KR101962162B1 - White Colored Emitting Graphene Quantum Dots Composition for FRET Mediated Biosensing And Manufacture Method Thereof - Google Patents

Abstract

The present invention relates to a white-emitting graphene quantum dot composition for FRET-mediated biosensing and a method of making the same.
The white emitting graphene quantum dot of the present invention is a quantum dot having a graphene structure and exhibiting excellent optical controllability, low cytotoxicity, and excellent optical stability, which is produced by a thermal decomposition method. The manufacturing cost is low and the manufacturing is easy. In addition, the white light-emitting graphene dot and the manganese oxide-coated white light-emitting graphene quantum dot of the present invention have a negative charge surface charge and an average particle diameter of 20 nm, which is excellent in biostability and excellent in cell membrane permeability. The white light-emitting graphene quantum dot coated with manganese oxide of the present invention is coated with manganese oxide reduced by hydrogen peroxide or glutathione and gives a FRET-mediated fluorescence quenching effect, so that hydrogen peroxide or glutathione present in a biological sample is detected or a concentration value is calculated There is an effect that can be done. The manganese oxide has the advantage of being selectively reduced to hydrogen peroxide or glutathione present in the biological sample because the manganese oxide has a specificity of being reduced only by hydrogen peroxide or glutathione without being reduced by protein, polysaccharide, amino acid, or the like present in the living body. The composition containing the white manganese oxide-coated white light emitting graphene quantum dot of the present invention is low cost and has excellent selectivity in comparison with the method of detecting hydrogen peroxide or glutathione by a conventional label. Therefore, the next generation hydrogen peroxide or It is expected to be used as a glutathione detection composition.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a white light emitting graphene quantum dot composition for FRET-mediated biosensing and a method for producing the same,

The present invention relates to a white color emitting emissive graphene quantum dot composition for FRET-mediated biosensing and a method for producing the same. Specifically, a white light emitting graphene quantum dot prepared by pyrolysis is coated with manganese oxide (MnO ₂ ) to realize a FRET-mediated fluorescence quenching effect, and then hydrogen peroxide or glutathione present in the sample Since the coated manganese oxide is selectively reduced and the white fluorescent effect of the white light emitting graphene quantum dot is restored, it is possible to detect hydrogen peroxide or glutathione present in the sample, Pin quantum dot, a composition comprising the same, and a method for producing the same.

Since white light emitting materials have many possibilities in the development of light emitting devices, they are highly expected materials for application and development in sensors, optical displays and next generation lighting devices. Typically, white luminescent materials are prepared by mixing different types of basic phosphors (red, green, blue) or complementary fluorescent materials (yellow, turquoise). Recent research has shown that organic molecules, rare earth metals, polymers, highly toxic quantum dot (quantum dot) materials and organic frameworks are used to produce white luminescent materials. However, these materials are toxic and relatively expensive, and it is difficult to quantitatively control the intensity of fluorescence emitted from each fluorescent substance, which results in a disadvantage that it inhibits white light emission rather. A single phosphorescent material capable of covering a wide visible light region has been popular as a material for white light emission. Graphene Quantum Dots (GQDs), based on nano-sized, dimensionless, and crystalline graphene, are based on Quantum Dot's limitations, size-dependent and bandgap-mediated optical controllability, low cytotoxicity, It has convenience to go beyond quantum dot and its application is attention. Particularly, these unique features of GQDs are suitable for application in various fields such as medicine, biosensor and optoelectronic device.

One of the most interesting features of GQDs is adjustable photoluminescence (PL). Although the exact mechanism is unknown, it is understood that the optical luminescence of GQDs is enhanced by the quantum limited to conjugated pi electrons, and the quantum is characterized by size, chemical functionalization, geometry, heteroatom doping, edge configuration and defects. Excitation and emission characteristics of GQDs that can be controlled by several previous studies have been reported, but little is known about the application of GQDs to produce white light.

Previous studies have shown that hummer's method, electrochemical stripping, and solvent-induced self-bonding are the methods for producing white light emitting GQDs (WGQDs). As an example, Sekiya et al. Performed edge functionalization using 4-propynyloxybenzylamine using a humming method using graphene powder to produce GQDs; Luk et al. Prepared white light using a GQD-agar composition and a method of coating a blue LED; Gosh et al. Prepared white light emitting graphene oxide quantum dots (GOQDs) using an acidic hydrolysis method from oxidized graphene; Joseph et al. Produced WGQDs using an electrochemical stripping method. However, these methods are disadvantageous in that not only high cost is consumed because they induce chemical changes, use severe acid treatment, or organic solvents, but also require a lot of steps to separate the produced WGQDs.

Multi-layered transition metal oxides such as molybdenum disulfide (MoS ₂ ), tungsten sulfide (WS ₂ ) and manganese dioxide (MnO ₂ ) have increased surface area and energy gain characteristics over volume. Due to the above properties, the metal oxide has been attracting great attention because it can be applied to photocatalyst, biosensor and photothermal therapy field. In particular, the metal oxide has been widely considered as a fluorescence quencher and a FRET mediated chemo / biosensing technology due to its rapid electron transfer and excellent light absorption characteristics.

Glutathione (GSH) and hydrogen peroxide (H ₂ O ₂ ) are considered as fundamental biomarkers to judge disease progression. Glutathione, an antioxidant in nature, plays an important role not only in maintaining redox homeostasis but also in regulating the production of free radicals. If glutathione levels are measured abnormally in a living system, it can be suspected that a variety of diseases have occurred, including Alzheimer's, cancer and HIV. Hydrogen peroxide is used as an antiseptic and oxidizing agent in various industrial and biological applications. In the case of biological systems, the increase in the concentration of hydrogen peroxide in the cell can be recognized as a factor for determining the tumorogenesis. Furthermore, the concentration of hydrogen peroxide present in the bladder can be used as a factor to determine the oxidative stress of the whole body. Most biosensing methods involve the quantitative analysis of glutathione and hydrogen peroxide using biological enzymes, organic fluorescent materials, electrochemical methods, and enzyme immunoassays. However, since the above methods are expensive and require a complicated apparatus for analysis, development of a label-free detection method for identifying the biomarkers is urgently required.

The method of measuring the selectivity and dissociation degree of manganese oxide (MnO ₂ ) and manganese ion (Mn ^{2 +} ) in the presence of hydrogen peroxide and glutathione is sufficient to be applied as a biosensing method. As an example of such a biosensing method, Yuan et al. Have used NIR uptake nanoparticles (UCNP) -manganese oxide complexes for the determination of hydrogen peroxide values; Deng et al. Have used UCNP-manganese oxide complexes to determine glutathione concentrations. However, the UCNP has a relatively low quantum yield and tends to be overheated due to its ability to absorb NIR.

