Robust Electrostatic-Templated Polymerization for Controllable Synthesis of Stable and Permeable Polyelectrolyte Vesicles.

Polymer vesicles are of profound interest for designing delivery vehicles and nanoreactors toward a variety of biomedical and catalytic applications, yet robust synthesis of stable and permeable vesicles remains challenging. Here, we propose an electrostatic-templated polymerization that enables fabrication of polyelectrolyte vesicles with simultaneously regulated stability and permeability. In our design, cationic monomers were copolymerized with cross-linkers in the presence of a polyanionic-neutral diblock copolymer as a template. By properly choosing the block length ratio of the template, we fabricated a type of polyion complex vesicle consisting of a cross-linked cationic membrane, electrostatically assembled with the template copolymer which can be removed by sequential dissociation and separation under concentrated salt. We finally obtained stable polyelectrolyte vesicles of regulated size, membrane permeability, and response properties by tuning the synthesis factors including ionic strength, cross-linker type, and fraction as well as different monomers and concentrations. As a proof-of-concept, lipase was loaded in the designed cationic vesicles, which exhibited enhanced enzyme stability and activity. Our study has developed a novel and robust strategy for controllable synthesis of a new class of stable and permeable polymer (polyelectrolyte) vesicles that feature great potential applications as functional delivery carriers and nanoreactors.

Stable and permeable polyion complex vesicles designed as enzymatic nanoreactors.

Polymeric vesicles are perspective vehicles for fabricating enzymatic nanoreactors towards diverse biomedical and catalytic applications, yet the design of stable and permeable vesicles remains challenging. Herein, we developed polyion complex (PIC) vesicles featuring high stability and a permeable membrane for adequate enzyme loading and activation. Our design relies on co-assembly of an anionic diblock copolymer (PSS96-b-PEO113) with cationic branched poly(ethylenimine) (PEI). The polymer combination endows strong electrostatic interaction between the PSS and PEI building blocks, so their assembly can be implemented at a high salt concentration (500 mM NaCl), under which the charge interaction of the enzyme-polymer is inhibited. This control realizes the successful and safe loading of enzymes associated with the formation of stable PIC vesicles with an intrinsic permeable membrane that is favourable for enhancing enzymatic activity. The control factors for vesicle formation and enzyme loading were investigated, and the general application of loading different enzymes for cascade reaction was validated as well. Our study reveals that proper design and combination of polyelectrolytes is a facile strategy for fabricating stable and permeable polymeric PIC vesicles, which exhibit clear advantages for loading and activating enzymes, consequently boosting their diverse applications as enzymatic nanoreactors.

Hierarchical self-assembly of metal-organic supramolecular fibers with lanthanide-derived functionalities.

Achieving organized assembly structures with high complexity and adjustable functionalities is a central quest in supramolecular chemistry. In this report, we study what happens when a discotic benzene-1,3,5-tricarboxamide (BTA) ligand containing three dipicolinic acid (DPA) groups is allowed to coordinate with lanthanide (Ln) ions. A multi-BTA coordination cluster forms, which behaves as a type of "supramolecular monomer", stacking into fibers via hydrogen bonds enabled by multiple BTA cores. The fibrous morphology and size, as well as the packing unit and the process by which it grows, were investigated by light scattering measurements, luminescence spectra, TEM images and molecular simulation data. More notably, by selecting the kind of lanthanide or mixture of lanthanides that is incorporated, tunable luminescence and magnetic relaxation properties without compromising the fibrous structure can be realized. This case of hierarchical self-assembly is made possible by the special structure of our BTA-like building block, which makes non-covalent bond types that are different along the radial (coordination bonds) and axial (H-bonds) directions, respectively, each with just the right strength. Moreover, the use of lanthanide coordination leads to materials with metal-derived optical and magnetic properties. Therefore, the established approach demonstrates a novel strategy for designing and fabrication of multi-functional supramolecular materials.

TCPP-Isoliensinine Nanoparticles for Mild-Temperature Photothermal Therapy.

PURPOSE: Photothermal therapy (PTT) is promising for the treatment of tumors due to its advantages including minimally invasive, easy implementation and selective localized treatment. However, single PTT suffers from several limitations, such as constrained light penetration and low delivery efficiency, typically leading to heterogeneous heating and incomplete elimination of cancer cells. Therefore, combination of PTT with other therapies, eg, chemotherapy is desirable in order to achieve synergistic effects in cancer treatment. METHODS: Here, we designed a new type of TCPP-Iso combined nanoparticle for synergetic therapy for breast cancer. Specifically, photothermal agent tetra(4-carboxyphenyl) porphine (TCPP) and anti-cancer drug isoliensinine (Iso) were encapsulated in PEG-b-PLGA polymeric nanoparticles through a precipitation process. RESULTS: The obtained NPs displayed well-controlled size and high stability over time. Tuning TCPP-Iso/polymer ratio, or total concentration of drug and polymers led to increased hydrodynamic radius of NPs from 65 to 108 nm without disturbing the narrow size distribution. Besides, the formed NPs showed a consequently cumulative release of TCPP and of Iso. The temperature elevation ability of both TCPP NPs and TCPP-Iso NPs was TCPP-concentration dependent. Solutions of TCPP NPs that contained equivalent amount of TCPP with respect to TCPP-Iso NPs, presented the same trend and exhibited non-obvious difference in temperature elevation under certain laser power. The viability of MDA-MB-231 cells treated with TCPP-Iso NPs could be inhibited effectively at a relatively mild temperature (42-43°C) compared to the other groups, which may minimize heat damage to the surrounding healthy tissues. CONCLUSION: The results indicate that the TCPP-Iso combined NPs showed hardly any toxicity to normal tissue cell line, but displayed an efficient synergistic effect for killing cancer cells under laser irradiation. Our study demonstrates that the successful combination of TCPP and Iso realized a synergistic therapy effect at a relatively mild temperature, and the insights obtained here shall be helpful for designing new combined PTT agents for cancer treatment.