CARBENE COMPOUND, CARBENE-METAL NANOPARTICLE COMPLEX AND PREPARATION METHOD THEREOF

Abstract

The present invention relates to a carbene compound having substituted at the terminal polyethylene glycol (PEG) having nitrogen-containing functional groups, a carbene-metal nanoparticle complex in which the carbene compound and metal nanoparticles are bounded, a preparation method thereof, and a biosensor using same.

Claims

1. A carbene compound represented by the following Chemical Formula 1 or 2 substituted with polyethylene glycol (PEG) having nitrogen-containing functional groups at a terminal: ##STR00012## wherein Chemical Formulas 1 and 2 above, R1, R2, R5 and R6 are equal to or different from each other, and each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a heteroaryl group having 2 to 30 carbon atoms, R3, R4, R7, R8, R9 and R10 are equal to or different from each other, and each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 2 to 30 carbon atoms, or a structure represented by the following Chemical 3, or two or more substituents adjacent to each other in R7 to R10 bind to form a hydrocarbon ring, at least one of R3 and R4 has a structure represented by the following Chemical Formula 3, at least one of R7 to R10 is a structure represented by the following Chemical Formula 3, or when two or more substituents adjacent to each other in R7 to R10 bind to form the hydrocarbon ring, at least one of hydrogens bound to carbons forming the hydrocarbon ring is substituted with a structure represented by the following Chemical Formula 3, ##STR00013## in Chemical Formula 3 above, n is an integer of 1 to 30 as the number of repeated units in parentheses, and A is an alkyl group having 1 to 20 carbon atoms containing nitrogen (N) atoms or a heteroaryl group having 2 to 30 carbon atoms containing nitrogen (N) atoms.

2. The carbene compound of claim 1, wherein the nitrogen-containing functional group is at least one selected from the group consisting of azide, phthalimide and amine.

3. The carbene compound of claim 1, wherein at least one of the R1 and R2 and at least one of the R5 and R6 are equal to or different from each other, and each independently an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group of 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a heteroaryl group of 2 to 30 carbon atoms.

4. A carbene-metal nanoparticle complex in which the carbene compound according to claim 1 binds to metal nanoparticles.

5. The carbene-metal nanoparticle complex of claim 4, wherein the particle size of the metal nanoparticle is 1 nm to 40 nm.

6. The carbene-metal nanoparticle complex of claim 4, wherein the metal is any one selected from the group consisting of copper (Cu), cobalt (Co), bismuth (Bi), silver (Ag), aluminum (Al), gold (Au), hafnium (Hf), chromium (Cr), indium (In), manganese (Mn), molybdenum (Mo), magnesium (Mg), nickel (Ni), niobium (Nb), lead (Pb), palladium (Pd), platinum (Pt), rhenium (Re), rhodium (Rh), antimony (Sb), tantalum (Ta), titanium (Ti), tungsten (W), vanadium (V), zirconium (Zr), zinc (Zn), iron (Fe), and mixtures thereof.

7. A preparation method of a carbene-metal nanoparticle complex comprising: preparing sulfur-metal nanoparticles by mixing polyethylene glycol containing a thiol group at one terminal and a nitrogen-containing functional group at the other terminal with metal nanoparticles; and mixing the sulfur-metal nanoparticles with the carbene compound according to claim 1.

8. The preparation method of the carbene-metal nanoparticle complex of claim 7, wherein the mixing of the sulfur-metal nanoparticles with the carbene compound comprises substituting metal-sulfur bonds present on the surfaces of the metal nanoparticles with metal-carbene bonds.

9. A biosensor comprising the carbene-metal nanoparticle complex according to claim 4 to which a bio-probe part is immobilized through a click reaction.

Description

DESCRIPTION OF DRAWINGS

[0021] FIG. 1 is a schematic diagram illustrating LFA using a carbene-gold nanoparticle complex according to an embodiment of the present invention.

[0022] FIG. 2 is a diagram illustrating an experimental result of pH stability according to Experimental Example 1 of the present invention.

[0023] FIG. 3 is a diagram illustrating an experimental result of salt stability according to Experimental Example 2<1> of the present invention.

[0024] FIG. 4 is a diagram illustrating an experimental result of solvent stability according to Experimental Example 2<2> of the present invention.

[0025] FIG. 5 is a diagram illustrating an experimental result of temperature stability according to Experimental Example 3 <1> of the present invention.