WGQDs can be produced by pyrolysis. However, the pyrolysis method has disadvantages that the precursors are broken by the heat applied to produce multi-color emission GQDs. Therefore, most of the WGQDs prepared by the above method are applied to general optoelectronics, and application to biology such as those used in biological medium is almost It is not known.

The patent documents and references cited herein are hereby incorporated by reference to the same extent as if each reference was individually and clearly identified by reference.

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The present inventors have found that there are many possibilities in the development of light emitting devices, but quantum dots having a low quantum efficiency and cytotoxicity, high manufacturing costs due to severe acid treatment and organic solvents, and complex purification processes, Quantum dot) can be fabricated by pyrolysis using deoxycholic acid to produce a white emitting graphene quantum dot, which has a graphene structure and emits white light, has an improved quantum efficiency and is less cytotoxic. (MnO ₂ ), which can be applied to FRET-mediated biosensing technology, can detect biomarkers such as hydrogen peroxide (H ₂ O ₂ ) and glutathione It is experimentally confirmed that the concentration of hydrogen peroxide (H ₂ O ₂ ) and glutathione can be calculated Thereby completing the present invention.

It is therefore an object of the present invention to provide a composition for the detection or numerical measurement of hydrogen peroxide (H ₂ O ₂ ) comprising white colored emitting graphene quantum dots coated with manganese oxide (MnO ₂ ) .

It is another object of the present invention to provide a composition for detecting or measuring glutathione comprising a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ).

It is another object of the present invention to provide a method for detecting hydrogen peroxide (H ₂ O ₂ ) or a composition for numerical measurement comprising a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ) .

Other objects and technical features of the present invention will be described in more detail with reference to the following detailed description, claims and drawings.

According to an aspect of the present invention, there is provided a method of detecting hydrogen peroxide (H ₂ O ₂ ) or measuring a hydrogen peroxide (H ₂ O ₂ ) containing white colored emitting graphene quantum dot coated with MnO ₂ Lt; / RTI >

According to another aspect of the present invention, there is provided a composition for detecting or measuring glutathione, which comprises a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ) to provide.

According to one embodiment of the present invention, the white emitting graphene quantum dot of the present invention has a hexagonal pattern graphene structure, and has a mean zeta potential of -50 mV and a mean particle diameter of 20 nm.

According to another embodiment of the present invention, the manganese oxide of the present invention covers the white emission graphene quantum dot to exhibit a fluorescence resonance energy transfer mediated quenching effect, and the manganese oxide MnO ₂ ) is reduced to manganese ion (Mn ^{2 +} ), and the white light emission of the white emitting graphene quantum dot is restored, the hydrogen peroxide or glutathione present in the sample can be detected or the concentration can be calculated.

In accordance with another aspect of the present invention, the present invention provides a method for preparing a light-emitting layer comprising a hydrogen peroxide (H ₂ O ₂ ) solution comprising a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ) ) Or a method for detecting or measuring a glutathione.

Step 1) Deoxycholic acid is heated in a heating mantle at 350 to 450 DEG C for 5 to 15 minutes to prepare a white emitting graphene quantum dot;

Step 2) dissolving potassium permanganate (KMnO ₄ ) in sodium hydroxide to prepare manganese oxide (MnO ₂ ); And

The third step is to mix the white emitting graphene quantum dot and the manganese oxide at a weight ratio of 5 to 20: 1 to prepare a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ) .

The present invention relates to a white-emitting graphene quantum dot composition for FRET-mediated biosensing and a method of making the same.

The white emitting graphene quantum dot of the present invention is a quantum dot having a graphene structure and exhibiting excellent optical controllability, low cytotoxicity, and excellent optical stability, which is produced by a thermal decomposition method. The manufacturing cost is low and the manufacturing is easy. In addition, the white light-emitting graphene dot and the manganese oxide-coated white light-emitting graphene quantum dot of the present invention have a negative charge surface charge and an average particle diameter of 20 nm, which is excellent in biostability and excellent in cell membrane permeability. The white light-emitting graphene quantum dot coated with manganese oxide of the present invention is coated with manganese oxide reduced by hydrogen peroxide or glutathione and gives a FRET-mediated fluorescence quenching effect, so that hydrogen peroxide or glutathione present in a biological sample is detected or a concentration value is calculated There is an effect that can be done. The manganese oxide has the advantage of being selectively reduced to hydrogen peroxide or glutathione present in the biological sample because the manganese oxide has a specificity of being reduced only by hydrogen peroxide or glutathione without being reduced by protein, polysaccharide, amino acid, or the like present in the living body. The composition containing the white manganese oxide-coated white light emitting graphene quantum dot of the present invention is low cost and has excellent selectivity in comparison with the method of detecting hydrogen peroxide or glutathione by a conventional label. Therefore, the next generation hydrogen peroxide or It is expected to be used as a glutathione detection composition.

