Methods for electrochemical detection/quantification of a nucleic acid

A method of electrochemically detecting and/or quantifying a target nucleic acid molecule by means of a detection electrode, the method comprising:

• (a) providing a detection electrode;
• (b) immobilizing on said detection electrode a nucleic acid capture molecule, which has a nucleotide sequence that is at least partially complementary to at least a portion of the target nucleic acid molecule;
• (c) contacting the electrode with a solution expected to comprise the target nucleic acid molecule;
• (d) allowing the target nucleic acid molecule to hybridize to the nucleic acid capture molecule on the electrode, thereby allowing formation of a complex between said nucleic acid capture molecule and said target nucleic acid molecule;
• (e) adding a polymerisable positively chargeable precursor, wherein said polymerisable positively chargeable precursor has an electrostatic net charge that is complementary to the electrostatic net charge of the target nucleic acid molecule, such that (i) said polymerisable positively chargeable precursor associates with the complex formed between said nucleic acid capture molecule and said target nucleic acid molecule, and (ii) the polymerisation of said precursor can be carried out by means of a suitable enzyme and a substrate molecule;
• (f) adding a suitable substrate molecule;
• (g) adding an enzyme attached to a detection probe nucleic acid molecule, wherein said probe nucleic acid molecule is at least partially complementary to at least a portion of the target nucleic acid molecule, wherein the detection probe hybridizes to a portion of the target nucleic acid different from the portion to which the capture nucleic acid molecule hybridizes, thereby (i) allowing the detection probe nucleic acid molecule to hybridise to the target nucleic acid molecule, and (ii) catalysing the polymerisation of said polymerisable positively chargeable precursor, wherein an electro conductive polymer is formed from the polymerisable precursor and this electroconductive polymer is associated with the complex formed between the nucleic acid capture molecule and the target nucleic acid molecule;
• (h) performing an electrochemical measurement at the detection electrode, and;
• (i) detecting and/or quantifying the presence of the target nucleic acid molecule.

A kit for the electrochemical detection of a target nucleic acid molecule, said kit comprising

• (a) a detection electrode,
• (b) a PNA capture molecule, which has a nucleotide sequence that is at least partially complementary to at least a portion of the target nucleic acid molecule,
• (c) a polymerisable positively chargeable precursor, wherein the electrostatic net charge of said polymerisable positively chargeable precursor is complementary to the electrostatic net charge of the target nucleic acid molecule, and
• (d) a suitable reactant molecule.

A kit for the electrochemical detection of a target nucleic acid molecule, said kit comprising

• (a) a detection electrode,
• (b) a nucleic acid capture molecule, which has a nucleotide sequence that is at least partially complementary to at least a portion of the target nucleic acid molecule,
• (c) a polymerisable positively chargeable precursor, wherein the electrostatic net charge of said polymerisable positively chargeable precursor is complementary to the electrostatic net charge of the target nucleic acid molecule,
• (d) a substrate molecule, and
• (e) an enzyme attached to a probe nucleic acid molecule, wherein said probe nucleic acid molecule is at least partially complementary to at least a portion of the target nucleic acid molecule.