[0026] FIG. 6 is a diagram illustrating an experimental result of temperature stability of gold nanoparticles according to Experimental Example 3<2> of the present invention.

[0027] FIG. 7 is a diagram illustrating an experimental result of a malaria diagnostic kit according to Experimental Example 4 of the present invention.

[0028] FIG. 8 is a diagram illustrating an experimental result of pH stability according to Experimental Example 5 of the present invention.

[0029] FIG. 9 is a diagram illustrating an experimental result of high-temperature stability according to Experimental Example 6 of the present invention.

[0030] FIG. 10 is a diagram illustrating an experimental result of low-temperature stability according to Experimental Example 7 of the present invention.

[0031] FIG. 11 is a diagram illustrating .sup.1H-NMR spectra of a carbene compound prepared according to Preparation Example 1 of the present invention.

[0032] FIG. 12 is a diagram illustrating .sup.1H-NMR spectra of a carbene compound prepared according to Preparation Example 3 of the present invention.

[0033] FIG. 13 is a diagram illustrating .sup.1H-NMR spectra of a carbene compound prepared according to Preparation Example 4 of the present invention.

[0034] FIG. 14 is a diagram illustrating .sup.1H-NMR spectra of a carbene compound prepared according to Preparation Example 5 of the present invention.

[0035] FIG. 15 is a diagram illustrating .sup.1H-NMR spectra of a carbene compound prepared according to Preparation Example 6 of the present invention.

[0036] FIG. 16 is a diagram illustrating a TEM image of a carbene-metal nanoparticle complex according to an embodiment of the present invention.

[0037] FIG. 17 is a diagram of comparing binding energy/bond distances of a gold-sulfur bond and a gold-carbene bond.

BEST MODE

[0038] Hereinafter, the present invention will be described in detail.

[0039] 1. Carbene Compound

[0040] The present invention provides a carbene compound represented by the following Chemical Formula 1 or 2 substituted with polyethylene glycol (PEG) having nitrogen-containing functional groups at a terminal.

[0041] The carbene compound may be prepared by introducing polyethylene glycol (PEG) substituted with nitrogen-containing functional groups to a terminal.

[0042] The carbene compound introduces a polyethylene glycol group to a terminal site to increase aqueous dispersibility, and introduces nitrogen-containing functional groups to the polyethylene glycol terminal to be functionalized to facilitate adhesion of a bio-probe part (e.g. antibody, DNA, aptamer, primer, etc.) to the nitrogen-containing functional groups through a click reaction below. Accordingly, in LFA and the like, unlike that the bio-probe part is typically bound by electrostatic attraction between metal nanoparticles, there is an advantage that the bio-probe part may be immobilized with strong chemical covalent bonds through the click reaction.

[0043] The nitrogen-containing functional group may be azide, phthalimide or amine.

[0044] The R1, R2, R5 and R6 may be equal to or different from each other and each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 30 carbon atoms.

[0045] The R1, R2, R5 and R6 may be equal to or different from each other and each independently hydrogen or an alkyl group having 1 to 20 carbon atoms.

[0046] The R1, R2, R5 and R6 may be equal to or different from each other and each independently hydrogen, isopropyl, or benzyl.

[0047] At least one of the R1 and R2 and at least one of the R5 and R6 may be equal to or different from each other and each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms.

[0048] At least one of the R1 and R2 and at least one of the R5 and R6 may be equal to or different from each other and each independently isopropyl or benzyl.

[0049] The R3, R4, R7, R8, R9 and R10 are equal to or different from each other, and each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 2 to 30 carbon atoms, or a structure represented by the following Chemical Formula 3, or two or more substituents adjacent to each other in R7 to R10 bind to each other to form a hydrocarbon ring.

[0050] The R3, R4, R7, R8, R9 and R10 are equal to or different from each other, and each independently hydrogen or a structure represented by the following Chemical Formula 3, or two or more substituents adjacent to each other in R7 to R10 bind to each other to form a hydrocarbon ring.

[0051] When the two or more substituents adjacent to each other in R7 to R10 bind to each other to form the hydrocarbon ring, at least one of hydrogens binding to carbons forming the hydrocarbon ring may be substituted with the structure represented by Chemical Formula 3.

[0052] At least one of R3 and R4 may be the structure represented by Chemical Formula 3. In addition, a least one of R7 to R10 may be the structure represented by Chemical Formula 3.

