KR100910032B1 - Method for fabrication of cationized ferritins on metal/Si substrate - Google Patents

Abstract

The present invention comprises the steps of preparing a silicon (Si) substrate; Etching the upper portion of the silicon (Si) substrate using a wet etching solution; Forming a metal layer on the etched silicon substrate by a thermal deposition method; And adsorbing cationized ferritin protein particles to a predetermined thickness on the metal layer by spin coating. The method of claim 1, wherein the cationized ferritin particles are formed on a metal / silicon substrate. According to the present invention, it is possible to provide a method for depositing ferritin protein, which is excellent in charge storage and electron transfer ability, on a Si substrate with a certain thickness, and increase the possibility of practical use of the biocell.

Silicon, Wet Etch, Ferritin, Cationic, Bio Cell

Description

Method for fabrication of cationized ferritins on metal / Si substrate}

The present invention relates to a method of forming cationized ferritin particles on a metal / silicon substrate. More particularly, the present invention relates to a method of forming ferritin protein particles on a metal / silicon substrate by electrostatic force by spin-self assembly (SSA). It relates to a method for manufacturing a bio-cell device to be deposited.

The cell business is developing significantly in the primary, secondary, and fuel cell areas, with a focus on the development of materials and structures that can accommodate more capacitance. Among them, fuel cells using Li-ion have exploded in demand due to the development of micro-fixing technology and the increase of power supply of micro precision devices and portable devices such as laptops, mobile phones, and digital cameras. The continuing development of IT technology has increased the amount of power used, making the field of batteries as a power supply medium increasingly important.

In the past, the battery market has been rapidly developing around primary batteries, but since the 21st century, the market of fuel cells has been growing rapidly due to the development of portable devices such as digital cameras, MP3s, mobile phones, and IT industries. It is expected to occupy most of the market. The important factors in the growth of the fuel cell market are battery capacity and safety. In particular, bio-cells using biomaterials have recently emerged with the development of medical devices such as biosensors that monitor changes in the body, and the necessity of insert-type power supplies to raise the need for human-friendly and environment-friendly batteries. Because there is an advantage that can be applied to the application field, the related research should be done as soon as possible.

To increase the capacity of the cell, the amount of charge storage layer must be increased. While reducing the size of the battery cell, the amount of charge electric field layer should be increased. However, the current time of the secondary battery is as short as 2-3 hours on a notebook basis, and because of the use of metal ions, there is a risk of explosion and the possibility of environmental pollution. On the other hand, bio-cells using human and animal proteins have no possibility of environmental pollution and explosion, and when they are made in a laminated structure, new secondary batteries can be realized due to an increase in charge storage due to nano-structures.

The present invention is designed to solve the difficulties of the existing technology. Conventional secondary batteries use heavy metals or ignition materials such as lithium ions or hydrogen ions in the manufacturing process, so there is always a risk of exothermic or reprocessing problems after use.

The present invention increases the total charge by uniformly and stably applying environmentally friendly biomaterials with a high charge storage amount, and can be operated for a long time using biomaterials that have no environmental problems after use, and thermally and environmentally. It is an object of the present invention to provide a method of forming cationized ferritin particles on a metal / silicon substrate in order to manufacture a stable biocell.

The present invention for achieving the above object,

Preparing a silicon (Si) substrate;

Etching the upper portion of the silicon (Si) substrate using a wet etching solution;

Forming a metal layer on the etched silicon substrate by a thermal deposition method; And

 And adsorbing cationized ferritin protein particles to a predetermined thickness on the metal layer by spin coating. The method provides a method of forming a cationized ferritin particle on a metal / silicon substrate.

The wet etching solution is preferably at least one selected from the group consisting of HF, HCl, H ₂ O, H ₂ O ₂ , NaOH and KOH.

The metal layer is preferably any one component selected from Au, Ag, Ti, and Al.

The ferritin protein layer preferably contains metal nanoparticles therein.

In the etching step, the etching time is 2 to 4 hours, and the thickness of the metal layer is preferably 10 to 100 nm.

The present invention relates to the fabrication of a bio-cell using a protein particle that can operate at a lower voltage as well as a sufficient operating time compared to a conventional bio-cell and its adsorption method.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention allows protein particles to be adsorbed to the surface of the substrate well by using a wet etching method of the bio-material protein is applied to the substrate to a certain thickness by using a spin coating to have a fixed capacitance has a charge capacity and power supply Can be used as

First, a substrate is prepared to complete the process as shown in FIG. 1 [(a)]. The etching solution is used to etch a portion of Si and the SiO ₂ layer 11 on the Si substrate 10 [(b)]. The etching solution is preferably at least one selected from the group consisting of HF, HCl, H ₂ O, H ₂ O ₂ , NaOH and KOH. The metal layer 20 is formed on the Si substrate 10 etched with the metal by thermal evaporation [(c)]. The metal layer 20 may be formed using any one component selected from Au, Ag, Ti, and Al. The ferritin protein particle layer 30 is formed by applying a ferritin protein to a predetermined thickness on the Si substrate 10 on which the metal layer 20 is formed using a spin coating method [(d)]. The ferritin protein particle layer 30 may contain metal nanoparticles therein.

