GOLD NANOPARTICLE MANUFACTURING METHOD

Abstract

The present invention relates to a method for manufacturing gold nanoparticles, including: (a) placing a gold (Au) target on a magnet cathode and injecting argon (Ar) gas to generate plasma; (b) discharging powder of a compound having an non-shared electron pair upwardly in parallel to a vertical rotation axis inside a stirrer, followed by circulating and agitating the same up and down; and (c) ejecting the gold particles and binding the same to the compound having the non-shared electron pair, as well as gold nanoparticles manufactured by the same.

The present invention relates to a method for obtaining gold nanoparticles bound to niacinamide through vacuum deposition, which is generally used to form a thin film, wherein niacinamide is used by circulating and agitating the same up and down under special conditions, so as to produce high purity gold nanoparticles in high yield.

Claims

1. A method for manufacturing gold nanoparticles, comprising: (a) placing a gold (Au) target on a magnet cathode and injecting argon (Ar) gas to generate plasma; (b) discharging powder of a compound having an non-shared electron pair upwardly in parallel to a vertical rotation axis inside a stirrer, followed by circulating and agitating the same up and down; and (c) ejecting the gold particles and binding the same to the compound having the non-shared electron pair.

2. The method according to claim 1, wherein the compound having a non-shared electron pair is a compound containing a thiol group or ketone group.

3. The method according to claim 2, wherein the compound containing a thiol group or ketone group is niacinamide.

4. The method according to claim 1, wherein the step (b) is conducted at a temperature of 40 to 100° C. and with a vacuum degree of 1.0 to 2.0×10.sup.−2 torr.

5. The method according to claim 1, wherein the gold nanoparticle has a diameter of 1 to 10 nm.

6. The method according to claim 3, further comprising (d) heating niacinamide.

7. Gold nanoparticles manufactured according to the method as set forth in claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 illustrates a vacuum device used for preparing gold nanoparticles of the present invention, wherein FIG. 1a is a diagram showing a vacuum chamber, and FIG. 1b is a diagram showing front and side views of a stirrer disposed in the vacuum chamber.

[0023] FIG. 2 is a diagram illustrating the state of the stirrer charged with niacinamide.

[0024] FIG. 3 illustrates TEM image of the gold nanoparticles manufactured by the method of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF INVENTION

[0025] Hereinafter, the present invention will be described in more detail by means of examples. However, these examples are for illustrative purposes only and the scope of the present invention is not limited to these examples.

Example 1. Preparation of Gold Nanoparticles

Example 1-1. Vacuum Chamber and Stirrer

[0026] In Examples to be described later, niacinamide was used as a representative example of the compound containing a ketone group. A stirrer was placed in the vacuum chamber to allow the niacinamide to move fluidly (or flow) by applying physical force in a vacuum state (FIG. 1a). The stirrer was specifically fabricated to have an angle of stirrer blades between 45 and 80° in order to prevent the niacinamide agitated in the stirrer from sticking together or to inhibit stagnant stirring, and was also formed in a screw type with application of a vertical rotation axis (FIG. 1b). Accordingly, niacinamide inside a cylinder surrounding the blades of the stirrer is discharged and scattered upwards in parallel to the vertical rotation axis inside the stirrer rather than in left and right sides (FIG. 2). Niacinamide in powder form is not stagnant or stopped, but continues to circulate up and down while freely falling and collides with the ejected gold (Au) atoms.

[0027] The vacuum chamber is connected to a mass flow controller (MFC) and a rotary pump, in order to maintain a constant temperature by supplying a coolant to an outer wall of the stirrer while maintaining a predetermined vacuum degree.

Example 1-2. Preparation of Gold Nanoparticles

[0028] Gold with a purity of 99.9% or more was used as a sputtering target, and was bound to a magnet cathode. After charging niacinamide into the stirrer and reaching the vacuum degree inside the chamber to 2.0 to 3.0×10.sup.−5 torr, argon gas was injected into the magnet cathode to generate plasma. Herein, the vacuum degree inside the chamber became to be rapidly changing to 1.0 to 2.0×10.sup.−2 torr. By operating the MFC (Mass flow controller) and rotary pump, the coolant was supplied to the outer wall of the stirrer while conducting agitation simultaneously in a state of maintaining the vacuum degree of 1.0 to 2.0×10.sup.−2 torr, followed by proceeding the work for at least 5 hours. At this time, the temperature inside the chamber was maintained at 60 to 70° C., and the niacinamide inside the stirrer also became to be maintained at 60 to 70° C.

