Smart Polymers in Medicine: Advancing Therapies and Understanding Diseases

• Biomedical Applications
• Polymeric Materials
• Research Center for Macromolecules and Biomaterials
• Shape-Memory Materials

Smart polymers can be deformed by applying force, retaining the new shape until exposed to external stimuli, such as heat or light, which trigger a return to their original form. While medical applications for these materials are progressing, challenges remain, particularly in optimizing shape recovery at lower temperatures. Koichiro Uto has developed techniques to control smart polymers at temperatures close to human body temperature, thereby expanding their potential for medical use.

Achieving sharp polymer responses at low temperatures

Smart polymers can transition between crystalline and amorphous states in response to external stimuli such as heat, light, or magnetic fields, enabling various deformations. Due to crosslinks between their molecules, they maintain stability even in the amorphous state, preserving and retaining their permanent shape memory.

Uto focuses on temperature-responsive smart polymers for medical applications. Among these materials, he frequently utilizes poly(ε-caprolactone) (PCL), which has a relatively low melting temperature of 60℃— the temperature at which it transitions from a crystalline to an amorphous state.

“I chose PCL for its low melting temperature,” Uto said. “However, 60°C is still much higher than body temperature, so it needed to be lowered. Another reason for selecting PCL is its biodegradability, which makes it environmentally friendly.”

Uto precisely controlled the PCL synthesis process, creating PCLs with varying numbers of branches and arm/chain lengths. By evaluating these materials, he identified a PCL that responds to lower temperatures. He can now fine-tune the melting temperatures of PCLs with a precision of approximately 1°C, within a range of 30°C to 43°C. Smart polymers with such precise low-temperature responsiveness are exceptionally rare worldwide.