Biotin-conjugated polychelating agent.

A procedure is described for preparing a polychelating agent-biotin conjugate through the interaction of biotin-maleimide with poly-L-lysine modified with multiple residues of diethylenetriaminepentaacetic acid and containing amino-terminal pyridylthio-propionate group. The conjugate can be easily loaded with multiple metal atoms, such as 111In, and preserves its ability to specifically interact with avidin (as avidin-agarose). Polychelate-biotin conjugate may be used for signal amplification in visualization and analytical protocols involving the application of the avidin-biotin system.