A receptor-based bioassay for quantitative detection of gallium

The detection of gallium in biological samples is required due to its role in the diagnosis of tumor and for possible treatment of malignancies. Howev er, the use of purely instrumental techniques is unsuitable for detection o f low levels of gallium in biological matrixes. We have synthesized new pro tein conjugates based on 4-(2-pyridylazo) Ligands. The conjugates were succ essfully employed for the detection of gallium in biological matrixes using a nonantibody-based sandwich assay format. The recovery level obtained was between 97 and 101.3 with a relative standard deviation of less than 5%. T he assay resulted in a detection limit of 5 x 10(-8) M and a remarkable sel ectivity for gallium(III) relative to other metals investigated. The new me thod provided adequate accuracy for gallium applicable for animal physiolog y and clinical toxicology.