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NIR photoregulated theranostic system based on hexagonal-phase upconverting nanoparticles for tumor-targeted photodynamic therapy and fluorescence imaging
  • So Yeon Kim,
  • Jongseon Choi,
  • Linlin Zhao
So Yeon Kim
Chungnam National University
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Jongseon Choi
Chungnam National University
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Linlin Zhao
Tianjin University of Technology
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Although photodynamic therapy (PDT) is an effective, minimally-invasive therapeutic modality with advantages in highly localized and specific tumor treatments, large and deep-seated cancers within the body cannot be successfully treated due to low transparency to visible light. To improve the therapeutic efficiency of tumor treatment in deep tissue and reduce the side effects in normal tissue, this study developed a near-infrared (NIR)-triggered upconversion nanoparticle (UCNP)-based photosensitizer (PS) carrier as a novel theranostics system. The NaYF4:Yb/Er UCNPs were synthesized by a hydrothermal method, producing uniformly small size (≈20 nm) nanoparticles and crystalline morphology of the hexagonal phase. These UCNPs were modified with folic acid-conjugated biocompatible block copolymers through a bidentate dihydrolipoic acid linker. The polymer modified hexagonal phase UCNPs (FA-PEAH-UCNPs) showed an improved dispersibility in the aqueous solution and strong NIR-to-vis upconversion fluorescence. The hydrophobic PS, pheophorbide a (Pha), was then conjugated to the stable vectors through a pH-sensitive linkage. Moreover, these UCNP-based Pha carriers containing tumor targeting folic acid ligands exhibited the significantly enhanced cellular uptake efficiency as well as PDT treatment efficiency. These results suggested that this system could extend the excitation wavelength of PDT to the NIR region and effectively improve therapeutic efficiency of PSs.

Peer review status:POSTED

04 Feb 2020Submitted to Biotechnology and Bioengineering
06 Feb 2020Assigned to Editor
06 Feb 2020Submission Checks Completed