Metal / etched Si leads to more cationic cationized ferritin than metal / unetched Si. The surface is negatively charged due to the state of charge at the interface between the metal and the etched Si substrate. Electrostatic forces generated at the surface induce cationized ferritin molecules.

In general, Si surfaces are highly reactive and can react with various kinds of materials. The silicon surface has a SiO _x of about 15 kPa when exposed to air. By etching, not only the oxygen film at the surface but also Si atoms are etched, which exists as a dangling bond (DB). In the case of bulk Si, two neighboring atoms contribute to each one atom to form a covalent bond, and the surface Si atoms have unsaturated DB with the atoms. This surface causes negative charge on the n-type Si, which is reactive due to the DB and has a high dopant concentration.

Due to the DB at the interface between the silicon and the metal, the metal (eg Au) surface is negatively charged. Si surfaces containing many DBs are negatively charged, and the electrostatic forces at the interface between the metal and the silicon substrate attract electrons from the metal film to the metal surface. Thus, the electrostatic force on the metal film strongly fixes the cationized ferritin on the metal surface. The number of electrons at the metal surface depends on the density of the DB and the thickness of the metal film in relation to the etching time.

The longer the etching time of the Si substrate, the more ferritin molecules are present on the gold film. The etching time in the etching step is preferably 2 to 4 hours. If the etching time is less than 2 hours, the effect of etching is insignificant and undesirable. If the etching time is more than 4 hours, the Si may be damaged and the density is drastically reduced.

2 shows the relationship between the dangling bond (DB) present on the Si substrate and the electrostatic force on the gold surface. Referring to FIG. 2, when there are many dangling bonds (DB), the electrostatic force on the Si substrate surface pushes the electrons in a gold film to the surface. On the other hand, if the gold surface is negatively charged, its electrostatic force induces cationized ferritin. In the case of a weak etched Si, the surface contains a small DB, attracting less electrons to the gold surface and inducing less ferritin. In addition, the larger the thickness of the gold film, the fewer the electrons on the gold surface. In other words, the reduction of the gold film thickness contributes to the reduction of the ferritin appearance density.

It is preferable that the thickness of the said metal layer is 10-100 nm. When the thickness of the metal layer is less than 10 nm, the effect of metal deposition is insignificant and undesirable. If the thickness of the metal layer is greater than 100 nm, the density of ferritin molecules decreases and the adsorption effect is lowered.

The present invention provides a method for depositing protein particles with a predetermined thickness on a semiconductor substrate to improve the bio-cell by increasing the operating power and operating time of the bio-cell using the protein.

In addition, the present invention can improve the performance of the battery by increasing the deposition power and deposition amount of the protein particles through a simple process in the bio-cell implementation.

Example

Example  One

Cationic ferritin was prepared using a chemical reaction based on the activation of the carboxyl group of ferritin and the activation of water-soluble carbodiimide (EDC) and the reaction of the activated carboxyl group with N, N-dimethyl-1,3-propanediamine (DMPA). Further purification was performed with a 100kDa membrane. The protein concentration was then measured using the Bradford method (9.7 g / L).

The N-type Si wafer was etched at 80 ° C. for 2, 4, 6 hours using HF solution. Each wafer thus prepared is then heated to a NH ₃ : H ₂ O ₂ : H ₂ O (1: 1: 5) base mixture at 80 ° C. for 15 minutes to completely etch the substrate surface and by N ₂ gas purge Dried.

The gold film was deposited to have a thickness of 10, 50, and 100 nm, respectively, in order to prevent passivation due to oxidation before being used for deposition of cationized ferritin on the prepared Si substrate.

Deposition is performed using spin self assembly (SSA). Specifically, one drop of the cationic ferritin solution was dissolved in 0.15 M NaCl solution deposited on the gold film using a spin coater rotating at a fixed rotational speed of 200 rpm. Immediately, the rotation speed was increased to 4,000 rpm. After deposition of the ferritin film, the substrate was thoroughly washed twice with a large amount of deionized water. The rotational speed of the spin coater in the washing step was 4,000 rpm as in the case of film deposition.

Results and rating

After etching the surface of the silicon (Si) substrate using an etching solution and depositing a metal on the thinly etched Si substrate by thermal evaporation, the ferritin protein particles dispersed in the solution using a spin coater are used to deposit the silicon substrate. The characteristics of ferritin protein were examined by applying the amount of the current flowing through the ferritin protein particles by applying on the Atomic Force Microscopy (AFM) and in-air photography (Nanoscope IV, Digital Instruments).

