Patent ID: 7045364

Claim:
A method for the electrochemical detection or quantification of a biological substance originally coupled to colloidal metal particles, said method comprising: (1a) coupling a biological substance to colloidal metal particles and contacting a solid phase with a solution of the coupled material to capture the colloidal metal particles from the coupled material onto the solid phase; or (1b) capturing a biological substance onto a solid phase and adding colloidal metal particles, in solution, to couple with said biological substance and to capture the colloidal metal particles from the coupled material onto the solid phase; (2) washing the colloidal particles captured onto the solid phase; (3) dissolving said colloidal metal particles in a solution of a reagent able to dissolve said metal particles, to afford a solution of the metal in ionic state; (4) contacting the resultant solution with an electrode and electrodepositing the metal thereon by reduction and/or precipitation; and (5) detecting or quantifying the amount of metal deposited on said electrode to determine therefrom the amount of biological substance originally coupled to the colloidal metal particles.