The rich chemistry of poly(2-alkyl-2-oxazoline)s (commonly abbreviated as PAOx, POx or POZ) allows tailoring the properties of these biocompatible materials and offers a great degree of freedom to explore multiple conjugation chemistries with potential applications in drug delivery or as biomaterials. Thiol and aldehyde groups represent some of the most important functional handles for bioconjugation, playing a key role in the covalent conjugation of PAOx with (bio)molecules but also surfaces and nanoparticles. In the present contribution, a straightforward strategy was applied to synthesize thiol functionalized poly(2-oxazoline)s by using potassium ethyl xanthogenate as a terminating agent on the living polymer. The free thiol group was obtained by dialysis of the polymer solution in hydrazine/H2O, which allows the deprotection of the xanthate group and avoids oxidation of the free thiol group. The quantification of free thiols is performed via Ellman’s methodology, which is very useful as a sulfhydryl assay reagent due to its specificity for -SH groups at neutral pH, high molar extinction coefficient and short reaction time. On the other hand, the synthesis of aldehyde groups at the α chain end was carried out by using 2-(2-bromoethyl)-1,3-dioxolane as the initiator. The free aldehyde polymer can be obtained by dialysis of the corresponding 1,3-dioxolane-PAOx in an aqueous solution of trifluoroacetic acid (TFA). The aldehyde-functional polymer was treated with benzophenone hydrazine in order to quantify end-group fidelity by ultraviolet-visible spectroscopy (UV-Vis).

Synthesis and characterization of thiol and aldehyde functionalized poly(2-oxazoline)s

2019 Spring National Meeting

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