An electrochemical lateral flow immunoassay test strip and a portable detection device

Abstract

The utility model discloses an electrochemical lateral flow immunoassay test strip and portable detection device. An electrochemical lateral flow immunoassay test strip, including sample pad, binding pad, NC membrane, absorbent pad and backplate, sample pad, binding pad, NC membrane, absorbent pad are laminated in backplate in proper order, the NC membrane is convex structure, and it is provided with working electrode, reference electrode, counter electrode and first wire, second wire, third wire, wherein, first wire, second wire, third wire and working electrode, reference electrode, counter electrode one -to -one corresponding connection, and first wire, second wire, third wire are evenly arranged in the convex extension area of NC membrane, are used for and external detection device butt joint. The portable detection device provided by the utility model can obtain detection result in shorter detection time, and simple operation can satisfy the on -the -spot rapid detection demand of disease diagnosis, food safety and the field, has greater application potential.

Description

Technical Field

[0001] This utility model relates to the field of biological detection technology, specifically to an electrochemical lateral flow immunoassay test strip and a portable detection device. Background Technology

[0002] In recent years, point-of-care testing (POCT) has been widely used in disease diagnosis, food safety, and environmental monitoring due to its rapid, portable, and real-time analysis capabilities. POCT is a highly efficient "sample in, result out" testing model achieved through miniaturized, integrated, and intelligent design. A typical example of POCT is lateral flow immunoassay (LFIA). LFIA offers advantages such as low cost, simple operation, rapid detection, and small sample volume, and has been widely used for the rapid analysis of various medical biomarkers, including proteins (e.g., cardiac markers, inflammatory markers), nucleic acids (miRNA in non-small cell lung cancer, ORF1ab nucleic acid of viruses), and small chemical molecules (aflatoxin B1, carbendazim).

[0003] Classical LFIA (Lateral Flow Immunoassay) is based on optical detection strategies, including colorimetry and fluorescence methods. Colorimetric LFIA offers a low-cost, user-friendly platform, but its sensitivity and quantification capabilities are insufficient. While fluorescence-based LFIA improves sensitivity and quantification, it requires complex equipment, limiting its application in point-of-care testing (POCT). In recent years, the emerging electrochemical lateral flow immunoassay (eLFIA) has attracted widespread attention from researchers and clinicians. eLFIA combines the advantages of traditional LFIA with electrochemical sensing, demonstrating unique technological advantages in the POCT field. Specifically, eLFIA retains the high separation characteristics of LFIA and the high selectivity based on specific probes (such as antibodies and nucleic acid aptamers). Furthermore, compared to optical detection strategies, electrochemical sensing is based on portable, cost-effective equipment, making it easier to miniaturize and integrate. These advantages have led to the widespread application of electrochemical sensing in the POCT field. For example, a commercially available home blood glucose meter costs only a few dollars for a single set of test strips and the device, making it suitable for daily health monitoring at home and providing a convenient technical means for the early diagnosis and long-term management of diseases.

[0004] Currently, eLFIA has shown application potential in multiple fields, detecting targets including cancer biomarkers, inflammatory biomarkers, myocardial biomarkers, pathogenic bacteria, and diabetes-related analytes. Current eLFIA architectures almost always consist of two independent devices: an integrated electrochemical sensor and an LFIA test strip. This design achieves the separation and quantitative analysis of target substances by closely attaching the detection electrode to the test line of a nitrocellulose membrane (NC membrane), but it still faces two major challenges:

[0005] At the detection level: The sensor electrode and the NC membrane are not tightly bonded, which leads to unstable contact between the target and the electrode after membrane separation, resulting in signal fluctuations and inaccurate detection results with poor repeatability and stability.

[0006] In terms of preparation: the preparation of the electrochemical sensor, the LFIA strip and subsequent assembly need to be completed separately, which makes the eLFIA preparation process complicated, making it difficult to prepare in batches and limiting the transformation, application and popularization of the technology.

[0007] To address the aforementioned issues, Ying et al. proposed an eLFIA scheme with built-in electrodes. By fabricating electrodes in situ on the NC membrane, the defect of poor adhesion between the sensing electrodes and the NC membrane was effectively solved. However, in this scheme, the electrodes are distributed on both sides of the NC membrane, resulting in a larger overall membrane size. Furthermore, when assembling the test strip, each functional area of ​​the membrane must be cut separately before subsequent operations are performed, which still does not solve the problem of complex eLFIA assembly. Utility Model Content

[0008] Therefore, this utility model provides an electrochemical lateral flow immunoassay test strip and a portable detection device.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] According to a first aspect of the present invention, the present invention provides an electrochemical lateral flow immunoassay test strip, comprising a sample pad, a conjugate pad, an NC membrane, an absorbent pad, and a backing plate. The sample pad, conjugate pad, NC membrane, and absorbent pad are sequentially stacked on the backing plate. The NC membrane has a convex structure and is provided with a working electrode, a reference electrode, a counter electrode, and a first lead wire, a second lead wire, and a third lead wire. The first lead wire, the second lead wire, and the third lead wire are connected to the working electrode, the reference electrode, and the counter electrode respectively, and the first lead wire, the second lead wire, and the third lead wire are all arranged in the convex extension area of ​​the NC membrane for docking with an external detection device.