Panel A of Figure 1) shows the fluorescence intensity differences of WGQDs prepared at different synthesis temperatures. Panel B) shows photographs taken at a UV lamp 365 nm wavelength against 5 mg / ml WGQDs prepared at different synthesis temperatures. Panel C) shows a CIE 1931 colorimetric standard observer showing the fluorescence emission results of temperature dependence WGQDs.
Panel A in Fig. 2) shows an FE-SEM image (scale bar: 100 nm) of WGQDs. Panel B) shows an FE-SEM image of WGQDs with a spherical shape (red dotted line). Panel C) shows the AFM image of the developed WGQDs. Panel D) shows the size profile of WGQDs measured using an AFM microscope.
Panel A of FIG. 3) shows the EDS spectrum confirming the basic constituents of WGQDs. Panel B) shows the FTIR spectrum of WGQDs.
Figure 4 shows the results of zeta potential analysis of WGQDs (1 mg / ml).
Panel A in Figure 5) shows the UV-Vis absorption spectrum of WGQDs (5 mg / ml). Panel B) shows excitation and emission profiles of WGQDs. The emission profile was recorded by excitation of WGQDs at 360 nm. Panel C) shows the optical luminescence spectrum according to the concentration of WGQDs. Panel D) shows fluorescence emission according to excitation of WGQDs (5 mg / ml) at different wavelengths from 330 to 510 nm each.
Panel A of Figure 6), shows a typical Raman spectrum of WGQDs representing the D band and the G band around the periphery of the 1520㎝ ^{-1 -1} 1357㎝ excited by a laser having a wavelength of 532.01㎚. Panel B) can show a D + G bands around 2953㎝ and 2D bands around 2860㎝ ^{-1 -1} confirmed that the graphene quantum dots of the present invention through the band has been successfully synthesized.
Figure 7 shows a confocal laser microscope image of KB cell line treated with WGQDs 0.5 mg / ml for 4 hours.
Panel A of FIG. 8) shows the results of intracellular absorption of KB cell line depending on treatment time and concentration of WGQDs. Panel B) shows the toxicological profiles of KB cell lines treated with different concentrations of WGQDs for 24 hours.
Panel A in Figure 9) shows the hemolytic activity of rat blood according to the concentration of WGQDs. Panel B) shows hemoglobin released due to the dissolution of red blood cells. The positive control group was 0.3% Triton X-100 and the negative control group was PBS.
Panel A of FIG. 10) is WGQD-MnO ₂ The FE-SEM image of the composite is shown. The inner picture panel is WGQD-MnO ₂ Shows enlarged image of composite nanoparticles. Panel B) shows that potassium permanganate and WGQD-MnO ₂ The panels C) and D) show the absorption spectra of manganese oxide and the optical luminescence spectra of WGQDs excited at 360 nm, respectively.
Figure 11 shows the TGA spectrum. Panel A) shows the TGA spectrum of WGQDs and panel B) shows WGQD-MnO ₂ The TGA spectrum of the composite nanoparticles is shown.
Panel A of FIG. 12 shows the photoluminescence spectra of WGQDs treated with various concentrations of potassium permanganate (mM). Panel B) shows the fluorescence intensities of WGQDs restored by hydrogen peroxide added to the WGQD-MnO ₂ complex nanoparticles. Panel C) shows the fluorescence intensities of WGQD-MnO ₂ complex nanoparticles treated with various concentrations of hydrogen peroxide.
Figure 13 shows the fluorescence intensity of recovered WGQD after addition of GSH to WGQD-MnO ₂ complex nanoparticles. Panel C) shows the fluorescence intensities measured after adding various concentrations of GSH to the WGQD-MnO ₂ complex nanoparticles The selectivity of WGQD-MnO ₂ composite nanoparticles to various interfering substances can be confirmed through this.

According to one aspect of the present invention, there is provided a composition for sensing or numerically measuring hydrogen peroxide (H ₂ O ₂ ) comprising a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ) .

According to another aspect of the present invention there is provided a composition for detecting or measuring glutathione comprising a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ) .

The composition of the present invention is a white light emitting graphene dot coated with manganese oxide (MnO ₂ ) to detect hydrogen peroxide or glutathione present in living tissue, cells, blood, urine, body fluids, or to measure the concentration of hydrogen peroxide or glutathione do.

According to one embodiment of the present invention, the white emission graphene quantum dot has a hexagonal pattern graphene structure and has an average zeta potential of -50 mV and an average particle diameter of 20 nm. The white emitting graphene quantum dot has a hexagonal pattern graphene structure, and thus has excellent optical controllability, low cytotoxicity, and improved light stability. In addition, the white light emitting graphene quantum dot has a surface charge of negative charge, thereby preventing adsorption of a protein having a negative charge, thereby inhibiting opsonization. The opsonization refers to a phenomenon in which foreign particles introduced into a living body are easily ingested by phagocytes and removed, thereby modifying the external particles. Therefore, the white light emitting graphene dot of the present invention is advantageous in that bioavailability is improved because the opsonin action is inhibited. When the surface charge of the external particles has an average of -50 mV, the amount of negative charge can be reduced by the protein existing in the living body and the effect of inhibiting the opsonin function can be reduced by half.

Conventional nanoparticles are known to have the property of passing a cell membrane freely if they have an average particle diameter of less than 100 nm. However, in the case of nanomaterials in which the surface charge is negatively charged, the surface charge of the cell membrane is negatively charged, and therefore, it is required to have a smaller particle size due to the repulsive force with the cell membrane. According to one embodiment of the present invention, the white light-emitting graphene dot quantum dot of the present invention has a negative charge on the surface and has an average particle diameter of only 20 nm in spite of the repulsive force against the cell membrane, have.

The white light emitting graphene quantum dot coated with manganese oxide of the present invention has the same physical properties as the uncoated white emitting graphene quantum dot after the manganese oxide is coated even when the surface charge and the particle diameter are not changed.

According to one embodiment of the present invention, the white-emitting graphene dot quantum of the present invention excites white light at 475 to 485 nm by excitation at 345 to 355 nm and emits white light at 5 to 6% (photoluminescence) quantum yields.

According to one embodiment of the present invention, the white emitting graphene quantum dot of the present invention can be produced by using pyrolysis as a precursor of deoxycholic acid. The white emitting graphene quantum dot prepared by the pyrolysis method is composed of 65 to 75% by weight of carbon and 25 to 35% by weight of oxygen. Preferably, the white light emitting graphene quantum dot is comprised of 68-72 wt% carbon and 28-32 wt% oxygen, preferably 70 wt% carbon and 30 wt% oxygen. The white light emitting graphene quantum dot may have different fluorescence properties depending on the thermal decomposition method.

According to another embodiment of the present invention, when the heat treatment is performed at 400 ° C. using the deoxycholic acid as a precursor, white light is emitted at the maximum emission at 480 nm, but the deoxycholic acid ) Is used as a precursor and heat treatment is performed at 200 ° C, it is confirmed that the blue light is emitted due to the largest emission at 410 nm. Therefore, the heat treatment for preparing the white light-emitting graphene dot of the present invention is performed at 350 to 450 ° C, preferably at 380 to 420 ° C, and more preferably at 400 ° C.

According to one embodiment of the present invention, the white emitting graphene quantum dot of the present invention exhibits a photoluminescence quantum yield of 5 to 6%.

According to the conventional method, white emitting quantum dot is produced by mixing red, green and blue quantum dot. However, it is difficult to implement white light through the above-described mixing method because it is difficult to control the color intensity. Therefore, there is a growing demand for materials emitting white light as a single substance. The white light-emitting graphene dot quantum dot of the present invention is a single substance that expresses white light, and the yield of quantum that expresses light luminescence is also 5 to 6%, which is advantageous in practical industrial applications.

According to an embodiment of the present invention, the white light-emitting graphene dot of the present invention is coated with manganese oxide, thereby realizing a fluorescence resonance energy transfer mediated quenching effect.

