KR101867670B1 - A method for preparation of paper-based surface enhanced raman scattering substrate using successive ionic layer adsorption and reaction method - Google Patents

Abstract

One object of the present invention is to provide a method of making a paper-based surface enhanced Raman scattering substrate using a continuous chemical reaction method; Based surface enhanced Raman scattering substrate comprising metal nanoparticles having a diameter of 1 to 100 nm adsorbed evenly on a designed pattern prepared by the above method and a method for site diagnosis including the paper based surface enhanced Raman scattering substrate Kit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper-based surface enhanced Raman scattering substrate using a continuous chemical reaction method,

One object of the present invention is to provide a method of making a paper-based surface enhanced Raman scattering substrate using a continuous chemical reaction method; Based surface enhanced Raman scattering substrate comprising metal nanoparticles having a diameter of 1 to 100 nm adsorbed evenly on a designed pattern prepared by the above method and a method for site diagnosis including the paper based surface enhanced Raman scattering substrate Kit.

Raman spectroscopy is a technique that provides molecular-specific information on biological and chemical samples. However, since the Raman signal is intrinsically weak, various studies have been conducted to enhance it. Surface enhanced Raman scattering (SERS) activity can significantly enhance the intensity of Raman spectra by absorbed energy at the surface. The enhancement factor (EF) used as a SERS scale is usually 10 ⁴ to 10 ⁸ and can reach 10 ¹⁴ , which can be detected at a single molecule level. Most studies on SERS EF increase focus on surface materials and substrate-related areas through nanostructure pattern formulas. Most SERS-active parts have been produced by complex and sophisticated methods including lithography or high temperature processes. This method of producing SERS-active base material has a long and complicated step of explosion, while the use of metal nanoparticles as a SERS substrate provides an easy synthesis method that can be controlled in size and shape by the reaction conditions and at low cost, Agglomerated nanoparticles can significantly enhance signaling to provide a single molecule level of sensitivity (XM Lin et al. , Anal. Bioanal . Chem . , 2009, 394: 1729-1745). These nanoparticles exhibit optical properties that absorb wavelengths used in Raman laser sources, that is, surface plasmon resonances (SPR) (S. Zeng et al. , Chem. Soc . Rev. , 2014, 43: 3426 -3452). In particular, gold, silver and copper nanoparticles can achieve SERS enhancement of 10 ³ times higher than other metal substrates (B. Ren et al. , Anal. Bioanal. Chem . , 2007, 388: 29-45) . Silver nanoparticles (AgNPs) exhibit superior SERS enhancement effects compared to gold nanoparticles (AuNPs). However, AgNPs are rapidly oxidized in the atmosphere to decrease SERS activity, while AuNPs form stable oxide SERS activity.

On the other hand, paper substrates having economy (low cost), portability, flexibility, ease of handling, and harmlessness are attracting attention as a new platform for analytical detection in biomedical and environmental fields (AW Martinez et al. , Angew ... Chemie - Int Ed, 2007, 46: 1318-1320). Such user-friendly advantages enable a variety of applications including paper colorimetry, electrochemical and biochemical analysis (C. Renault et al. , J. Am. Chem . Soc. , 2014, 136: 4616-4623) . These advantages of paper substrates are well suited for point-of-care (POC) applications, but overcome the limited detection limit of analytes by the use of enzymes, redox dyes and handling of complex soluble compounds There is a problem.

Thus, the present inventors have made extensive efforts to find a method for producing a SERS active platform in which metal nanoparticles are introduced on a paper substrate at low cost and simple process, and as a result, they have found that by using a continuous chemical reaction method in a series of aqueous solutions It is possible to provide a substrate which not only exhibits excellent surface enhanced Raman scattering effect but also exhibits high reproducibility, by forming metal nanoparticles uniformly on the surface of a substrate, and completed the present invention.

One object of the present invention is to provide a method of manufacturing a semiconductor device, comprising: a first step of immersing a paper substrate in a first metal precursor solution to adsorb a first metal precursor on a substrate; A second step of immersing the paper base material adsorbed on the first metal precursor in the first buffer solution and washing the paper base material; A third step of immersing the cleaned paper substrate in a reducing agent solution to form first metal nanoparticles; And a fourth step of immersing the paper substrate on which the first metal nanoparticles have been grown in a first buffer to wash the surface of the paper base.

