Poly(2-oxazolines) with varying alkyl chain lengths (e.g., methyl, ethyl, aryl) and molar masses have been tested for cell cytotoxicity in vitro. A standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used for the estimation of cell viability. Two monomers, 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline, were found to provide polymers with non-cytotoxic properties. The dependence of cell viability on molar mass confirmed the expected trend; the viability increased with the higher molar mass of poly(2-ethyl-2-oxazoline) (PETOX), up to 15,000 g/mol. The results obtained for the polymers with aliphatic side chains were compared with the analogues that possessed an aromatic moiety. All results confirmed low cytotoxicity of the polymers prepared by cationic polymerization of 2-alkyl- and 2-aryl-2-oxazolines, which supports their utilization in biomedical applications. Fluorescence microscopy and steady-state fluorescence were used to observe pyrene-labeled polymer interactions with living cells. Polymer accumulated within the cells was found to be dependent on polymer concentration in media. The immunoefficiency of aromatic and aliphatic oxazoline polymers and copolymers was also studied. Phagocytic and metabolic activities of macrophages were used to assess the immunosuppressive effects of the selected copolymers for possible applications in drug delivery and immunobiology. Overall, the tested polymers demonstrated no significant influences on the cellular immunological parameters.

Poly(2-alkenyl-2-oxazoline)s are promising functional polymers for a variety of biomedical applications, such as drug delivery systems, peptide conjugates, or gene delivery. In this study, poly(2-isopropenyl-2-oxazoline) (PIPOx) is prepared through free-radical polymerization initiated with azobisisobutyronitrile. Reactive 2-oxazoline units in the side chain support an addition reaction with different compounds containing a carboxylic group, which facilitates the preparation of polymers labeled with two different fluorescent dyes. The cytotoxicities of 2-oxazoline monomers, PIPOx, and fluorescently labeled PIPOx are evaluated in vitro using an 3-(4,5-Dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and ex vivo using a cell proliferation assay with adenosine triphosphate bioluminescence. The cell uptake of labeled PIPOx is used to determine the colocalization of PIPOx with cell organelles that are part of the endocytic pathway. For the first time, it is shown that poly(2-isopropenyl-2-oxazoline) is a biocompatible material and is suitable for biomedical applications; further, its immunomodulative properties are evaluated.

Poly(2-oxazolines) represent promising polymer materials for biomedical applications. The activation of mouse lymphoid macrophage line P388.D1 (clone 3124) by two selected representatives of poly(2-oxazolines), namely poly(2-ethyl-2-oxazoline) (PETOX100) and poly[2-(4-aminophenyl)-2-oxazoline-co-2-ethyl-2-oxazoline] (AEOX10), was assessed in vitro. The immunomodulatory efficacy of both polymers was evaluated via the induced release of pro-inflammatory cytokines (TNF-α, IL-1α and IL-6) and the acceleration of reactive free radicals. The present study revealed effective structure-immunomodulating associations of AEOX10 and PETOX100, which are desirable in biomedical and pharmaceutical applications of aliphatic and aromatic poly (2-oxazolines) in vivo.