Evaluation of polymersome permeability as a fundamental aspect towards the development of artificial cells and nanofactories.

Polymersomes are synthetic vesicles with potential use in healthcare, chemical transformations in confined environment (nanofactories), and in the construction of artificial cells and organelles. In this framework, one of the most important features of such supramolecular structures is the permeability behavior allowing for selective control of mass exchange between the inner and outer compartments. The use of biological and synthetic nanopores in this regard is the most common strategy to impart permeability nevertheless, this typically requires fairly complex strategies to enable porosity. Yet, investigations concerning the permeability of polymer vesicles to different analytes still requires further exploration and, taking these considerations into account, we have detailed investigated the permeability behavior of a variety of polymersomes with regard to different analytes (water, protons, and rhodamine B) which were selected as models for solvents, ions, and small molecules. Polymersomes based on hydrophilic blocks of poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) or PEO (poly(ethylene oxide)) linked to the non-responsive blocks poly[N-(4-isopropylphenylacetamide)ethyl methacrylate] (PPPhA) or poly(methyl methacrylate) (PMMA), or to the stimuli pH-responsive block poly[2-(diisopropylamino)ethyl methacrylate] (PDPA) have been investigated. Interestingly, the produced PEO-based vesicles are notably larger than the ones produced using PHPMA-containing block copolymers. The experimental results reveal that all the vesicles are inherently permeable to some extent with permeability behavior following exponential profiles. Nevertheless, polymersomes based on PMMA as the hydrophobic component were demonstrated to be the least permeable to the small molecule rhodamine B as well as to water. The synthetic vesicles based on the pH-responsive PDPA block exhibited restrictive and notably slow proton permeability as attributed to partial chain protonation upon acidification of the medium. The dye permeability was evidenced to be much slower than ion or solvent diffusion, and in the case of pH-responsive assemblies, it was demonstrated to also depend on the ionic strength of the environment. These findings are understood to be highly relevant towards polymer selection for the production of synthetic vesicles with selective and time-dependent permeability, and it may thus contribute in advancing biomimicry and nanomedicine.

Hybrid nanogels by direct mixing of chitosan, tannic acid and magnetite nanoparticles: processes involved in their formation and potential catalytic properties.

Magnetite (Fe3O4) nanoparticles (MNPs) as nanocatalysts have drawn considerable attention because of their unique properties such as peroxidase-like activity. However, their biodistribution and availability for specific treatments still need to be improved. In this study, a simple and convenient strategy for the synthesis of hybrid nanogels (NGs) is described, which involves direct mixing of biomaterials such as chitosan (Ch) and tannic acid (TA), with the incorporation of MNPs, under oxidising conditions, using the inverse nanoemulsion method. The different processes involved in the formation of these hybrid nanosystems as well as their morphological and chemical structure are investigated using optical, spectroscopic, and electron microscopic techniques (DLS, UV-VIS, FT-IR, XPS, TEM, and SEM-EDS). It is demonstrated that ∼11 nm synthesized MNPs, post-functionalized with oxidised TA, act as covalent crosslinkers. As a proof of concept, the potential use of these materials in nanocatalytic medicine was evaluated using a colorimetric method based on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in hydrogen peroxide. The results show that these hybrid nanogels have the same peroxidase-like activity as bare MNPs, indicating that the organic nanostructure stabilises the inorganic nanoparticles without any significant change in the catalytic properties. Therefore, this kind of nanomaterial has promising potential for use in nanocatalytic medicine with improved biocompatibility and biodistribution.

Poly(N-vinylcaprolactam) Nanogels with Antiviral Behavior against HIV-1 Infection.

Stimuli-responsive nanogels offer promising perspectives for the development of next generation formulations for biomedical applications. In this work, poly(N-vinylcaprolactam) nanogels were synthesized varying the concentration of monomer and crosslinking agent. Thus, the inhibitory effect of poly(N-vinylcaprolactam) nanogels against HIV-1 infection is presented for the first time. In particular, we have demonstrated that one of the synthesized poly(N-vinylcaprolactam) nanogels with initial concentration of 80 mg of vinylcaprolactam and 4% of crosslinking agent shows antiviral behavior against HIV-1 infection since this nanogel inhibits the viral replication in TZM.bl target cells.