Singlet oxygen-responsive micelles for enhanced photodynamic therapy

Publication date: 28 August 2017
Source:Journal of Controlled Release, Volume 260
Author(s): Xiaodan Li, Min Gao, Keting Xin, Ling Zhang, Dan Ding, Deling Kong, Zheng Wang, Yang Shi, Fabian Kiessling, Twan Lammers, Jianjun Cheng, Yanjun Zhao
Photodynamic therapy (PDT) efficacy is limited by the very short half-life and limited diffusion radius of singlet oxygen (¹O2). We report a ¹O2-responsive micellar nanoplatform subject to considerable size-expansion upon light triggering to facilitate on-demand release of photosensitizers. Imidazole, a well-known ¹O2 scavenger, was incorporated in the hydrophobic core of amphiphilic copolymer micelles, and was used to coordinate with biocompatible Zn²⁺ and encapsulate the photosensitizer chlorin e6 (Ce6). The micelles are highly sensitive to light irradiation: ¹O2 triggering induced dramatic particle size expansion due to the conversion of imidazole to hydrophilic urea, resulting in instantaneous release of Ce6 and rapid intracellular distribution. This ¹O2-responsive, size-expandable nanosystem delivered substantially more Ce6 to tumor sites as compared to free Ce6, and exhibited improved anti-tumor efficacy in vivo in 4T1 tumor-bearing mice. This work opens new avenues of particle expansion-induced PDT enhancement by controlled imidazole chemistry.

Graphical abstract

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