Another object of the present invention is to provide a paper-based surface enhanced Raman scattering substrate comprising metal nanoparticles having a diameter of 1 to 100 nm adsorbed evenly over a designed pattern.

It is a further object of the present invention to provide a field diagnostic kit comprising the paper-based surface enhanced Raman scattering substrate.

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: a first step of immersing a paper substrate in a first metal precursor solution to adsorb a first metal precursor on a substrate; A second step of immersing the paper base material adsorbed on the first metal precursor in the first buffer solution and washing the paper base material; A third step of immersing the cleaned paper substrate in a reducing agent solution to form first metal nanoparticles; And a fourth step of immersing the paper substrate on which the first metal nanoparticles have been grown in a first buffer to wash the surface of the paper base.

A second aspect of the present invention is to provide a paper-based surface enhanced Raman scattering substrate comprising metal nanoparticles having a diameter of 1 to 100 nm adsorbed evenly over a designed pattern.

A third aspect of the present invention is to provide a field diagnostic kit comprising the paper-based surface enhanced Raman scattering substrate.

Hereinafter, the present invention will be described in detail.

The present invention relates to a method for manufacturing a surface enhanced Raman scattering base material based on paper that can be easily secured even at a low cost, and a base material thereof. For example, paper is made of fibers and has a rough texture of fibers on a microscopic scale. In general, considering that the surface enhanced Raman scattering exhibits the effect of enhancing the Raman scattering signal on the rough surface, a method of utilizing the texture of the paper can be considered. However, the texture of the paper surface is due to irregularly arranged fibers. Due to the irregularity, the non-uniform distribution of the metal nanoparticles introduced on the surface is accumulated at a high density in the depressions, The signal detection may be difficult or the signal may be reduced due to the offset due to the phase mismatch of the generated signal. Therefore, it is necessary to find a method of uniformly distributing the metal nanoparticles in order to take advantage of the paper substrate and to eliminate the disadvantages that may be caused by the irregular surface structure.

As a part of such efforts, in the present invention, not only can it be carried out easily in an aqueous solution by using a continuous chemical reaction method, for example, a method of repeatedly immersing in a series of reaction solutions and washing with a buffer solution repeatedly, Since it is based on paper, it is possible to provide a higher surface area and adsorbed reactants easily. Therefore, when the metal nanoparticles are uniformly distributed over the entire designed area, Lt; RTI ID = 0.0 > SERS < / RTI > activity. In addition, when the metal nanoparticles are formed by the continuous chemical reaction method using two or more kinds of metals that can complement each other's advantages and disadvantages, it is possible to maximize the SERS effect synergistically when forming the composite nanoparticles, Physical properties such as stability can be improved.

The paper-based surface enhanced Raman scattering material according to the present invention comprises a first step of immersing a paper substrate in a first metal precursor solution to adsorb a first metal precursor on a substrate; A second step of immersing the paper base material adsorbed on the first metal precursor in the first buffer solution and washing the paper base material; A third step of immersing the cleaned paper substrate in a reducing agent solution to form first metal nanoparticles; And a fourth step of immersing the paper substrate on which the first metal nanoparticles have been grown in a first 'buffer solution for washing.

For example, the first to fourth steps may be repeated two to ten times in order to form particles having an appropriate size, but the present invention is not limited thereto.

A first step of immersing the paper substrate obtained in the fourth step in a second metal precursor solution to adsorb a second metal precursor on the substrate; A second step of immersing the paper base material adsorbed on the second metal precursor in a second buffer solution to be washed; A third step of immersing the cleaned paper substrate in a reducing agent solution to form second metal nanoparticles; And a fourth step of immersing the paper substrate on which the second metal nanoparticles have been grown in a second 'buffer solution for washing, thereby further providing a substrate on which the composite nanoparticles containing the first metal and the second metal are formed have.

For example, the first to fourth steps may be repeated two to five times in order to form particles having an appropriate size, but the present invention is not limited thereto.

