Biotin-conjugated polychelating agent

A procedure is described for preparing a polychelating agent-biotin conjuga te 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 l oaded with multiple metal atoms, such as In-111, and preserves its ability to specifically interact with avidin (as avidin-agarose). Polychelate-bioti n conjugate may be used for signal amplification in visualization and analy tical protocols involving the application of the avidin-biotin system.