Browsing by Author "Akkaya, Engin U."

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    “Off–on” switching of intracellular singlet oxygen release under biocompatible conditions
    (Royal Society of Chemistry, 2019-10) Uçar, Esma; Xi, D.; Seven, Özlem; Kaya, Cansu; Peng, X.; Sun, W.; Akkaya, Engin U.
    Precise spatiotemporal control of singlet oxygen generation is of immense importance considering its involvement in photodynamic therapy. In this work, we present a rational design for an endoperoxide which is highly stable at ambient temperatures yet, can rapidly be converted into a highly labile endoperoxide, thus releasing the “stored” singlet oxygen on demand. The “off–on” chemical switching from the stable to the labile form is accomplished by the reaction with fluoride ions. The potential utility of controlled singlet oxygen release was demonstrated in cell cultures.
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    Photosensitization and controlled photosensitization with BODIPY dyes
    (Elsevier, 2017) Türksoy, Abdurrahman; Yıldız, Deniz; Akkaya, Engin U.
    Highly versatile BODIPY dyes proved themselves to be very useful as photosensitizers. These dyes can be derivatized to absorb essentially anywhere in the visible the near IR region of the spectrum. As a result of their diverse reactivity, singlet oxygen generation efficiency can be modulated very precisely, leading to a number of selective photosensitizers for photodynamic therapy. Among the biologically relevant modulators, glutathione concentration and pH received particular attention. In this review, we highlight modulatable BODIPY-based photodynamic photosensitizers, and various synthetically useful chemical reactions triggered by singlet oxygen and other reactive oxygen species generated by BODIPY-based photosensitizers.
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    Proof-of-principle for two-stage photodynamic therapy: Hypoxia triggered release of singlet oxygen
    (Royal Society of Chemistry, 2020-11) Ayan, Seylan; Günaydın, G.; Yeşilgül-Mehmetcik, Nisa; Gedik, M. E.; Seven, Özlem; Akkaya, Engin U.
    We propose to overcome oxygen deficiency and light attenuation problems in photodynamic therapy (PDT), by separating photoexcitation and singlet oxygen delivery of the PDT process into two distinct operations to be carried out sequentially, at different locations. We now demonstrate the viability of this approach, using 2-pyridone derivative which yields a relatively stable endoperoxide. The initial storage endoperoxide obtained is transformed enzymatically into a more labile compound when placed in hypoxic cell cultures, and releases singlet oxygen significantly faster. The potential of this approach in advancing PDT beyond its current limits is exciting.