Atomic force microscopy (AFM) images of ferritin protein particles deposited on unetched silicon substrates are shown in FIGS. 3A and 3B. FIG. 3A is an AFM image of a gold surface with a thickness of 50 nm on an unetched silicon surface, and FIG. 3B shows an AFM image of peripine molecules deposited on the surface using the SSA method. 3A and 3B show little difference between the images, meaning that the ferritin protein molecules were hardly adsorbed onto the etched silicon substrate and the gold film.

In addition, the silicon substrate was etched for 4 hours, gold was deposited on the etched silicon substrate, and the cationic ferritin protein was deposited using the SSA method. Images of ferritin molecules aligned on the substrate are shown in FIGS. 4A and 4B. Figures 4a and 4b shows the shape of ferritin protein deposited on the Au / etched Si substrate.

3A, 3B, 4A, and 4B, the cationized ferritin protein molecules are not adsorbed on the Au film, but the etched silicon substrate allows Au to adsorb ferritin well.

5 is a transmission electron microscope (TEM) photograph of a gold layer and a ferritin protein particle layer sequentially deposited on a silicon substrate.

Given height using the software provided by the AFM manufacturer and standard normal distribution (SND) to find the optimal etch conditions and accurate measurement of how much ferritin is present on each manufactured substrate The upper ferritin content of was investigated. This method can obtain additional information about the statistical deviation from the mean height. By using SND, the content of ferritin located above any height can be calculated as a percentage. 6 shows a histogram derived from SND analysis at a specific height based on the calculation of the pixel for the Z height.

Roughness analysis yielded the percent ferritin over 4 nm height from the substrate, the average height of the gold film, as shown in FIGS. 7A and 7B. Referring to FIG. 7A, the distribution of ferritin according to Au thickness at the same etching time (4 hours) is shown. Referring to FIG. 7B, the distribution of ferritin according to the etching time at the same Au thickness (50 nm) is shown. This result means that the density of ferritin molecules decreases as the Au thickness is increased first. Also, the longer the etching time of Si substrate, the more ferritin molecules are present on the gold film. If it exceeds time, it may damage Si and it shows that density falls rapidly. These experimental results confirm that the dominant factor for the adsorption of ferritin molecules on the Au surface is wet etching of the Si substrate.

8A to 8D show AFM images of the Si surface before and after 2, 4 and 6 hours after etching, respectively. The etched Si substrate shows a more non-uniform surface compared to the unetched substrate. This breaks down the weak oxygen via wet etching and breaks the weak Si bonds which can create a DB in contact at the surface / air interface. The other structure of the Au, Au / Si interface deposited on the etched Si allows the gold surface to further induce ferritin molecules as compared to the case of unetched Si. It can be seen that when the etching time is 6 hours, Si is seriously damaged and interferes with the preparation of the DB.

1 is a process diagram of a method of depositing ferritin protein particles on a silicon substrate.

2 shows the relationship between the dangling bond (DB) present on the Si substrate and the electrostatic force on the gold surface.

3A is an Atomic Force Microscopy (AFM) photograph of a gold surface deposited on a silicon substrate, each of which is not subjected to a deposition process.

3B is an atomic force microscope (AFM) photograph of ferritin protein deposited on a gold surface using SSA method.

4A and 4B are Atomic Force Microscopy (AFM) photographs of ferritin protein particles deposited on a silicon substrate using a deposition process.

5 is a transmission electron microscope (TEM) photograph of a gold layer and a ferritin protein particle layer sequentially deposited on a silicon substrate.

6 shows a histogram of a specific height based on the calculation of a pixel represented at the Z height.

Figure 7a shows the distribution of ferritin according to Au thickness, Figure 7b shows the distribution of ferritin according to the etching time.

8A shows the roughness of the Si substrate before etching, FIG. 8B shows the roughness of the Si substrate after etching for 2 hours, FIG. 8C shows the roughness of the Si substrate after etching for 4 hours, and FIG. 8D shows the etching for 6 hours. The roughness of the Si substrate is then shown.

<Explanation of symbols for the main parts of the drawings>

10 Si substrate 11 SiO ₂ layer

20: Au layer

30: kemperitin protein particle layer

Claims (5)

Preparing a silicon (Si) substrate; Etching the upper portion of the silicon (Si) substrate using a wet etching solution; Forming a metal layer on the etched silicon substrate by a thermal deposition method; And Adsorbing cationized ferritin protein particles on the metal layer using spin coating; and forming cationized ferritin particles on the metal / silicon substrate. The method of claim 1, wherein the wet etching solution is formed of cationized ferritin particles on the metal / silicon substrate, characterized in that at least one selected from the group consisting of HF, HCl, H ₂ O, H ₂ O ₂ , NaOH and KOH. How to. The method of claim 1, wherein the metal layer is any one selected from Au, Ag, Ti, and Al. The method of claim 1, wherein the ferritin protein layer contains metal nanoparticles therein. The method of claim 1, wherein the etching time in the etching step is from 2 to 4 hours, and the thickness of the metal layer is from 10 to 100 nm.

Images