According to one embodiment of the present invention, the coated manganese oxide is coated with 0.5 to 1.5 wt% based on 100 wt% of the white light emitting graphene dot coated with manganese oxide. Preferably 0.8 to 1.2 wt%, more preferably 1 wt%, based on 100 wt% of the white light emitting graphene dot coated with manganese oxide. The manganese oxide is one of the multi-layered transition metal oxides, and has an improved surface area to volume and an improved energy recovery characteristic. The multi-layered transition metal oxide also exhibits a FRET-mediated quenching effect that inhibits the excitation and emission of quantum dot by covering the white emitting graphene quantum dot. Therefore, the white light emitting graphene quantum dot coated with the manganese oxide has no photoluminescence property. (MoS ₂ ) and tungsten sulfide (WS ₂ ), but the molybdenum sulfide (MoS ₂ ) and tungsten sulfide (WS ₂ ) can be used as the white emitting graphene quantum dot It is inappropriate to cover.

The white manganese-coated white emitting graphene quantum dot of the present invention is biologically applied to detect hydrogen peroxide and glutathione present in a sample or to calculate the concentration value thereof. The manganese oxide is reduced to manganese ions and oxygen by hydrogen peroxide or glutathione (see Chemical Formulas 1 to 2 below). Therefore, when a white light emitting graphene dot coated with the present invention is added to a sample and reacted with hydrogen peroxide or glutathione present in the sample, the coated manganese oxide is reduced to an ionic state to remove the manganese oxide coating, The optical luminescence characteristic is restored. When the amount of recovered luminoleness is measured and analyzed by a graph, the concentration of hydrogen peroxide or glutathione present in the sample can be detected or its concentration value can be calculated. However, other multi-layered transition metal oxides, such as molybdenum sulfide and tungsten sulfide, are not reduced by hydrogen peroxide or glutathione. Therefore, when the white light emitting graphene quantum dot is covered with the sulfide or tungsten sulfide, the photoluminescence property is not recovered by the hydrogen peroxide or glutathione present in the sample. Therefore, the molybdenum sulfide or the tungsten sulfide is used as the white light emitting It is inappropriate to use it as a coating material for graphene quantum dot.

According to one embodiment of the present invention, the white manganese-coated white emitting graphene quantum dot of the present invention detects not only the presence of hydrogen peroxide but also the concentration of hydrogen peroxide in the range of 0.01 to 1.5 mmol / L hydrogen peroxide . In order to calculate the concentration of hydrogen peroxide present in the sample, the amount of the luminoluminescence (fluorescence) restored by the hydrogen peroxide and the amount of hydrogen peroxide present in the sample must have a linear relationship with a correlation coefficient close to 1.

According to an embodiment of the present invention, the white manganese oxide-coated white emitting graphene quantum dot can calculate the concentration of hydrogen peroxide in a range of hydrogen peroxide concentration of 0.001 to 1.5 mmol / L, preferably 0.005 The concentration of hydrogen peroxide can be calculated numerically in the hydrogen peroxide concentration range of 1 mmol / L. More preferably, the white manganese oxide-coated white emitting graphene quantum dot of the present invention can calculate the concentration of hydrogen peroxide in the range of the hydrogen peroxide concentration of 0.008 to 0.5 mmol / L, wherein the correlation coefficient is 0.9905.

According to one embodiment of the present invention, the white manganese-coated white emitting graphene quantum dot of the present invention not only detects the presence or absence of glutathione, but also detects the concentration of glutathione in a glutathione concentration range of 0.005 to 0.7 mmol / . Preferably, the concentration of glutathione can be calculated numerically in a glutathione concentration range of 0.0065 to 0.7 mmol / L. More preferably, the white light emitting graphene dot coated with manganese oxide of the present invention can calculate the concentration of glutathione in a range of glutathione concentration of 0.007 to 0.5 mmol / L, wherein the correlation coefficient is 0.9977.

According to one embodiment of the present invention, the white light-emitting graphene dot and the manganese oxide-coated white light-emitting graphene quantum dot of the present invention have a slight cytotoxicity and excellent cell absorption ability. In addition, the white light-emitting graphene dot and the manganese oxide-coated white light-emitting graphene quantum dot of the present invention are not reduced by the protein, the polysaccharide and the amino acid. Therefore, the white light-emitting graphene dot and the manganese oxide-coated white light-emitting graphene quantum dot of the present invention can be used as a sample for improving the preservation of cells and tissues in tissue, cells, blood, urine, A polysaccharide or an amino acid.

According to another aspect of the present invention, the present invention provides a method for preparing a composition for sensing or numerically measuring hydrogen peroxide or glutathione, which comprises a white light emitting graphene dot coated with manganese oxide comprising the steps of:

Step 1: Deoxycholic acid is heated in a heating mantle at 350 to 450 ° C for 5 to 15 minutes to prepare a white emitting graphene quantum dot;

Step 2: dissolving potassium permanganate (KMnO ₄ ) in sodium hydroxide to prepare manganese oxide (MnO ₂ ); And

Step 3: The white emitting graphene quantum dot and the manganese oxide are mixed at a weight ratio of 5 to 20: 1, respectively, and a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ) ≪ / RTI >

The fabrication of the white emitting graphene quantum dot (first step) will be described in detail as follows.

Step 1-1) Heat 0.3-0.7 g of deoxycholic acid in a 350-450 ° C heating mantle for 5-15 minutes until the color changes from white to brown to produce white-emitting graphene quantum dot. Preferably, the deoxycholic acid is 0.5 g of sodium dioxycholate, heated at 370-420 占 폚 in a heating mantle for 7-12 minutes, more preferably 0.5 g of sodium dioxycholic acid and heated at 400 占 폚 in a heating mantle Heat for 10 minutes.

1-2) 40-60 ml of distilled water was added to the white emitting graphene quantum dot, and ultrasonication was performed for 25-35 minutes to prepare a white emitting graphene quantum dot dispersion solution. Preferably, 50 ml of distilled water is added to the white emitting graphene quantum dot, and ultrasonication is performed for 30 minutes to prepare a white emitting graphene quantum dot dispersion solution.

1-3) The white light-emitting graphene quantum dot dispersion solution is dialyzed against distilled water for 2 days to remove the remaining deoxycholic acid.

1-4) The dialyzed white luminescent graphene quantum dot dispersion solution is lyophilized to obtain a white luminescent graphene quantum dot powder.

The process of covering the white light emitting graphene quantum dot with manganese oxide (the second step and the third step) will be described in detail as follows.

Step 2-1) Potassium permanganate (KMnO ₄ ) is dissolved in 1 N sodium hydroxide (NaOH) to prepare a solution of manganese oxide 1-3 mg / ml. Preferably, potassium permanganate (KMnO ₄ ) is dissolved in 1 N sodium hydroxide (NaOH) to prepare a 2 mg / ml solution of manganese oxide.

