A coacervate-forming biodegradable polyester with elevated LCST based on bis-(2-methoxyethyl)amine?

Polymer Chemistry Pub Date: 2016-06-01 DOI: 10.1039/C6PY00814C

Abstract

Recently, we reported a new class of biodegradable, thermoresponsive polyesters (TR-PEs) inspired by polyacrylamides and elastin-like peptides (ELPs). The polyesters exhibit tunable cloud point temperatures (Tcp) and thermoresponsive coacervation in aqueous solution as shown via UV-vis spectroscopy, 1H NMR, and DLS. However, the Tcp of all TR-PEs remained low (<15 °C), and higher thermoresponsivity would be beneficial for many applications. This study examines the synthesis, polymerization, and analysis of a new monomer bearing a more hydrophilic pendant group, bis-2-methoxyethylamine (bMoEtA). The resulting TR-PE, TR-bMoEtAPE, displays a threefold increase in Tcp (ca. 50 °C) that is affected by solution (DI water vs. phosphate buffered saline), concentration (1–40 mg mL?1) molecular weight (20–130 kDa), and cosolutes (Hofmeister salts and urea). The Tcp and Tg of random TR-bMoEtAPE copolymers can be tuned via comonomer feed. Variable temperature 1H NMR indicated a cooperative coacervation mechanism above Tcp, further reinforced by DLS measurements. As evidenced by UV-vis and SEC analysis, TR-bMoEtAPE underwent rapid degradation over a period of 7 days in DI water and PBS. Finally, cytotoxicity studies suggested that TR-bMoEtAPE is non-cytotoxic even at high concentrations (ca. 1000 μg mL?1). The increased Tcp and tunability suggests TR-bMoEtAPE as a potential candidate for future functionalized TR-PE therapeutic-delivery systems.

Graphical abstract: A coacervate-forming biodegradable polyester with elevated LCST based on bis-(2-methoxyethyl)amine
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