For example, the first step and the first step may be performed independently for 10 seconds to 120 seconds, and the third step and the third step may be performed independently for 10 seconds to 120 seconds, But is not limited thereto.

When the first step (or the first step) and / or the third step (or the third step) are performed in less than 10 seconds when the first step to the fourth step are regarded as one set, It is difficult to expect reproducibility because the precursor is not sufficiently adsorbed or the reaction by the reducing agent is not completed properly and nanoparticle formation is incomplete. On the other hand, when each step is performed for about 120 seconds, it is sufficient to complete the formation of the metal particles by the adsorption of the metal precursor or the reducing agent. Therefore, unnecessary time may be wasted if performed in excess of this time, and side reactions may occur.

The number of repetitions of the first to fourth steps and the first to fourth steps may be determined by maximizing the SERS effect in consideration of the concentration of the precursor solution and / or the reducing agent solution used, A person skilled in the art can appropriately select.

The paper used in the present invention is a substrate which can be easily secured even at a low cost, and it can be seen that it is formed of fibers and has a rough texture of irregularly arranged fibers when microscopically observed. Unlike substrates made of other metallic or inorganic materials, for example, the paper surface includes micropores formed by entanglement of fibers, and due to such a structure, the fluid is not simply adsorbed on the surface of the substrate by the capillary force, And can store it, so that it is possible to provide a high surface area when the reaction is carried out by absorbing the reaction liquid to the paper substrate (FIG. 2).

For example, in the paper substrate, a hydrophobic substance may be treated to a portion other than the surface enhanced Raman scattering active portion to be formed before the reaction to form a pattern. Specifically, the hydrophobic substance may be a wax, but is not limited thereto. When a sample is analyzed using the surface enhanced Raman scattering substrate according to the present invention, the effective area analyzed in a single rotation is limited to an area within a few millimeters in diameter where the light source is concentrated due to the characteristics of the spectroscopic detection method. Therefore, when the Raman active part is formed more widely than necessary, the sample spreads widely. Therefore, when the same amount of sample is used, the amount of analyte present per unit area is decreased, and detection of a trace amount of analyte may be difficult. Therefore, it may be desirable to form a Raman active moiety in a limited region in order to prevent waste of such a sample and improve detection efficiency. Accordingly, in order to prevent the metal nanoparticles from being coated on the region other than the designed Raman active region, a method of blocking the interaction with the metal nanoparticles by penetrating or coating the region with a hydrophobic material may be used. As examples of the hydrophobic substance, wax is usable. Considering that the substrate of the present invention is paper-based, it is possible to form a surface-enhanced Raman scattering active portion of a desired pattern by painting a portion other than the Raman active portion on the paper substrate and then waxing it. For example, since paper can absorb wax, even if it is applied to only one side, both sides can be blocked. The wax Forming a pattern to form a pattern is an embodiment, but the scope of the present invention is not limited thereto.

For example, the first metal and the second metal may be different from each other and may be independently gold, silver, platinum, aluminum, iron, zinc, copper, tin, bronze, brass, nickel or an alloy thereof. For example, any metal that can be uniformly distributed in the form of particles and exhibit the surface enhanced Raman scattering effect can be used without limitation.

For example, a substrate comprising gold-silver composite double metal nanoparticles including both gold and silver may be prepared by selecting silver as the first metal and gold as the second metal, or vice versa . The silver alone has an excellent SERS effect but is easily oxidized. On the other hand, when the silver alone is used, the SERS effect is somewhat lower than that of silver, but has excellent oxidation stability.

In a specific embodiment of the present invention, silver is used as the first metal and gold is used as the second metal, and a sequential chemical reaction method is sequentially performed to form composite double metal nano-particles in the form of gold nanoparticles surrounded by silver nanoparticles In the case of the substrate comprising the composite double metal nanoparticles, the simple substance exhibited an increased SERS effect as compared with the substrate including the nanoparticles, and the stability against oxidation was remarkably improved. It was confirmed that the Raman intensity did not substantially decrease (Fig. 10).

For example, the first metal precursor solution and the second metal precursor solution are different from each other, and each may be an aqueous solution containing a metal in an ionic form. Specifically, the first metal precursor solution and the second metal precursor solution may be independently HAuCl ₄ , NaAuCl _4, or AgNO ₃ aqueous solutions, but are not limited thereto.

