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We study the layer-by-layer (LbL) deposition of a pair of strong polyelectrolytes within the nanopores of track-etched membranes, for pore diameters ranging from ∼50 to 850 nm. The end-to-end distance of the polyelectrolyte chains in solution was varied from 10 to 50 nm by selecting polyelectrolytes of low and high molar mass and by playing with ionic strength. On flat model surfaces, a linear growth is obtained for all probed conditions and the growth increment is independent of molar mass and substrate nature. When LbL assembly is performed within nanopores, a very different picture of growth emerges, with increments of thickness per cycle of deposition being much larger than on flat surfaces (by factors as large as 100 in some cases), and no significant dependence on molar mass or ionic strength. These observations indicate that polyelectrolyte complexation occurs within a dense gel filling the whole nanopore, resulting from entanglement of the chains which are in a concentrated regime when passing in the confined space of the pore; upon drying, the gel collapses in a tube of wall thickness roughly proportional to its diameter. By using polyelectrolytes of lower molar mass, pore diameters as small as 50 nm could be filled, opening opportunities for the facile fabrication of LbL nanowires of very large aspect ratio.

Cell survival during the early stages of transplantation and before new blood vessels formation is a major challenge in translational applications of 3D bioprinted tissues. Supplementing oxygen (O2) to transplanted cells via an O2 generating source such as calcium peroxide (CPO) is an attractive approach to ensure cell viability. Calcium peroxide also produces calcium hydroxide that reduces the viscosity of bioinks, which is a limiting factor for bioprinting. Therefore, adapting this solution into 3D bioprinting is of significant importance. In this study, a gelatin methacryloyl (GelMA) bioink that is optimized in terms of pH and viscosity is developed. The improved rheological properties lead to the production of a robust bioink suitable for 3D bioprinting and controlled O2 release. In addition, O2 release, bioprinting conditions, and mechanical performance of hydrogels having different CPO concentrations are characterized. As a proof of concept study, fibroblasts and cardiomyocytes are bioprinted using CPO containing GelMA bioink. Viability and metabolic activity of printed cells are checked after 7 days of culture under hypoxic condition. The results show that the addition of CPO improves the metabolic activity and viability of cells in bioprinted constructs under hypoxic condition.

This study reports on the development of thermoresponsive core/shell magnetic nanoparticles (MNPs) based on an iron oxide core and a thermoresponsive copolymer shell composed of 2-(2-methoxy)­ethyl methacrylate (MEO2MA) and oligo­(ethylene glycol)­methacrylate (OEGMA) moieties. These smart nano-objects combine the magnetic properties of the core and the drug carrier properties of the polymeric shell. Loading the anticancer drug doxorubicin (DOX) in the thermoresponsive MNPs via supramolecular interactions provides advanced features to the delivery of DOX with spatial and temporal controls. The so coated iron oxide MNPs exhibit superparamagnetic behavior with a saturation magnetization of around 30 emu g–1. Drug release experiments confirmed that only a small amount of DOX was released at room temperature, while almost 100% drug release was achieved after 52 h at 42 °C with Fe3−δO4@P­(MEO2MA60OEGMA40), which grafted polymer chains displaying a low critical solution temperature of 41 °C. Moreover, the MNPs exhibit magnetic hyperthermia properties as shown by specific absorption rate measurements. Finally, the cytotoxicity of the core/shell MNPs toward human ovary cancer SKOV-3 cells was tested. The results showed that the polymer-capped MNPs exhibited almost no toxicity at concentrations up to 12 μg mL–1, whereas when loaded with DOX, an increase in cytotoxicity and a decrease of SKOV-3 cell viability were observed. From these results, we conclude that these smart superparamagnetic nanocarriers with stealth properties are able to deliver drugs to tumor and are promising for applications in multimodal cancer therapy.

Strong, stretchable, and durable biomaterials with shape memory properties can be useful in different biomedical devices, tissue engineering, and soft robotics. However, it is challenging to combine these features. Semi‐crystalline polyvinyl alcohol (PVA) has been used to make hydrogels by conventional methods such as freeze–thaw and chemical crosslinking, but it is formidable to produce strong materials with adjustable properties. Herein, a method to induce crystallinity and produce physically crosslinked PVA hydrogels via applying high‐concentration sodium hydroxide into dense PVA polymer is introduced. Such a strategy enables the production of physically crosslinked PVA biomaterial with high mechanical properties, low water content, resistance to injury, and shape memory properties. It is also found that the developed PVA hydrogel can recover 90% of plastic deformation due to extension upon supplying water, providing a strong contraction force sufficiently to lift objects 1100 times more than their weight. Cytocompatibility, antifouling property, hemocompatibility, and biocompatibility are also demonstrated in vitro and in vivo. The fabrication methods of PVA‐based catheters, injectable electronics, and microfluidic devices are demonstrated. This gelation approach enables both layer‐by‐layer and 3D printing fabrications.

Novel supported membranes based on polyvinyl alcohol (PVA) were developed using two strategies: first, by the modification of the PVA network, via so-called bulk modification, with the formation of the selective layer accomplished through the introduction of fullerenol and/or poly(allylamine hydrochloride), and second, by the functionalization of the surface with successive depositions of multilayered films of polyelectrolytes, such as poly(allylamine hydrochloride) and poly(sodium 4-styrenesulfonate) on the PVA surface. The membrane surface modifications were characterized by scanning electron microscopy and contact angle measurements. The modified PVA membranes were examined for their dehydration transport properties by the pervaporation of isopropyl alcohol-water (80/20% w/w), which was chosen as a model mixture. Compared with the pristine PVA membrane, the main improvement was a marked increase in permeance. It was found that the surface modifications mainly gave rise to a higher global flux but with a strong reduction in selectivity. Only the combination of both bulk and surface modifications with PEL could significantly increase the flux with a high water content in the permeate (over 98%). Lastly, it should be noted that this study developed a green procedure to prepare innovative membrane layers for dehydration, making use of only water as a working medium.

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