[0053] The n may be an integer of 1 to 30 as the number of repeated units in parentheses, and preferably 1 to 10. When the n is less than 1, the aqueous dispersibility of the carbene compound is lowered, and when the n is more than 30, a distance between the bio-probe parts is increased due to a long chain of polyethylene glycol, and thus, the bio sensing efficiency rather decreases.

[0054] The A is an alkyl group having 1 to 20 carbon atoms containing nitrogen (N) atoms or a heteroaryl group having 2 to 30 carbon atoms containing nitrogen (N) atoms. Specifically, the A may be azide, phthalimide or amine.

[0055] In the present invention, the “adjacent” group may mean a substituent substituted to an atom linked directly to an atom substituted with the corresponding substituent, a substituent that is located stereoscopically closest to the corresponding substituent, or another substituent substituted to an atom substituted with the corresponding substituent. For example, it will be interpreted that two substituents substituted in ortho sites in a benzene ring and two substituents substituted to the same carbon in an aliphatic ring are groups “adjacent” to each other.

[0056] The alkyl group may be a linear or branched chain, and may have 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. More preferably, the alkyl group may have 1 to 6 carbon atoms. Specific examples of the alkyl group include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylobutyl, 2-ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, cyclopentyl methyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethylpropyl, 1,1-dimethylpropyl, ishexyl, 4-methylhexyl, 5-methylhexyl, benzyl, etc., but are not limited thereto.

[0057] The cycloalkyl group may have 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms. Specific examples of the cycloalkyl group include cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, etc., but are not limited thereto.

[0058] The aryl group may have 6 to 30 carbon atoms, preferably 6 to 10 carbon atoms. The aryl group may be a monocyclic aryl group or a polycyclic aryl group. Specific examples of the monocyclic aryl group include a phenyl group, a biphphenyl group, a terphenyl group, etc., and the specific examples of the polycyclic aryl group include a naphthyl group, an anthracenyl group, a phenanthyl group, a pyrenyl group, a perylenyl group, a chrysenyl group, a fluorenyl group, a triphenylene group, etc., but are not limited thereto.

[0059] The heteroaryl group may be an aromatic ring group including one or more selected from N, O, P, S, Si and Se as a heteroatom, and may have 2 to 30 carbon atoms, preferably 2 to carbon atoms. Specific examples of the heteroaryl group include a thiophene group, a furan group, a pyrrole group, an imidazole group, a triazole group, an oxazole group, an oxadiazole group, a triazole group, a pyridyl group, a pyrimidyl group, a triazine group, a triazole group, an acryldyl group, a quinolinyl group, a quinazoline group, a quinoxalinyl group, a phtalazyrinyl group, an isquinoline group, an indole group, a carbazole group, a benzoxazole group, a benzimidazoline group, a benzothiazole group, a benzocarbazole group, a benzothiophene group, a dibenzothiophene group, a benzofuranyl group, etc., but are not limited thereto.

[0060] In addition, the alkyl group, the cycloalkyl group, the aryl group, the heteroaryl group, or the hydrocarbon ring may be substituted or unsubstituted with an alkyl group, a cycloalkyl group, an aryl group or a heteroaryl group again.

[0061] 2. Carbene-Metal Nanoparticle Complex and Preparation Method Thereof

[0062] The present invention also provides a carbene-metal nanoparticle complex in which the carbene compound described above binds to metal nanoparticles.

[0063] The particle diameter of the metal nanoparticle may be 1 nm to 40 nm. When the particle diameter of the metal nanoparticle is less than 1 nm, it is difficult to introduce a required level of carbene compound to the surface of the metal nanoparticle, and thus, the efficiency as a biosensor is deteriorated. When the particle diameter of the metal nanoparticle is more than 40 nm, the carbene-metal nanoparticle complex is not uniform, and thus, the efficiency and reproducibility of the biosensor may be deteriorated. That is, if the particle diameter of the metal nanoparticle exceeds 40 nm, a possibility that the agglomeration of the metal nanoparticles may occur is increased only by a small change in environment.

