as a novel anticancer drug. © 2011 John Wiley & Sons A/S.
Szafranski M.,Adam Mickiewicz University
Journal of Physical Chemistry B | Year: 2011
Dielectric, calorimetric, and X-ray diffraction methods have been employed to characterize the crystals of guanidinium tetrafluoroborate and guanidinium perchlorate, both built of two-dimensional honeycomb hydrogen-bonded sheets. The room-temperature ferroelectricity of these isosymmetric complexes (space group R3m) has been evidenced by the polarization switching in an external electric field and pyroelectric effect. The analysis of structural data as a function of temperature showed that the high values of spontaneous polarization of about 8.5 μC cm-2 originate mainly from the ionic displacements, while the exceptional thermally induced increase of polarization is related with the apparent weakening of the N-H•••F/N-H•••O hydrogen bonds at elevated temperatures. An excellent correlation between the donor-acceptor distance and the relative displacement of the ions in the crystal lattice along the polar direction has been found. The huge entropy change at the two-closely spaced high-temperature phase transitions in guanidinium perchlorate, together with the large crystal polarization, suggest a large electrocaloric effect, the property strongly desired for solid-state cooling applications. © 2011 American Chemical Society.
Juskowiak B.,Adam Mickiewicz University
Analytical and Bioanalytical Chemistry | Year: 2011
It is well known that nucleic acids play an essential role in living organisms because they store and transmit genetic information and use that information to direct the synthesis of proteins. However, less is known about the ability of nucleic acids to bind specific ligands and the application of oligonucleotides as molecular probes or biosensors. Oligonucleotide probes are single-stranded nucleic acid fragments that can be tailored to have high specificity and affinity for different targets including nucleic acids, proteins, small molecules, and ions. One can divide oligonucleotide-based probes into two main categories: hybridization probes that are based on the formation of complementary base-pairs, and aptamer probes that exploit selective recognition of nonnucleic acid analytes and may be compared with immunosensors. Design and construction of hybridization and aptamer probes are similar. Typically, oligonucleotide (DNA, RNA) with predefined base sequence and length is modified by covalent attachment of reporter groups (one or more fluorophores in fluorescence-based probes). The fluorescent labels act as transducers that transform biorecognition (hybridization, ligand binding) into a fluorescence signal. Fluorescent labels have several advantages, for example high sensitivity and multiple transduction approaches (fluorescence quenching or enhancement, fluorescence anisotropy, fluorescence lifetime, fluorescence resonance energy transfer (FRET), and excimer-monomer light switching). These multiple signaling options combined with the design flexibility of the recognition element (DNA, RNA, PNA, LNA) and various labeling strategies contribute to development of numerous selective and sensitive bioassays. This review covers fundamentals of the design and engineering of oligonucleotide probes, describes typical construction approaches, and discusses examples of probes used both in hybridization studies and in aptamer-based assays. © The Author(s) 2010. This article is published with open access at Springerlink.com.
Huczynski A.,Adam Mickiewicz University
Bioorganic and Medicinal Chemistry Letters | Year: 2012
The natural polyether ionophore antibiotics might be important chemotherapeutic agents for the treatment of cancer. In this article, the pharmacology and anticancer activity of the polyether ionophores undergoing pre-clinical evaluation are reviewed. Most of polyether ionophores have shown potent activity against the proliferation of various cancer cells, including those that display multidrug resistance (MDR) and cancer stem cells (CSC). The mechanism underlying the anticancer activity of ionophore agents can be related to their ability to form complexes with metal cations and transport them across cellular and subcellular membranes. Increasing evidence shows that the anticancer activity of polyether ionophores may be a consequence of the induction of apoptosis leading to apoptotic cell death, arresting cell cycle progression, induction of the cell oxidative stress, loss of mitochondrial membrane potential, reversion of MDR, synergistic anticancer effect with other anticancer drugs, etc. Continued investigation of the mechanisms of action and development of new polyether ionophores and their derivatives may provide more effective therapeutic drugs for cancer treatments. © 2012 Elsevier Ltd. All rights reserved.
Nawrocki J.,Adam Mickiewicz University
Applied Catalysis B: Environmental | Year: 2013
The aim of this work is to point out a number of controversies in the results of research on catalytic ozonation, discuss them and indicate their possible reasons. The existing literature has provided many quite well documented proposals of possible mechanisms of catalytic ozonation. However, a closer analysis of all these proposals reveals that many of them are simply contradictory. The number of controversies in the field of catalytic ozonation may indicate our poor understanding of the mechanisms of the process. It is also possible that the reasons for the controversies lie in some basic experimental errors. © 2013 Elsevier B.V.