Flexible electroretinogram detection contact lens and preparation method thereof

Abstract

The invention discloses a flexible electroretinogram detection contact lens and a preparation method, and belongs to the technical field of flexible electronic devices, the contact lens comprises a contact lens layer, an inner MXene layer, a silver nanowire layer and an outer MXene layer, the inner MXene layer is an aqueous dispersion liquid obtained by aminating MXene, the silver nanowire layer is a silver nanowire layer, and the outer MXene layer is an aqueous dispersion liquid obtained by aminating MXene. The silver nanowire layer is isopropanol silver nanowire dispersion liquid wrapping thiolated molecules, and the outer MXene layer is aqueous dispersion liquid of MXene doped chitosan. According to the flexible electroretinogram detection contact lens, the interface impedance is reduced and the structural stability is improved through various physical bonding and chemical bonding effects, and compared with a commercial electroretinogram detection electrode Jet electrode in performance, the flexible electroretinogram detection contact lens has high comfort, dynamic deformation adaptability and high biocompatibility compared with a traditional Jet electrode, so that the flexible electroretinogram detection contact lens has a wide application prospect. And a safer and more reliable mode is provided for future electroretinogram detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible electronic devices, and particularly relates to a flexible electroretinogram detection contact lens and a preparation method thereof. Background Art

[0002] Electroretinogram (ERG) detection is a key means to evaluate retinal function. Traditional ERG detections mostly use rigid contact lens electrodes (such as Jet electrodes) to collect bioelectrical signals through corneal contact. However, rigid contact lens electrodes have significant defects: insufficient comfort. Jet electrodes are usually made of hard materials (such as polymethyl methacrylate, PMMA), which are prone to cause corneal compression and dry eye symptoms when worn, and may cause corneal epithelial damage after long-term use, restricting the continuous monitoring ability; there is a contradiction between light transmittance and signal interference. To achieve high conductivity, Jet electrodes need to embed thick metal grids (such as gold or platinum), resulting in insufficient light transmittance (usually <70%), affecting the clarity of the patient's vision; at the same time, the rigid metal grid is prone to generate motion artifacts during eye movement, reducing the signal-to-noise ratio; biocompatibility limitations. The surface of traditional electrodes lacks a flexible adaptation design, has a low matching degree with the corneal curvature, and long-term contact may induce inflammatory reactions.

[0003] In recent years, the development of flexible electronic technology has promoted the exploration of contact lens electrodes, but the electrode performance still faces challenges: selection of conductive materials. Existing flexible electrodes mostly rely on single materials (such as graphene or conductive polymers), and it is difficult to balance the requirements of high conductivity and light transmittance; structural stability defects. When multiple layers of materials are stacked, the interfacial bonding force is weak, and it is easy to delaminate due to eye deformation or tear erosion, affecting signal stability; long-term wearing adaptability: material oxidation (such as the formation of silver nanowire sulfide) or too high surface roughness may cause discomfort during wearing. Summary of the Invention

[0004] The purpose of the present invention is to provide a contact lens for flexible electroretinogram detection, including a contact lens layer, an inner MXene layer, a silver nanowire layer, and an outer MXene layer arranged in sequence; the inner MXene layer uses MXene after amino-functionalization treatment.

[0005] Furthermore, the silver nanowire layer uses silver nanowires wrapped with thiolated molecules; the outer MXene layer is doped with chitosan.

[0006] Furthermore, the contact lens layer is a hydrogel contact lens or a silicone hydrogel contact lens; the amino group on the surface of the inner MXene layer undergoes an amidation reaction with the carboxyl group in the contact lens layer to form a covalent bond.

[0007] Further, the surface of the inner MXene layer is covered with a silver nanowire layer and an outer MXene layer; physical bonding and chemical bonding are formed at the contact surface between the inner MXene layer and the outer MXene layer; the physical bonding refers to van der Waals forces, and the chemical bonding refers to hydrogen bonds.

[0008] Further, the outer MXene layer is in conformal contact with the silver nanowire layer.

