Limitations of PEG in drug delivery have been reported from clinical trials. PEtOx (0.4-40 kDa) as alternative is synthesized by a living, microwave-assisted polymerization, and is directly compared to PEG of similar molar mass regarding cytotoxicity and hemocompatibility. In short-term treatments, both types of polymers are well tolerated even at high concentrations. Moderate concentration and molar mass dependent cytotoxic effects occurred only after long-term incubation at concentrations higher than therapeutic doses. PEtOx possesses not only an easy route of synthesis and beneficial physicochemical characteristics such as low viscosity and high stability, which are advantageous over PEG, but additionally in vitro toxicology comparable to PEG.

Poly(2-oxazoline)s (POxs) are a versatile class of biocompatible polymers, which have been investigated as poly(ethylene glycol) (PEG) alternatives. In recent years, POxs have drawn significant attention as coatings for antifouling applications. In this tutorial review different approaches to immobilize POxs on surfaces as well as properties and applications of POx coated surfaces will be presented.

The synthesis of linear polyethyleneimine (LPEI) by acidic hydrolysis of poly(2‐ethyl‐2‐oxazoline) is studied and optimized to reach the highest degree of hydrolysis within the shortest time range using a microwave synthesizer. In addition, the purification procedure is significantly improved; the fast batch processing combined with an excellent control of the actual heating time represents a well‐suited alternative to the conventional synthesis on the way to “pharmagrade” PEI. The developed protocol for the preparation of methyl and proton‐initiated LPEIs shows a high reproducibility, and the identity and purity of the LPEIs is proven by means of 1H NMR and IR spectroscopy as well as MALDI‐TOF‐ and ESI‐Q‐TOF‐MS. magnified image

The antifouling properties against the simultaneous attack of five different bacteria and the stability of surface tethered poly(2-ethyl-2-oxazoline)s were investigated.

To date, cationic polymers with high transfection efficiencies (TE) often have a high cytotoxicity. By screening an 18-membered library of cationic 2-oxazoline-based polymers, a polymer with similar TE as linear poly(ethylene imine) but no detectable cytotoxicity at the investigated concentrations could be identified. The influence of the polymer side chain hydrophobicity and the type and content of amino groups on the pDNA condensation, the TE, the cytotoxicity, the cellular membrane interaction as well as the size, charge, and stability of the polyplexes was studied. Primary amines and an amine content of at least 40% were required for an efficient TE. While polymers with short side chains were non-toxic up to an amine content of 40%, long hydrophobic side chains induced a high cytotoxicity.