A protein molecule-based biophototransistor and a preparation method thereof

Abstract

The application provides a protein molecule-based biophototransistor and a preparation method thereof, and belongs to the field of photoelectric sensing. The biophototransistor comprises a substrate, a dielectric layer, a channel layer and a photosensitive active layer. A silicon dioxide dielectric layer is grown on a silicon substrate, a semiconductor material is transferred to the dielectric layer to form a channel layer, a pre-designed electrode pattern is exposed on the semiconductor material by an electron beam exposure method, an electrode is evaporated, a semiconductor transistor is prepared, photosensitive protein molecules are grafted to the semiconductor transistor as a photosensitive active layer, and the biophototransistor is prepared.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoelectric sensing, and particularly relates to a biological photoelectric transistor based on a protein molecule and a preparation method thereof. BACKGROUND

[0002] The description in this section is only provided for the background information related to the present disclosure, and does not constitute the prior art.

[0003] Zinc oxide, as a representative of the third generation semiconductor material, has advantages of a wide band gap, high thermal conductivity, high stability, low cost and the like. The nano zinc oxide structure has a large specific surface area and high carrier mobility, which makes it a hotspot in the research of photoelectric materials in recent years. However, the band gap of zinc oxide is 3.34 eV, and the light response band is limited to 360 nm-390 nm, which can only absorb ultraviolet light in the sunlight, and the ultraviolet light accounts for only about 3% of the entire sunlight spectrum, so the utilization rate of solar energy of the zinc oxide device is low.

[0004] Bacteriorhodopsin is a light-sensitive membrane protein extracted from the cell membrane of halophilic bacteria, which has the characteristics of fast and high-sensitivity light response, and is widely used in optogenetics. Since it still has the characteristics of light response in the in vitro environment, it has been applied as a photoelectric material in solar cells, biosensing, artificial retinas and the like in recent years. Its response in the visible light band can widen the response band of zinc oxide and supplement the absorption of solar energy in the visible light band, so as to achieve the purpose of energy saving.

[0005] In addition, with the improvement of the integration level of integrated circuits, the development of very large scale integrated circuits has reached the limit, and the element size will reach the nanometer level, which is equivalent to the size of molecules, and researchers have proposed the idea of taking molecules as the smallest unit on the chip. The size of the protein molecule device can reach the nanometer level, and it has important application prospects in the field of molecular electronics.

[0006] It should be noted that the above introduction to the technical background is only for the convenience of clearly and completely describing the technical scheme of the present application, and for the convenience of understanding by those skilled in the art. The above technical scheme cannot be considered as known by those skilled in the art only because it is described in the background section of the present disclosure. SUMMARY

[0007] The present application proposes a biological photoelectric transistor based on a protein molecule and a preparation method thereof, aiming at widening the light response band of nano zinc oxide material to improve the utilization rate of solar energy, and embedding the protein molecule into the transistor to explore the function characteristics such as recognition, switching and conduction of the molecular transistor, so as to provide a more reliable basis for the application of protein molecules in the field of molecular electronics.

[0008] The technical scheme adopted by the present application is:

[0009] The present application provides a preparation method of a bio-optoelectric transistor based on protein molecules, which comprises the following steps:

[0010] A layer of silicon dioxide medium layer is grown on a silicon substrate, and semiconductor material is transferred to the medium layer to form a channel layer;

[0011] A pre-designed electrode pattern is exposed on the semiconductor material by an electron beam exposure method, and an electrode is evaporated to form a semiconductor transistor;

[0012] A photosensitive protein molecule is grafted as a photosensitive active layer on the semiconductor transistor to obtain the bio-optoelectric transistor.

[0013] Preferably, the semiconductor material is zinc oxide.

[0014] Preferably, the number of electrodes prepared on the semiconductor material is two, and a channel is arranged between the two electrodes, and the channel size is 2-8 μm in length and 2-8 μm in width. Preferably, the electrode material prepared on the semiconductor material is a gold electrode.

[0015] Preferably, the photosensitive protein molecule is a bacteriorhodopsin.