[0011] Furthermore, the working electrode is coated with capture antibodies, and the binding pad is coated with a probe complex containing detection antibodies.

[0012] Furthermore, the NC film is also provided with a PDMS film, which at least covers the junction of the working electrode, the reference electrode, the counter electrode and the corresponding wires to achieve insulation and sealing.

[0013] Furthermore, the working electrode, reference electrode, and counter electrode are arranged in parallel, and the distance between the working electrode, reference electrode, and counter electrode is 2 mm.

[0014] Furthermore, the sample pad has a size of 20 mm × 200 mm, the binding pad has a size of 14 mm × 200 mm, the NC membrane has a size of 25 mm × 200 mm, and the absorbent pad has a size of 24 mm × 200 mm; the working electrode, the reference electrode, and the counter electrode all have a size of 6 mm × 1 mm.

[0015] According to a second aspect of the present invention, the present invention provides a portable detection device, the detection device comprising an electrically connected electrochemical workstation, an electrochemical lateral flow immunoassay strip as described in any of the preceding claims, and a smartphone.

[0016] Furthermore, the detection device also includes a spring test clip, which is used to electrically connect the working electrode, the reference electrode, and the counter electrode to the electrochemical workstation.

[0017] The present invention has the following advantages:

[0018] This invention utilizes screen printing technology to in-situ construct electrochemical sensing electrodes onto an NC membrane, forming an integrated structure between the electrode and the membrane. This fundamentally avoids the defects of poor adhesion between the electrode and the NC membrane in traditional methods, reduces signal fluctuations caused by unstable contact between the target and the electrode, and significantly improves the accuracy, repeatability, and stability of the detection results. Furthermore, by placing the wires connecting each electrode within the convex extension area of ​​the NC membrane, double-sided processing or post-processing and splicing of the membrane is eliminated, simplifying the preparation and assembly process of the eLFIA test strip and facilitating mass production.

[0019] This invention forms a portable detection device that integrates an electrochemical workstation, eLFIA test strips, and a smartphone. The smartphone can directly receive and process the detection data from the electrochemical workstation without the need for additional data transmission or analysis equipment. It can obtain detection results in a shorter detection time and is easy to operate. It can meet the needs of rapid on-site detection in fields such as disease diagnosis and food safety, and has great application potential. Attached Figure Description

[0020] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0021] Figure 1 A schematic diagram of the structure of the electrochemical lateral flow immunoassay test strip provided by this utility model;

[0022] Figure 2 A schematic diagram of a pattern for manufacturing NC film provided by this utility model;

[0023] Figure 3 A schematic diagram of the portable detection device provided by this utility model;

[0024] Among them, 1-sample pad; 2-binding pad; 3-NC membrane; 4-absorbent pad; 5-electrode area; 6-lead area; 7-working electrode; 8-reference electrode; 9-counter electrode; 10-first lead; 11-second lead; 12-third lead; 13-PMDS coverage area; 14-support shell; 15-spring clip; 16-eLFIA test strip; 17-portable potentiostat. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0026] Example 1

[0027] This embodiment provides an electrochemical lateral flow immunoassay strip (eLFIA), the structure of which is as follows: Figure 1 As shown, the device includes a sample pad 1, a conjugate pad 2, an NC membrane 3 (with a convex structure), an absorbent pad 4, and a backplate (not shown). The sample pad, conjugate pad, NC membrane, and absorbent pad are sequentially stacked on the backplate. The NC membrane includes an electrode region 5 and a conductor region 6. The electrode region is provided with a working electrode 7, a reference electrode 8, and a counter electrode 9. The conductor region 6 is provided with a first conductor 10, a second conductor 11, and a third conductor 13. The first conductor 10, the second conductor 11, and the third conductor 13 are electrically connected to the working electrode 7, the reference electrode 8, and the counter electrode 9 in a one-to-one correspondence.

[0028] The sample pad and conjugate pad are made of glass fiber. The conjugate pad is coated with capture antibodies, and the working electrode is coated with a probe complex containing detection antibodies. The lead wire is made of silver, the working electrode and counter electrode are made of carbon ink and carboxylated carbon nanotubes, and the reference electrode is made of silver / silver chloride.