[0009] The present invention also provides a method for preparing a contact lens, the contact lens includes a contact lens layer, an inner MXene layer, a silver nanowire layer, and an outer MXene layer arranged in sequence; the preparation method includes the following steps:

[0010] Step 1, spraying an aqueous dispersion of amino-functionalized MXene on the semi-dehydrated contact lens layer, and after drying, forming the inner MXene layer on the surface of the contact lens layer;

[0011] Step 2, preparing a silver nanowire dispersion, spraying the silver nanowire dispersion on the surface of the inner MXene layer, and after drying, obtaining the silver nanowire layer;

[0012] Step 3, preparing an aqueous dispersion of MXene-doped chitosan, spraying the dispersion on the surface of the inner MXene layer and the nanowire layer, and after drying, obtaining the outer MXene layer.

[0013] Further, in step 1, the concentration of the aqueous dispersion of amino-functionalized MXene is 0.2 - 0.5 mg / mL; the amino groups of the amino-functionalized MXene in the inner MXene layer react with the carboxyl groups in the contact lens layer to form amide bonds, forming covalent bonds.

[0014] Further, the surface of the silver nanowires in step 2 is coated with thiolated molecules.

[0015] Further, in the aqueous dispersion of MXene-doped chitosan, the mass ratio of MXene to chitosan is 3 to 1.

[0016] Further, the surface of the inner MXene layer is covered with a silver nanowire layer and an outer MXene layer; physical bonding - van der Waals forces and chemical bonding - hydrogen bonds are formed at the contact surface between the inner MXene layer and the outer MXene layer.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following remarkable features:

[0018] This patent proposes a flexible electroretinogram detection contact lens and a preparation method, which break through the rigid constraints of traditional Jet electrodes through enhanced physical bonding, enhanced chemical bonding, and interface optimization design:

[0019] 1. Flexible adhesion and high light transmittance: Utilizing the ultrathin characteristics of MXene nanosheets and the low-density network structure of silver nanowires, a high light transmittance (72%-82%) is achieved on the premise of high conductivity, which is superior to that of Jet electrodes (65%);

[0020] 2. Dynamic deformation adaptability: Through the chemical cross-linking layer and physical densification process, the bending resistance of the electrode is improved to adapt to frequent blinking and eye rotation;

[0021] 3. Biocompatibility guarantee: The materials used are all biocompatible materials, and surface functionalization reduces mechanical friction. Combining with the antibacterial properties of MXene, the risk of corneal irritation is reduced. Description of the Drawings

[0022] Figure 1 It is a SEM image of the conformal contact of the three-layer structure on the surface of the contact lens;

[0023] Figure 2 It is a schematic diagram of the three-layer structure of the contact lens;

[0024] Figure 3 It is a schematic diagram of the bonding effect of the three-layer structure of the contact lens;

[0025] Figure 4 It is a light transmittance diagram of the three-layer structure contact lens;

[0026] Figure 5 It is a performance comparison diagram of the three-layer structure contact lens and the commercial Jet electrode in detecting electroretinogram.

[0027] Among them, 1. Inner MXene layer; 2. Silver nanowire layer; 3. Outer MXene layer. Detailed Embodiments

[0028] A flexible electroretinogram detecting contact lens of the present invention includes a four-layer structure, which are successively a contact lens layer, an inner MXene layer 1, a silver nanowire layer 2 and an outer MXene layer 3; as Figure 1 shown is a SEM image of the conformal contact of the three-layer structure on the surface of the contact lens, Figure 2 It is a schematic diagram of the three-layer structure of the contact lens, and the three layers are respectively an inner MXene layer 1, a silver nanowire layer 2 and an outer MXene layer 3.

[0029] The contact lens layer is a commercial hydrogel contact lens or a silicone hydrogel contact lens.

[0030] The inner MXene layer 1 is an aqueous dispersion of MXene after amination treatment;

[0031] The silver nanowire layer 2 is an isopropanol silver nanowire dispersion solution wrapped with mercapto molecules;

[0032] The outer MXene layer 3 is an aqueous dispersion of MXene-doped chitosan.

