The present disclosure is generally concerned with highly sensitive and selective biosensors and method of use of such biosensors. More particularly, the present disclosure concerns such biosensors that include a perforated insulation layer laid on an electrode of an electrochemical biosensor to form nanowells.
Biosensors are used to detect the presence of biological molecules such as proteins, amino acids (e.g., DNA and/or RNA containing specific base sequences), or other organic molecules. Some of the examples of biosensors include pregnancy tests and glucose monitoring sensors. These biosensors can detect biomolecules such as human chronic gonadotropin (hCG) or glucose that are present in bodily fluids such as blood or urine.
In order to detect specific analytes (e.g., biological molecules), biosensors may contain an analyte-binding surface where probes specific for an analyte (e.g., single-strand DNA or antibody specific for the target molecule) are immobilized to the analyte-binding surface. Different types of biosensors using distinct scientific principles have been developed that can detect presence of specific biological molecules.
Examples of different types of biosensors include electrochemical biosensors, nano-cantilever biosensors, and micro- or nano-electromechanical systems (MEMS/NEMS). Like other types of biosensors, electrochemical biosensors comprise an analyte-binding surface that is capable of interacting with and/or binding to specific biomolecules (e.g., a specific protein or a specific sequence of DNA). In particular, electrochemical biosensors use the principle of electrochemical analysis to detect specific analytes, where chemical response to an electrical excitation applied to a system is measured and analyzed to detect whether an analyte is bound to the surface of an electrode. Unlike nano-cantilever biosensors and MEMS/NEMS, electrochemical biosensors' signals can be directly detected by an electronic device for analysis, allowing for fast diagnosis.
Potential future applications for electrochemical biosensors include diagnosis in traditional medical and healthcare setting (e.g., blood and/or urine sample testing for specific biological molecules); medical diagnosis non-hospital setting (e.g., military use in combat zone and/or self-administered consumer diagnostics), non-medical detection of biological and/or small molecule detection (e.g., water quality testing, environmental testing, quality control and/or quality assurance testing in food industry); companion diagnostics for pharmaceutical therapeutics; research applications where detection of small molecules are required; and/or other settings or circumstances where detection of biological molecules is needed. A person skilled in the art will appreciate that, although the present disclosure is called “biosensors,” its application is not limited to detection of biological molecules. In other words, the present disclosure may be used for detection of other small non-biological (e.g., inorganic, metallic, solute, electrolyte, and/or elemental) molecules. In addition, although examples provided here consist of detection in fluidic and/or aqueous milieu, one skilled in the art will appreciate that the present disclosure may be used to detect small molecules in other fluidic milieu such as in oil, solvents, gas, and/or colloidal solutions.
In order for electrochemical biosensors to be adapted widely for a broad range of applications, the biosensors must be highly sensitive and selective, and cost of manufacturing of such sensor must be competitive. Electrochemical biosensors with significantly improved sensitivity and selectivity may enable miniaturization of such devices, which in turn may reduce the production cost and further contribute to adoption of electrochemical biosensors for a wide range of applications.
To the best of the applicant's knowledge, currently, there are no electrochemical sensors that can detect multiple analytes that are present in fM-range in biological samples with high selectivity. Accordingly, there is a need for electrochemical biosensors that can detect multiple analytes that are present in fM range in biological samples. There is also a need for such biosensors that can be reliably and stably produced in large scale at a low cost.
Electrochemical biosensor devices and methods of using such devices are provided for detecting low concentration of an analyte in a biological fluid sample. One exemplary embodiment of an electrochemical biosensor device includes a plurality of electrodes made of a buffer layer laid on a substrate layer, an electrode layer laid on the buffer layer, and a perforated insulator layer laid on the electrode layer, such that a plurality of nanowells are formed on the electrode layer and the dimensions of the nanowells are defined by the sizes of the perforations, walls of the nanowells are defined by the insulator layer, and the bottom floors of the nanowells are defined by an upper surface of the electrode layer. In some instances, the nanowells of the biosensors have a pitch ratio of 1:1. In other instances, the biosensors can detect analytes that are present in fM concentration range.
In some embodiments, the electrochemical biosensor can include glass substrate layer, silicon substrate layer, silicon dioxide insulator layer, titanium buffer layer, chromium buffer layer, and/or gold electrode layer.
In yet other embodiments, the electrochemical biosensor can have perforated insulator layer, wherein the perforations (e.g., bores and/or holes) may define dimensions of nanowells such that the nanowells are cylindrical in shape. In yet some other embodiments, the nanowells have circular openings with a diameter of about 230 nm, 100 nm, and/or 50 nm. In further yet other embodiments, the nanowells have pitch ratio of about 1:5, about 1:3 and/or about 1:1.
In some embodiments, the electrochemical biosensor can operate in conjunction with an electronic device, whereby the electrochemical biosensor is capable of sending signals to the electronic device such that one or more electrochemical reaction parameters between the electrode containing a reference sample and the electrode containing a test sample can be detected by the electronic device using the signals to determine whether an analyte is present in the test sample. In an exemplary embodiment, the electrochemical reaction comprises oxidation reaction and reduction reaction. In a further exemplary embodiment, the parameters comprises variation in redox current.
