Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
  • G01N27/622—Ion mobility spectrometry
  • G01N27/623—Ion mobility spectrometry combined with mass spectrometry
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
  • B82B1/00—Nanostructures formed by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
  • G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J49/00—Particle spectrometers or separator tubes
  • H01J49/02—Details
  • H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
  • H01J49/0409—Sample holders or containers
  • H01J49/0418—Sample holders or containers for laser desorption, e.g. matrix-assisted laser desorption/ionisation [MALDI] plates or surface enhanced laser desorption/ionisation [SELDI] plates

Definitions

• This invention relates to a nanowire-assisted method for mass spectrometric analysis of a specimen. More specifically, this invention, by using nanowire, can fix a specimen and perform desorption/ ionization of the specimen while effectively transferring laser energy to the specimen to be irradiated, thereby performing mass spectrometric analysis without using a matrix solution.
• Mass spectrometer is an analytical device for measuring a mass of a compound. It generally determines molecular weight of a compound by measuring the value of mass-to-charge (m/z) by ionizing the compound by charging. There are many methods to ionize a compound such as electron ionization using electron beams, high speed collision of atoms, a method using laser, and a method to spray a specimen into an electric field.
• MALDI-Tof Mass Spectroscopy Matrix Assisted Laser Desorption/ Ionization Time of Flight Mass Spectroscopy; hereinafter MALDI
• MALDI MALDI-Tof Mass Spectroscopy
• these devices can measure molecular weight of polymers with molecular weight of 300 kDa or higher by using matrix which not only assists the transfer of energy to a substance to be analyzed but also facilitates ionization of the substance.
• specimens are prepared as follows. (1) A small amount of matrix solution is added onto a target board made of a metal plate, dried and then a specimen solution to be analyzed is further added on top of it and dried; or A matrix substance is mixed with a specimen solution, placed onto a target plate and then crystallized. (2) The area of the matrix and crystallized specimen is irradiated with laser and the specimen becomes desorbed/ ionized being assisted with the matrix.
• Typical mass spectrometer has a structure that it applies an electric field between the target board where a specimen is located and a sensor for mass analysis so that ionized specimen can be moved into a sensor due to the difference in potentials.
• the mass of the specimen can be analyzed based on variables such as the time required for the specimen to reach the sensor.
• the above MALDI method is very useful for mass analysis but it is still necessary to select a matrix substance suitable for ionization depending on the properties of a specimen. Examples of the matrix substance are nicotinic acid, cinnamic acid, 2,5-dihydroxybenzoic acid and the like.
• MALDI has a disadvantage that its use is largely limited to substances having a molecular weight greater than 1,000 Da because low molecular weighted matrix substance and matrix decomposed product are indicated on the mass spectrometry spectrum in the course of ionization of a specimen by a laser- activated matrix.
• the ionization of a decomposed product is determined according to the selection of a matrix and thus it becomes necessary to select a most suitable matrix substance and it becomes difficult to perform an anlaysis for an unknown substance in a mixture (G. Suizdak, 1. Ion sources and sample introduction, In: Mass spectroscopy for biotechnology, Academic press, 1996, pl3).
• MALDI method has another disadvantage that the spatial distribution of a crystallized specimen obtained via specimen preparation process is not uniform and therefore the amount of a specimen being excited by laser varies depending on the location of irradiation. Therefore, for appropriate quantitative analysis, the various results obtained by irradiating various locations are interpreted statistically.
• a widely known method for quantitative analysis via MALDI method is to measure spectrum of a compound having an almost identical structure as the one to be analyzed by incorporating an internal standard substance labeled with a radioisotope in a predetermined ratio (M. J. Kang, E. Heinzle, Rapid Communications in Mass Spectrometry, 15 (2001) 1327-1333).
• M. J. Kang, E. Heinzle, Rapid Communications in Mass Spectrometry, 15 (2001) 1327-1333 M. J. Kang, E. Heinzle, Rapid Communications in Mass Spectrometry, 15 (2001) 1327-1333.
• DIOS MS Desorption Ionization on Silicon Mass Spectroscopy
• DIOS is a method for analyzing mass of a specimen using porous silicon as a target without matrix.
• the porous silicon is manufactured by electric etching and DIOS becomes possible by adjusting porosity and degree of oxidation.
