Electrospinning evolved as a powerful technology to produce membranes consisting of nano- to micron-scaled fibers offering unique membrane properties due to the extremely high surface-to-volume ratio and high membrane porosity. However, this technology is often far removed from a green and environmentally-friendly process, as it employs solvents with issues such as high flammability, toxicity, difficult disposal, or energy-intensive synthesis. Indeed, the most commonly used solvents in the electrospinning field are halogenated (e.g. chloroform, trifluoroethanol) and toxic solvents (e.g. dimethylformamide), the use of which is now restricted by the Chemical Control Regulation in the European Union (REACH). This is especially important when considering the commercialization of electrospun products due to the more limited solvent choice. In order to render electrospinning more attractive as a commercial technique and further improve scalability, solvent alternatives and other green routes have to be established, which adhere to societal and legal restrictions especially in regard to the environmental and health impact. Therefore, this review provides the current ecological and economical context of this technology, and summarizes recent approaches towards green electrospinning. Since electrospinning from solutions and dispersions constitutes the predominantly used form of this technique both in research and industry, the focus of this work is set on the use of solvents or solvent mixtures classified exclusively by the term “green”. The approaches presented comprehensively cover the production of polymeric fibers via solution, emulsion, suspension, and in situ cross-linking electrospinning.

Major challenges that confront nanoscience in medicine today include the development of efficacious therapies with minimum side effects, diagnostic methods featuring significantly higher sensitivities and selectivities, and personalized diagnostics and therapeutics for theragnostic approaches. With these goals in mind, combining biological molecules and synthetic carriers/templates, such as polymer supramolecular assemblies, represents a very promising strategy. In this critical review, we present protein–polymer systems as reaction spaces at the nano-scale in which the enzymatic reactions take place inside polymer supramolecular assembly, at its interface with the environment or in a combination of both. The location of the protein(s) with respect to the polymer assembly generates a diversity of systems ranging from nanoreactors to active enzymatic polymer surfaces. We describe these both in terms of general modelling and addressing the specific conditions and requirements related to the medical domain. We will particularly present protein–polymer nanoreactors that provide protected spaces for enzymatic reactions. We also show how polymer supramolecular structures, such as micelles, capsules, dendrimers and vesicles, can accommodate sensitive biomolecules to mimic natural systems and functions, and to serve as avenues for new medical approaches. Even though not yet on the market, we will emphasize possible applications of protein–polymer systems that generate reaction nanospaces—as novel ways to advanced medicine (264 references).

Recent observations that some membrane proteins act as gas channels seem surprising in view of the classical concept that membranes generally are highly permeable to gases. Here, we study the gas permeability of membranes for the case of CO ₂ , using a previously established mass spectrometric technique. We first show that biological membranes lacking protein gas channels but containing normal amounts of cholesterol (30–50 mol% of total lipid), e.g. , MDCK and tsA201 cells, in fact possess an unexpectedly low CO ₂ permeability (P _CO2 ) of ~0.01 cm/s, which is 2 orders of magnitude lower than the P _CO2 of pure planar phospholipid bilayers (~1 cm/s). Phospholipid vesicles enriched with similar amounts of cholesterol also exhibit P _CO2 ≈.01 cm/s, identifying cholesterol as the major determinant of membrane P _CO2 . This is confirmed by the demonstration that MDCK cells depleted of or enriched with membrane cholesterol show dramatic increases or decreases in P _CO2 , respectively. We demonstrate, furthermore, that reconstitution of human AQP‐1 into cholesterol‐containing vesicles, as well as expression of human AQP‐1 in MDCK cells, leads to drastic increases in P _CO2 , indicating that gas channels are of high functional significance for gas transfer across membranes of low intrinsic gas permeability.—Itel, F., Al‐Samir, S., Öberg, F., Chami, M., Kumar, M., Supuran, C. T., Deen, P. M. T., Meier, W., Hedfalk, K., Gros, G., Endeward, V. CO ₂ permeability of cell membranes is regulated by membrane cholesterol and protein gas channels. FASEB J. 26, 5182–5191 (2012). www.fasebj.org