Ureido-Derivatized Polymers Based on Both Poly(allylurea) and Poly(l-citrulline) Exhibit UCST-Type Phase Transition Behavior under Physiologically Relevant Conditions

• Published in: Biomacromolecules Vol. 12; no. 10; pp. 3418 - 3422
• Main Authors: Shimada, Naohiko, Ino, Haruka, Maie, Kenji, Nakayama, Miki, Kano, Arihiro, Maruyama, Atsushi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 10.10.2011
• Subjects: Aminoacid polymers; Applied sciences; Biocompatible Materials - analysis; Biocompatible Materials - chemical synthesis; Biotechnology - methods; Citrulline - chemistry; Exact sciences and technology; Hydrogen-Ion Concentration; Organic polymers; Phase Transition; Physicochemistry of polymers; Polymers - analysis; Polymers - chemical synthesis; Properties and characterization; Sodium Chloride - chemistry; Solution and gel properties; Solutions; Synthetic biopolymers; Transition Temperature; Urea - analogs & derivatives; Urea - analysis; Urea - chemical synthesis; Water; Cloud point; Salt effect; Ionic strength; Aminoacid copolymer; pH; Allylic derivative copolymer; Aqueous solution; Experimental study; Saline solution; Amine copolymer
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm2010752

There are few examples of polymers that exhibit upper critical solution temperature (UCST) behavior under physiological conditions of temperature, pH, and ionic strength. In this study, we demonstrated that polymers with ureido groups undergo UCST-type phase transitions under physiologically relevant conditions. Poly­(allylurea) copolymers showed UCST behavior at pH 7.5 in 150 mM NaCl even at the low polymer concentration of 0.13 mg/mL. Their phase separation temperatures (T p) could be controlled up to 65 °C. Similar thermosensitivity was observed with copolypeptides consisting of l-citrulline having an ureido group. This is the first demonstration of a non-vinyl polymer that shows UCST behavior under physiologically relevant conditions. We suggest that the ureido modification will be useful for production of polymer materials with UCST behavior in aqueous media.