Synthesis and characterization of star-shaped oligo(ethylene glycol) with tyrosine derived moieties under variation of their molecular weight

Issue title: Special issue: Advanced Functional Polymers in Medicine (AFPM): Liège, Belgium, May 2014; Guest-Editors: Christine Jérôme and Andreas Lendlein

Article type: Research Article

Authors: Julich-Gruner, Konstanze K.^a | Roch, Toralf^a | Ma, Nan^{a; b} | Neffe, Axel T.^a | Lendlein, Andreas^{a; b; *}

Affiliations: ^aInstitute of Biomaterial Science and Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Teltow, Germany | ^bDepartment of Biology, Institute of Chemistry and Biochemistry, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany

Correspondence: [*] Corresponding author: Andreas Lendlein, Institute of Biomaterial Science and Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Helmholtz-Zentrum Geesthacht, Kantstrasse 55, 14513 Teltow, Germany. Tel.: +49 3328 352 450; Fax: +49 3328 352 452; andreas.lendlein@hzg.de

Abstract: Desamino tyrosine (DAT) and desamino tyrosyl tyrosine (DATT) can be used to functionalize the end groups of water soluble polymers. The phenolic groups may enable physical interactions by π– π interaction and hydrogen bonds, which might lead to the formation of a hydrogel by physical crosslinking. However, using star-shaped oligo(ethylene glycols) (sOEG) with a molecular weight of 5 kDa for functionalization with DAT or DATT resulted in the formation of surfactants and not in hydrogels. As the molecular weight of the sOEG polymer chain can have an influence on forming physical cross links, DAT(T)-fuctionalization of sOEGs with higher molecular weight was investigated, the polymers were structurally characterized and for their mechanical properties were evaluated by rheological measurements. Aqueous solutions of DAT(T)-sOEGs with 10 and 20 kDa showed lower storage and loss moduli compared to unfunctionalized sOEGs indicating also the formation of surfactants. Cell-based assays showed that all sOEG solutions did not impair cell viability and were free of endotoxins, which could otherwise induce uncontrolled immune responses. Conclusively, our data suggested that the sOEG solutions have surface active properties without inducing unwanted cellular responses, which is required e.g. in pharmaceutical applications to solubilize hydophobic substances.

Keywords: Oligo(ethylene glycol), star polymers, self-organization, surfactant, biocompatibility

DOI: 10.3233/CH-151938

Journal: Clinical Hemorheology and Microcirculation, vol. 60, no. 1, pp. 13-23, 2015