KR20050055456A - Biosensor using zinc oxide nanorod and preparation thereof - Google Patents

Abstract

The present invention relates to a biosensor using zinc oxide nanorods and a method for manufacturing the same, wherein the nanosensor fabricated using the zinc oxide nanorod grown by the organometallic chemical vapor deposition method according to the present invention using the sensing unit of the sensor Sensitive, stable and reproducible, it is possible to observe the interactions of antigens / antibodies, enzymes / substrates, receptors / effectors and enzyme inhibitors, as well as to detect various biomolecules. It can be advantageously used for future biotechnology technologies such as genetic analysis and disease diagnosis at the biomolecular level.

Description

Biosensor using zinc oxide nanorod and manufacturing method thereof {BIOSENSOR USING ZINC OXIDE NANOROD AND PREPARATION THEREOF}

The present invention relates to a nano-biosensor capable of observing a biomolecule individual at the macromolecular level by using an oxide semiconductor nanorods, and to fabrication thereof. Specifically, a zinc oxide-based nanorod grown using an organometallic chemical vapor deposition method The present invention relates to a novel biosensor manufactured by forming electrodes on a horizontal or vertical orientation.

Nano-sized materials have emerged as a very important field in the recent scientific community due to their new physical and chemical properties, namely their unique electrical, optical and mechanical properties. The research on nanostructures that have been carried out to date shows new possibilities such as quantum size effects and the potential of new optical device materials of the future. In particular, nano-sized materials can be used in various sensors because the small size increases the surface area / volume ratio, so that the electrochemical reaction occurring on the surface becomes superior.

However, most nanomaterials made by stacking methods are very difficult to artificially manipulate, and thus are difficult to apply to actual devices. However, since one-dimensional nanomaterials such as nanotubes, nanowires, and nanorods are easy to operate due to their large aspect ratio, they are first implemented as nanodevices and are closest to practical application. Recently, various electronic devices and nanosensors using the one-dimensional semiconductor nanomaterial have been manufactured and attract attention.

For example, in 2000, H. Dai's research team at Stanford University developed a chemical sensor that can detect gas molecules such as NO ₂ and NH ₃ using single-walled carbon nanotubes (Science 287, 622 (2000)), and in 2003, Alexander Star team of Nanomix developed a biosensor that detects biotin-streptavidin binding using carbon nanotubes ( Alexander star et al ., Nano letters, 2003, vol 3, 459). However, since gas and biomolecules can be detected only by using nanomaterials exhibiting semiconductor characteristics, nanotubes, which are difficult to control metallicity and semiconductivity, have many limitations.

In contrast, the semiconductor nanowires can easily control the electrical conductivity through impurity doping, thereby facilitating device fabrication and improving the sensitivity of the device. For example, in 2001, a team of professors H. Park and CM Lieber of Harvard University in the United States detected various biomolecules by modifying the surface of a silicon nanowire, a type of non-oxide nanowire, with a receptor. Nano sensors have been developed (Science 293, 1289 (2001)). However, when fabricating a biosensor using non-oxide nanowires, there is a problem that the sensitivity is lowered because an oxide, which is an insulating layer, is formed on the surface of the nanowires.

From this point of view, the oxide semiconductor nanorods have the advantages of being chemically stable, excellent in sensitivity, and having low contact resistance between the electrode and the metal electrode when fabricated as nanodevices. In particular, the zinc oxide nanorod has a direct transition band structure of 3.4 eV, the band gap can be adjusted to 2.8 to 4.1 eV by adding Cd or Mg, and the conductivity is controlled by doping with Al or Ga. It is expected to be a key material for next generation nano biosensor. However, no studies on biosensors using zinc oxide nanorods have been reported worldwide.

Accordingly, an object of the present invention is a biosensor capable of observing a biomolecular entity at the macromolecular level, using a oxide semiconductor nanorod having a large surface area / volume ratio and having a chemically stable surface, with excellent sensitivity and stability. To provide.

In order to achieve the above object, the present invention provides a biosensor comprising an insulating substrate, a sensing layer including a zinc oxide nanorod on the substrate and an electrode layer formed on the sensing layer.

