Single Chain Core-Shell Nanostructure

A combination of static and dynamic laser light scattering has revealed that at temperatures higher than ~33^∘C a linear poly(N-isopropylacrylamide) chain grafted with poly(ethylene oxide) (PNIPAM-g-PEO) in water can undergo a ``coil-to-globule'' transition to form a stable single chain core-shell nanostructure with the collapsed PNIPAM chain backbone as the hydrophobic core and the grafted PEO branches as the hydrophilic shell. It was also found that there still exists ~75% of water in the collapsed hydrophobic core which might be useful for biomedical applications because the core-shell nanostructure can be easily switched on and off by a simple temperature variation of 1--2 ^∘{}C.