Step 2-2) Distilled water was added to the above-mentioned white light-emitting graphene quantum dot powder to prepare a 4-6 mg / ml white light-emitting graphene quantum dot solution. Preferably, the white light emitting graphene quantum dot powder is added with distilled water to prepare a 5 mg / ml white light emitting graphene quantum dot solution.

Step 2-3) The above manganese oxide solution and the above-mentioned white light emitting graphene quantum dot solution were mixed to prepare white light emitting graphene quantum dots containing 0.5 to 10 mg and 0.05 to 0.2 mg of white light emitting graphene dot and manganese oxide, To prepare a mixed solution of manganese oxide. Preferably, white light emitting graphene quantum dot coated with manganese oxide for hydrogen peroxide sensing and numerical measurement is prepared by mixing a white emitting graphene quantum dot-manganese oxide mixture containing 10 mg of white light emitting graphene quantum dot and 0.2 mg of manganese oxide White-emitting Graphene-Manganese-Coated Solution for Glutathione Sensing and Numerical Measurement A white-emitting graphene dot-manganese oxide mixed solution containing 0.5 mg of white-emitting graphene quantum dot and 0.05 mg of manganese oxide is prepared.

Step 2-4) The white luminescent graphene dot-manganese oxide mixed solution was stirred at room temperature for 5-15 minutes until the color changed from pink to green and finally changed to brown, and white luminescent graphene dot-oxidation Manganese complex.

Step 2-5) The white light-emitting graphene dot-manganese oxide mixed solution of the white light emitting graphene dot-manganese oxide composite synthesized was centrifuged at 10,000 g for 10 minutes to obtain a precipitate (white light emitting graphene quantum dot-manganese oxide Complex) is obtained and the precipitate is washed twice more with ethanol.

2-6) The washed white luminescent graphene dot-manganese oxide complex is dried to obtain a powdery form.

The obtained white manganese oxide-coated white luminescent graphene dot (white luminescent graphene dot-manganese oxide complex) improves the preservation of cells and tissues when using tissues, cells, blood, urine, body fluids as a sample For example, a BSA protein, a polysaccharide or an amino acid.

Example

Experimental Method

1) Synthesis of white emitting graphene quantum dot

White emitting Graphene Quantum Dots (WGQDs) were prepared by pyrolysis using dioxycholic acid (DOCA) as a precursor. WGQDs and Temperature Dependent Deoxycholic acid was purchased from Sigma-Aldrich (MO, USA) for the synthesis of WGQDs. For synthesis of WGQDs, 500 mg of the above dioxycholic acid was placed in a glass bottle and heated in a heating mantle at 400 DEG C for 10 minutes. After 10 minutes of heating, if the dioxycholic acid changes from white to brown, 50 ml of distilled water was added and ultrasonication was performed for 30 minutes in a water bath for 30 minutes. The dissolved WGQDs solution was dialyzed with distilled water for 2 days and the distilled water was replaced every 6 hours. The dialyzed samples were stored frozen and dried.

The temperature dependent WGQDs were fabricated by the above method, and the heating temperature was 200 to 300 ° C. CIE 1931 colorimetric standard observers were recorded using colorimetric software.

2) WGQDs-manganese oxide (MnO ₂ ) Synthesis of Composite Nanoparticles

WGQDs-manganese oxide composite nanoparticles (white light emitting graphene quantum dot coated with manganese oxide) were prepared by adding 100 μl of a 2 mg / ml solution of manganese oxide (KMnO ₄ ) to 2 ml of the 5 mg / ml WGQDs solution prepared in Example 1, . The manganese oxide solution was prepared by dissolving 30 μl of 15 mg / ml potassium permanganate (KMnO ₄ ) in 5 ml of 1N sodium hydroxide (NaOH). The sample was stirred for 10 minutes at room temperature until the color of the WGQDs solution turned dark brown. The color of the solution changes from pink to green and finally becomes brown. The sample was used for further analysis. The sample was centrifuged at 10,000 g for 10 minutes, washed twice with ethanol, and further washed with water.

3) Physical and chemical characterization of WGQDs

The morphology of WGQDs and WGQDs-manganese oxide complexes was measured using a scanning electron microscope (TEM, JEOL, Japan). The shape and size of the WGQDs were measured using an atomic force microscope (AFM, Digital Instrument Nanoscope IV, Veeco, Santa Barbara, Calif., USA) and tapping mode at room temperature. The morphology of WGQDs and WGQDs-manganese oxide complexes was measured using a JSM-7610F field emission scanning electron microscope (FESEM; Jeol, Tokyo, Japan). An energy-dispersive X-ray spectrometer (EDS, 51-XMX1034; Oxford Instruments, Abingdon, UK) equipped with a JSM-7610F Field Emission Scanning Electron Microscope was charged with WGQDs and WGQDs- The relative contents of carbon, nitrogen, and manganese present in manganese oxide were analyzed. Fourier transform infrared spectra were obtained using an FT-IR spectrometer (Bruker, Billerica, MA, USA). UV absorption of WGQDs was measured using a UV spectrometer (Mecasys Co. Ltd, South Korea). The fluorescence intensity of WGQDs was determined using a photoluminescence spectroscope (Sinco, South Korea). The thermal stability of WGQDs and WGQDs-manganese oxide composites was measured by heating to 800 ° C at a heating rate of 10 ° C per minute in a nitrogen atmosphere using a TA-Q50 thermogravimetric analyzer (TA, DE). The Raman spectrum of the WGQDs was measured using a Raman mini-spectrometer (Jasco, NRS-3200) and a laser having a wavelength of 514.5 nm.

4) Evaluation of in vitro cell uptake

Cellular uptake of WGQDs was performed using a KB cell line and a confocal laser scanning microscope (Zeiss LSM510, Germany). The KB cell line was obtained from the Korean Cell Line Bank (Seoul, Korea). Under freeze-drying by dissolving a WGQDs to clean RPMI culture medium WGQDs solution (100㎍ / ㎖) the manufacture and after the addition of the solution to the cell culture WGQDs that KB cells incubated 37 ℃ for 4 h, 5% CO ₂ atmosphere, the culture Respectively. After incubation for 4 hours, cells were obtained, washed twice with PBS and fixed with 4% formaldehyde. All of the above procedures were carried out in the state that the light was blocked. Cell images were obtained using a confocal laser scanning microscope equipped with a long-pass emission filter (88543 nm) and visualized GQD in the cells. Cellular uptake by time and concentration was assessed. KB cell line (1 x 10 ⁴ cells / well) was inoculated in a 96-well plate and cultured at 37 ° C in a 5% CO ₂ atmosphere for 24 hours. Various concentrations of WGQDs were dissolved in the RPMI culture medium, and then the cell culture medium was replaced with the WGQDs-containing culture medium. After a certain period of time, the cells were washed 3 times with PBS and the cells were lysed in the cell fusion buffer solution and lyophilized. The lyophilized cells were measured for light illuminance using a multi-mode scanner (Ex: 350 nm and Em: 480 nm).

