Poly(epsilon-caprolactone)/poly(N-isopropylacrylamide) (PCL/PNIPAM) core-shell particles are obtained by localizing the polymerization of NIPAM and crosslinker methylene bisacrylamide around the surface of PCL nanoparticles. The resultant particles are converted to hollow PNIPAM spheres by simply degrading the PCL core with an enzyme. The hollow spheres are thermosensitive and display a reversible swelling and de-swelling at similar to 32 degrees C.