In addition, the present invention provides a method for manufacturing a biosensor, comprising forming an electrode after the zinc oxide nanorods grown by organometallic chemical vapor deposition are oriented horizontally or vertically on a substrate.

Hereinafter, the present invention will be described in more detail.

Specifically, the biosensor according to the present invention separates the zinc oxide nanorod grown on the substrate from the substrate and then oriented horizontally on the insulating substrate, or directly using the zinc oxide nanorod array oriented vertically on the substrate. Can be prepared.

In the present invention, the zinc oxide nanorod used as the sensing material in the sensing layer is injected with zinc-containing organometallic and oxygen-containing gas or oxygen-containing organic material into the reactor through separate lines, and argon as the carrier gas. It can be prepared by an organometallic chemical vapor deposition method characterized in that the precursors of the reactants are chemically reacted using an inert gas such as and the like.

In the present invention, the diameter, length, and density of the grown zinc oxide nanorods can be variously adjusted according to the growth temperature, pressure, and the flow rate of the reactant, and can be selectively sensed while improving the sensitivity of the sensor. Various organic or inorganic materials such as Mg, Cd, Ti, Li, Cu, Al, Ni, Y, Ag, Mn, V, Fe, La, Ta, Nb, Ga, In, S, Se, P, At least one selected from the group consisting of As, Co, Cr, B, N, Sb, and H, or various heterogeneous materials such as GaN, AlN, InN, GaAs, InP, GaP, or alloys thereof may be coated on zinc oxide. have.

The zinc oxide nanorod according to the present invention is excellent in electrical and optical characteristics because the reaction precursors are grown directly to the nucleating agent without using a metal catalyst, thereby preventing contamination by the catalyst.

Examples of the insulating substrate used in the present invention include a silicon substrate, a glass substrate, a quartz substrate, a Pyrex substrate, a sapphire substrate, a plastic substrate, and a substrate coated with an insulating film.

The biosensor according to the present invention may be manufactured in various forms. For example, after separating the zinc oxide nanorod grown by the organometallic chemical vapor deposition method from the substrate, one or several zinc oxide nanorods are insulated from each other. The electrode may be prepared by placing the electrode horizontally on the substrate and then attaching the electrode. Alternatively, the electrode may be directly formed on the zinc oxide nanorod array vertically oriented on the substrate.

Specifically, since the zinc oxide nanorod has a large aspect ratio and is easy to be artificially manipulated, it is possible to manufacture nanodevices using individual nanorods relatively easily. As shown in FIG. For example, by scraping with a sharp tool such as a knife to separate from the substrate, a single zinc oxide nanorod is dissolved in an organic solvent such as ethanol, and then dispersed on an insulating substrate, and the metal layer is patterned by electron beam lithography. After the formation, the nano biosensor may be manufactured by forming an ohmic electrode by sequentially depositing and thermally treating a metal layer such as titanium (Ti) and gold (Au) using heat or electron beam evaporation.

In addition, as shown in FIG. 2A, a biosensor may be manufactured by forming an electrode on a zinc oxide-based nanorod deposited by vertically depositing growth on a substrate by an organometallic chemical vapor deposition method. Using the substrate on which the zinc-based nanorods and the metal electrode are deposited, the nanosensor can be more easily manufactured.

The biosensor using the zinc oxide nanorod of the present invention is a biosensor to PEG (polyethylene glycol), PEI (polyethyleneimine), PLA ( Polymer solutions selected from PEG modified with polylactic acid) and the like; Or zinc oxide type immersed in an organic solvent such as polydiallyldimethylammonium chloride, polysodium 4-styrenesulfonate and diazo resin for 12 to 14 hours, as shown in FIG. The nanorod surface can also be used by coating with the polymer or organic solvent.

Biosensors prepared using zinc oxide-based nanorods according to the present invention are biotin or antigen-antibody binding of biotin or modified biotin and streptavidin or modified streptavidin, and LDL, DNA and biological proteins. Biological molecules such as and the like, and their interactions.

