Water-soluble and surface charge-tunable amine-functionalized polyhydroxylated fullerene nanoparticles with a strong green emission were synthesized by grinding and hydrothermal treatment. The quantum yield of the nanoparticles was as high as 17%, which is the highest value recorded for fluorescent fullerene materials. The amine-functionalized polyhydroxylated fullerene nanoparticles with high surface charge were found to easily penetrate into breast cancer cells, HeLa cells and cardiac progenitor stem cells, opening up great opportunities for their bio-medical applications. (C) 2016 Elsevier Ltd. All rights reserved.