[0064] The metal nanoparticle may be any one selected from the group consisting of copper (Cu), cobalt (Co), bismuth (Bi), silver (Ag), aluminum (Al), gold (Au), hafnium (Hf), chromium (Cr), indium (In), manganese (Mn), molybdenum (Mo), magnesium (Mg), nickel (Ni), niobium (Nb), lead (Pb), palladium (Pd), platinum (Pt), rhenium (Re), rhodium (Rh), antimony (Sb), tantalum (Ta), titanium (Ti), tungsten (W), vanadium (V), zirconium (Zr), zinc (Zn), iron (Fe), and mixtures thereof (e.g., bimetallic nanoparticles). Preferably, the metal may be gold (Au) when considering stability and crystallizability in various environments of the biosensor to which the carbene-metal nanoparticle complex is applied and a binding force between the carbene compound and the surfaces of the metal nanoparticles.

[0065] The carbene-metal nanoparticle complex may have a uniform form, as illustrated in a TEM image of FIG. 16, and the aqueous dispersibility becomes excellent because the carbene-metal nanoparticle complex has the uniform form.

[0066] Further, the present invention provides a preparation method of a carbene-metal nanoparticle complex comprising preparing sulfur-metal nanoparticles by mixing polyethylene glycol containing a thiol group at one terminal and a nitrogen-containing functional group at the other terminal with metal nanoparticles, and mixing the sulfur-metal nanoparticles with the carbene compound described above.

[0067] Specifically, in the case of mixing the polyethylene glycol containing the thiol group at the one terminal and the nitrogen-containing functional group at the other terminal with the metal nanoparticles, the polyethylene glycol including the nitrogen-containing functional group at the terminal may be introduced to the surface of the metal nanoparticles, by mediating a metal-sulfur bond of sulfur of the thiol group on the metal surface. When the above-described carbene compound according to the present invention is introduced to the sulfur-metal nanoparticles formed above, while the metal-sulfur bond present on the surface of the metal nanoparticles is substituted with a metal-carbene bond, finally, the carbene-metal nanoparticle complex may be formed.

[0068] At this time, the reaction for substituting the metal-sulfur bond present on the surface of the metal nanoparticles with the metal-carbene bond may occur at room temperature (20° C. to 30° C.). Since the binding force of the metal-carbene bond is stronger than that of the metal-sulfur bond as known above, the substitution reaction may occur even only when left at room temperature for 1 to 10 hours. Particularly, referring to FIG. 17, when the metal is gold (Au), the intensity of the gold-carbene bond (binding energy: −63.55 Kcal/mol, bond distance: 2.03 Å) is stronger than that of the gold-sulfur bond (binding energy: −14.36 Kcal/mol, bond distance: 2.60 Å), and thus, as described above, the metal-sulfur bond may be easily substituted with the gold-carbene bond even at room temperature (see Chem. Soc. Rev. 2017 Apr. 18; 46(8):2057-2075).

[0069] Since the nitrogen group is exposed to the terminal as described above, the carbene-metal nanoparticle complex has an advantage of more easily bonding the bio-probe part (biomaterial). In particular, unlike the metal-sulfur bond, due to the stability of the metal-carbene bond, even in various environments of a high-concentration salt condition, a strong acid or weak base condition, and high temperature and ultra low temperature, the metal-carbene bond is maintained, so that there is an effect that the agglomeration of the carbene-metal nanoparticle complex may not occur.

[0070] 3. Biosensor

[0071] The present invention provides a biosensor comprising the carbene-metal nanoparticle complex described above.

[0072] The biosensor, in particular, the color thereof is changed by a particle size, a material, a shape, and a surrounding environment of the metal nanoparticles, and as a result, the biosensor may be a nano biosensor using a changed surface plasmon band of the metal nanoparticles, but is not limited thereto. The biosensor may be a lateral flow assay (LFA) diagnostic kit for field diagnosis manufactured to be easily portable, and in addition, a surface-enhanced raman spectroscopy (SERS)-based biosensor, a dark field-based biosensor, and the like may be applied.

[0073] At this time, it is important to immobilize a bio-probe part (e.g. antibody, DNA, aptamer, primer, etc.), which specifically binds to a biomaterial to be analyzed, to a substrate or metal nanoparticle.

