Nanoporous silica-based materials can be used to package drugs that are poorly water soluble. But production of these materials is expensive, so Delalat et al. used the diatom microalga Thalassiosira pseudonana to produce nanoporous biosilica on which is attached an immunoglobulin G (IgG)-binding domain of protein G. Thus, these molecules could be attached to antibodies that target certain tumour cells. Treatment of mice bearing neuroblastoma xenografts with drug-loaded, antibody-targeted biosilica nanoparticles induced tumour regression.