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Synthesis of Titania Coated Upconversion Nanoparticles with the Capability of Being Utilized in Photodynamic Therapy Under the Near-Infrared Radiation

Ghorashi, Maryam Sadat | 2021

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 54850 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Madaaah Hosseini, Hamid Reza; Soleimani, Masoud; Mohajerani, Ezeddin
  7. Abstract:
  8. Development of novel photosensitizers and photocatalysts with near-infrared (NIR) light activity and efficient sunlight harvesting is of great importance in photodynamic therapy and environmental remediation. In this work, very small (20 nm) upconverter SrF2:Yb,Tm@CaF2:Yb@Fluorine-doped TiO2 heteronanoparticles (denoted as UCNPs@TiO2) with strong UV-blue emission and wide-spectrum photocatalytic activity were synthesized via a facile three-step hydrothermal method, for the first time. The SrF2: Yb,Tm upconverter nanoparticles were produced as the light-emitting core, epitaxially-grown CaF2 : Yb as the middle shell to enhance the Upconversion luminescence efficiency and TiO2 as the photocatalyst outermost layer. Superior photocatalytic performance of UCNPs@TiO2 was approved through methylene blue degradation under illumination by 980 nm laser light and different bands of simulated solar light, referring to TiO2 P25. The visible and NIR bands of simulated solar light could promote splendid photocatalytic performance in the presence of UCNPs@TiO2 due to F-doping of TiO2 and UCNPs integration, respectively. Furthermore, the efficacious reactive oxygen species (ROS) generation capability of UCNPs@TiO2 was verified under NIR light, suggesting their applicability as PDT agents. Based on the obtained results, UCNPs@TiO2 nanoparticles could serve as broadband photocatalyst and photosensitizing agents for efficient deep-tissue PDT. Lanthanide-doped upconversion nanocparticles have shown great promise in bioapplications. However, they are still restricted by low upconversion efficiency. remarkably enhanced ultraviolet upconversion luminescence was achieved via Bi3+ doping in very small, monodisperse and uniform SrF2:Yb3+,Tm3+ NPs. There have been several reports on NIR-excitable upconverting nanoparticles capable of working in biological mixtures and cellular settings. Unfortunately, most of these nanosystems are based on ytterbium’s upconversion at 980 nm, concurrent with water’s absorption. Thus, methods to produce robust upconverting nanoplatforms that can be efficiently excited with other than 980 nm NIR sources, such as 808 nm and 1064 nm, are required for biomedical applications. Herein, we have developed water dispersible SrF2: 22% Yb3+, 0.2% Tm3+, 1% Nd3+ @SrF2: 22% Nd3+ upconverting nanoparticles that can be activated with 808 nm excitation sources, thus avoiding unwanted heating processes
  9. Keywords:
  10. Upconversion Nanoparticles ; Titania ; Hydrothermal Synthesis ; Photodynamic Therapy ; Reactive Oxygen Species (ROS) ; Degradation Pollutants ; Dopants ; Ytterbium Dopant ; Thulium Dopant ; UV-vis-NIR Photocatalysis

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