[0074] In the biosensor, the carbene-metal nanoparticle complex of the present invention may serve to immobilize the bio-probe part. Specifically, the carbene-metal nanoparticle complex of the present invention includes the nitrogen-containing functional group at the terminal, so that the bio-probe part (e.g., antibody, DNA, aptamer, primer, etc.) may adhere to the nitrogen-containing functional group using a click reaction. Accordingly, generally, unlike that the bio-probe part binds to the metal nanoparticle by electrostatic attraction, since the bio-probe part may be immobilized to the metal nanoparticle by a stronger chemical bond, when the bio-probe part is applied to fields such as a biosensor and the like, there are advantages of enhancing the applicability to various environments in addition to the excellent storability and ease of storage of the product.

[0075] Hereinafter, the present invention will be described in more detail with reference to preferred Examples.

[0076] However, these Examples are to describe the present invention in more detail, and the scope of the present invention is not limited thereto.

<PREPARATION EXAMPLES> PREPARATION OF CARBENE COMPOUND

Preparation Example 1

[0077] ##STR00003##

[0078] According to Reaction Formula above, carbene compound 1 was prepared.

[0079] FIG. 11 illustrated a result of .sup.1H-NMR analysis of carbene compound 1.

Preparation Example 2

[0080] ##STR00004##

[0081] According to Reaction Formula above, carbene compound 2 was prepared.

Preparation Example 3

[0082] ##STR00005##

[0083] According to Reaction Formula above, carbene compound 3 was prepared.

[0084] FIG. 12 illustrated a result of .sup.1H-NMR analysis of carbene compound 3.

Preparation Example 4

[0085] ##STR00006##

[0086] According to Reaction Formula above, carbene compound 4 was prepared.

[0087] FIG. 13 illustrated a result of .sup.1H-NMR analysis of carbene compound 4.

Preparation Example 5

[0088] ##STR00007##

[0089] According to Reaction Formula above, carbene compound 5 was prepared.

[0090] FIG. 14 illustrated a result of .sup.1H-NMR analysis of carbene compound 5.

Preparation Example 6

[0091] ##STR00008##

[0092] According to Reaction Formula above, carbene compound 6 was prepared.

[0093] FIG. 15 illustrated a result of .sup.1H-NMR analysis of carbene compound 6.

<EXAMPLES> PREPARATION OF CARBENE-METAL NANOPARTICLE COMPLEX

Example 1

[0094] ##STR00009##

[0095] First, a thiol-PEG compound in which azide was introduced to a terminal was added into gold nanoparticles dispersed in an organic solvent to prepare a gold nanoparticle complex (Au NPs Thiol) by gold-sulfur bonds.

[0096] Thereafter, carbene compound 1 prepared in Preparation Example 1 was added, and the gold-sulfur bond was substituted with the gold-carbene bond to prepare a carbene-gold nanoparticle complex (Au NPs Carbene).

Comparative Example 1

[0097] A gold nanoparticle complex such as the following structure was prepared.

##STR00010##

Comparative Example 2

[0098] A gold nanoparticle complex such as the following structure was prepared.

##STR00011##

EXPERIMENTAL EXAMPLES

<Experimental Example 1> pH Stability Experiment

[0099] Solutions of pH 1 to 12 were prepared, respectively, and added with the carbene-gold nanoparticle complex (Au NPs Carbene) and the gold nanoparticle complex (Au NPs Thiol) of Example 1, and then changes in colors of the solutions were observed, and the result was shown in FIG. 2.

<Experimental Example 2> Salt Stability Experiment

[0100] <1> Aqueous solutions of water and NaCl of concentrations of 10 mM, 50 mM, 100 mM, 250 mM, 500 mM, and 1,000 mM were prepared, respectively, and added with the carbene-gold nanoparticle complex (Au NPs Carbene) and the gold nanoparticle complex (Au NPs Thiol) of Example 1, and then changes in colors of the solutions were observed, and the result was shown in FIG. 3.

[0101] <2> To confirm the stability in a high-concentration salt ion aqueous solution, the NaCl aqueous solution of 1,000 mM was added with the carbene-gold nanoparticle complex (Au NPs Carbene) of Example 1 and the gold nanoparticle complex of Comparative Example 2, and then changes in colors of the solution were observed, and the result was shown in FIG. 4.

<Experimental Example 3> Temperature Stability Experiment

[0102] <1> Aqueous solutions of low temperature of −20° C. and ultra low temperature of −78° C. in which the carbene-gold nanoparticle complex (Au NPs Carbene) was mixed were prepared, left at room temperature, and then changes in colors of the solutions were observed after 1 day, 3 days, 5 days, and 7 days, and the result thereof was shown in FIG. 5.

