Abstract
Thermo-responsive polymers have been used in biomaterial applications. However, polymers used in the applications were lower critical solution temperature type polymers, because polymers showing upper critical solution temperature (UCST) type behavior were very rare. We found that ureido polymers showed the UCST-type phase separation behavior under physiological pH and salt conditions. Furthermore, phase separation temperatures (Tp) could be controlled from 5 to 65°C by changing the molecular weight and ureido contents. UCST-type ureido copolymers are suitable media for simple and rapid bioseparations because thermal denaturation and damage to biocomponents can be minimized. Ureido polymers having ionic groups electrostatically interacted with proteins, and then the captured proteins were quickly separated without significant damage by chilling and spinning. Interestingly, cells in monolayer culture were converted to spheroids by the addition of ureido polymers below Tp. By increasing the culture temperature above Tp, the spheroids began to collapse into a monolayer of cells. These results indicated that cell morphology could be reversibly switched by changing the culture temperature in the presence of ureido polymers.