[0029] The sample pad measures 20 mm × 200 mm, the binding pad measures 14 mm × 200 mm, the NC membrane measures 25 mm × 200 mm, and the absorbent pad measures 24 mm × 200 mm. The working electrode, reference electrode, and counter electrode all measure 6 mm × 1 mm and are arranged in parallel with the counter electrode, with a spacing of 2 mm between them.

[0030] The preparation method of the above-mentioned electrochemical lateral flow immunoassay test strip is as follows:

[0031] The pattern was designed using Adobe Illustrator. Figure 2 Electrode materials were prepared using screen printing technology. First, insulating oil was printed onto the NC film as the outer frame and dried at 55°C for 30 minutes. Then, silver paste was printed onto the corresponding areas of the first, second, and third conductors and dried at 55°C for 30 minutes to serve as conductors. Next, carbon ink and carboxylated carbon nanotubes were printed onto the NC film onto the corresponding areas of the working and counter electrodes and dried at 55°C for 1 hour to prepare the working and counter electrodes. Silver / silver chloride ink was printed onto the NC film onto the corresponding area of ​​the counter electrode using the same procedure and dried to provide the reference electrode. Finally, PDMS was printed at the junction of the electrode and conductor areas to prevent solution from flowing onto the conductors and causing short circuits, thus obtaining the NC film.

[0032] The NC membrane is adhered to the corresponding area of ​​the backplate, and the capture antibody is sprayed onto the working electrode and dried. The probe complex containing the detection antibody is dropped onto the binding pad, dried, and then cut to the appropriate size. Then, the absorption pad, binding pad, and sample pad are sequentially adhered to the corresponding areas of the backplate, with each part overlapping by 2 mm. The strips are then cut according to the outer frame lines to obtain multiple eLFIA test strips.

[0033] Example 2

[0034] This embodiment provides a portable detection device, the structural schematic of which is shown in [see diagram]. Figure 2 The portable testing device consists of the following components: a support housing 14, a spring clip 15, and a portable potentiostat 17. The support housing is made using 3D printing technology and has a long groove on its side for holding the eLFIA test strip 16. One end of the spring clip is electrically connected to the portable potentiostat, and the other end can be connected to the three wires of the eLFIA test strip.

[0035] After adding the sample to the sample pad of the eLFIA test strip, immediately press the spring test clip with your finger and insert the eLFIA test strip horizontally into the designated groove. Electrochemical analysis can be performed via the PStouch Application available on an Android smartphone.

[0036] Although the present invention has been described in detail above with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. An electrochemical lateral flow immunoassay test strip, characterized in that, The device includes a sample pad, a conjugate pad, an NC membrane, an absorbent pad, and a backplate. The sample pad, conjugate pad, NC membrane, and absorbent pad are stacked sequentially on the backplate. The NC membrane has a convex structure and is provided with a working electrode, a reference electrode, a counter electrode, and a first wire, a second wire, and a third wire. The first wire, the second wire, and the third wire are connected to the working electrode, the reference electrode, and the counter electrode respectively, and the first wire, the second wire, and the third wire are all arranged in the convex extension area of ​​the NC membrane for docking with an external detection device.

2. The electrochemical lateral flow immunoassay strip according to claim 1, characterized in that, The working electrode is coated with capture antibodies, and the binding pad is coated with a probe complex containing detection antibodies.

3. The electrochemical lateral flow immunoassay strip according to claim 1, characterized in that, The NC film is further provided with a PDMS film, which at least covers the junction of the working electrode, the reference electrode, the counter electrode and the corresponding wire.

4. The electrochemical lateral flow immunoassay strip according to claim 1, characterized in that, The working electrode, reference electrode, and counter electrode are arranged in parallel, and the distance between the working electrode, reference electrode, and counter electrode is 2 mm.

5. The electrochemical lateral flow immunoassay strip according to claim 1, characterized in that, The sample pad measures 20 mm × 200 mm, the binding pad measures 14 mm × 200 mm, the NC membrane measures 25 mm × 200 mm, and the absorbent pad measures 24 mm × 200 mm; the working electrode, reference electrode, and counter electrode all measure 6 mm × 1 mm.

6. A portable detection device, characterized in that, The detection device includes an electrochemical workstation electrically connected to the device, an electrochemical lateral flow immunoassay strip as described in any one of claims 1-5, and a smartphone.

7. The portable detection device according to claim 6, characterized in that, The detection device also includes a spring test clip, which is used to electrically connect the working electrode, reference electrode, and counter electrode to the electrochemical workstation.

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