METHOD FOR DETECTION OF A PCR PRODUCT

1 . A method for detecting a target nucleic acid molecule in a sample with a sensor comprising a first electrode and a second electrode coupled to a sensor surface in a spaced apart arrangement and a plurality of capture probes coupled to the sensor surface between the first electrode and the second electrode, the method comprising:

performing nucleic acid molecule amplification via polymerase chain reaction (PCR) using a first primer having a 5′-tail and a second primer having no 5′-tail to form a plurality of double-stranded amplicons having a first strand with a 5′-tail and a second strand with no tail;

hybridizing the plurality of amplicons to the plurality of capture probes;

converting the plurality of amplicons to a plurality of single strand molecules;

binding a catalyst cluster to an interior section of each of the plurality of single strand molecules;

contacting the plurality of single strand molecules having a catalyst cluster bound thereon with a metal or metal alloy to deposit the metal or metal alloy on the catalyst cluster; and

determining if an electrical current can be carried between the electrodes, the electrical current between the electrodes indicating presence of the target nucleic acid molecule in the sample.

2 . The method of claim 1 , wherein converting the plurality of amplicons to the plurality of single strand molecules comprises employing an exonuclease to digest the second strand with no tail.

3 . The method of claim 1 , wherein the catalyst cluster comprises a catalyst gold cluster and wherein the metal comprises gold.

4 . The method of claim 1 , further comprising forming a target specific catalyst cluster configured to bind to an interior region of the first strand of the amplicon.

5 . The method of claim 1 , wherein the catalyst cluster is a generic cluster having an adaptor oligonucleotide coupled thereto.

6 . The method of claim 5 , wherein the generic cluster has a plurality of oligonucleotides coupled thereto, each oligonucleotide configured to target a different amplicon.

7 . The method of claim 1 , wherein binding the catalyst cluster comprises binding a plurality of catalyst clusters to interior sections of each of the single strand molecules.

8 . A method for preparing a nucleic acid molecule detector comprising a first electrode and a second electrode coupled to a sensor surface in a spaced apart arrangement and a plurality of capture probes coupled to the sensor surface between the first electrode and the second electrode, the method comprising:

receiving a biological sample;

amplifying a nucleic acid molecule within the biological sample to generate an amplicon having a single 5′-tail;

coupling the 5′-tail of the amplicon to one of the plurality of capture probes;

employing an exonuclease to digest one strand of the amplicon to convert the amplicon to a single strand molecule;

synthesizing a target-specific catalyst cluster; and

contacting the catalyst cluster with the single strand molecule of the amplicon to bind the target-specific catalyst cluster to an interior region of the single strand molecule.

9 . The method of claim 8 , wherein the catalyst cluster comprises a catalyst gold cluster.

10 . The method of claim 8 , wherein synthesizing the target-specific catalyst cluster comprises hybridizing a base generic cluster with an adaptor oligonucleotide to form a catalyst cluster having a plurality of adaptor oligonucleotides coupled thereto.

11 . The method of claim 10 , wherein the adaptor oligonucleotide has a cluster binding sequence and an amplicon-specific binding sequence.

12 . The method of claim 10 , wherein hybridizing the base generic cluster comprises hybridizing the generic cluster with a plurality of adaptor oligonucleotides, each adaptor oligonucleotide configured to target a different amplicon.

13 . The method of claim 8 , wherein amplifying the nucleic acid molecule comprises performing polymerase chain reaction (PCR) using a first primer having a 5′-tail and a second primer having no 5′-tail.

14 . The method of claim 8 , wherein each of the plurality of capture probes comprises a functionalized oxide surface configured to immobilize molecules to the sensor surface.