Electrochemical immunoassays using colloidal metal markers

Abstract

The invention concerns a method for detecting or quantifying a biological substance coupled with a colloidal metal particle by electrochemical detection, characterized in that it comprises a step which consists in dissolving by chemical treatment of said colloidal metal particle, prior to detection.

1 . A diagnostic kit, comprising at least one reagent labeled with colloidal metal particles and at least one electrode, and also an agent for chemically dissolving said colloidal metal particles.  
   
   
       2 . The kit according to  claim 1 , further comprising a reagent capable of complexing the metal ions.  
   
   
       3 . The kit according to  claim 1 , further including instructions for the electrochemical detection or quantification of a biological substance using said kit.  
   
   
       4 . The kit according to  claim 1 , wherein the agent for dissolving said colloidal metal particles is an acidic medium containing an oxidant.  
   
   
       5 . The kit according to  claim 2 , wherein the reagent capable of complexing the metal ions is in solution.  
   
   
       6 . The kit as claimed in  claim 1 , wherein the colloidal particles are selected from the group consisting of particles comprising metal and metal compounds.  
   
   
       7 . The kit as claimed in  claim 6 , wherein the colloidal particles are gold.  
   
   
       8 . The kit as claimed in  claim 1 , wherein the colloidal particles are each between 1 and 200 nm in size.  
   
   
       9 . The kit as claimed in  claim 4 , wherein the acidic medium containing an oxidant is a solution of hydrobromic acid containing bromine, hypobromous acid or a mixture of these two compounds.  
   
   
       10 . The kit as claimed in  claim 1 , wherein the electrode is a screen-printed electrode.