Filters

2016 - 20202

More filters

2021 - 20222
Reset filters

Settings

Subject: Complexation ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Silver Nanoparticles Surface-Modified with Carbosilane Dendrons as Carriers of Anticancer siRNA
    (Basel : Molecular Diversity Preservation International, 2020) Pędziwiatr-Werbicka, Elżbieta; Gorzkiewicz, Michał; Horodecka, Katarzyna; Abashkin, Viktar; Klajnert-Maculewicz, Barbara; Peña-González, Cornelia E.; Sánchez-Nieves, Javier; Gómez, Rafael; Javier de la Mata, F.; Bryszewska, Maria
    Gene therapy is a promising approach in cancer treatment; however, current methods have a number of limitations mainly due to the difficulty in delivering therapeutic nucleic acids to their sites of action. The application of non-viral carriers based on nanomaterials aims at protecting genetic material from degradation and enabling its effective intracellular transport. We proposed the use of silver nanoparticles (AgNPs) surface-modified with carbosilane dendrons as carriers of anticancer siRNA (siBcl-xl). Using gel electrophoresis, zeta potential and hydrodynamic diameter measurements, as well as transmission electron microscopy, we characterized AgNP:siRNA complexes and demonstrated the stability of nucleic acid in complexes in the presence of RNase. Hemolytic properties of free silver nanoparticles and complexes, their effect on lymphocyte proliferation and cytotoxic activity on HeLa cells were also examined. Confocal microscopy proved the effective cellular uptake of complexes, indicating the possible use of this type of silver nanoparticles as carriers of genetic material in gene therapy. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
  • Thumbnail Image
    Item
    Novel quinoxaline based chemosensors with selective dual mode of action: nucleophilic addition and host–guest type complex formation
    (2016) Ishtiaq, Marium; Munir, Iqra; al-Rashida, Mariya; Maria, Maria; Ayub, Khurshid; Iqbal, Jamshed; Ludwig, Ralf; Khan, Khalid Mohammed; Ali, Syed Abid; Hameed, Abdul
    New quinoxalinium salts 1–5 have been exploited as chemosensors via naked eye, UV-Vis absorption, fluorescence quenching and 1H NMR experiments. New sensors 1–5 showed a dual mode, nucleophilic addition and a host–guest type complex towards anion (F−, AcO− and ascorbate) detection. Small anions (F−/AcO−) showed nucleophilic addition at the C2 position of the quinoxalinium cation, while larger anions (ascorbate), revealed the formation of a host–guest type complex due to the steric hindrance posed by the C3 of the phenyl ring. Nucleophilic addition of small anions (F−/AcO−) leads to the de-aromatization of the quinoxalinium cation. However in the case of the larger anion, ascorbate, the host–guest type complex formation induces changes in the absorption/fluorescence signals of the quinoxalinium moiety. This selective binding has been confirmed on the basis of the 1H NMR spectroscopic technique, whereupon nucleophilic addition of small anions (F−/AcO−) was confirmed by monitoring the characteristic proton NMR signals of Ha and the methylene protons (CH2), which were clearly shifted in the cases of fluoride and acetate ion addition confirming the de-aromatization and nucleophilic addition. Whereas no such peak shifting was observed in the case of ascorbate ion addition confirming the non-covalent addition of ascorbate. Theoretical insight into the selectivity and complexation behavior of the ascorbate ion with the quinoxaline moiety is gained through density functional theory (DFT) calculations. Moreover, the absorption properties of these complexes are modeled theoretically, and compared with the experimental data. In addition, the thermal decomposition of sensors (1 and 2) has been studied by the means of differential scanning calorimetry (DSC), thermogravimetry (TG), and differential thermogravimetry (DTG) to signify their utility at variable temperatures.