On page 1813 Chuanbin Mao, Shengmin Zhang, and co-workers show that selenite-doped bone mineral nanoparticles can retard the growth of osteosarcoma, inhibit tumor metastasis and improve the functions of liver, kidney and heart in a nude mice model, which is achieved through sustained release of selenite ions from the nanoparticles via a degradation-mediated fashion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.