A new type of monodispersed mesoporous silica nanoparticles with a core-cone structure (MSN-CC) has been synthesized. The large cone-shaped pores are formed by silica lamellae closely packed encircling a spherical core, showing a structure similar to the flower dahlia. MSN-CC has a large pore size of 45 nm and a high pore volume of 2.59 cm(3) g(-1) . MSN-CC demonstrates a high loading capacity of large proteins and successfully delivers active β-galactosidase into cells, showing their potential as efficient nanocarriers for the cellular delivery of proteins with large molecular weights.