Method for Identifying and Quantifying Organic and Biochemical Substances
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Abstract
The invention relates to a method for identifying organic or biochemical substances and for determining their concentration in a fluid medium using a nanogap sensor that comprises at least two electrodes. The invention is characterized in that: a nanogap sensor) with electrodes of different materials is used, a respective probe molecule is bonded to each surface of the two electrodes of the sensor and the free remainder of the probe molecules have at least one bondable group with specificity for bonding to a sought substance or to an analyte molecule in the fluid medium. The analyte molecule has at least two binding sites and passes selectively out of the fluid medium in which it is contained, binds to the free ends of the probe molecules, forming a bridge with the probe molecule, and modifies the resulting impedance between the electrodes. The concentration of the substance in the fluid medium can be determined as a result of the modification.
57 Citations
22 Claims
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1-10. -10. (canceled)
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11. A method for identifying organic and biochemical substances, said substances being molecules, molecule sequences, molecule parts or similar molecular substances, and for determining the quantity or concentration of said substances in a fluid, said fluid being a liquid or gaseous medium, wherein a nanogap sensor having at least two electrodes is used for said identifying method, said method comprising:
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a) providing a nanogap sensor, said sensor has at least two electrodes separated from one another by an electrically isolating layer or by a non-material gap, said electrodes being formed of materials being different from one another, said electrodes are electrically conductive and/or principally semi-conductive, wherein said conductivity is a relatively high conductivity with regard to conductivity of a semiconductor; b) providing on a surface of a first electrode of said sensor, a first affinity or probe molecule, said first affinity molecule is oriented in at least partial longitudinal orientation in relation to said first electrode, said first affinity molecule has a sensor-binding area wherein said sensor-binding area is specifically or individually, respectively, sensor-bound to the material of said first electrode at one of its ends or in the proximity of one of its ends, and said sensor binding area is immobilized on said first electrode, wherein a free residue of said first affinity molecule has at least one free binding or bondable group, molecule sequences or similar structure providing suitable affinity binding sites which have at least one certain specificity for bonding to a sought substance, said sought substance being an analyte, analyte molecule or auxiliary molecule; C) providing on the surface of said second electrode of said nanogap sensor, a second affinity or probe molecule said second affinity molecule is oriented in at least partial longitudinal orientation in relation to said second electrode wherein said second affinity molecule orientation differs in relation to said first affinity or probe molecule orientation, said second affinity molecule having a binding area that is specifically or individually sensor-bound to the material of said second electrode, the material of said second electrode differs from the material of said first electrode said binding area being at or in proximity to one end of said second electrode, and said binding area being immobilized on said second electrode, wherein said second probe molecule has a free residue and an affinity binding site having at least one free binding or bondable group, molecule sequences or similar structure having at least certain specificity for bonding to a sought substance said sought substance being an analyte, analyte molecule, or auxiliary molecule; d) providing a fluid medium) to be checked by said method, said fluid medium having various molecules, molecule sections, molecule parts, molecule sequences, or combinations thereof flowing around each of said electrodes and said gap, there between, said fluid medium having an analyte molecule or auxiliary molecule to be detected in its quantity and/or concentration, said analyte molecule or auxiliary molecule is formed by a known molecule, known molecule section, or known molecule part, known molecule sequence having any shape, said electrodes having at least two binding sites at a distance from one another for said sensor-bound, immobilized probe molecules or for mobile free ends having free affinity binding sites; e) selectively passing said fluid medium to be analyzed between said electrodes, wherein said electrodes have exposed binding sites arranged at exposed points, at said binding sites on ends or in proximity to ends of said electrodes; f) forming a bond with specific binding or bondable groups, molecule sequences or combinations thereof with binding or bondable, groups, molecule sequences representing affinity binding sites respectively, at free mobile ends of said first and second affinity or probe molecules wherein each of said first and second probe molecules have specifically sensor-bound sites attached to said electrodes, each of said electrodes being formed of different materials, g) forming a bridge molecule or bridge whereby said two electrodes of different materials are connected with one another, whereby said connection is by said probe molecules and said analyte molecule or auxiliary molecule respectively bridging said isolator layer or gap between said two electrodes of different materials; h) alternatively, containing an auxiliary molecule in an existing bridge, binding said auxiliary molecule to said two probe molecules whereby said binding is by sensor-bound binding with sensor binding sites on said electrodes whereby said auxiliary molecule is separated from at least one of said probe molecules and bound to said electrodes by the interaction of an analyte molecule contained in said fluid medium said analyte molecule being capable of binding to at least one binding site of said auxiliary molecule with a resultant bond being stronger than at least one of said binding groups between said auxiliary molecule and at least one of said two probe molecules; i) dissolving a previously existing bridge, and j) detecting modification or change of impedance or of a frequency spectrum of an alternating current applied to said two electrodes, occurring during the bridge formation or the bridge dissolution process, the presence, the quantity or concentration of the sought molecule is determined, wherein in case of a bridge formation, the absence of the sought analyte molecule at the electrodes is present before bridge molecule formation and the presence of said sought analyte molecule at the electrodes present following the bridge formation;
or in bridge dissolution, a selective connection of said analyte molecule to at least one component of a bridge pre-manufactured using an auxiliary molecule resulting in said modification of said analyte molecule having a direct or indirect connection with said sensor surface or dissolving said connection following a reaction. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification