SPP1 and prostate cancer: More recently, Lerner et al. utilised a carbon nanotube to design an immunoassay for the detection of osteopontin (OPN), a disease marker for prostate cancer.146 The group attached an anti-OPN ScFv to a carbon nanotube and were able to detect OPN in serum samples at concentrations as low as 1 pg mL–1, a detection limit three orders of magnitude lower than commercial ELISA assays against the same marker.