Core-Shell Structurized Fe3O4@C@MnO2 Nanoparticles as pH Responsive T1-T2* Dual-Modal Contrast Agents for Tumor Diagnosis.

Biocompatible core-shell Fe3O4@C@MnO2 nanoparticles (named as FOCMO NPs) with an average size at 130 nm prepared through an effortless yet efficient strategy were employed as pH-activatable T1-T2* dual-modality magnetic resonance imaging (MRI) contrast agents (CAs). The release rate of Mn ions in acidic PBS (pH = 5.0) was approximately 10 times to that under condition with pH value of 7.4. Benefiting from excellent acid responsiveness, which facilitates the release of ions from FOCMO NPs at tumor region with acidic microenvironment and organelles, the diagnosis accuracy was commendably improved. After intravenous injection of FOCMO NPs, an efficiently intensive contrast in tumors are realized with a distinct enhancement of 127% in T1 MRI signal 24 h after the administration. Moreover, a significant decreasement of 71% is witnessed in T2 MRI signal. Those demonstrated that FOCMO NPs can achieve the purpose of positive/negative MRI simultaneously. Furthermore, obtained FOCMO NPs showed great hemocompatibility and negligible toxicity.

Biodegradable Core-shell Dual-Metal-Organic-Frameworks Nanotheranostic Agent for Multiple Imaging Guided Combination Cancer Therapy.

Metal-organic-frameworks (MOFs) possess high porosity, large surface area, and tunable functionality are promising candidates for synchronous diagnosis and therapy in cancer treatment. Although large number of MOFs has been discovered, conventional MOF-based nanoplatforms are mainly limited to the sole MOF source with sole functionality. In this study, surfactant modified Prussian blue (PB) core coated by compact ZIF-8 shell (core-shell dual-MOFs, CSD-MOFs) has been reported through a versatile stepwise approach. With Prussian blue as core, CSD-MOFs are able to serve as both magnetic resonance imaging (MRI) and fluorescence optical imaging (FOI) agents. We show that CSD-MOFs crystals loading the anticancer drug doxorubicin (DOX) are efficient pH and near-infrared (NIR) dual-stimuli responsive drug delivery vehicles. After the degradation of ZIF-8, simultaneous NIR irradiation to the inner PB MOFs continuously generate heat that kill cancer cells. Their efficacy on HeLa cancer cell lines is higher compared with the respective single treatment modality, achieving synergistic chemo-thermal therapy efficacy. In vivo results indicate that the anti-tumor efficacy of CSD-MOFs@DOX+NIR was 7.16 and 5.07 times enhanced compared to single chemo-therapy and single thermal-therapy respectively. Our strategy opens new possibilities to construct multifunctional theranostic systems through integration of two different MOFs.