Redox- and pH-Responsive Water-Soluble Flexible Organic Frameworks Realize Synergistic Tumor Photodynamic and Chemotherapeutic Therapy

Water-soluble 3D polymers with inherent nanoscale pores have been shown to be ideal platforms for the inclusion and delivery of drugs and hold a great promise as biocompatible materials for diagnostic and therapeutic purposes. Herein, a low cytotoxic water-soluble flexible organic framework FOF-S6 with a hydrodynamic diameter of about 127.5 nm is synthesized through the formation of a hydrazone bond from a semirigid tetraaldehyde and a flexible biacylhydrazines which contains a disulfide bond (1:2). FOF-S6 has the ability to dissociate and release inclusion complexes in response to weakly acidic media and glutathione (GSH) overexpressed in tumor cells. More importantly, a facile strategy is developed to contain and deliver aggregation-induced emission photosensitizers (AIE PS, TBD-DQA-540) and chemotherapeutic drugs (Doxorubicin hydrochloride, DOX). DOX-PS@FOF-S6 is synthesized by a one-pot method, which can realize efficient photo-chemotherapy under the guidance of fluorescence imaging, thereby improving the multidrug resistance of tumor cells and the instability of photosensitizers, so as to improve the tumor treatment efficacy.

Adsorption-Based Detoxification of Endotoxins by Porous Flexible Organic Frameworks

Bacterial lipopolysaccharides (LPS, endotoxins) cause sepsis that is responsible for a huge amount of mortality globally. However, their neutralization or detoxification remains an unmet medical need. We envisaged that cationic organic frameworks with persistent hydrophobic porosity may adsorb and thus neutralize LPS through a combination of cooperative ion-pairing electrostatic attraction and hydrophobicity. We here report the preparation of two water-soluble flexible organic frameworks (FOF-1 and FOF-2) from tetratopic and ditopic precursors through quantitative formation of hydrazone bonds at room temperature. The two FOFs are revealed to possess hydrodynamic diameters, which range from 20 to 120 nm, depending on the concentrations. Dynamic light scattering and isothermal titration calorimetric and chromogenic limulus amebocyte lysate experiments indicate that both frameworks are able to adsorb and thus reduce the concentration of free LPS molecules in aqueous solution, whereas cytokine inhibition experiments with RAW264.7 support that this adsorption can significantly decrease the toxicity of LPS. In vivo experiments with mice (five males per group) show that the injection of FOF-1 at a dose of 0.6 mg/kg realizes the survival of all of the mice administrated with LPS of the d-galactosamine (d-Gal)-sensitized absolute lethal dose (LD₁₀₀, 0.05 mg/kg), whereas its maximum tolerated dose for mice is determined to be 10 mg/kg. These findings provide a new promising sequestration strategy for the development of porous agents for the neutralization of LPS.