• the porous silicon used in DIOS is expected to provide ionization of a specimen by absorbing laser energy as in the case of matrix but the exact energy transfer pathway for desoprtion/ ionization of a specimen is not known yet. It is known that DIOS enables to perform a quantitative analysis, without using matrix, of substances with high molecular weight such as proteins and nucleic acids as well as compounds with relatively low molecular weight (J. Wei, J. M. Burlak, G.
• the present invention provides a method for a nano wire-assisted laser desorption/ ionization mass spectrometric analysis wherein the nanowire, which is used instead of the traditional porous silicon, can fix a specimen and enables to perform mass analysis of a specimen without using a matrix solution while effectively transferring laser energy to a specimen to be irradiated.
• a nanowire- assisted method for mass spectrometric analysis of a specimen via desorption/ ionization using laser as an energy source comprising: (a) forming a nanowire spot by growing a plurality of minute nanowires in a selected area of a conductive material or a semiconductor board capable of applying voltage; (b) placing the specimen containing a substance to be analyzed in the nanowire spot and crystallizing it by drying; and (c) performing mass spectrometric analysis of the ionized material to be analyzed in a state where voltage is applied in the board, while simultaneously irradiating laser onto the nanowire spot, wherein the specimen is adsorbed to and crystallized in the nanowire under reduced pressure, to transfer energy to the specimen through the nanowire.
• a nanowire-assisted method for mass spectrometric analysis of a specimen via desorption/ ionization using laser as an energy source comprising: (a) manufacturing nanowire suspension containing a plurality of minute nanowires; (b) forming a nanowire islet after drying the nanowire suspension coated on a selected area of a conductive material or a semiconductor board capable of applying voltage; (c) placing said specimen containing a substance to be analyzed in the nanowire spot and crystallizing it by drying; and (d) performing mass spectrometric analysis of the ionized material to be analyzed in a state where voltage is applied in said board, while simultaneously irradiating laser onto the nanowire spot, wherein the specimen is adsorbed to and crystallized in the nanowire under reduced pressure, to transfer energy to said specimen through the nanowire.
• a nanowire- assisted method for mass spectrometric analysis of a specimen via desorption/ ionization using laser as an energy source comprising: (a) manufacturing nanowire suspension by mixing a sample solution containing a plurality of minute nanowires and materials to be analyzed; (b) forming a nanowire islet comprising nanowire and a specimen adsorbed and crystallized to said nanowire after drying the nanowire suspension coated on the selected area of a conductive material or a semiconductor board capable of applying voltage; (c) performing mass spectrometric analysis of the ionized material to be analyzed in a state where voltage is applied in said board, while simultaneously irradiating laser onto the nanowire spot, under reduced pressure, to transfer energy to the specimen through said nanowire.
• This invention relates to a method for a nanowire-assisted laser desorption/ ionization mass spectrometric analysis (NADI MS: NADI hereinafter) of a specimen wherein the nanowire, which is used instead of the traditional porous silicon, can fix a specimen and enables to perform mass analysis of a specimen without using a matrix solution while effectively transferring laser energy to a specimen to be irradiated.
• NADI MS nanowire-assisted laser desorption/ ionization mass spectrometric analysis
• Nanowire is preferred to have a diameter of 500 nm or less and an aspect ratio of 10 or higher. If the nanowire is grown to have a diameter of greater than 500 nm it becomes difficult to amplify the laser energy being irradiated or uniform distribution within a specimen while if it is grown to have an aspect ratio of less than 10 it becomes difficult to effectively transfer energy while amplifying the laser energy being irradiated.
• the nanowire to be grown is selected from the group consisting of a single metal containing silicon, oxide, carbide, nitride, phosphide and arsenide semiconductor nanowires. Further, it is preferable from the quantitative point of view that the area of the nanowire spot be formed so that it is equal to or smaller than the area being irradiated for desorption/ ionization of a specimen. Then, the specimen containing a substance to be analyzed is placed in an area where the nanowire is grown by using the method in MALDI process so that it can be adsorbed to the nanowire and crystallized by drying.
• the specimen comprises a salt and a material to be analyzed, wherein the concentration of the salt is greater than 10 mM while the concentration of the material to be analyzed is contained in the specimen less than 1 femto mole.