5) Evaluation of cytotoxicity in vitro

KB cell line was inoculated at 96x10 < ⁶ > cells / well and cultured for 24 hours. WGQDs were added to 96 wells at concentrations of 0, 0.025, 0.05, 0.1, 0.25, 0.5, and 1 mg / ml. The cell culture was further cultured in a light-blocked environment at 37 ° C for 24 hours. 50 占 퐇 of the MTT liquid solution was added to each well for 20 hours in culture, and the supernatant was removed after further incubation for 4 hours. MTT assay kit, trypsin-EDTA, and 2,7-dichlorofluorescein diacetate (DMA) were purchased from Sigma-Aldrich (MO, USA). MTT lysis solution (100 占 퐇) was added to each well and pipetting was performed to dissolve the formazan crystal. The absorbance was then measured using a Varioskan flash (Thermo Scientific, USA) at a wavelength of 570 nm. The absorbance results were converted to cell activity using a standard curve and analyzed. Cell activity was calculated by the following equation. Cell activity (%) = (absorbance of sample cell / absorbance of control cell) X 100.

6) In vitro hemolyzing essay

The hemolysis essay was performed according to reference 30. From 7-week-old female SD rats, 2 ml of hematocrit was collected using a tube coated with EDTA and centrifuged at 4 ° C and 2500 rpm for 10 minutes. The supernatant was removed and the precipitate was washed 3 times with PBS. The precipitate was then dissolved in 1 ml of PBS and used in the experiment. To analyze erythrocyte lysis in the presence of WGQDs, various concentrations of WGQDs were dissolved in 1 ml of PBS and 50 쨉 l of the separated red blood cells were added. Triton X100 0.3% and PBS were used as positive control and negative control, respectively. The samples were incubated at 37 ° C for 60 minutes and the cultured samples were centrifuged at 4 ° C and 2500 rpm for 10 minutes. The supernatant was collected and the hemolysis of the red blood cells was measured at the optical density 540 nm.

7) Detection of hydrogen peroxide and glutathione by WGQD-manganese oxide composite nanoparticles

To confirm the detection of hydrogen peroxide in the WGQD-manganese oxide composite nanoparticles, 2 ml of 5 mg / ml WGQDs was mixed with 100 쨉 l of 2 mg / ml potassium permanganate (KMnO ₄ ) and incubated at room temperature for 10 minutes. After that, various solutions of hydrogen peroxide were added and the photoluminescence spectrum was measured.

In order to confirm the ability of the WGQD-manganese oxide composite nanoparticles to detect glutathione (GSH), 25 μl of manganese oxide was added to 2 ml of 0.25 mg / ml WGQDs and mixed. The samples were incubated at room temperature for 10 minutes and various concentrations of GSH solution were added. The optical luminescence spectrum of the sample to which GSH was added was measured after 10 minutes. The optical luminescence spectra of all the samples were recorded after exciting the nanoparticles at 350 nm. To determine the selectivity of GSH and hydrogen peroxide in WGQD-MnO nanoparticles, different types of interferents were added to the WGQD-MnO 4 solution at a concentration similar to GSH and WGQDs, excited nanoparticles at 350 nm, The spectrum was measured.

2. Experimental results

1) Synthesis and characterization results of WGQDs

WGQDs used sodium deoxycholic acid (DOCA) as a source of carbon. The DOCA was pyrolyzed at respective temperatures (200 ° C., 300 ° C. and 400 ° C.) and optical luminescence characteristics were evaluated by means of photoluminescence spectroscopy. Conventional methods for preparing WGQDs, such as hummers or solution inducer binding methods, require acid treatment or coarse chemical treatment. However, the pyrolysis method of the present invention is simple and has a high yield, so that WGQDs can be efficiently produced in less than one hour.

Usually, the pyrolysis process may produce blue GQDs. Interestingly, the fluorescence properties of the prepared WGQDs are temperature dependent. Panel A of FIG. 1 shows the results of spectral analysis of GQDs prepared at different temperatures. According to the above results, GQDs produced at 200 ° C exhibit blue shift in the optical luminescence spectrum, whereas GQDs produced at 400 ° C exhibit the largest emission at 480 nm. In addition, Panel B of FIG. 1 shows that the color of the GQDs changes in a temperature-dependent manner. When DOCA is pyrolyzed at 200 ° C, the GQDs produced are blue. However, when the thermal decomposition temperature is 400 ° C, the produced GQDs have white (GQDs, WGQDs). The CIE 1931 colorimetry standard observer of Panel C of Figure 1 shows that the CIE coordinates of GQDs vary from blue to white as the synthesis temperature of WGQDs increases. In addition, the CIE coordinates (0.26, 0.34) of WGQDs synthesized at 400 ° C are included in the white region. The results are confirmed in the synthesis of the following WGQDs. The WGQDs synthesized at 400 < 0 > C have a photoluminescence quantum yield of 5.58%. The above result is further confirmed later.

