Detectable threading intercalator

Abstract

A threading intercalator of general formula I: IG 1 -DG-IG 2 -(DG-IG 3 ) n   (I) wherein IG 1 , IG 2 , and IG 3 are the same or different and represent an intercalating group comprising a planar polyaromatic group; wherein DG represents an electrochemical, a chemiluminescent, a catalytic or an electrochemiluminescent detectable group; and wherein n represents 0 or 1. This invention also relates to a process of detecting a double strand nucleic acid molecule using the threading intercalator.

1 . A threading intercalator of general formula I:
   IG 1 -DG-IG 2 -(DG-IG 3 ) n   (I)   wherein
 IG 1 , IG 2  and IG 3  are the same or different and each of IG 1 , IG 2  and IG 3  is an intercalating group that is a naphthalene imide derivative or a naphthalene diimide derivative, with at least one of IG 1 , IG 2  and IG 3  being a napthalene imide derivative having a structure of formula III: 
   
     
       
         
         
             
             
         
       
       
         R 1  is a group which is capable of forming a coordinative bond with the detectable group and has a structure of formula IV:
   —R 6 -AG  (IV) 
 wherein 
 R 6  is a branched or unbranched, saturated or unsaturated C 1 -C 10  alkylene; or a branched or unbranched, saturated or unsaturated C 1 -C 10  heteroalkylene having from 1 to 3 heteroatoms selected from the group consisting of N, O, S and P; and 
 AG is a saturated or unsaturated 5 to 10-membered heterocyclic group having from 1 to 3 heteroatoms selected from the groups consisting of N, O, S and P; 
 DG is a catalytic, electrochemical, a chemiluminescent or an electrochemiluminescent detectable group having a structure of formula II:
   -M[(L) n′ ]-  (II) 
 
 wherein 
 M represents a metal selected from the group consisting of Ru, Fe, Co, Cu and Os; 
 L is a coordinative binding ligand that is a C 5 -C 30  heterocyclic group comprising from 1 to 6 heteroatoms selected from the group consisting of N, O, S and P, optionally substituted by 1 to 6 groups independently selected from C 1 -C 6  alkyl, C 2 -C 6  alkene and halogen; and 
 n′ is an integer from 1 to 6; and 
 
         n is 0 or 1. 
       
     
   
   
       2 . The threading intercalator according to  claim 1 , wherein n is 0. 
   
   
       3 . The threading intercalator according to  claim 1 , wherein the detectable group is electrochemiluminescent. 
   
   
       4 . The threading intercalator according to  claim 1 , wherein the metal has an oxidation state of +2, +3 or +4. 
   
   
       5 . The threading intercalator according to  claim 1 , wherein the ligand is bipyridine, biimidazole, 1,10-phenanthroline or dipyridophenazine. 
   
   
       6 . The threading intercalator according to  claim 1 , wherein the ligand is bipyridine. 
   
   
       7 . The threading intercalator according to  claim 1 , wherein the detectable group is Ru(bipyridine) 2   2+ . 
   
   
       8 . The threading intercalator according to  claim 1 , wherein AG is pyridinyl, bipyridinyl, imidazolyl or biimidazolyl. 
   
   
       10 . A complex comprising a double stranded nucleic acid molecule and a threading intercalator as claimed in  claim 1 , wherein the threading intercalator is intercalated in said double stranded nucleic acid molecule. 
   
   
       11 . A process for detecting a single stranded nucleic acid molecule complementary to a nucleic acid probe immobilized onto an electrode substrate, which comprises the steps of:
 (a) contacting the probe molecules with an oligo- or poly-nucleotide sample in the presence of a threading intercalator as claimed in  claim 1  to form by hybridization a complex comprising a double stranded hybrid of the probe molecules and the complementary single stranded nucleic acid molecules in the oligo- or poly-nucleotide sample, in which hybrid is intercalated the threading intercalator;   (b) exciting the complex formed in step (a) by irradiating the complex with a light source or applying an electric current to the electrode; and   (c) detecting photoluminescence or a change in voltametric peak current caused by a detectable group comprised in the threading intercalator.   
   
   
       12 . A process for detecting a single stranded nucleic acid molecule complementary to a nucleic acid probe immobilized onto an electrode substrate, which comprises the steps of:
 (a) contacting the probe molecules with an oligo- or poly-nucleotide sample to form by hybridization a complex comprising a double stranded hybrid of the probe molecules and the complementary single stranded nucleic acid molecules in the oligo- or poly-nucleotide sample;   (b) contacting a threading intercalator as claimed in  claim 1  with the complex formed in step (a) so as to intercalate the threading intercalator into the complex formed in step (a);   (c) exciting the complex formed in step (b) by irradiating the complex with a light source or applying an electric current to the electrode; and   (d) detecting photoluminescence or a change in voltametric peak current caused by a detectable group comprised in the threading intercalator.   
   
   
       13 . A kit for detecting a single stranded nucleic acid molecule complementary to a nucleic acid probe, which comprises an electrode substrate on which is immobilized the nucleic acid probe, and a threading intercalator as claimed in  claim 1 .