Morphology-controlled hollow nanospheres of functionalized dextran by self-assembly in aqueous solution

Dextran propionate tryptophanate ester (DPT) was synthesized by two-step esterification to self-assemble into regular hollow nanospheres during a dialysis process. Hollow nanospheres self-assembled in the dimethylacetamide (DMAc) exchange against polymer solution, with a size in the range of 80–500 nm outside diameter and 15–110 nm shell thickness. The organic solvent had a great influence on the morphology and the size of these nanospheres. No hollow nanospheres but only nanoparticles with no cavum could self-assemble in furfuryl alcohol with the range of 57–257 nm, in DMSO with the range of 61–292 nm, in N-methyl-2-pyrrolidone with the range of 82–348 nm and in DMF with the range of 262–670 nm. The stability of these hollow nanospheres was also influenced by storage time. They were relatively stable in 2 months in deionized water stored at 25 °C or 37 °C, which can be verified by SEM and pH value variation.