• the board where the nanowires and the crystallized specimen is adsorbed to are irradiated with laser on the nanowire spot while during which the ionized specimen is concurrently placed under mass spectrometric analysis in a state where voltage is applied onto the board.
• desorbed/ ionized specimen is being transferred to a sensor by an electric field applied to between a board and a sensor for analysis to perform a mass spectrometric analysis.
• a plurality of minute nanowires are grown on a predetermined board and the nanowires are separated from the board and mixed with a volatile solution such as distilled water, aqueous solution or alcohol depending on the kind of nanowire substance and manufacture the nanowire suspension.
• a volatile solution such as distilled water, aqueous solution or alcohol depending on the kind of nanowire substance and manufacture the nanowire suspension.
• the nanowire suspension can be prepared by placing the board where nanowires are grown ('nanowire chip' hereinafter) in a volatile solution and then separating the nanowires from the board by applying ultrasonic wave.
• the nanowire suspension can be prepared by separating the nanowires from the board where the nanowires are grown by scratching and mixing with a volatile solution to spray it on the board.
• each nanowire is preferred to have a diameter of 500 run or less and an aspect ratio of 10 or higher.
• the nanowire is selected from the group consisting of a single metal containing silicon, oxide, carbide, nitride, phosphide and arsenide semiconductor nanowires. Then, the above nanowire suspension is sprayed onto the selected area of the board that can be used in the typical MALDI process and dried to form a nanowire islet.
• the board to be used is a conductor or a semiconductor board that can apply voltage.
• the nanowire islet is formed by spraying the nanowire suspension onto the selected area of the board.
• the area of the nanowire islet is preferred to have a size equal to or smaller than that of the area to be irradiated by laser for desorption/ ionization of a specimen. Then, the specimen solution containing a substance for mass analysis is coated on the above-mentioned nanowire islet, dried and crystallized. Here, the specimen becomes adsorbed to the nanowires which serve as a cage to hold the specimen within the area of spray so that the mixture of the crystallized specimen and nanowires can be appropriately located.
• the above specimen consists of a salt and a substance to be analyzed.
• the concentration of the salt is greater than 10 mM while the concentration of the material to be analyzed is contained in the specimen less than 1 femto mole.
• desorbed/ ionized specimen is being transferred to a sensor by an electric field applied in between a board and a sensor for analysis to perform a mass spectrometric analysis.
• a plurality of minute nanowires are grown on a predetermined board and the nanowires are separated from the board and mixed with a specimen solution containing a substance to be analyzed and the nanowire suspension is finally prepared.
• the nanowire suspension containing nanowires and a specimen can be prepared by placing the board, where nanowires are grown (i.e., 'nanowire chip'), in a volatile solution and then separating the nanowires from the board by applying ultrasonic wave and added with a specimen solution.
• the nanowire suspension can be prepared by separating the nanowires from the board where the nanowires are grown by scratching and then mixing with a volatile solution to enable a spray on the board.
• each nanowire is preferred to have a diameter of 500 nm or less and an aspect ratio of 10 or higher.
• the nanowire is selected from the group consisting of a single metal containing silicon, oxide, carbide, nitride, phosphide and arsenide semiconductor nanowires.
• the above specimen consists of a salt and a substance to be analyzed.
• the concentration of the salt is greater than 10 mM while the concentration of the material to be analyzed is contained in the specimen less than 1 femto mole.
• the above nanowire suspension is sprayed onto a selected area of the board that can be used in the typical MALDI process and dried to form a nanowire islet and the specimen is crystallized.
• the board to be used is a conductor or a semiconductor board that can apply voltage.
• the nanowire islet is formed by spraying the nanowire suspension onto the selected area of the board.
• the area of the nanowire islet is preferred to have a size equal to or smaller than that of the area to be irradiated by laser for desorption/ ionization of a specimen.
• irradiations are performed using laser having an energy greater than the bandgap of nanowires depending on the kind of nanowires, and the vacuum pressure, i.e., atmospheric pressure, is set below 10" 16 torr.
• the vacuum pressure i.e., atmospheric pressure
• about 5,000N to 30,000N is applied and in the course of mass spectrometric analysis of an ionized substance to be analyzed the value of mass over electric charge (m/z) of ions is measured.