The physical forms of WGQDs were analyzed by FE-SEM, FE-TEM and AFM microscopy. The FE-SEM and FE-TEM images of panel A of FIG. 2 and panel B of FIG. 4 show spherical shaped WGQDs with a grating space of 0.275. + -. 0.035 nm and an average particle size of 20 nm. In addition, according to the fast Fourier transform pattern disclosed in Panel B) of FIG. 4, it has been confirmed that the WGQDs have a hexagonal pattern of graphene structure. The AFM images disclosed in panel C) and panel D) of FIG. 2 also show spherical shapes of WGQDs with 2.8 nm similar to the thickness of graphene oxide films 5 to 6. The basic constructions of the EDS spectrum show that there is 69.63% carbon and 30.37% oxygen in the WGQDs (see panel A of FIG. 3). Smaller size nanoparticles can pass through the Reticulo endothelial system and are thus suitable for biomedical applications because they can function in target cells with ease. Since the WGQDs of the present invention have an average size of 20 nm, it is judged that they are suitable for biomedical use. FTIR was used to identify functional groups distributed in WGQDs (see panel C in FIG. 3). Strong peak is identified in 3400㎝ ^-1 represents a hydrogen present in WGQDs peak identified in 2863㎝ 2963㎝ ^-1 and ^-1 represents the CH stretching (CH stretching) of WGQDs. In addition, the peak seen on 1043㎝ ^-1 denotes a CO stretch (CO stretching) of WGQDs 1560㎝ ^-1, the peak seen on 1406㎝ 1656㎝ ^-1 and ^-1 is asymmetric and symmetric of COO- groups present in WGQDs Stretching. It was confirmed from the experiment that WGQDs of the present invention are distributed over a wide range of carboxyl groups and hydroxyl groups, and it was confirmed that WGQDs has a negative surface zeta potential. In addition, the surface charge of WGQDs was analyzed (see FIG. 4). As a result, the average WGQDs zeta potential of -50 mV is more suitable for biomedical applications because WGQDs having negative zeta potential of the present invention can inhibit aggregation. In addition, WGQDs of the present invention have an advantage of improving circulation time in vivo because they inhibit opsonization by preventing adsorption of proteins having negative charges existing in vivo. The adsorption and opsonization of the protein is the most common factor associated with the activation of the immune system and the early nanoparticle removal mechanism of the biological system. As a result, the WGQDs having a negative charge of the present invention prevent the adsorption of proteins having a negative charge, thereby contributing to improving the bioavailability of WGQDs. According to the absorption spectrum of WGQDs disclosed in the panel A of Fig. 5, it is confirmed that WGQDs exhibits a strong absorption intensity at 250 nm. According to the optical luminescence excitation and emission spectrum disclosed in Fig. 5, panel B), WGQDs exhibit the largest excitation and emission at 350 nm and 480 nm, respectively. The concentration-dependent emission spectrum disclosed in panel C) of FIG. 5 shows that fluorescence intensity decreases as the concentration of WGQDs decreases. The GQDs of the present invention exhibit an emissive profile according to the present invention similar to conventional GQDs. According to the panel D of FIG. 5, it is confirmed that the emission wavelength of the WGQDs is red shifted (450-600 nm) as the excitation wavelength increases from 350 nm to 500 nm. The excitation characteristics according to the emission phenomenon are useful for various biological and biomedical applications and can penetrate light to deeper tissues compared to blue GQDs. Raman spectroscopy was used to analyze the physico - chemical properties of WGQDs. According to panel A of FIG. 6, the two peaks observed at 1357 cm ^-1 and 1520 cm ^-1 respectively indicate D band and G band of the directional domain of GQDs. In addition, according to Panel B) of FIG. 6, the 2D band identified at 2860 cm ^-1 shows the graphene quantum dot structure of WGQDs. Interestingly, in the WGQDs D 'band is found at around 1600cm ^-1 D + G band is found at around 2960cm ^-1. Previous studies have shown that the D 'band and the D + G band are known to be observed due to the phonon spawning period and that they are identified as unaligned in the graphene structure. The above results are considered to allow the various emission positions to be distributed in the carbon core as well as the white emission. However, other mechanisms such as size distribution or trap location need to be identified as well.

2) WGQDs  Cellular uptake and cytotoxicity evaluation results

Cellular uptake of WGQDs was analyzed using KB cell lines. 7, bright fluorescence is observed in cells treated with WGQDs. KB cells were used to confirm the degree of WGQDs uptake of cells over time. As shown in the panel A of FIG. 8, when the WGQDs were treated at a concentration of 1 mg / ml of WGQDs for 4 hours, the degree of cell uptake was increased compared to the case of WGQDs of 0.25 mg / . In addition, cell sorption experiments of WGQDs over time showed similar profiles. It was confirmed that increasing the incubation time of WGQDs increased the amount of WGQDs absorption of the cells. Cytotoxicity of biomaterials is the most important criterion to judge biomedical applicability. GQDs should be proposed as an alternative to conventional quantum dot because of the high toxicity of QDs. In the present invention, hemolysis analysis and in vitro cytotoxicity were analyzed to analyze the toxicological profile of WGQDs. According to the MTT assay results for the KB cell line, the WGQDs of the present invention were found to show a slight toxicity profile even when treated at a high concentration of 1 mg / ml. The panel A of FIG. 9 shows hemolysis analysis results and it was confirmed that the WGQDs in blood showed a slight toxicity profile. Panel B) of FIG. 9, it was confirmed that the degree of destruction of erythrocytes was similar to that of PBS-treated blood. In addition, the OD values of the blood samples treated with WGQDs and the PBS samples treated with PBS were similar to each other, indicating that the toxicity of WGQDs is insignificant.

3) Biosensing application of WGQD-MnO2 complex

For biomedical applications of the WGQDs of the present invention, the surface of the WGQDs was covered with manganese oxide (MnO ₂ ) (see panel A of FIG. 10). Potassium permanganate (KMnO ₄ ) was used as a precursor for synthesizing the WGQD-MnO ₂ complex. It can be seen that the potassium permanganate was converted into manganese oxide by the fact that the peak of potassium permanganate was not confirmed at first at 550 nm (panel B in FIG. 10). The FE-SEM image shown in FIG. 10, panel A) shows the WGQD-MnO ₂ Shows that the particle size of the composite is slightly increased compared to the particle size of WGQDs. When the image is enlarged and analyzed, it can be seen that sediments or agglomerates of WGQDs are located inside the manganese oxide. In addition, WGQD-MnO ₂ The composites were found to be less prone to collapse compared to WGQDs, which is believed to be due to the coating of manganese oxide on WGQDs. Previous results indicate that manganese oxide is used as a fluorescence quencher in the FRET mechanism. Coating of manganese oxide on WGQDs leads to quenching of the fluorescence intensity of WGQDs. 10), it is confirmed that the absorption spectrum of manganese oxide overlaps with the emission spectrum of WGQDs, which means that manganese oxide exhibits a FRET-mediated fluorescence quenching effect on WGQDs. The fluorescence quenching effect of WGQDs is determined by the concentration of added potassium permanganate. According to panel A of FIG. 12, the extinction efficiency is improved with increasing concentration of potassium permanganate. When 3 mM of potassium permanganate was used, the light extinction efficiency to WGQDs reached 100%. WGQD-MnO ₂ prepared after coating manganese oxide The EDS spectrum of the complex was obtained and analyzed to confirm that it contained 61.66% carbon, 29.21% oxygen and 0.98% manganese (see panels D and E in FIG. 10). In addition, WGQD-MnO ₂ Thermal analysis of the complex revealed that WGQDs were decomposed at 390 ° C compared with WGQD-MnO ₂ It was confirmed that the composite started decomposition at a temperature higher than 400 ° C (see panels A and B in FIG. 11). WGQD-MnO ₂ The EDS spectrum and WGQD-MnO ₂ It shows the existing constituent substances composing the complex. According to the present invention, the selective decomposition of manganese oxide into manganese ions (Mn ²⁺ ) can be carried out in the presence of hydrogen peroxide and glutathione (GSH). The fluorescence quenching by the manganese oxide mediation of WGQDs can be reversed by the addition of hydrogen peroxide. WGQD-MnO ₂ When hydrogen peroxide is added to the complex, the manganese oxide is reduced to manganese ions, whereby the fluorescence of WGQDs is restored (fluorescence ON state) (see panel A of FIG. 12)). The mechanism by which manganese oxide is reduced to manganese ions by hydrogen peroxide is explained by the following formula (1).

