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Photodynamic Therapy: Membrane and Enzyme Photobiology
Published in Barbara W. Henderson, Thomas J. Dougherty, Photodynamic Therapy, 2020
Tom M. A. R. Dubbelman, Carla Prinsze, Louis C. Penning, John van Steveninck
The molecular mechanism of the photodynamically induced K+ leakage is not yet totally elucidated. There are indications that a membrane-spanning protein—band 3, the anion transporter—is involved. The situation is rather complicated, because the anion transport itself is inhibited, probably by cross-link formation between a histidine residue and anion transport-regulating lysine moieties. The evidence that band 3 is also involved in the induction of K+ leakage results from experiments with the sensitizer eosin isothiocyanate, which binds to band 3 and with the thiol-specific sensitizer CuHPD [19,20]. From a detailed kinetic analysis of photohemolysis Pooler [21] concluded that a dimer must be involved, most likely, again, band 3. This does not necessarily mean that the anion transport channel is involved (Fig. 3A); another possibility is a decrease in the interaction between band 3 and the surrounding phospholipids, resulting in the observed quite dramatic increase in flip-flop and the induction of leakage (see Fig. 3B) [16]. When photodynamic treatment is followed by heat treatment, the result is a synergistic effect upon the K+ leakage. In the Arrhenius kinetics, both the activation energy of the heat-induced leakage and the frequency factor decrease significantly (Fig. 4). This means that probably photodynamic treatment and heat treatment have the same target, as a different target would probably mean an unchanged activation energy. If this is true, it means that K+ leakage induced by heat treatment also proceeds through band 3.
Preparation of high-strength and high flame-retardant PMIA/P(an-VC) composite fibers and its conductive fibers
Published in The Journal of The Textile Institute, 2023
Qingquan Song, Wenwen Wu, Junrong Yu, Zuming Hu, Yan Wang
Dai et al. (2018). used the method of infrared peak splitting to study the hydrogen bond changes between the modified polyimide molecular chains, and divided the hydrogen bond formed between the nitrogen-hydrogen bond and the carbon-oxygen double bond into 4 peaks, which correspond to C = O. symmetric, asymmetric stretching, intermolecular and intramolecular H-bonding on C = O symmetric, 'free' C = O symmetric stretching. In order to analyze the interactions between PMIA and P(AN-VC), we use infrared peak splitting to better understand the hydrogen bonding between the two through Origin 9.0, the results are shown in Figure 5(a)–(e), labeled as curve fitting. Based on this principle, first by identifying different C = O stretching vibrations, the infrared spectrum in the wavenumber range of 1620 to 1700 cm−1 is peak-divided to study the hydrogen bond interactions in these blend fibers. Four peaks are identified, among which band 1 and band 4 correspond to the C = O symmetrical and asymmetrical extension of the intermolecular chemical bond. The band 2 and the band 3 are corresponding to the “free” C = O symmetric stretching and hydrogen-bonded C = O symmetric stretching of the cyclic imides, respectively. For a quantitative evaluation, the percentage of the hydrogen-bonded imides can be calculated by formula (3). I1, I2, I3, I4 represents the area of the respective peak.