• ⁇ ADI process the basic principle of the effective desorption/ ionization of a specimen provided by nanowires without using matrix is explained in detail as follows.
• Nanowires upon exposure to laser irradiation, can absorb energy and generate photons, wherein the nanowires themselves have a cavity structure which can amplify photons (l.J. Johnson, Heon-Jin Choi, K.P. Knutsen, R.D. Schaller, P. Yang, R.J. Saykally, "Single Gallium Nitride Nanowire Laser, " Nature Materials, 1, 2, 106-110 (2002)). Accordingly, nanowires can spontaneously amplify laser energy being transferred from the outside and again deliver the amplified energy to a specimen in the form of a stimulated emission.
• the nanowires used in the present invention are needle-shaped having a diameter of a few nanometers and a relatively large aspect ratio. Therefore, both ends of the nanowires are of very sharp tips at the level of atom. These geographical structures can generate an extremely high electric field at the front tips of nanowires when an electric field is applied between a board and a sensor in the device for mass spectrometric analysis, and the high electric field at the front tips of nanowires cause field desorption thereby enabling the desorption/ ionization of a specimen.
• the front tips of nanowires can generate a relatively high electric field at the front tips of nanowires induced by laser upon laser irradiation (J. M. Bermond, M. Lenoir, J. P. Prulhiere, M. Drechsler, Sur. Sci. 42, 306 (1974)).
• the generation of extremely high local electric field can accelerate the release of desorption/ ions release at the front tips of nanowires thereby easing the desorption/ ionization of a specimen.
• the geographical shape of the front tips of nanowires can allow release of electrons when an electric field is applied and this electron release can ease the ionization of a specimen (N. E. Frankevich, J. Zhang, S. D. Friess, M. Dashtiev, R.
• the specimen distribution within the crystallized specimen thus securing more precise data. That is, the use of nanowires can accurately control the growth location via catalytic patterns on the board.
• silicon nanowires can be grown by supplying SiCl 4 at 500 °C onto the silicon board via chemical vapor deposition (CND) after depositing Au, a metal serving as a catalyst, on a surface of the silicon board to have a predetermined thickness and diameter with a circular shape using a mask via sputtering vapor deposition method.
• In ⁇ nanowires can be grown by supplying InCl 3 and ⁇ H 3 at 500 °C onto the silicon board via chemical vapor deposition after depositing Au, a metal serving as a catalyst, on a surface of the silicon board to have a predetermined thickness and diameter with a circular shape using a mask via sputtering vapor deposition method.
• the nanowires serve the role of a three dimensional cage to retain a liquid specimen until the specimen is crystallized thereby forming a crystal center of the specimen where the nanowires are located.
• the distributed nanowires serve the role of a cage to fix a specimen in the course of drying and thus it is possible to fix the specimen within the size of diameter of laser. Accordingly, only 1 to 2 times of laser irradiations will sufficiently promote the ionization of the specimen that enables the measurement of its molecular weight thus allowing the quantitative analysis.
• the typical porous silicon has limitations on the selection of a suitable substance for the process and therefore there are also limitations on making effective utilization of laser energy.
• the laser energy being transferred to a specimen can be appropriately adjusted within the scope of desired energy level using nanowires having various energy gaps.
• the porous structure should be used only in the limited area. That is, the specimen solution penetrates a porous structure and becomes crystallized in the course of injecting the specimen solution and drying and thus the crystalline size of the specimen is not limited.
• the specimen is crystallized using a nanowire cage and thus the crystalline size of the specimen can be limited.
• NADI of the present invention using nanowires unlike in the case of DIOS using the typical porous silicon wherein recycling of used targets is difficult, it is possible to recycle used targets after appropriate washes by using the conventional metal plate as a target.
• DIOS it has been reported that DIOS efficiency becomes deteriorated due to oxidation and thus it should be kept sealed.
• the target plates using nanowires can use oxidized products and thus it allows easy packaging and also long-term storage at atmospheric environment is made possible.
• ZnO nanowire chips were prepared by depositing a surface of the silicon board with Au, which serves as a catalyst, via sputtering vapor deposition method to a thickness of 2 nm to a predetermined area, and supplying diethylzinc and oxygen at 500 °C via chemical vapor deposition method, thereby allowing growth of ZnO nanowires on a selected area.
