Capacity affinity sensor
First Claim
1. A capacity affinity sensor for determining the presence of and/or the quantity of a compound of interest in a liquid sample, comprising:
- a noble metal surface; and
a first immobilized and electrically insulating layer having a first measurable capacitance, wherein the first immobilized and electrically insulating layer comprises a first self-assembled monolayer-forming compound having coupled thereto an affinity compound, and a second self-assembled monolayer-forming compound, the noble metal surface being at least 99% covered with the first immobilized and electrically insulating layer;
wherein the affinity compound, upon contact with the liquid sample, is capable of specifically binding the compound of interest so as to form a second immobilized and electrically insulating layer having a second measurable capacitance.
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Abstract
This invention describes a capacity affinity sensor based on self-assembled monolayers on an electrode with immobilized recognition elements available to analyte in the surrounding solution. Additional insulation is provided by auxiliary self-assembled molecules. The sensor has exceptional sensitivity and wide operating range due to these parts of the invention. It is versatile because different kinds of recognition elements can be immobilized directly on the surface of the measuring electrode. The electrode then becomes selective to those molecules in the solution, the analytes, that show affinity to the recognition element on the surface. Compared to capacitive sensors described before those described here shows at least a 1000-fold better sensitivity because of the properties of the layer binding the recognition element.
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Citations
18 Claims
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1. A capacity affinity sensor for determining the presence of and/or the quantity of a compound of interest in a liquid sample, comprising:
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a noble metal surface; and
a first immobilized and electrically insulating layer having a first measurable capacitance, wherein the first immobilized and electrically insulating layer comprises a first self-assembled monolayer-forming compound having coupled thereto an affinity compound, and a second self-assembled monolayer-forming compound, the noble metal surface being at least 99% covered with the first immobilized and electrically insulating layer;
wherein the affinity compound, upon contact with the liquid sample, is capable of specifically binding the compound of interest so as to form a second immobilized and electrically insulating layer having a second measurable capacitance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
(a) contacting the sensor of claim 1 with a reference liquid not containing the compound of interest and determining the capacitance of the sensor;
(b) contacting the sensor with a sample suspected of containing the compound of interest so as to bind the compound of interest and determining the capacitance of the sensor having the compound of interest bound thereto; and
(c) calculating the difference between the capacitance measured in step (a) and the capacitance measured in step (b) and optionally calculating the amount of the compound of interest by using prerecorded calibration data.
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15. The method of claim 14 wherein the compound of interest is human chorionic gonadotropin hormone (HCG), interleukin-2, human serum albumin, atrazine, or a DNA sequence.
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16. A capacity affinity sensor for determining the presence of and/or the quantity of a compound of interest in a liquid sample, comprising:
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a noble metal surface; and
a first immobilized and electrically insulating layer having a first measurable capacitance, wherein the first immobilized and electrically insulating layer comprises a first self-assembled monolayer-forming compound and a second self-assembled monolayer-forming compound, the noble metal surface being at least 99% covered with the first immobilized and electrically insulating layer;
wherein upon contact with the liquid sample, the first self-assembled monolayer-forming compound is capable of specifically binding the compound of interest so as to form a second immobilized and electrically insulating layer having a second measurable capacitance. - View Dependent Claims (17, 18)
(a) contacting the sensor of claim 16 with a reference liquid not containing the compound of interest and determining the capacitance of the sensor;
(b) contacting the sensor with a sample suspected of containing the compound of interest so as to bind the compound of interest and determining the capacitance of the sensor having the compound of interest bound thereto; and
(c) calculating the difference between the capacitance measured in step (a) and the capacitance measured in step (b) and optionally calculating the amount of the compound of interest by using prerecorded calibration data.
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18. The method according to claim 17 wherein the compound of interest is human chorionic gonadotropin hormone (HCG), interleukin-2, human serum albumin, atrazine, or a DNA sequence.
Specification