[0033] The present invention also provides a method for preparing a flexible electroretinogram detection contact lens, in which an inner MXene layer 1, a silver nanowire layer 2 and an outer MXene layer 3 are sequentially formed on the contact lens. The specific steps are as follows:

[0034] Step 1, form the inner MXene layer 1 on the surface of the contact lens layer as Figure 1 shown. MXene is usually represented by the chemical formula Mn+1XnTm, where M represents a transition metal element (such as titanium, vanadium, chromium, etc.), X represents carbon or nitrogen, and T represents a functional group on the material surface (such as a hydroxyl group, a halogen group, etc.);

[0035] First, perform amination treatment on MXene. Specifically, by condensing the hydroxyl group of silane with the -OH group on the surface of MXene to form a Si-O-M bond and introducing an amino group -NH2 to obtain aminated MXene. In this specific embodiment, when M in MXene is titanium, for example, MXene is Ti3C2T x 、Ti2CT x etc., after dehydration condensation, a Si-O-Ti bond is formed.

[0036] Disperse the aminated MXene in water to form an aqueous dispersion of aminated MXene with a concentration of 0.2 - 0.5 mg / mL;

[0037] Secondly, take out the hydrogel contact lens or the care solution of the silicone hydrogel contact lens and place it in the natural state for 10 - 15 minutes to make the contact lens in a semi-dehydrated state; spray the aqueous dispersion of aminated MXene on the semi-dehydrated contact lens and dry it at a low temperature (60 - 80 °C) for 1 - 2 hours to form the inner MXene layer 1;

[0038] During the drying process of the aqueous dispersion of aminated MXene sprayed on the contact lens, the semi-dehydrated contact lens spontaneously absorbs water, enhancing the capillary force between the inner MXene layer 1 and the contact lens. The layered structure of the MXene nanosheets and the physical entanglement of the polymer chains of the contact lens can generate van der Waals forces, and the MXene nanosheets are embedded in the polymer network to form a mechanical interlocking structure, thereby promoting the physical bonding between the inner MXene layer 1 and the contact lens; as Figure 3 shown, the amino group (-NH2) on the surface of the inner MXene layer 1 undergoes an amidation reaction with the carboxyl group (-COOH) in the contact lens material to form a stable covalent bond. The -NH2 of the aminated MXene can be protonated at physiological pH to form an ionic bond with the carboxylate group (-COO-) in the contact lens material through electrostatic attraction, thereby promoting the chemical bonding between the inner MXene layer 1 and the contact lens.

[0039] Step 2: Form a silver nanowire layer 2 on the surface of the inner MXene layer 1.

[0040] In this specific embodiment, the surface of the silver nanowires is coated with thiolated molecules, and the thiolated molecules are thiolated polyethylene glycol to enhance biocompatibility and prevent silver oxidation.

[0041] Disperse the silver nanowires coated with thiolated molecules in an isopropanol dispersion to enhance the dispersion of the silver nanowires and make the silver nanowires spray more evenly on the surface.

[0042] After spraying the silver nanowire dispersion on the surface of the inner MXene layer 1, dry it at a high temperature (120 - 140 °C) for 10 - 15 minutes to cause physical bonding at the positions where the silver nanowires contact each other and reduce the contact impedance between the silver nanowires.

[0043] Step 3: Spray again to form an outer MXene layer 3.

[0044] The outer MXene layer 3 includes MXene and chitosan to enhance interfacial adhesion and biocompatibility and form a protective layer to prevent the silver nanowires from falling off when contacting with tears.

[0045] Form an aqueous dispersion of MXene and chitosan, with the mass ratio of MXene to chitosan being 3:1. After spraying the aqueous dispersion of MXene doped with chitosan on the surface of the inner MXene layer 1 and the nanowire layer 3, dry it at a low temperature (60 - 80 °C) for 1 - 2 hours to enhance the bonding between the outer MXene layer 3 and the inner MXene layer 1 and the silver nanowires.

[0046] Some positions of the sprayed outer MXene layer 3 are in direct contact with the inner MXene layer 1, and physical bonding - van der Waals forces and chemical bonding - hydrogen bonds are formed between the inner and outer MXenes to increase the interfacial stability.

[0047] The outer MXene layer 3 is in conformal contact with the silver nanowire layer 2, further reducing the interfacial impedance and enhancing the conductivity.

[0048] The spraying volumes of the inner MXene layer 2 and the outer MXene layer 3 remain unchanged at 25 μL respectively, and the spraying volumes of the silver nanowire dispersion are sequentially increased to 50 μL, 100 μL, 150 μL, 200 μL, 250 μL. The light transmittance under different spraying volumes is as Figure 4 shown. As the spraying volume of the silver nanowires increases, the light transmittance of the contact lens ranges from 82% to 72%, and the light transmittance is higher than 65% of the existing Jet electrodes for electroretinogram detection.