• the target plate where the board with thus prepared nanowires was inserted into specimen inspection plate of a mass spectrometric analysis device was manufactured as shown in Fig. 1.
• reference numeral 1 indicates inspection plate
• reference numeral 2 indicates a target plate
• reference numeral 3 indicates a board
• reference numeral 1 indicates inspection plate
• reference numeral 2 indicates a target plate
• reference numeral 3 indicates a board and reference numeral
• FIG. 4 indicates nanowire spot.
• Fig. 1(a) shows a picture of a board that formed ZnO nanowire spot and a target plate where the board was inserted to specimen inspection plate of a mass spectrometric analysis device.
• Fig. 1(b) and (c) show an enlarged picture of grown nanowires taken by scanning electron microscope. The
• ZnO growth conditions for nanowires grown on nanowire spot (4) were restricted to have an average diameter of is 100 nm, an average length of 3 ⁇ m, an average density of about lxl0 6 nanowire(NWs)/mm 2 .
• the diameter of nanowire spot (4) was restricted to be 0.2 mm and the crystals of specimens were irradiated by the circular spot of laser (diameter: 0.2 mm) for the ionization of specimens.
• the majority of specimen crystals is exposed to laser and thus the ionized amount of a specimen through the crystalline surface of the specimen was made to have a quantitative relationship with the concentration of the specimen.
• Reflex 3 from Bruker Daltonics (Germany) was used.
• Fig. 2 is a graph showing the peak of molecular weight after laser irradiation on ZnO nanowires without a specimen. As shown in Fig.2, ZnO nanowires do not generate a peak of molecular weight which may raise confusion with the peak of a specimen.
• Fig. 3 shows a result of mass analysis after adding leucine enkephalin to ZnO nanowires chip with the concentration of 0.13, 0.25, 0.50 and 1.0 mg/mL, respectively.
• mass analysis is possible by using ZnO nanowires chip. Further, mass comparison result according to the respective concentration of the ZnO nanowires chip reveals that the height of peak for the molecular weight of leucine enkephalin and the above concentration has a quantitative relationship.
• Fig. 4 shows a result of mass analysis after adding angiotensin to ZnO nanowires chip with the concentration of 0.25, 0.50 and 1.0 mg/mL, respectively. As is the case with leucine enkephalin, mass comparison result reveals that the height of peak for the molecular weight of angiotensin and the above concentration has a quantitative relationship.
• a method using nanowire suspension via a metal target plate used in the typical MALDI for quantitative analysis instead of nanowire spot enables to perform mass analysis within the range of molecular weight of 1,000 dalton by using the metal target plate without deformation without using nanowire spot and without interference with the peak of matrix.
• nanowire islet was formed focusing on one spot of the metal target plate so that the crystal center of a specimen can correspond to the position of laser irradiation, and for this purpose was used a target plate with arranged ankers (MTP plate, Bruker
• the anker point of the target plate is the place where a solvent of a specimen is dried to form crystals in case of an aqueous specimen.
• nanowire islet was forced to heavily form in these anker points while the solvent of the nanowire suspension prepared in an aqueous solution becomes dried. That is, nanowire islet was formed by mixing nanowire suspension with volatile isopropanol and dividing it into a metal target plate.
• specimen crystals were prepared by dividing a small amount of specimen into a nanowire islet followed by drying.
• nanowire suspensions of ZnO, SiC, Sn0 2 , GaN were used.
• nanowire chip (the board where nanowires are grown) grown to the density of about 5000 NWs/mm 2 in silicon board was placed in distilled water and separated nanowires by applying ultrasonic wave thereby manufacturing a nanowire suspension where the nanowires made of the above-mentioned substance and distilled water.
• Fig. 5 shows peaks of molecular weight of peptides obtained by using the above four different kinds of nanowires.
• Fig. 6 shows the result of mass analysis of leucine enkephalin (MW 1014, Sigma Chemical Co., USA) at a concentration of 0.5 mg/mL after recyclings via 10 times of washes of ZnO nanowire chip. The result clearly shows that nanowire chip can be reused after washing.
