Researchers at the University of New Mexico and Albuquerque company Senior Scientific are testing a new breed of iron oxide-based magnetic nanoparticles that are encased in a biocompatible coating. The coating is "conjugated" with antibodies that can recognise specific cancer cells. This causes the nanoparticles to stick to the cancer cells, magnetising them. Then, during a biopsy procedure, a magnetic field can be applied to the needle, pulling the magnetic cancer cells onto the needle. Tests in the dish showed that large numbers of cells could be picked up in this way in just a few minutes. The technique may help to reduce the rate of false negative biopsies where samples fail to pick up rare cancer cells in some patients. The researchers suggest that it may prove helpful in leukaemias, breast, prostate and ovarian tumours. Other doctors commenting on the approach has also suggested that it might help to pick up signs of "silent" cancer spread into an organ previously believed to be free of disease.