Poly(2‐oxazoline) hydrogels crosslinked with aliphatic bis(2‐oxazoline)s: Properties, cytotoxicity, and cell cultivation

Abstract

A series of hydrogels from 2-ethyl-2-oxazoline and three bis(2-oxazoline) crosslinkers-1,4-butylene-2,2 0 -bis(2-oxazoline), 1,6-hexamethylene-2,2 0 -bis(2-oxazoline), and 1,8-octamethylene-2,2 0 -bis(2-oxazoline)-are prepared. The hydrogels differ by the length of aliphatic chain of crosslinker and by the percentage of crosslinker (2-10%). The influence of the type and the percentage of the crosslinker on swelling properties, mechanical properties, and state of water is studied. The equilibrium swelling degree in water ranges from 2 to 20. With a proper selection of the crosslinker, Young's modulus can be varied from 10 kPa to almost 100 kPa. To evaluate the potential for medical applications, the cytotoxicity of extracts and the contact toxicity toward murine fibroblasts are measured. The hydrogels with the crosslinker containing a shorter aliphatic exhibit low toxicity toward fibroblast cells. Moreover, the viability and the proliferation of pancreatic b-cells incubated inside hydrogels for 12 days are analyzed.

Poly(2‐oxazoline) Hydrogels: State‐of‐the‐Art and Emerging Applications

“…Following gelation, the ethanol was exchanged to water and toxicity determined on extracts and in direct contact with 3T3 fibroblasts. The extracts were found to be toxic in high concentrations but in all cases direct contact toxicity was low, and similarly to the previous work by the same group, [69] the more hydrophobic the cross-linker the lower the swelling. The softness of the hydrogels was also measured using a small-probe indentation method revealing relatively low moduli in between 6.3 and 128 kPa for the most and least swollen hydrogels, respectively.…”

“…In a demonstration of the versatility of the polymerization-gelation method, Kronek and co-workers synthesized a series of hydrogels from EtOx and a homologous series of [64] www.advancedsciencenews.com www.mbs-journal.de three bis(2-oxazoline) cross-linkers, with butyl, hexyl, or octyl spacers between the 2-oxazoline rings and methyl-4-nitrobenzenesulfonate as an initiator with a polymerization temperature of 110 °C for 5 h. [69] As expected, an inverse relationship between the swelling of the hydrogels in water and the length of the alkyl spacers in the bis(2-oxazoline) cross-linkers was observed. The moduli of the hydrogels increased with increasing cross-linker content and spacer length, attributed to a lower proportion of intrachain cross-linking for longer spacers.…”

Chain and Step Growth Polymerizations of Cyclic Imino Ethers: From Poly(2‐oxazoline)s to Poly(ester amide)s

“…This approach has been applied if the respective nitrile was not available but the desired functional groups permit the use of strong bases, such as in the case of 2‐(3‐ethylheptyl)‐2‐oxazoline (EHOx), 2‐(but‐4‐enyl)‐2‐oxazoline (ButEnOx) and 2‐(3‐(1,3‐dioxolan‐2‐ylpropyl)‐2‐oxazoline (DPOx) . Using these three approaches a large number of functional CIEs and also bis(2‐oxazoline)s and bis(2‐oxazine)s, which contain two Ox/Oz covalently connected to an aromatic or aliphatic spacer, have been obtained.…”

Investigation of the swelling behavior of hydrogels derived from high‐molecular‐weight poly(2‐ethyl‐2‐oxazoline)

“…However, POx‐based hydrogels have been found to show no sharp phase transition, but to transit from a highly to a lowly swollen state due to a change of the swelling–deswelling rate d S /d T over a broad temperature range . Such POx‐hydrogels are prepared by end‐group linking, simultaneous copolymerization of a monomer with a multifunctional cross‐linker, or only using a radical starter and a multifunctional cross‐linker …”

“…[31,[46][47][48][50][51][52] However, POxbased hydrogels have been found to show no sharp phase transition, but to transit from a highly to a lowly swollen state due to a change of the swelling-deswelling rate dS/ dT over a broad temperature range. [46,48,53] Such POxhydrogels are prepared by end-group linking, [48,[54][55][56] simultaneous copolymerization of a monomer with a multifunctional cross-linker, [57][58][59][60][61][62][63] or only using a radical starter and a multifunctional cross-linker. [8] Goal of this study was to find out if this broad transition stems from the inherent properties of the linear polymer used for hydrogel synthesis or if this is due to the used cross-linking approach.…”