[0103] <2> Aqueous solutions were prepared by preparing 5 nm of gold nanoparticles (Aldrich) and 20 nm of gold nanoparticles (BBI solution) and then frozen to −20° C., respectively, and left at room temperature for 5 days again, and changes in aqueous solutions were observed, and the result was shown in FIG. 6.

<Experimental Example 4> Malaria Diagnostic Kit

[0104] A malaria antibody was introduced into the carbene-gold nanoparticle complex (Au NPs Carbene) in Example 1 to prepare a malaria diagnostic kit (LFA).

[0105] A diagnostic test was performed with 100 ng/ml, 10 ng/ml, and 1 ng/ml of malaria antigen samples and the result was shown in FIG. 7.

<Experimental Example 5> pH Stability Experiment

[0106] Solutions of pH 1 to 12 were prepared, respectively, and added with the carbene-gold nanoparticle complex (Au NPs Carbene) of Example 1 and the gold nanoparticle complex of Comparative Example 1, and changes in colors of the solutions were observed, and the result was shown in FIG. 8.

<Experimental Example 6> High-Temperature Stability Experiment

[0107] Aqueous solutions added with the carbene-gold nanoparticle complex (Au NPs Carbene) of Example 1 and the gold nanoparticle complex of Comparative Example 1 were prepared, respectively, and left at 100° C. for 6 hours, and then changes in colors of the solutions were observed, and the result was shown in FIG. 9.

<Experimental Example 7> Low-Temperature Stability Experiment

[0108] Aqueous solutions added with the carbene-gold nanoparticle complex (Au NPs Carbene) of Example 1 and the gold nanoparticle complex of Comparative Example 1 were prepared, respectively, and left at −20° C. for 6 hours, and then changes in colors of the solutions were observed, and the result was shown in FIG. 10.

[0109] According to Experimental Examples 1 and 5, the gold nanoparticles (Au NPs Thiol) bound with the thiol-PEG and the gold nanoparticles (Au NPs) showed purple (indicated by a dotted square in FIG. 2) due to the agglomeration of the gold nanoparticles because ligands bound to the gold nanoparticles were separated under a strong acid (about pH 1-3) or strong base (about pH 12) condition. On the other hand, in the carbene-gold nanoparticle complex (Au NPs Carbene) according to the present invention, it was confirmed that the gold nanoparticles were not agglomerated but stably maintained in the entire range of pH (there was no color change in the entire range of pH). In addition, according to FIG. 8, in the case of the gold nanoparticle composite of Comparative Example 1, it was confirmed that the gold nanoparticles were agglomerated under strong acid conditions (pH 1 to 3), indicating a purple color.

[0110] According to Experimental Examples 2<1> and <2>, the gold nanoparticles (Au NPs Thiol) bound with the thiol-PEG and the gold nanoparticles (Au NPs) showed dark red due to the agglomeration of the gold nanoparticles because ligands bound to the gold nanoparticles were separated around concentrations of 50 mM and 100 mM, respectively (gradually from dark red to purple). On the other hand, in the carbene-gold nanoparticle complex (Au NPs Carbene) according to the present invention, it was confirmed that the gold nanoparticles were not agglomerated but stably maintained in the entire concentration range (0 to 1,000 mM) of NaCl salt (no color changed).

[0111] According to Experimental Examples 3<1>, 6, and 7, the gold nanoparticles introduced by gold-sulfur bonds showed purple due to the agglomeration of the gold nanoparticles because ligands bound to the gold nanoparticles were separated at high temperature (70° C.) and low temperature (−20° C.). On the other hand, in the carbene-gold nanoparticle complex (Au NPs Carbene) according to the present invention, it was confirmed that the gold nanoparticles were not agglomerated but stably maintained even in high temperature (70° C.), low temperature (−20° C.), and ultra low temperature (−78° C.) (no color changed).

[0112] Meanwhile, according to Experimental Example 3<2>, in the case of gold nanoparticles as a control group, it was confirmed that the gold nanoparticles were agglomerated and precipitated in water within a few hours at low temperature (−20° C.)

[0113] According to Experimental Example 4, as shown in FIG. 7, in the malaria diagnostic kit applied with the carbene-gold nanoparticle complex (Au NPs Carbene) according to the present invention, it was confirmed that the diagnosis was enabled by finding that the Control line and Test line were observed even at a low concentration of 10 ng/ml.