[0016] Preferably, the step of grafting the photosensitive protein molecule as a light absorption layer on the semiconductor transistor comprises:

[0017] The photosensitive protein molecule is dissolved in a buffer solution PBS to obtain a bio-photosensitive protein suspension;

[0018] The photosensitive protein suspension is transferred to the semiconductor transistor, a 1 mV voltage is applied between the source and the drain, the photosensitive protein molecules are directionally arranged on the semiconductor transistor, and the photosensitive protein molecules are heated and dried at 40-50℃ for 10 minutes or naturally air-dried for 1-2 hours to achieve the purpose of grafting the photosensitive protein molecules on the semiconductor transistor.

[0019] The present application also provides an application of the bio-optoelectric transistor device as a photoelectric detection, wherein the gate voltage range of the bio-optoelectric transistor device is-5-5V.

[0020] The present application also provides a bio-optoelectric transistor based on protein molecules, which is prepared by the preparation method of the optoelectric transistor provided by the present application.

[0021] Advantages and effects of the present application

[0022] The biological photoelectric transistor device provided by the application uses biological photosensitive protein molecules as photosensitive units and zinc oxide as a conductive channel, which can not only further explore the photoresponse mechanism and application mechanism of biological photosensitive molecules, but also broaden the response band of zinc oxide and has good sensitivity and specificity.

[0023] The application of the biological photoelectric transistor device provided by the application as a photoelectric detector not only uses light as a gate to control the photocurrent of the transistor, but also adjusts the photocurrent response characteristics of the transistor by adjusting the size of the gate voltage, especially the rising time of the light response, which provides a good idea for the application of a biological photoelectric switch.

[0024] The biological protein molecules of the biological photoelectric transistor device provided by the application can be nanosized, and zinc oxide has good biocompatibility, so that the transistor is expected to be implanted into a biological body in the future to realize some functions of a photoelectric bionic device. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The structure of the protein-based biological photoelectric transistor described in the application is shown.

[0026] Figure 2 The I-t curve (good performance) of the semiconductor transistor described in the application under the irradiation of a 375nm laser light source.

[0027] Figure 3 The I-t curve (poor performance) of the semiconductor transistor described in the application under the irradiation of a 375nm laser light source.

[0028] Figure 4 The transfer characteristic curve of the biological photoelectric transistor based on protein molecules described in the application under dark conditions and light conditions

[0029] Figure 5 The I-t curve of the biological photoelectric transistor based on protein molecules described in the application under the irradiation of a 520nm laser light source

[0030] Figure 6 The I-t curve of the biological photoelectric transistor based on protein molecules described in the application under the irradiation of a 520nm laser light source when the gate voltage is 5V

[0031] Figure 7 The I-t curve of the biological photoelectric transistor based on protein molecules described in the application under the irradiation of a 520nm laser light source when the gate voltage is -5V. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0033] The present application provides a protein molecule-based biophototransistor and a preparation method thereof. In order to make the purpose, technical solutions and advantages of the present application more clear, the present application will be described in detail below in combination with embodiments and drawings.

[0034] Embodiment 1

[0035] Figure 1 is a structural schematic diagram of the protein molecule-based biophototransistor in Embodiment 1 of the present application.

[0036] As shown in Figure 1 , the phototransistor structure in Embodiment 1 mainly includes, from bottom to top, a substrate, a dielectric layer, a channel layer, two gold electrodes and a photosensitive active layer.

[0037] The substrate in Embodiment 1 is a silicon substrate, and the dielectric layer is silicon dioxide with a thickness of 300 nm.

[0038] The channel layer is nanoscale flaky zinc oxide grown by CVD, and has a two-dimensional flaky structure with a size of 8 μm in length and 7 μm in width. In some other embodiments, the size of the flaky zinc oxide can be appropriately selected according to actual conditions, and the range is generally a two-dimensional flaky structure of a square or rectangle with a length of 2-8 μm and a width of about 2-8 μm.

[0039] The electrode pattern designed in advance is exposed on the surface of the channel layer by an electron beam exposure method, and the gold electrode is evaporated by a vacuum thermal evaporation method.

[0040] The photosensitive active layer is a bacteriorhodopsin, which is a photosensitive protein extracted from halophilic bacteria. The concentration of the obtained suspension after extraction is 1.1 mg / mL. The photosensitive protein suspension is drop-coated on the conductive channel layer. In some other examples, the concentration of the suspension can be 1 mg / mL-3 mg / mL.

[0041] In Embodiment 1, the zinc oxide is grown on a sapphire insulating substrate. In other examples, the zinc oxide can be directly grown on a silicon dioxide dielectric layer.