The first reducing agent solution and the second reducing agent solution containing a reducing agent for reducing metal ions as a metal precursor adsorbed on the substrate are the same or different from each other, and sodium borohydride (NaBH ₄ ), trioctylphosphine be a pin-oxide (TOPO), sodium citrate, hexadecyl trimethyl ammonium chloride (HTAC), cetyltrimethylammonium bromide (CTAB), an aqueous solution containing NH ₄ OH, or a combination thereof, but is not limited thereto.

For example, water may be used as the first buffer, the first buffer, the second buffer and the second buffer, but is not limited thereto. If the metal precursor and / or the metal nanoparticles loosely adhered to the surface of the substrate can be removed without modifying or reacting with the metal precursor and / or the reducing agent adsorbed on the substrate or inhibiting their reaction Can be used without restrictions.

The first buffer solution and / or the second buffer solution may be independently different depending on the kind of the metal. For example, organic solvents such as ethanol and chloroform may be used, but the present invention is not limited thereto.

For example, the first to fourth steps may be sequentially performed as one set, but one or more sets may be repeatedly performed. Specifically, by repeating the process of forming and washing metal nanoparticles by adsorption-washing-reduction of a metal precursor, the surface enhanced Raman scattering effect can be obtained by controlling the size, density and thickness of the particle layer formed on the substrate It is possible to search for the optimum condition that maximizes.

The present invention provides a paper-based surface enhanced Raman scattering substrate comprising metal nanoparticles having a diameter of 1 to 100 nm adsorbed evenly over a designed pattern.

Conventionally, when a metal nanoparticle having a predetermined size is formed on a substrate and then adsorbed on the substrate, or when the thin metal nanoparticle is fabricated in a thin film form, nanoparticles having a size of several tens of nanometers are generally used or a metal thin film layer having a thickness of several tens nm is formed. As in the present invention, a method of growing nanoparticles by adsorbing a metal precursor on a substrate and treating the nanoparticles by reducing the treatment with a reducing agent can form particles at a level of several nanometers by controlling the reaction time and the number of repetitions, Lt; RTI ID = 0.0 > Raman scattering. ≪ / RTI >

Specifically, the metal nanoparticles may have a diameter of 1 to 30 nm, and more specifically, may have a diameter of 1 to 10 nm, but the present invention is not limited thereto.

For example, the metal nanoparticles may be composite metal nanoparticles containing two or more different metals, wherein the composite metal nanoparticles may be one in which one or more metal nanoparticles are adsorbed on one metal nanoparticle But is not limited thereto.

Further, the present invention can provide a field diagnostic kit including the paper-based surface enhanced Raman scattering substrate according to the present invention.

The field diagnostic kit can be used for qualitative and / or quantitative analysis of target analytes in various fields such as medicine, agriculture, animal husbandry, food, military, environment, as well as diagnosis or inspection of various diseases. For example, it can be used for detecting a target analyte from a biological sample such as a mammal, specifically whole blood, blood cells, serum, plasma, bone marrow fluid, sweat, urine, tears, saliva, skin, mucous membrane and hair separated from human. Or environmental pollutants, in particular, wastewater and sewage, but application examples thereof are not limited thereto.

The field diagnostic kit of the present invention is characterized by being capable of qualitatively and / or quantitatively detecting a target analyte in a sample by Raman spectroscopy.

Specifically, a field diagnostic kit comprising a paper-based surface enhanced Raman scattering substrate according to the present invention can exhibit synergistic signal enhancement effects when additional Raman active materials are present. At this time, the Raman spectrum does not change, that is, it can provide a spectrum of increased intensity at the same peak position. The Raman active material includes, without limitation, Raman active materials known in the art. Specifically, it may be rhodamine B, rhodamine 6G, 2-naphthalenethiol (2-NAT), but is not limited thereto.

According to a specific embodiment of the present invention, when rhodamine B is applied as a Raman active molecule on a surface-enhanced scattering substrate, even if the same concentration is applied, Raman signal increased by about 1000 times as compared with that applied on a pure paper substrate Respectively. In Experimental Example 2 of the present invention, when rhodamine B was treated at a concentration of 1 mM, the intensity of 1201 cm ^-1 band of rhodamine B was 31 on pure paper, whereas the same , It was confirmed that the Raman signal of 29328 increased to about 1000 times.