[0029] By generating plasma on the surface of the gold target in a vacuum state, pure gold particles of several nanometers are freely ejected. The ejected gold particles are induced to bind to the surface of niacinamide. At this time, in order to prevent the gold particles bound to niacinamide from being recombined between gold particles and increasing a size of the particles, the stirrer was built in the vacuum chamber to make the niacinamide flow physically. The ejected gold particles are either weakly bound to niacinamide or unbound and agitated along with niacinamide in the form of particles, and the same process is repeated until the agitation is stopped and the vacuum is broken off. As a result, since niacinamide flowing up and down prevented recombination between the ejected gold particles, perfectly separated gold nanoparticles having a size of 1 to 5 nm were obtained (FIG. 3).

[0030] In other words, instead of forming a thin film by utilizing vacuum deposition, the ejected gold atoms did not bind strongly to niacinamide before formation of a thin film, and recombination between gold atoms was prevented by secondary physical agitation, thereby obtaining nanometer-scale gold particles. Therefore, according to a process performed in a high vacuum state, it is possible to produce nanoparticles having the same purity as that of gold prepared as a target without the presence of moisture, harmful gas, foreign substances, and the like.

Example 2. Comparison of Yield of Gold Nanoparticles

[0031] In order to compare the yield of gold nanoparticles according to a stirring direction of the carrier, i) the stirrer of the present invention in which the carrier is discharged upwardly and circulates up and down in parallel to a vertical rotation axis (Experimental Example 1), ii) a stirrer in which the carrier rotates about the vertical rotation axis (Comparative Example 1), and iii) a stirrer in which the carrier rotates about a horizontal rotation axis (Comparative Example 2), were fabricated, respectively. Then, niacinamide powder was charged into the stirrer, followed by preparing gold nanoparticles in the same manner as described in Example 1. The yield of gold nanoparticles bound to niacinamide was measured, and the average values thereof are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Division Yield Experimental Example 1 76.6% Comparative Example 1 49.3% Comparative Example 2 61.6%

[0032] As a result, it was confirmed that the stirrer of Experimental Example 1 in which niacinamide is discharged upward and circulates up and down in parallel to the vertical rotation axis has the most remarkable yield of 76.6%, whereas the stirrer of Comparative Example 1 in which niacinamide rotates about the vertical rotation axis showed the lowest gold nanoparticle yield. The reason for the above results is considered because, as compared to the stirrer of Experimental Example 1 where most of input energy is used to vertically move niacinamide toward gold particles as the gold particles are incident in the vertical direction, the stirrer of Comparative Example 1 or Comparative Example 2 uses most of the input energy to rotate niacinamide horizontally or vertically to thus reduce collision efficiency. That is, in the production of gold nanoparticles through vacuum deposition according to the present invention, it could be understood that the stirring direction of niacinamide had significant effects on the yield, and the stirring method of the present invention, in which niacinamide is discharged upward in parallel to the vertical rotation axis and collides with the gold particles, exhibited the highest yield.

Example 3. Comparison of Size and Purity of Gold Nanoparticles

[0033] Gold nanoparticles were prepared using glucose and hydroxyl ethyl cellulose (HEC) generally used as carriers on which nanoparticles are formed, and the yield and size of the particles were compared. Specifically, 120 g of 99.9% pure gold was placed on a magnet cathode, and niacinamide powder, glucose powder and a HEC chip were incorporated into a stirrer, followed by preparing gold nanoparticles bound to each carrier in the same manner as in Example 1. Thereafter, by heating the niacinamide powder to which gold nanoparticles were bound to sublimate niacinamide, only pure gold nanoparticles were obtained. Further, nanoparticles in which glucose and HEC are used as carriers were dissolved in glucose and HEC by adding water, thereby obtaining dispersed gold nanoparticles. The obtained gold nanoparticles were subjected to measurement of diameter and purity through TEM and component analysis, and the average value was calculated and shown in Table 2 below.

TABLE-US-00002 TABLE 2 Division Diameter of nanoparticle Purity Niacinamide 2.9 nm 99.9% Glucose 8.9 nm 91.7% HEC 13.2 nm 87.2%

[0034] As a result, it was confirmed that, when niacinamide was used as a carrier, it has the same purity (99.9%) as the target and, whereas the purity was significantly reduced when glucose or HEC was used as a carrier. The above results are judged to be due to the difference in processes of separating the carrier from the gold nanoparticles (heating or dissolving in water), and it could be seen that high purity gold nanoparticles can be obtained when niacinamide is used according to the present invention. Further, the nanoparticles are significantly smaller in size when niacinamide is used, as compared to use of glucose or HEC, whereby the present invention can be utilized in the production of finer gold nanoparticles compared to the conventional manufacturing process. This would be interpreted as a result of combining gold particles with a ketone group included in the molecular structure of niacinamide.

[0035] From the above description, those skilled in the art to which the present invention pertains will understand that the present invention may be embodied in other specific forms without changing the technical spirit or essential characteristics thereof. In this regard, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. It should be construed that, rather than the above detailed description, all changes or modifications derived from the meaning and scope of the claims described below and their equivalents are included in the scope of the present invention.