[0042] In Embodiment 1, according to the intermolecular interaction force, the zinc oxide can be transferred to the silicon dioxide dielectric layer through the sapphire substrate to form the channel layer.

[0043] In the present embodiment 1, the channel layer is cleaned with isopropyl alcohol, dried with a nitrogen gun, and the zinc oxide is observed under a 50x microscope and photographed to obtain a micrograph.

[0044] In the present embodiment 1, the electrode pattern is drawn according to the micrograph, the channel layer surface is subjected to electron beam exposure, and the electrode is evaporated to obtain the semiconductor transistor.

[0045] In the present embodiment 1, the electrode is evaporated by vacuum thermal evaporation, and after evaporation, the electrode is taken out after being soaked in acetone solution for 1 hour, washed with isopropyl alcohol for 5 seconds, and dried with a nitrogen gun. The electrode material is a gold electrode, but is not limited thereto, and in some other embodiments, the electrode can be selected according to actual conditions.

[0046] In the present embodiment 1, the semiconductor transistor is subjected to electrical performance testing. The I-V curve and transfer characteristic curve of the semiconductor transistor are tested by a source table and a probe station under dark conditions.

[0047] In the present embodiment 1, the semiconductor transistor is subjected to ultraviolet photoelectric performance testing. The semiconductor transistor is irradiated with a 375nm laser light source, and the light intensity is 0.2mW / cm 2 The I-V curve, transfer characteristic curve, and I-t curve of the semiconductor transistor are tested by a source table and a probe station, so as to determine whether the semiconductor transistor is good in performance.

[0048] Figure 2 The I-t curve of the semiconductor transistor in the present embodiment 1 is shown in the following figure. Figure 2 It can be determined that the semiconductor transistor is good in performance, and the preparation of the protein-based biophototransistor can be performed.

[0049] Figure 3 The I-t curve of the semiconductor transistor in some other embodiments of the present application is shown in the following figure. Figure 3 It can be determined that the semiconductor transistor is poor in performance, and cannot meet the design requirements of the device, and the preparation of the protein-based biophototransistor cannot be performed.

[0050] The preparation method of the protein-based biophototransistor provided in the present embodiment 1 further comprises the following steps:

[0051] 1.1mg of photosensitive protein molecular powder is weighed and dissolved in 1mL of buffer solution PBS (pH=6.5), and ultrasonic treatment is performed for 3 minutes, so that the protein is uniformly distributed in the solution, thereby obtaining a biophototransistor suspension;

[0052] 10 μL of the photosensitive protein suspension is dropped onto the surface of the semiconductor transistor by using a pipette, a 1 mV voltage is applied between the source and the drain, the photosensitive protein molecules are oriented and arranged on the surface of the semiconductor transistor, and the photosensitive protein molecules are grafted onto the semiconductor transistor by heating and drying at 50 °C for 10 minutes. In other embodiments, different dosages of the photosensitive protein suspension can be dropped onto the surface of the semiconductor transistor according to actual needs by using a pipette.

[0053] In this embodiment 1, the electrical performance of the biological photoelectric transistor is studied. The I-V curve and the transfer characteristic curve of the biological photoelectric transistor are tested by using a source table and a probe station under dark conditions.

[0054] In this embodiment 1, the photoelectric performance of the biological photoelectric transistor is studied. The biological photoelectric transistor is irradiated by using a 520 nm laser light source, the light intensity is 0.2 mW / cm 2 , and the light irradiation frequency is 0.5 Hz. The I-V curve, the transfer characteristic curve, and the I-t curve of the biological photoelectric transistor are tested by using a source table and a probe station.

[0055] Figure 4 The transfer characteristic curve of the biological photoelectric transistor described in this embodiment 1 of the application under dark and 520 nm light irradiation conditions.

[0056] Figure 5 The I-t curve of the biological photoelectric transistor described in this embodiment 1 of the application under 520 nm light irradiation conditions.

[0057] In this embodiment 1, a positive gate voltage of 5 V is applied to the gate of the biological photoelectric transistor. The biological photoelectric transistor is irradiated by using a 520 nm laser light source, the light intensity is 0.2 mW / cm 2 , and the laser light source is pulsed, with a frequency of 0.5 Hz. Figure 6 The I-t curve of the biological photoelectric transistor described in this embodiment 1 of the application is tested by using a source table and a probe station.