As shown in panel B) of Fig. 12, restoration of WGQDs fluorescence appears after addition of hydrogen peroxide. The recovery of the incremental WGQDs fluorescence intensity is proportional to the concentration of added hydrogen peroxide. Also, a linear relation showing a correlation coefficient of 0.9905 is observed in the range of 0.5 to 0.0078 mmol L ^-1 (see panel C in FIG. 12). The selective dissociation of manganese and manganese ions by GSH was studied. GSH, which is classified as non-protein chemical thiol, may have selective interrelation with manganese oxide and oxidized disulfide (GSSG) may be formed by the above correlation. The following formula 2 shows the relationship between manganese oxide and GSH.

Therefore, WGQDs (WGQD-MnO ₂ complex) coated with manganese oxide are selectively correlated with GSH, resulting in restoration of WGQD fluorescence. WGQD-MnO ₂ Various concentrations of GSH were added to the complexes and the fluorescence intensities of the fluorescence intensity were analyzed by measuring the luminoluminescence spectra. As shown in FIG. 13, panel A), it was confirmed that the fluorescence intensity of WGQDs also increased with increasing concentration of GSH. It was also confirmed that WGQDs shows a linear relation with a correlation coefficient of 0.9977 in the range of 0.0313 to ¹ mmolL ^-1 (see panel B of FIG. 13). Certain types of chemical or biological interferences present in the blood or urine may be difficult to remove or may be mobilized by a wide variety of purification methods to obtain purified single biomarkers. However, these methods are expensive and may affect the detection efficiency. Therefore, the biosensor should discriminate the desired biomarkers selectively and sensitively. Finally, we confirmed the selectivity of WGQD-MnO ₂ fluorescence on / off by various chemical interferents and biological interferents. According to panel C) of Figure 13, it was confirmed that the selectivity of WGQDs of GSH and hydrogen peroxide was superior to other interfering substances. In addition, it was confirmed that fluorescence intensity was not restored by BSA, polysaccharide such as protein, fructose and amino acid. According to the above results, it would be very effective to apply the WGQD-MnO ₂ complex to the detection of GSH and hydrogen peroxide.

3. Conclusion

In the present invention, novel white emitting emitting graphene quantum dots (WGQDs) were synthesized by a pyrolysis method having a low cost advantage. It was confirmed that the synthesized WGQDs had excellent cytotoxicity with excellent optical luminescence characteristics. In the present invention, WGQDs-MnO ₂ composite nanoparticles were prepared by coating manganese oxide (MnO ₂ ) on the surface of WGQDs, and it was confirmed whether the nanoparticles could be applied as a biosensor for detecting GSH and hydrogen peroxide. As a result, it was confirmed that the WGQDs-MnO ₂ composite nanoparticles of the present invention had a detection limit of 0.0313 to 1 mmol / L and 0.5 to 0.0078 mmol / L for GSH and hydrogen peroxide, respectively. Therefore, it is considered that the WGQDs of the present invention can be applied to various applications for detecting GSH and hydrogen peroxide as a biomedical or biosensor platform.

The specific embodiments described herein are representative of preferred embodiments or examples of the present invention, and thus the scope of the present invention is not limited thereto. It will be apparent to those skilled in the art that modifications and other uses of the invention do not depart from the scope of the invention described in the claims.

Claims (9)

A composition for sensing or numerically measuring hydrogen peroxide (H ₂ O ₂ ) comprising white colored emitting graphene quantum dots coated with manganese oxide (MnO ₂ )
The white light emitting graphene quantum dot has a hexagonal pattern of graphene structure, has an average zeta potential of -50 mV, and has an average particle diameter of 20 nm. The hydrogen peroxide (H ₂ O ₂ ) Composition for measurement
delete 4. The method of claim 1, wherein the white emission graphene quantum dot excites at a light wavelength of 345 to 355 nm to emit white light at a light wavelength of 475 to 485 nm and emits white light of 5 to 6% photoluminescence < / RTI > quantum yield.
2. The composition of claim 1, wherein the manganese oxide covers the white emitting graphene quantum dot and exhibits a fluorescence resonance energy transfer mediated quenching effect.
The method according to claim 1, wherein the detection or numerical measurement of hydrogen peroxide (H ₂ O ₂ ) is performed by reducing the manganese oxide (MnO ₂ ) to manganese ions (Mn ²⁺ ) by the hydrogen peroxide, Characterized in that a phenomenon that light emission is restored is used
The method according to claim 1, wherein the numerical measurement of the hydrogen peroxide (H ₂ O ₂ ) is carried out in a hydrogen peroxide concentration range of 0.001 to 1.5 mmol / L
delete Heating deoxycholic acid in a heating mantle at 350 to 450 DEG C for 5 to 15 minutes to prepare a white emitting graphene quantum dot;
Dissolving potassium permanganate (KMnO ₄ ) in sodium hydroxide to prepare manganese oxide (MnO ₂ ); And
Mixing the white emitting graphene quantum dot and the manganese oxide at a weight ratio of 5 to 20: 1 to prepare a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ ) ;
(H ₂ O ₂ ) sensing or numerical measurement composition comprising a white colored emitting graphene quantum dot coated with manganese oxide (MnO ₂ )
9. The method of claim 8 wherein the composition is a biological tissue, cells, blood, urine, BSA, polysaccharides, or additionally contain manganese oxide characterized in that an amino acid to prevent the cell lysis of existing in the body fluid sample (MnO ₂₎ is Process for the preparation of compositions for the detection or numerical measurement of hydrogen peroxide (H ₂ O ₂ ) comprising coated white emitting emitting graphene quantum dots

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