The subject matter disclosed herein relates to a detecting target molecules, such as nucleic acid molecules and, more particularly, to systems for electrical sensing of the target molecules.
Various methods have developed for analyzing biological samples and detecting the presence of target molecules, such as nucleic acid molecules. These methods can be used, for example, in detecting pathogens in samples.
Typically, detection methods use disruption techniques, such as Polymerase Chain Reaction (PCR) to extract and replicate nucleic acid molecules from a sample. PCR is a technique that allows for replicating and amplifying trace amounts of DNA fragments into quantities that are sufficient for analysis. As such, PCR can be used in a variety of applications, such as DNA sequencing and detecting DNA fragments in samples.
An electronic sensor for detection of specific target nucleic acid molecules can include capture probes immobilized on a sensor surface between a set of paired electrodes. An example of a system and method for detecting target nucleic acid molecules is described in U.S. Pat. No. 7,645,574, the entirety of which is herein incorporated by reference. Following PCR, amplified products or amplicons derived from targeted pathogen sequences are captured by the probes Nano-gold clusters, functionalized with a complementary sequence, are used for localized hybridization to the amplicons. Subsequently, using a short treatment with a gold developer reagent, the nano-gold clusters serve as catalytic nucleation sites for metallization, which cascades into the development of a fully conductive film. The presence of the gold film shorts the gap between the electrodes and is measured by a drop in resistance, allowing the presence of the captured amplification products to be measured. However, such sensors can be insensitive to small quantities of target molecules, resulting in false negative results or a failure to detect the target molecules.
A system for detection of a target molecule includes a source terminal, a drain terminal, a gate positioned between the source terminal and the drain terminal, and a functionalized sensor surface between the source terminal and the drain terminal. The sensor surface is configured to bind target molecules and the target molecules are configured to bind functionalized nanoparticles. A sensor is coupled to the source terminal and drain terminal to monitor changes in electrical signals and detect the target molecules when changes in the electrical signals are detected.
In an embodiment, a system for detecting a target molecule in a sample is disclosed. The system includes a source terminal, a drain terminal, a sensor coupled to the source terminal and the drain terminal. The sensor is configured to monitor electrical signals across the source terminal and drain terminal. A gate is positioned adjacent to one of the source terminal and the drain terminal and extends partially across a gap between the source terminal and drain terminal. A sensor surface is exposed between the gate and one of the source terminal and the drain terminal. The sensor surface is a functionalized sensor surface configured to bind the target molecule.
A sensor surface is positioned between the source terminal and the drain terminal. The sensor surface includes a functionalized sensor surface configured to bind the target molecule. A gate is positioned adjacent to one of the source terminal and the drain terminal and extends partially across the sensor surface.
In another embodiment, a system for detecting a target molecule in a sample is disclosed. The system includes a source terminal, a drain terminal, and a sensor coupled to the source terminal and the drain terminal. The sensor is configured to monitor electrical signals across the source terminal and drain terminal. A gate is positioned between the source terminal and the drain terminal and a channel is positioned above the gate. The channel includes a functionalized sensor surface configured to bind the target molecule.
In yet another embodiment, a system for detecting a target molecule in a sample is disclosed. The system includes a substrate, a first transducer positioned on the substrate, and a second transducer positioned on the substrate. The first transducer has a signal input and the second transducer has a signal output. A sensor is coupled to the signal input to input a signal and to the signal output to measure an output signal. A delay area is positioned between the first transducer and the second transducer. The delay area has a functionalized coating configured to bind the target molecule.
An advantage that may be realized in the practice of some disclosed embodiments is increased sensitivity of nucleic acid sensors and improved detection of low concentrations of target materials.
The above embodiments are exemplary only. Other embodiments are within the scope of the disclosed subject matter.
So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiment, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the disclosed subject matter encompasses other embodiments as well. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views.
Corresponding reference characters indicate corresponding parts throughout several views. The examples set out herein illustrate several embodiments, but should not be construed as limiting in scope in any manner.
A disposable cartridge is described for use in a portable/automated assay system such as that described in commonly-owned, co-pending U.S. patent application Ser. No. 15/157,584 filed May 18, 2016 entitled “Method and System for Sample Preparation” which is hereby included by reference in its entirety. While the principal utility for the disposable cartridge includes DNA testing, the disposable cartridge may be used to detect any of a variety of diseases which may be found in either a blood, food or biological detecting hepatitis, autoimmune deficiency syndrome (AIDS/HIV), diabetes, leukemia, graves, lupus, multiple myeloma, etc., just naming a small fraction of the various blood borne diseases that the portable/automated assay system may be configured to detect. Food diagnostic cartridges may be used to detect salmonella, e-coli, staphylococcus aureus or dysentery. Diagnostic cartridges may also be used to test samples from insects and specimen. For example, blood diagnostic cartridges may be dedicated cartridges useful for animals to detect diseases such as malaria, encephalitis and the west nile virus, to name but a few.
