Ellagic acid-Fe nanoscale coordination polymer with higher longitudinal relaxivity for dual-modality T1-weighted magnetic resonance and photoacoustic tumor imaging

SU-101: a Bi(III)-based metal-organic framework as an efficient heterogeneous catalyst for the CO2 cycloaddition reaction

A non-porous version of SU-101 (herein n-SU-101) was evaluated for the CO2 cycloaddition reaction. The findings revealed that open metal sites (Bi3+) are necessary for the reaction. n-SU-101 displays a high styrene oxide conversion of 96.6% under mild conditions (3 bar and 80 °C). The catalytic activity of n-SU-101 demonstrated its potential application for the cycloaddition of CO2 using styrene oxide.

pH-responsive hollow Fe-gallic acid coordination polymer for multimodal synergistic-therapy and MRI of cancer

Tumor-microenvironment (TME) responsive nanostructures are attractive for drug delivery in clinical cancer treatment. The coordination polymer Fe-gallic acid (Fe-GA) is one of the promising drug carriers due to its pH-response, good biocompatibility, and minimal side effects. However, the hollow nanostructures of Fe-GA have not been reported until now, which seriously limits the quantity of drug delivery. Herein, hollow Fe-GA nanospheres were prepared for the first time with bovine serum albumin (BSA) combination (denoted as Fe-GA/BSA) under mild reaction conditions. Then, the antitumor drug doxorubicin (DOX) was loaded in the hollow Fe-GA/BSA to obtain Fe-GA/BSA@DOX. A series of experiments in vitro and in vivo indicated that the Fe-GA/BSA@DOX could efficiently respond to TME and release DOX and Fe(iii) ions. Furthermore, the Fe(iii) could consume overexpressed glutathione (GSH) in cancer cells and generate Fe(ii) to trigger the Fenton reaction, producing ·OH for chemodynamic treatment (CDT) of cancer. In addition, the Fe-GA/BSA@DOX could effectively convert near-infrared (NIR) light into heat by acting as a photothermal therapy (PTT) agent. Besides that, magnetic resonance imaging (MRI) data also showed that the Fe-GA/BSA had beneficial T1 and T2 imaging effects, demonstrating that the hollow Fe-GA/BSA has potential for multimodal synergistic cancer MRI diagnosis and therapies of drugs, CDT, and PTT.

Fe3O4 assembly for tumor accurate diagnosis by endogenous GSH responsive T2/T1 magnetic relaxation conversion

Superparamagnetic iron oxide nanoparticles with high magnetization strength and good biological safety have been widely used as magnetic resonance imaging (MRI) contrast agents for tumors. However, the accuracy of tumor diagnosis is still low due to the lack of tumor targeting and the interference signals from normal tissues. Endogenous substances in tumor (such as high levels of GSH and pH) stimuli-responsive contrast agents could offer higher sensitivity for tumor diagnosis. Herein, based on the characteristic of overexpression of GSH in tumors, we propose an ultra-small Fe₃O₄ assembly as an endogenous GSH responsive MRI contrast agent. The ultra-small superparamagnetic Fe₃O₄ are bonded to the crosslinker cystamine to synthesize Fe₃O₄ nanoclusters, which exhibit a T₂ imaging effect. When the contrast agent reaches the tumor tissue, the disulfide bond in cystamine is induced by GSH to break, the Fe₃O₄ nanoclusters are disassembled into ultra-small Fe₃O₄ nanoparticles, and the relaxation signal changes from T₂ to T₁, which is helpful for accurate diagnosis of tumors. In vivo experiments have shown that Fe₃O₄ nanoclusters can rapidly respond to overexpressed GSH in tumor sites for T₂/T₁ switchable imaging. This work not only designed an endogenous GSH responsive platform through simple synthesis methods, but also improved the accuracy of tumor diagnosis through the transformation of T₂/T₁ MRI signals.