Detection of purine and pyrimidine nucleotides and underivatized nucleic acids by sinusoidal voltammetry
First Claim
1. A method for detecting nucleotides and nucleic acid polymers in a sample comprising the steps of:
- contacting a surface of an electrocatalytic metal electrode with the sample dissolved in a high pH aqueous buffer;
applying a sinusoidal voltage having an amplitude and a fundamental frequency to the electrode, the amplitude being sufficient to elicit a redox reaction of at least one form of nucleotides and nucleic acid polymers in contact with the electrode;
measuring a current at the electrode, the current resulting from the elicited redox reaction;
producing a frequency spectrum of the measured current; and
detecting the nucleotides and nucleic acid polymers by reference to a harmonic of the frequency spectrum greater than the fundamental frequency.
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Abstract
Sinusoidal voltammetry was employed to detect both purine and pyrimidine-based nucleic acids. Adenine and cytosine, representing these two classes of nucleic acids, could be detected with nanomolar detection limits at a copper electrode under these conditions, where the sensitivity for adenine was much higher than that for cytosine. Detection limits for purine-containing nucleotides (e.g., adenosine 5'"'"'-monophosphate (AMP), adenosine 5'"'"'-diphosphate (ADP), and adenosine 5'"'"'-triphosphate (ATP)) were on the order of 70-200 nM using this method. These detection limits are achieved for native nucleotides and are over two orders of magnitude lower than those found with UV absorbance detection. Pyrimidine-based nucleotides could also be detected with high sensitivity due to the presence of a sugar backbone which is electroactive at the copper surface. This detector is not fouled by the nucleotides and can be used for the sensitive detection of analyses eluting continuously from a chromatography column or a electrophoresis capillary. Entire nucleic acid molecules can be readily detected. For example, both single stranded and double stranded DNA is detected with a detection limit in the picomolar concentration range (i.e., 10-12 moles/L). In the present invention, the signal from a double stranded DNA is roughly twice that arising from a single stranded DNA strand of the same length.
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Citations
24 Claims
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1. A method for detecting nucleotides and nucleic acid polymers in a sample comprising the steps of:
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contacting a surface of an electrocatalytic metal electrode with the sample dissolved in a high pH aqueous buffer; applying a sinusoidal voltage having an amplitude and a fundamental frequency to the electrode, the amplitude being sufficient to elicit a redox reaction of at least one form of nucleotides and nucleic acid polymers in contact with the electrode; measuring a current at the electrode, the current resulting from the elicited redox reaction; producing a frequency spectrum of the measured current; and detecting the nucleotides and nucleic acid polymers by reference to a harmonic of the frequency spectrum greater than the fundamental frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device for detecting nucleotides and nucleic acid polymers in a sample comprising:
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an electrocatalytic metal electrode; means for bringing a sample into contact with the electrode; means for applying a sinusoidal voltage having an amplitude and a fundamental frequency to the electrode, the amplitude being sufficient to elicit a redox reaction of at least one form of nucleotides and nucleic acid polymers at the electrode; means for measuring a current at the electrode, the current resulting from the elicited redox reaction; means for producing a frequency spectrum of the measured current; and means for analyzing signal at of least one harmonic of the frequency spectrum greater than the fundamental frequency to detect nucleotides and nucleic acid polymers. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for detecting nucleotides and nucleic acid polymers in a sample comprising the steps of:
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contacting a surface of a copper electrode with the sample dissolved in an aqueous buffer with a pH of more than 7.0; applying a sinusoidal voltage having an amplitude of from about 0.05 V to about 0.55 V, measured against a silver/silver chloride electrode, and a fundamental frequency of 2 Hz. to the copper electrode to elicit a redox reaction of at least one form of nucleotides and nucleic acid polymers at the copper electrode; measuring a current at the copper electrode, the current resulting from the elicited redox reaction; producing a frequency spectrum of the measured current; and detecting the nucleotides and nucleic acid polymers by reference to a harmonic of the frequency spectrum greater than the fundamental frequency. - View Dependent Claims (18, 19, 20)
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21. A device for detecting nucleotides and nucleic acid polymers in a sample comprising:
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a copper electrode; means for contacting the copper electrode with the sample dissolved in a high pH aqueous buffer; means for applying a sinusoidal voltage having an amplitude of from about 0.05 V to about 0.55 V, measured against a silver/silver chloride electrode, and a fundamental frequency of 2 Hz. to the copper electrode to elicit a redox reaction of nucleotides and nucleic acid polymers at the copper electrode; means for measuring a current at the copper electrode, the current resulting from the elicited redox reaction; means for producing a frequency spectrum of the measured current; and means for detecting the nucleotides and nucleic acid polymers by reference to a harmonic of the frequency spectrum greater than the fundamental frequency. - View Dependent Claims (22, 23, 24)
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Specification