For example, biotin belongs to the vitamin B group and is a vitamin necessary for metabolism and growth of the human body. When lack of biotin, the body becomes tired easily and causes depression, myalgia, hair loss, anemia, and LDL. It is an important cause factor. Therefore, the nano biosensor according to the present invention can detect such biomolecules and can be used for genetic analysis, disease diagnosis, and the like.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the invention only.

Example 1 Preparation of Biosensor Using Single Zinc Oxide Nanorod

Argon is used as a carrier gas via separate lines to inject the reaction precursors dimethylzinc (Zn (CH ₃ ) ₂ ) and O ₂ gas into the reactor at flow rates ranging from 1 to 10 sccm and 20 to 100 sccm, respectively, The materials were chemically reacted on the substrate to deposit and grow a zinc oxide nanorod. During the growth of the nanowires over about 1 hour, the pressure in the reactor was maintained at 0.1 to 100 torr, and the temperature was maintained at room temperature to 800 ℃.

Subsequently, the grown zinc oxide nanorods were scraped off with a knife, separated from the substrate, mixed with ethanol, and then dispersed in an insulating substrate, SiO ₂ / Si, placed in the correct position using an electron microscope, and the zinc oxide nanorods. Ti (300 mW) / Au (500 mW) was deposited on the tip portion by heat or electron beam evaporation and then heat treated at about 300 ° C. for 1 minute to form an ohmic electrode, as shown in FIG. 1A. A biosensor having a horizontal orientation with a nanorod was manufactured.

In addition, the scanning electron micrograph of the prepared biosensor is shown in Figure 1b.

Example 2 Preparation of Biosensor Using Vertically Oriented Zinc Oxide Nanorods

Using argon as a carrier gas through separate lines, the reaction precursors, dimethylzinc and O ₂ gas, were injected into the reactor at flow rates ranging from 1 to 10 sccm and 20 to 100 sccm, respectively, and the chemicals were reacted on the substrate. The zinc oxide nanorods were deposited and grown. During the growth of the nanowires over about 1 hour, the pressure in the reactor was maintained at 0.1 to 10 torr, the temperature was maintained at room temperature to 800 ℃.

Subsequently, titanium (Ti) (300 kPa) and gold (Au) (500 kPa) were sequentially deposited on the grown zinc oxide nanorod tips by heat or electron beam evaporation, followed by heat treatment at about 300 ° C. for 1 minute. By forming an upper ohmic electrode, as shown in FIG. 2a, a biosensor having a zinc oxide nanorod was vertically oriented was manufactured.

In addition, a scanning electron micrograph of the prepared biosensor is shown in Figure 2b.

Test Example 1: Measurement of biotin-streptavidin binding detection

The biosensor prepared in Example 1 was immersed in a solution in which 0.0337 g of PEG was dissolved in 2250 μl of deionized water for about 20 hours, and the zinc oxide nanorod surface was coated with PEG as shown in FIG. 3. Subsequently, 5 μl of biotin at a concentration of 1 μM and 5 μl of biotin (biotin PEG) modified with PEG were dropped onto the sensor, respectively, to adsorb the biotin and biotin PEG on the PEG coated zinc oxide nanorods, respectively. The current was measured while varying the voltage, and the results are shown in FIGS. 4A and 4B, respectively. Then, 5 μl of streptavidin at a concentration of 200 μM as an antigen was dropped onto the sensor, and the current was measured while changing the voltage of the biosensor. The results are shown in FIGS. 4A and 4B, respectively. 4A and 4B, when only biotin or biotin modified with PEG is adsorbed to the zinc oxide nanorod coated with PEG, the current hardly changes even when the voltage is increased, but the saturation current rapidly increases with the introduction of streptomycin. It can be seen that the biosensor according to the present invention can detect biotin-streptavidin binding.