More specifically, and referring to
The disposable cartridge 20 provides an automated process for preparing the fluid sample for analysis and/or performing the fluid sample analysis. The sample preparation process allows for disruption of cells, sizing of DNA and RNA, and concentration/clean-up of the material for analysis. More specifically, the sample preparation process of the instant disclosure prepares fragments of DNA and RNA in a size range of between about 100 and 10,000 base pairs. The chambers can be used to deliver the reagents necessary for end-repair and kinase treatment. Enzymes may be stored dry and rehydrated in the disposable cartridge 20, or added to the disposable cartridge 20, just prior to use. The implementation of a rotary actuator allows for a single plunger 26, 28 to draw and dispense fluid samples without the need for a complex system of valves to open and close at various times. This greatly reduces potential for leaks and failure of the device compared to conventional systems. Finally, it will also be appreciated that the system greatly diminishes the potential for human error.
In
In an embodiment, a sample including the target molecules 74 is mixed with a solution containing magnetic nanoparticles (not shown) and the target molecules 74 and magnetic nanoparticles hybridize. Using a magnet (not shown), the hybridized target molecules are attracted to the functionalized sensor surface 70 for binding to the capture probe molecules 72.
After the target molecules 74 are bound to or captured by the capture probe molecules 72 (
Following hybridization of the captured target molecules 74 with the catalytic nanoparticles 76, metallization of the catalytic nanoparticles 76, which serve as catalytic nucleation sites, can be performed to form a conductive film 78 (
A gate 96 is separated from the source terminal 84 by the spacer 94 and extends partially across a gap between the source terminal 84 and drain terminal 86 toward the drain terminal 86, exposing the functionalized sensor surface 92. Alternatively, the gate 96 can be separated from the drain terminal 86 by the spacer 94 and extend toward the source terminal 84. The gate 96 can be formed from a metal material or from a polysilicon (polycrystalline silicon). In an embodiment, the system 80 is in the form of an incomplete metal oxide semiconductor field effect transistor (MOSFET) in which the gate 97 is incomplete, exposing a portion of the gate dielectric. In one embodiment, the gate 96 is formed as a complete gate extending across the gap and a portion of the gate 96 is removed. In another embodiment, the gate 96 is formed as a partial gate.
At block 100 of the method 96 (
At block 102, a conductive film 112 can be formed by applying a reagent to the catalytic nanoparticles 110. For example, a bath can be applied to the catalytic nanoparticles to initiate development of the conductive film 112. In an embodiment, the catalytic nanoparticles 110 are gold clusters that act as nucleation sites for the development of a gold film. The conductive film 112 can further increase the development of the gate material, bridging the gap between the gate 96 and the drain terminal 86 or source terminal 84 and completing the MOSFET. In an embodiment, development of the conductive film 112 is optional.
At block 104 (
As described above with respect to
The development of the top gate serves to change the conductive state of the transistor 115. By monitoring the state of the transistor 115 via the sensor 130, the presence of the target molecules 134 can be detected. For example, if changes in the conductive state of the transistor 115 are detected, the presence of the target molecules 134 is detected. If there are not changes in the conductive state of the transistor 115, the top gate has not developed and no target molecules 134 are detected.
A functionalized delay area 170 is positioned on the substrate 156 between the first transducer 158 and the second transducer 160. In an embodiment, the surface 172 of the delay area 170 is functionalized with a bio-specific coating 173 (
Returning to
At block 146 (
At block 148 (
While the detection systems 80, 114, 154 have been discussed in terms of independent detection systems, it is to be under stood that the detection systems 80, 114, 154 can be incorporated in other systems, such as the portable assay system 10 or disposable assay cartridge 20 described above with respect to
Possible advantages of the above described method include improved sensitivity of target molecule detection and improved detection of small quantities of target molecules.
While the present invention has been particularly shown and described with reference to certain exemplary embodiments, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention that can be supported by the written description and drawings. Further, where exemplary embodiments are described with reference to a certain number of elements it will be understood that the exemplary embodiments can be practiced utilizing either less than or more than the certain number of elements.
The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
To the extent that the claims recite the phrase “at least one of” in reference to a plurality of elements, this recitation is intended to mean at least one or more of the listed elements, and is not limited to at least one of each element. For example, “at least one of an element A, element B, and element C,” is intended to indicate element A alone, or element B alone, or element C alone, or any combination thereof. “At least one of element A, element B, and element C” is not intended to be limited to at least one of an element A, at least one of an element B, and at least one of an element C.
This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 62/374,985, filed Aug. 15, 2016 and entitled “TECHNIQUES FOR ELECTRICAL SENSING OF BIOMOLECULAR TARGETS,” the entirety of which is incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/US2017/046877 | 8/15/2017 | WO | 00 |
Number | Date | Country | |
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62374985 | Aug 2016 | US |