DNAzymes are oligonucleotides capable of specific catalysis of target mRNA. To date, a delivery vehicle for DNAzymes has not been developed. Chitosan is a biomaterial obtained abundantly in nature. A biocompatible c-jun (an oncogene) DNAzyme nanoparticle formulated from chitosan was found to be more active against osteosarcoma (bone cancer) cells, inducing apoptotic cell death in these cells. The formulation was stable in serum for a week and at room temperature for a month. Clinically, knockdown of c-jun gene expression with chitosan nanobiotechnology may improve treatment outcome for tumours growing in bone.