Test Example 2: LDL Detection Measurement

1 ml of LDL was dissolved in a mixed solution of 0.5 ml of 0.15 M NaCl and 0.5 ml of 0.01% EDTA at pH 7.4, and then 0.004 mg of the freeze-dried LDL mixture was dissolved in 1 ml of ethanol. After dropping on the biosensor manufactured by the present invention while measuring the current while changing the gate voltage of the biosensor, the results are shown in Figure 5 with the current measurement results of the biosensor not treated with LDL. From FIG. 5, a biosensor having a single zinc oxide nanorod manufactured in accordance with the present invention, which is horizontally oriented on a substrate, can detect LDL because the current decreases after treatment with LDL than before dropping LDL. Able to know.

Test Example 3: LDL Detection Measurement

Except for using the biosensors prepared in Example 2 instead of the biosensors prepared in Example 1, by performing a similar process to Test Example 2 to determine whether the LDL detection as shown in Figure 6, LDL It can be seen that the biosensor using the zinc oxide nanorod oriented vertically to the substrate prepared according to the present invention can detect the LDL after the current is decreased after the LDL is injected rather than before dropping.

Biosensors manufactured using zinc oxide nanorods, which are oxide semiconductors according to the present invention, are highly sensitive, stable, and reproducible, and can observe individual biomolecules and their interactions. It provides biotechnology-based technologies such as diagnostics, and is expected to create tremendous added value as it can be applied to ultra-high-density electronic devices and biochips for implementing functional nanosystems in the future.

1A and 1B are structural diagrams and scanning electron microscopy (SEM) photographs of a biosensor using a single zinc oxide nanorod oriented horizontally on a substrate according to the present invention, respectively.

2A and 2B are structural diagrams and scanning electron microscope (SEM) photographs of a biosensor using zinc oxide-based nanorods oriented perpendicular to a substrate, respectively, according to the present invention;

3 is a structural diagram of a biosensor using a single zinc oxide-based nanorod coated with PEG according to the present invention,

4A and 4B are graphs showing electrical property changes according to detection of biotin-streptavidin and biotinPEG-streptavidin binding of a biosensor using a single zinc oxide-based nanorod coated with PEG according to the present invention.

5 is a graph showing a change in electrical characteristics according to the detection of the LDL of the biosensor using a single zinc oxide nanorod according to the present invention,

FIG. 6 is a graph illustrating changes in electrical characteristics according to LDL detection of a biosensor using zinc oxide-based nanorods oriented perpendicular to a substrate according to the present invention.

Claims (10)

A biosensor comprising an insulating substrate, a sensing layer on the substrate, and an electrode formed on the sensing layer, wherein the sensing layer comprises a zinc oxide nanorod. The method of claim 1, Zinc oxide nanorods include Mg, Cd, Ti, Li, Cu, Al, Ni, Y, Ag, Mn, V, Fe, La, Ta, Nb, Ga, In, S, Se, P, As, Co, Biosensor characterized in that it further comprises at least one heterogeneous material selected from the group consisting of Cr, B, N, Sb and H. The method of claim 1, Biosensor characterized in that the zinc oxide nano-rod further comprises a GaN, AlN, InN, GaAs, InP, GaP or alloys thereof. The method of claim 1, And a zinc oxide nanorod is coated with a polymer selected from the group consisting of PEG, PEI and modified PEG. The method of claim 1, A biosensor characterized in that the zinc oxide nanorod is coated with an organic solvent selected from polydiallyldimethylammonium chloride, polysodium 4-styrenesulfonate and diazo resin. The method of claim 1, A biosensor, wherein the substrate is selected from a silicon substrate, a glass substrate, a quartz substrate, a Pyrex substrate, a sapphire substrate, a plastic substrate, and a substrate coated with an insulating film. The method of claim 1, A biosensor, which is used for detection of antigen-antibody binding, biomolecules and their interactions. The method of claim 7, wherein A biosensor, wherein the antigen is streptavidin or modified streptavidin and the antibody is biotin or modified biotin. The method of claim 7, wherein Biosensor, characterized in that the biomolecule is LDL, DNA or protein. 10. A method of manufacturing a biosensor according to any one of claims 1 to 9, comprising aligning a zinc oxide nanorod grown by an organometallic chemical vapor deposition method horizontally or vertically on a substrate and then forming an electrode.