Phenethyl Isothiocyanate-Conjugated Chitosan Oligosaccharide Nanophotosensitizers for Photodynamic Treatment of Human Cancer Cells

Inho Bae; Taeyu Grace Kim; Taeyeon Kim; Dohoon Kim; Doug-Hoon Kim; Jaewon Jo; Young-Ju Lee; Young-Il Jeong

doi:10.3390/ijms232213802

Phenethyl Isothiocyanate-Conjugated Chitosan Oligosaccharide Nanophotosensitizers for Photodynamic Treatment of Human Cancer Cells

Int J Mol Sci. 2022 Nov 9;23(22):13802. doi: 10.3390/ijms232213802.

Authors

Inho Bae¹, Taeyu Grace Kim^{2

3}, Taeyeon Kim⁴, Dohoon Kim², Doug-Hoon Kim⁵, Jaewon Jo⁶, Young-Ju Lee⁶, Young-Il Jeong²

Affiliations

¹ Department of Dental Materials, College of Dentistry, Chosun University, Gwangju 61452, Korea.
² Tyros Biotechnology Inc., 75 Kneeland St. 14 floors, Boston, MA 02111, USA.
³ Brookline High School, 115 Greenough St., Brookline, MA 02445, USA.
⁴ College of Art & Science, University of Pennsylvania, 249 S 36th St., Philadelphia, PA 19104, USA.
⁵ Department of Optometry, Masan University, Changwon 51217, Korea.
⁶ Gwangju Center, Korea Basic Science Institute, Gwangju 61186, Korea.

Abstract

The aim of this study is to synthesize phenethyl-conjugated chitosan oligosaccharide (COS) (abbreviated as ChitoPEITC) conjugates and then fabricate chlorin E6 (Ce6)-incorporated nanophotosensitizers for photodynamic therapy (PDT) of HCT-116 colon carcinoma cells. PEITC was conjugated with the amine group of COS. Ce6-incorporated nanophotosensitizers using ChitoPEITC (ChitoPEITC nanophotosensitizers) were fabricated by dialysis method. ¹H nuclear magnetic resonance (NMR) spectra showed that specific peaks of COS and PEITC were observed at ChitoPEITC conjugates. Transmission electron microscope (TEM) confirmed that ChitoPEITC nanophotosensitizers have spherical shapes with small hydrodynamic diameters less than 200 nm. The higher PEITC contents in the ChitoPEITC copolymer resulted in a slower release rate of Ce6 from nanophotosensitizers. Furthermore, the higher Ce6 contents resulted in a slower release rate of Ce6. In cell culture study, ChitoPEITC nanophotosensitizers showed low toxicity against normal CCD986Sk human skin fibroblast cells and HCT-116 human colon carcinoma cells in the absence of light irradiation. ChitoPEITC nanophotosensitizers showed a significantly higher Ce6 uptake ratio than that of free Ce6. Under light irradiation, cellular reactive oxygen species (ROS) production of nanophotosensitizers was significantly higher than that of free Ce6. Especially, PEITC and/or ChitoPEITC themselves contributed to the production of cellular ROS regardless of light irradiation. ChitoPEITC nanophotosensitizers showed significantly higher PDT efficacy against HCT-116 cells than that of free Ce6. These results indicate that ChitoPEITC nanophotosensitizers have superior potential in Ce6 uptake, ROS production and PDT efficacy. In the HCT-116 cell-bearing mice tumor-xenograft model, ChitoPEITC nanophotosensitizers efficiently inhibited growth of tumor volume rather than free Ce6. In the animal imaging study, ChitoPEITC nanophotosensitizers were concentrated in the tumor tissue, i.e., fluorescence intensity in the tumor tissue was stronger than that of other tissues. We suggest that ChitoPEITC nanophotosensitizers are a promising candidate for the treatment of human colon cancer cells.

Keywords: nanophotosensitizers; oral cancers; photodynamic therapy; reactive oxygen species; tumor-targeting.

MeSH terms

Animals
Carcinoma*
Chitosan*
Colonic Neoplasms* / drug therapy
Humans
Mice
Oligosaccharides
Reactive Oxygen Species

Substances

phenethyl isothiocyanate
Chitosan
Reactive Oxygen Species
Oligosaccharides

Grants and funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2021R1I1A1A01049945).