• Fig. 1(a) shows a picture of a board that formed ZnO nanowire spot and a target plate where the board was inserted to specimen inspection plate of a mass spectrometric analysis device
• Fig. 1(b) and (c) show an enlarged picture of grown nanowires taken by scanning electron microscope
• Fig. 2 is a graph showing the peak of molecular weight after laser irradiation on ZnO nanowires without a specimen
• FIG. 3 shows a result of mass analysis after adding leucine enkephalin to ZnO nanowires chip with the concentration of 0.13, 0.25, 0.50 and 1.0 mg/mL, respectively;
• Fig. 4 shows a result of mass analysis after adding angiotensin to ZnO nanowires chip with the concentration of 0.25, 0.50 and 1.0 mg/mL, respectively;
• Fig. 5 shows peaks of molecular weight of peptides obtained by using the above four different kinds of nanowire suspensions of ZnO, SiC, Sn0 2 , GaN; and Fig.
• reference numeral 1 indicates inspection plate
• reference numeral 2 indicates a target plate
• reference numeral 3 indicates a board
• reference numeral 1 indicates inspection plate
• reference numeral 2 indicates a target plate
• reference numeral 3 indicates a board
• Example 1 Mass Spectrometric Analysis using Nanowires
• a surface of a silicon board was deposited with Au via sputtering vapor deposition method to a thickness of 2 nm, wherein the area for deposition was made circular with a diameter of 200 ⁇ m using a mask. Then, the board was supplied with SiCl at 500 °C via chemical vapor deposition (CVD) method, thereby allowing the growth of silicon nanowires, and Fig. 1 shows the silicon nanowires grown on the board.
• the silicon nanowires used were restricted to have a length of 5 ⁇ m, a diameter of 100 nm and a density of about 1.8 xlO 6 NWs/mm 2 .
• the board with thus grown nanowires was inserted into a specimen inspection plate of a mass spectrometric analysis device.
• the mass analysis was performed using Reflex 3 from Bruker Daltonics (Germany).
• the specimens used were two peptides, angiotensin and leucine enkephalin.
• the diameter of nanowire spot was restricted to be 0.2 mm and the crystals of specimens were irradiated by the circular spot of laser (diameter: 0.2 mm) for the ionization of specimens.
• the majority of specimen crystals are exposed to laser and thus the ionized amount of a specimen was made to have a quantitative relationship with the amount of the specimen.
• Example 2 Mass Spectrometric Analysis using Nanowire Suspension A surface of a silicon board was deposited with Au via sputtering vapor deposition method to a thickness of 2 nm, wherein InN nanowires were grown by supplying with InCl 3 and NH 3 at 500 °C via chemical vapor deposition (CVD) method.
• CVD chemical vapor deposition
• Nanowire suspension was prepared by separating nanowires from the board by placing the above silicon board in isopropyl alcohol and then applying with ultrasonic wave for 10 sec.
• the MALDI measurement was performed using the nanowire suspension by using MALDI target from Bruker Daltonics (Germany) instead of the typical matrix. Taking advantage of the special property of the MALDI target that crystal center of a specimen is concentrated on ankers, a small amount of nanowire suspension was treated to form nanowire islets around the ankers. Then, peptides as a specimen was dropped in the above nanowire islets and allowed to form crystals of the specimen. Upon inspection, it was found that nanowire suspsension can replace matrix and quantitative results were obtained as a result.
• Example 3 Detection of Coupling Reaction using Nanowires
• a nanowire target where nanowires are grown as in Example 1 was added with hepatitis B antigen solution and allowed to incubate at a 37 °C water-saturated thermostat for an hour so that the hepatitis B antigen can be fixed. Then, the nanowire target was dipped into a washing solution to separate unfixed hepatitis B antigens. A specimen solution containing the hepatitis B antigen was added to the nanowires to induce an antibody-antigen reaction and then placed the nanowire target into the washing solution to remove the specimen which was left after the antibody-antigen reaction.
• MALDI enables to perform quantitative as well as qualitative analyses of antigen-antibody coupler which was coupled to nanowires.
• the present invention by using the above nanowires, enables to effectively perform desorption/ ionization of a specimen using the above-mentioned nanowire, thereby effectively performing qualitative-, quantitative-, and micro- analyses of specimens as well as low molecular weighted specimens. Further, this invention also enables to the typical device of mass spectrometric analysis used in MALDI-Tof MS.
• the invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of the disclosure, may make modifications and improvements within the scope and spirit of the invention.

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