In addition, when a continuous chemical reaction method is applied to a substrate other than a paper substrate, even when the surface morphology is observed, even when the reaction is performed under the same conditions, the metal nano-particles formed on the paper substrate are uniformly distributed to exhibit a reproducible signal enhancement effect On the other hand, when reacted with aluminum foil or glass as a substrate, the metal nanoparticles were unevenly distributed, and the Raman signal thus measured exhibited different values depending on the measurement time for the same sample, indicating that the reproducibility of the measurement was remarkably low (Figs. 3 and 6).

In addition, composite nanoparticles made of silver and gold, such as silver nanoparticles obtained by further forming gold nanoparticles after forming silver nanoparticles on a paper substrate by the method of the present invention, Composite nanoparticles in which a plurality of nanoparticles are adsorbed have excellent SERS effect of gold and stability of gold and exhibit enhanced enhancement factor (EF) up to 10 ¹² , and even when stored for up to 30 days, (FIG. 10).

As described above, the field diagnostic kit including the paper-based surface enhanced Raman scattering substrate according to the present invention can exhibit a remarkable effect of increasing the Raman intensity and can provide reproducible results. Therefore, the kit can be combined with the Raman spectroscopic method, It can be useful for analysis.

The sample that can be analyzed by the field diagnostic kit may be a biological sample such as a tear, a blood appendage, sweat urine, various chemical substances, environmental pollutants, and the like. If the target analyte comprises a Raman active molecule, it can be directly analyzed without a separate labeling substance. Otherwise, the target analyte in the sample can be labeled with a Raman active substance.

According to the present invention, a method for producing a surface enhanced Raman scattering base material by a continuous chemical reaction method can be easily carried out through a simple process at low cost. The surface-enhanced Raman scattering substrate can be easily manufactured in an aqueous solution, and it can be provided with a high surface area because it is based on an inexpensive and absorbent paper. Therefore, the adsorption of the reactants is easy, When the metal nanoparticles are formed, the nanoparticles formed are uniformly distributed throughout the active portion to exhibit SERS activity, and can provide reproducible results. In particular, it can be used effectively as a detection kit for field diagnosis, which is capable of exhibiting a synergistic signal enhancement effect in the presence of additional Raman active material, and is lightweight, easy to handle and portable because it is based on paper.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically illustrating a method for producing a paper-based surface enhanced Raman scattering substrate using a continuous chemical reaction method according to the present invention.
Fig. 2 is a diagram showing the result of observing the microstructure of the surface of a paper substrate which has not been treated with SEM. Fig.
3 is a diagram showing the appearance and microscopic surface structure of the surface enhanced Raman scattering base prepared by applying a continuous chemical reaction method to various substrates according to Example 1 of the present invention and Comparative Examples 1 to 3. FIG.
4 is a graph showing the intensity of a signal for Raman shift of rhodamine B (RhB) on a substrate prepared by different methods. The substrate may be a paper-based substrate containing gold nanoparticles prepared by a continuous chemical reaction method, a paper-based substrate produced by screen printing using an ink containing carboxymethylcellulose and gold nanoparticles, A formed gold thin film substrate and an untreated paper substrate were used.
FIG. 5 is a graph showing the results of measurement of the concentration of 1 mM RhB (1 mM) coated on a substrate containing gold nanoparticles prepared by continuous chemical reaction based on paper, aluminum foil, glass, PET film (OHP film) ≪ / RTI >
FIG. 6 is a graph showing the deviation of the Raman signal of RhB independently measured five times using aluminum foil, glass, and paper-based surface enhanced Raman scattering substrate manufactured by a continuous chemical reaction method.
FIG. 7 is a graph showing a Raman signal enhancement effect on a paper-based surface-enhanced Raman scattering material containing silver nanoparticles prepared by increasing the number of repetitions of a continuous chemical reaction method five times to five times from 20 to 5 times.
Figure 8 shows the formation of gold-silver composite nanomaterials (Au @ AgNP) on a paper-based surface enhanced Raman scattering substrate according to a sequential chemical reaction method using a TEM and limited area electron ) diffraction (SAD or SAED).
FIG. 9 is a graph showing the relationship between the binding of double metal nanoparticles to a paper substrate with XPS, (C) with (B) and ) Shows the results of XRD analysis of the crystal structure of each component.
10 is a graph showing the Raman signal enhancement effect of rhodamine 6G (R6G) as a SERS probe on a paper-based surface enhanced Raman scattering substrate having gold-silver composite double metal nanoparticles incorporated therein according to a continuous chemical reaction method . (A) shows Raman intensity at 1361 cm ^-1 , Raman intensity at Raman spectra at (B and C) and Raman spectrum at (Raman) (E) shows the Raman spectrum over time of Au @ AgNP, and (F) shows the Raman spectra over time of the silver nanoparticles.
FIG. 11 is a graph showing changes in Raman intensity according to the number of repetitions of the gold nanoparticle formation process in the preparation of the paper-based surface enhanced Raman scattering base material to which the gold-silver composite double metal nanoparticles according to the continuous chemical reaction method are introduced.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for further illustrating the present invention, and the scope of the present invention is not limited by these examples.