[0049] Adult rabbits were taken, and electroretinogram (ERG) test comparison experiments were carried out using the contact lenses of the present invention and traditional Jet electrodes. The specific steps were as follows: ① The rabbits were dark adapted for 30 to 60 minutes. ② The rabbits were mydriatic. ③ After anesthesia, the contact lenses of the present invention were applied to the cornea of the left eye of the rabbits, and normal Jet corneal electrodes were used on the right eye of the rabbits. The contact lenses of the present invention and the Jet corneal electrodes were respectively connected to the ERG signal amplifier through metal wires. ④ The rabbits were given flash stimuli with intensities of 0.01, 3.0, and 10.0 cd·s / m 2 The (dark adaptation) ERG response was measured. After each response, dark adaptation was replenished for 3 minutes. ⑤ The oscillatory potential test under 3.0 cd·s / m 2 dark adaptation was carried out. ⑥ Light adaptation for 10 min. ⑦ Light adaptation at 3.0 (30 cd / m2 background illumination, 3.0 cd*s / m2 flash). ⑧ Four light flashes were given. The total time was about 1 hour. The obtained electroretinograms are as Figure 5 shown. The electroretinograms measured through the contact lenses of the present invention and those measured through Jet corneal electrodes are similar in shape, but the contact lenses of the present invention are more comfortable for electroretinogram measurement.

Claims

1. A contact lens, characterized in that, It includes a contact lens layer, an inner MXene layer, a silver nanowire layer, and an outer MXene layer arranged in sequence; In the inner MXene layer, amino-functionalized MXene is used.

2. The contact lens according to claim 1, wherein In the silver nanowire layer, silver nanowires wrapped with thiolated molecules are used; In the outer MXene layer, chitosan is doped.

3. The contact lens according to claim 1, wherein The contact lens layer is a hydrogel contact lens or a silicone hydrogel contact lens; The amino groups on the surface of the inner MXene layer react with the carboxyl groups in the contact lens layer to form a covalent bond through amidation reaction.

4. The contact lens according to claim 1, wherein, The surface of the inner MXene layer is covered with a silver nanowire layer and an outer MXene layer; physical bonding and chemical bonding are formed at the contact surface between the inner MXene layer and the outer MXene layer; the physical bonding refers to van der Waals force, and the chemical bonding refers to hydrogen bond.

5. The contact lens according to claim 1, wherein The outer MXene layer and the silver nanowire layer exhibit conformal contact.

6. A method for preparing a contact lens, characterized in that, The contact lens includes a contact lens layer, an inner MXene layer, a silver nanowire layer, and an outer MXene layer arranged in sequence; The preparation method includes the following steps: Step 1, spray a water dispersion of amino-functionalized MXene on the semi-dehydrated contact lens layer, and after drying, form the inner MXene layer on the surface of the contact lens layer; Step 2, prepare a silver nanowire dispersion, spray the silver nanowire dispersion on the surface of the inner MXene layer, and after drying, obtain the silver nanowire layer; Step 3, prepare a water dispersion of MXene doped with chitosan, spray the dispersion on the surface of the inner MXene layer and the nanowire layer, and after drying, obtain the outer MXene layer.

7. The preparation method of a contact lens according to claim 6, characterized in that, In Step 1, the concentration of the water dispersion of amino-functionalized MXene is 0.2 - 0.5 mg / mL; The amino groups of the amino-functionalized MXene in the inner MXene layer react with the carboxyl groups in the contact lens layer to form a covalent bond through amidation reaction.

8. The preparation method of a contact lens according to claim 6, wherein, In Step 2, the silver nanowires are wrapped with thiolated molecules.

9. The preparation method of a contact lens according to claim 6, wherein, In the water dispersion of MXene doped with chitosan, the mass ratio of MXene to chitosan is 3 to 1.

10. The preparation method of a contact lens according to claim 6, characterized in that, The surface of the inner MXene layer is covered with a silver nanowire layer and an outer MXene layer; physical bonding force and chemical bonding are formed at the contact surface between the inner MXene layer and the outer MXene layer; the physical bonding refers to van der Waals force, and the chemical bonding refers to hydrogen bond.

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