In some other embodiments, the electrochemical biosensor can be used to detect analytes in sample solutions by (1) applying the test sample to sensing electrodes of the electrochemical biosensor to allow binding of any analytes that may be present in the test sample; (2) rinsing the sensing electrodes with an appropriate buffer to wash away any unbound and/or non-specifically bound analytes and/or non-analytes from the sensing electrodes; (3) applying electric current to the sensing electrode in such a way to cause chemical changes to the sensing electrode; (4) measuring electrochemical properties of the sensing electrode using an electronic device; and (5) analyzing difference in electrochemical properties between the test sample and the reference sample to determine presence of an analyte on the sensing electrode. In an exemplary embodiment, the electrochemical properties of the sensing electrode is measured using cyclic voltammetry.
Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, and use of the devices disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present disclosure is defined solely by the claims. The features illustrated or described in collection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present application.
Additionally, the figures are not necessarily to scale and, to the extent that linear or circular dimensions are used in the description of the disclosed devices and methods, such dimensions are not intended to limit the types of shapes and sizes that can be used in conjunction with such devices and methods. A person skilled in the art will recognize that an equivalent to such linear and circular dimensions can easily be determined for any geometric shape. Still further, sizes and shapes of the devices, and the components thereof, can depend at least on the anatomy of the subject in which the device will be used, the size and shape of components with which the device will be used, and the methods and procedures in which the device will be used.
Furthermore, while the exemplary embodiments provided herein describe use of the device in detecting biomolecules (e.g., proteins and/or nucleic acid molecules), a person skilled in the art will recognize that the device may be adopted to be used to detect presence of non-biological molecules and/or samples that are not biological samples. As an example, presence of inorganic material may be detected using the present invention for water quality testing, environmental testing and/or quality control/quality assurance testing in other industrial settings).
In order for an electrochemical sensor to be adopted in a wide range of applications such as diagnosis in traditional medical, pharmaceutical, and/or healthcare settings (e.g., blood and/or urine sample testing for specific biological molecules), medical diagnosis in non-hospital setting (e.g., military use in combat zone, self-administered consumer diagnostics such as pregnancy test or blood glucose monitoring), non-medical detection of biological and/or small molecule detection (e.g., water quality testing, environmental testing, quality control and/or quality assurance testing in food industry), companion diagnostics for pharmaceutical therapeutics; research applications where detection of small molecules are required, and/or other settings or circumstances where detection of biological molecules is needed, the electrochemical sensor must be sensitive (i.e., being able to detect low concentrations of analyte), selective (i.e., being able to distinguish and differentiate target analytes in the presence of other components), easy to use (i.e., simple to operate, requires small amounts of test samples), and readily available to users (i.e., able to manufacture scalably, in large quantities, and/or at a low cost).
The present disclosure is directed to highly sensitive and highly selective electrochemical biosensors made using components that are more resilient and stable compared to past electrochemical biosensors.
In one embodiment, the substrate layer 210 may be made of glass. The substrate layer may also comprise silicon, silicon dioxide (e.g., quartz), borosilicate, and/or other glass compositions used in semiconductor manufacturing. In other embodiments, the glass or silicon substrate layer 210 may be a circular wafer. In yet other embodiments, the glass or silicon substrate layer 210 may be configured to accommodate a plurality of electrochemical biosensors, as illustrated in
The buffer layer 220 of the sensing electrode 120 may provide enhanced bonding of the electrode layer 230 to the substrate layer 210 thereby minimizing risk of the electrode layer 230 detaching from the substrate layer 210. In other words, the buffer layer 220 allows the electrode layer 230 and the substrate layer 210 to form a tighter seal. Such enhanced bonding or formation of seal between the electrode layer 230 and substrate layer 210 may enable easier and more reliable manufacturing of the electrochemical biosensor and/or reduce cost of manufacture. In one preferred embodiment, the buffer layer may comprise titanium, chromium, and/or alloys of titanium or chromium.
The insulator layer 240 of the sensing electrode 120 may be perforated, such that the insulator layer 240 comprises a plurality of bores 241 (i.e., holes). The plurality of bores is also illustrated in
In some embodiments, where the opening of the nanowell is circular, the diameter of the circular opening of the nanowells 242 may be less than 1000 nm. In other embodiments, the diameter of the circular opening of the nanowells 242 may be less than 300 nm. In yet other embodiments, the diameter of the circular opening of the nanowells 242 may be approximately 230 nm, 100 nm, and/or 50 nm. Although the embodiments described above has nanowells 242 that are cylindrical in shape with a circular opening, a person skilled in the art will recognize that the nanowells 242 may have various other opening shapes, such as rectangular, oval, and/or polygonal shapes. In these embodiments having nanowells 242 with various other opening shapes, the dimension of the opening may be less than 1000 nm or 300 nm, or may be approximately 230 nm, 100 nm, and/or 50 nm. In addition, a person skilled in the art will also recognize that the present invention is not limited to the compositions and structure described above, but may also include compositions and structure with similar characteristics, or improved characteristics.
In other embodiments, the bottom surfaces 231a of the nanowells 242 (e.g., top surface of the electrode layer that is not covered by the insulator layer) may comprise probe molecules 245 that are capable of binding with specific analytes. As an example, as shown in
While the foregoing description has been directed to specific embodiments, it will be apparent that other variations and modifications may be made to the described embodiments, with the attainment of some or all of their advantages. Accordingly this description is to be taken only by way of example and not to otherwise limit the scope of the embodiments herein. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the embodiments described herein. Finally, all publications and references cited herein are expressly incorporated by reference in their entirety.
This application further expressly incorporates by reference and makes a part hereof the U.S. Provisional Patent Application Ser. Nos. 62/288,439, filed Jan. 29, 2016.
Number | Date | Country | |
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62288439 | Jan 2016 | US |