Example  1: Successive ionic layer adsorption and reaction; SILAR ) Based on gold nanoparticles adsorbed on paper Surface enhanced Raman scattering  Manufacture of substrate

10 mL of 10 mM HAuCl ₄ aqueous solution as a gold precursor solution and 10 mL of a 10 mM NaBH ₄ aqueous solution as a reducing agent solution were prepared. Distilled water was used as a buffer solution for washing. The gold precursor solution and the reducing agent solution were prepared in a separate beaker, and distilled water for washing was also prepared in two beakers.

A 2 mm diameter circle was drawn on a filter paper of 8 mm x 20 mm size to display the surface enhancement Raman scattering active part and the outer part except for the circular inner part was wax coated and treated in a drying oven at 130 캜 for 45 seconds To uniformly penetrate the wax and dried at room temperature. The filter paper impregnated with the wax was immersed in a gold precursor solution prepared in advance for 30 seconds to allow the gold ions to be adsorbed on the paper substrate. The filter paper was removed from the gold precursor solution by soaking in a first distilled water beaker and washed. The washed paper substrate was immersed in distilled water, soaked in a beaker containing the reducing agent solution, and held for 30 seconds to allow gold nanoparticles to grow from the gold ion adsorbed on the paper substrate. After the reaction was completed, the paper substrate on which the gold nanoparticles were formed was taken out from the reducing agent solution and immersed in a second distilled water beaker. In the above series of steps, the level of the solution was adjusted so that the surface-enhanced Raman scattering activity portion indicated in advance was sufficiently immersed in the solution. By repeating the above series of steps in one cycle 5 times.

Example  2: Preparation of paper-based surface enhanced Raman scattering substrate on which silver nanoparticles were adsorbed using a continuous chemical reaction method

A continuous chemical reaction method was carried out in the same manner as in Example 1 except that instead of HAuCl ₄ aqueous solution as the gold precursor solution, a 10 mL concentration aqueous AgNO ₃ solution was used as a metal precursor solution, silver nano A paper - based surface enhanced Raman scattering substrate on which particles were adsorbed was prepared. The number of repetition times was increased five times, ten times, fifteen times, and twenty times, respectively, to produce four kinds of substrates.

Comparative Example  1: Fabrication of aluminum foil-based surface enhanced Raman scattering substrate with gold nanoparticles adsorbed by continuous chemical reaction

The reaction was carried out in the same manner as in Example 1, except that aluminum foil was used instead of the filter paper as the base material to prepare an aluminum foil-based surface enhanced Raman scattering base on which gold nanoparticles were adsorbed.

Comparative Example  2: Fabrication of glass-based surface enhanced Raman scattering substrates adsorbed by gold nanoparticles using a continuous chemical reaction method

A glass-based surface enhanced Raman scattering substrate on which gold nanoparticles were adsorbed was prepared by carrying out the reaction in the same manner as in Example 1, except that a glass substrate was used in place of the filter paper as the substrate.

