CC BY
0The 30th International Conference on Advanced Laser Technologies B-I-3
ALT'23
Visualization of complexes of upconversional nanoparticles with a photosensitizer in biological objects
V. I. Kochubey,12 A. M. Mylnikov,3 N. A. Navolokin,3'4'5 I. Yu. Yanina1'2
1- Saratov State University (National Research University), Institute of Physics, 83 Astrakhanskaya str., Sa-
ratov 410012, Russia
2- Tomsk State University (National Research University), Laboratory of laser molecular imaging and ma-
chine learning, 36Lenin's av., Tomsk 634050, Russia 3- Saratov State Medical University, Department of Pathological Anatomy, 112 B Kazachaya str., Saratov 410012,
Russia
4- Saratov State Medical University, Center for Collective Use of Experimental Oncology, Experimental Department,
112 B Kazachaya str., Saratov 410012, Russia
5- State Healthcare Institution "Saratov City Clinical Hospital No. 1 named after Yu.Ya. Gordeev", 19 Kholzunova st.,
Pathological Department, Saratov 410017, Russia
e-mail: irina-yanina@list.ru
Photodynamic therapy (PDT), has the potential to cure cancerous tissue with minimal side effects [1]. However, conventional PDT mostly uses visible (VIS) light range with the application of hydrophobic photosensitizers (PSs), which may not be sufficient in clinical practice, especially for deep-seated cancer cells, due to poor penetration of VIS wavelengths.
Upconversion nanoparticles (UCNPs) with unique optical properties are considered a promising platform for creating tumor markers that provide real-time optical visualization of tissues with high sensitivity and contrast, enabling them to be used for intraoperative diagnostics [2,3]. UCNPs are also promising platforms for enhancing the therapeutic response of cancer cells to PDT [4]. When coupled with UCNPs, the PSs in PDT are indirectly activated by near-infrared (NIR) excitation allowing for deeper tissue penetration and reduced attenuation. To achieve maximum performance, the up-converted emission peak of the UCNPs and the absorption band of the PSs must overlap significantly. However, the spectral mismatch between the up-converted emission maximum of UCNPs (predominantly in the green) and the absorption maximum of most available PSs (in the red) severely limits the therapeutic efficacy of current UCNP-PDT platforms. In this paper, we present data on stable surface coating of the UCNPs with human serum albumin (HSA) and PS. The choice was based on the overlap of the NP luminescence and PS absorption bands. We have been carried out studies on the visualization of nanoparticles in sections of rat organs and tumors by direct registration of a luminescent image. Samples of skin, organs and tumors were obtained surgically from rats with model liver cancer after intravenous injection of the NaYF4:Yb,Er -HSA-PS complex. Nanoparticles embedded in biological tissue are displayed as light spots whose size of which is determined by the size of the diffraction spot formed by the optical system. The images show a significant number of nanoparticles, both single and aggregated. UCNPs accumulate mainly in the spleen, as confirmed by histopathological analysis data. When the particles are injected intravenously twice, their maximum accumulation occurs in the tumor tissue. In general, no significant damage to organs, tissues, and erythrocytes was observed during particle accumulation. It can be concluded that the studied particles do not cause a pronounced toxic effect, and any changes that occur on the background of their introduction are reversible and not persistent.
We have proposed a promising complex for photodynamic therapy. The study was supported by a grant Russian Science Foundation No. 21-72-10057, https://rscf.ru/pro-ject/21-72-10057/
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