MnO₂ Gatekeeper: An Intelligent and O₂-Evolving Shell for Preventing Premature Release of High Cargo Payload Core, Overcoming Tumor Hypoxia, and Acidic H₂O₂-Sensitive MRI

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• 作者：Zhifang Ma ; Xiaodan Jia ; Jing Bai ; Yudi Ruan ; Chao Wang ; Jianming Li ; Mengchao Zhang and Xiue Jiang
• 刊名：Advanced Functional Materials
• 出版年：2017
• 出版时间：January 26, 2017
• 年：2017
• 卷：27
• 期：4
• 全文大小：4569K
• ISSN：1616-3028

文摘

Premature leakage of photosensitizer (PS) from nanocarriers significantly reduces the accumulation of PS within a tumor, thereby enhancing nonspecific accumulation in normal tissues, which inevitably leads to a limited efficacy for photodynamic therapy (PDT) and the enhanced systematic phototoxicity. Moreover, local hypoxia of the tumor tissue also seriously hinders the PDT. To overcome these limitations, an acidic H₂O₂-responsive and O₂-evolving core–shell PDT nanoplatform is developed by using MnO₂ shell as a switchable shield to prevent the premature release of loaded PS in core and elevate the O₂ concentration within tumor tissue. The inner core SiO₂-methylene blue obtained by co-condensation has a high PS payload and the outer MnO₂ shell shields PS from leaking into blood after intravenous injection until reaching tumor tissue. Moreover, the shell MnO₂ simultaneously endows the theranostic nanocomposite with redox activity toward H₂O₂ in the acidic microenvironment of tumor tissue to generate O₂ and thus overcomes the hypoxia of cancer cells. More importantly, the Mn(ΙΙ) ion reduced from Mn(ΙV) is capable of in vivo magnetic resonance imaging selectively in response to overexpressed acidic H₂O₂. The facile incorporation of the switchable MnO₂ shell into one multifunctional diagnostic and therapeutic nanoplatform has great potential for future clinical application.