[0058] In this embodiment 1, a negative gate voltage of -5 V is applied to the gate of the biological photoelectric transistor. The biological photoelectric transistor is irradiated by using a 520 nm laser light source, the light intensity is 0.2 mW / cm 2 , and the laser light source is pulsed, with a frequency of 0.5 Hz. Figure 7 The I-t curve of the biological photoelectric transistor described in this embodiment 1 of the application is tested by using a source table and a probe station.

[0059] Embodiment 2

[0060] The embodiment differs from embodiment 1 in that, in the preparation of the protein-based biophototransistor, the photosensitive protein molecules are drop-casted on the surface of the semiconductor transistor, and then tested after natural air drying for 2 hours.

[0061] Embodiment 3

[0062] The embodiment differs from embodiment 1 in that, in the preparation of the protein-based biophototransistor, the channel layer of the semiconductor transistor, i.e. the sheet-shaped zinc oxide, has a size of 2 μm in length and 7 μm in width.

[0063] In summary, the biophototransistor device prepared according to the preparation method of the present application can further explore the light response characteristics of the photosensitive protein molecule bacteriorhodopsin, and belongs to the application field research of biological photosensitive materials. In addition, previous research on protein-based photovoltaic cells requires providing an electrolyte conductive loop environment for the device, and the electrolyte solution will bring a large dark current to the device loop. The protein-based biophototransistor can provide a conductive channel for the device by using the semiconductor material zinc oxide to form a conductive loop, without the need to achieve it through an electrolyte solution, thereby reducing the influence of dark current noise.

[0064] In the present application, the channel layer provides a conductive channel for the photosensitive active layer, and the conductive channel adjusts the electrical properties of the device and controls the migration speed of the charge carriers by changing the source-drain voltage.

[0065] In the present application, the biophototransistor is regulated by the gate voltage under light conditions. When the gate voltage is positive, the response speed of the photocurrent is accelerated; when the gate voltage is negative, the response speed of the photocurrent is slowed down. Based on this experimental phenomenon, the biophototransistor is expected to be made into a photoelectric switch device.

[0066] In the present application, the biophototransistor widens the light response band of zinc oxide, so that zinc oxide can absorb the energy of the visible light band, and also has specific wavelength selectivity, and only responds to a certain band of visible light.

[0067] The above-described embodiments are only preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Any equivalent replacement or transformation made by those skilled in the art on the basis of the present application is within the protection scope of the present application. The protection scope of the present application is subject to the claims.

Claims

1. A method for fabricating a protein-based bio-optotransistor, characterized in that: A silicon dioxide dielectric layer is grown on a silicon substrate, and a semiconductor material is transferred to the dielectric layer to form a channel layer; a pre-designed electrode pattern is exposed on the semiconductor material using electron beam lithography, and electrodes are deposited by vapor deposition to form a semiconductor transistor. The bio-optotransistor is fabricated by grafting photosensitive protein molecules, which serve as the photosensitive active layer, onto the semiconductor transistor. The aforementioned photosensitive protein molecule is bacterial rhodopsin. The steps of grafting photosensitive protein molecules as a light-absorbing layer onto the semiconductor transistor include: The aforementioned photosensitive protein molecules were dissolved in a buffer solution PBS to obtain a biological photosensitive protein suspension; The photosensitive protein suspension is transferred to the semiconductor transistor. A 1mV voltage is applied between the source and drain electrodes to orient the photosensitive protein molecules on the semiconductor transistor. The transistor is then heated and dried at 40-50°C for 10 minutes or air-dried for 1-2 hours to graft the photosensitive protein molecules onto the semiconductor transistor. The semiconductor material is nanoscale sheet-like zinc oxide.

2. The method for fabricating a bio-phototransistor according to claim 1, characterized in that, Two electrodes are fabricated on the semiconductor material, and a channel is provided between the two electrodes. The channel has a length of 2-8 μm and a width of 2-8 μm.

3. The method for fabricating a bio-photoelectric transistor according to claim 2, characterized in that, The electrode material prepared on the semiconductor material is a gold electrode.

4. The bio-phototransistor prepared by the method for preparing a protein-based bio-phototransistor according to any one of claims 1-3 is used for photoelectric detection, characterized in that... The gate voltage range of the bio-photoelectric transistor is -5 to 5V.

5. A protein-based bio-photoelectric transistor, characterized in that, The phototransistor was prepared using the fabrication method described in any one of claims 1-3.

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