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  2. The effect of Gd-DOTA locations within PLGA- b-PEG micelle encapsulated IR-1061 on bimodal over-1000 nm near-infrared fluorescence and magnetic resonance imaging

The effect of Gd-DOTA locations within PLGA- b-PEG micelle encapsulated IR-1061 on bimodal over-1000 nm near-infrared fluorescence and magnetic resonance imaging

  • Biomater Sci. 2022 Oct 25;10(21):6244-6257. doi: 10.1039/d2bm01213h.
Thi Kim Dung Doan 1 2 Masakazu Umezawa 3 Kyohei Okubo 3 Masao Kamimura 3 Masayuki Yamaguchi 2 Hirofumi Fujii 2 Kohei Soga 1 3
Affiliations

Affiliations

  • 1 Research Institute for Biomedical Science, Tokyo University of Science, 2669 Yamazaki, Noda, Chiba 278-0022, Japan. doan@rs.tus.ac.jp.
  • 2 Division of Functional Imaging, Exploratory Oncology Research & Clinical Trial Center, National Cancer Center, 6-5-1 Kashiwanoha, Kashiwa 277-8577, Japan.
  • 3 Department of Material Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan.
Abstract

Multimodal imaging is attractive in biomedical research because it can provide multidimensional information about objects that individual techniques cannot accomplish. In particular, combining over one-thousand-nanometer near-infrared (OTN-NIR) fluorescence and magnetic resonance (MR) imaging is promising for detecting lesions with high sensitivity and structural information. Herein, we describe the development of a bimodal OTN-NIR/MRI probe from gadolinium-tetraazacyclododecanetetraacetic acid (Gd-DOTA) conjugated poly(lactic-co-glycolic acid)-block-poly(ethylene glycol) copolymer (PLGA-b-PEG) micelle encapsulated IR-1061 at two different locations. One configuration contains Gd-DOTA at the end of the PEG of the hydrophilic shell and the Other contains Gd-DOTA at the border of PLGA/PEG. The two structures show remarkable differences in fluorescence and R1 relaxation rates in biological environments; the structure with Gd-DOTA at the border of PLGA/PEG exhibits stable fluorescence and T1 signal distribution in live mice. The introduction ratio of Gd-DOTA to PEG is significant for controlling the properties of both structures; a higher Gd-DOTA ratio is preferable for the contrast enhancement effect. We found that Gd-DOTA ratios higher than 10% degraded the fluorescence intensity when Gd-DOTA was bound to the end of PEG. In contrast, the introduction of 70% Gd-DOTA at the border of PLGA/PEG did not exhibit a degraded signal, and the structural stability was enhanced with higher ratios of Gd-DOTA. In conclusion, we confirmed that the location of Gd-DOTA is a crucial factor in designing high-performance probes. The overall properties improve when Gd-DOTA is set on the border of PLGA/PEG. These improvements in the properties by controlling the probe structures are promising for future biomedical applications.

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