Comparative Example  3: Preparation of surface enhanced Raman scattering substrate based on PET film adsorbed gold nanoparticles by continuous chemical reaction method

A PET film-based surface enhanced Raman scattering substrate on which gold nanoparticles were adsorbed was prepared by carrying out the reaction using the same reagents and methods as those in Example 1 except that PET film was used instead of filter paper as a base material.

Comparative Example  4: Carboxymethylcellulose and  Preparation of paper-based surface-enhanced Raman scattering substrate on which gold nanoparticles were adsorbed using a mixed solution of gold nanoparticles

First, CMC-AuNPs inks for screen printing including gold nanoparticles and carboxymethyl cellulose (CMC) were prepared. Specifically, by heating at 90 ℃ for 20 minutes on a hot plate with the addition of 38.8 mM citric acid trisodium anhydride of 1 mL to 10 mL of 1 mM HAuCl ₄ and magnetic stirring. The color of the solution changed from light yellow to dark purple. The heating of the reaction flask was then immediately stopped and the solution was cooled to room temperature while stirring was maintained.

1 mL of the colloidal AuNP prepared as described above was taken and concentrated at 6000 rpm for 10 minutes to remove 99% of the supernatant. The concentrated AuNPs were mixed with 2 wt% sodium CMC aqueous solution in a volume ratio of 1: 7 to prepare CMC-AuNPs inks.

A filter paper prepared by waxing in the same manner as in Example 1 was adjusted to have the same center as a 2 mm diameter surface enhanced Raman active portion pre-marked with a 3 mm diameter and a 180 占 퐉 thick cut-out hole Respectively. Four microliters of CMC-AuNPs ink was applied to the stencil holes, the blades were moved across the stencil and applied and dried on a hot plate at 50 DEG C for 120 seconds. The process of applying and drying the CMC-AuNPs ink was repeated one more time.

Experimental Example  1: The adsorption power of gold nanoparticles according to the type of substrate during continuous chemical reaction method

According to Example 1 and Comparative Examples 1 to 3, gold nanoparticles were formed by applying a continuous chemical reaction method using paper, aluminum foil, glass, and PET film as substrates, respectively, and the appearance and microscopic The surface structure is visual and x20 optic respectively The result was observed with a microscope and the results are shown in Fig.

As shown in FIG. 3, when the paper was used as a substrate, the gold nanoparticles were uniformly distributed on the surface, while the aluminum foil or glass was irregularly distributed. When the PET film was used, gold nanoparticles were not attached at all .

Experimental Example  2: Raman intensity change of Raman active molecule according to kinds of substrate and manufacturing method

A rhodium-active molecule, rhodamine B (RhB), was treated at a concentration of 1 mM on a paper substrate, gold thin film, and untreated paper containing gold nanoparticles according to Example 1 and Comparative Example 4, Raman spectra were measured. From the above measurement, a graph of the intensity for raman shift was derived. The results are shown in Fig. 4. The results are shown in Fig. 4, and the results are shown in Fig. 4. The peak of RhB at the peak of 3 Raman shifts (620, 1201 and 1356 cm ^-1 ) The strengths are summarized in Table 1 below.

Specifically, Raman spectra were acquired using a SENTERRA confocal Raman system (Bruker Optics, Billerica, MA, USA). At a power of 10 mW, a 785 nm diode laser source was focused on a spot size of about 2.4 μm with a 20 × objective (NA = 0.4). Each of the spectra at the point (point) was recorded twice at room temperature from 417 to 1782 cm ^-1 to 5 cm ^-1 range optical resolution of 30 seconds acquisition time. The Raman spectra of each sample were measured at 10 randomly printed spots on the surface enhanced Raman scattering active area to confirm their reliability. Raman spectra were evaluated using 2 μl of analytical drop of 1 mM RhB as a sample.

Raman peak of RhB SILAR (Example 1) AuNPs + CMC (Comparative Example 4) Au film Raw paper 620 cm ^-1 7533 4868 3186 45 1201 cm ^-1 29328 6120 2103 31 1356 cm ^-1 22383 5680 4945 75

As shown in Fig. 4 and Table 1, it was difficult to detect almost no signal even at the peak position from the Raman active molecule coated on any untreated paper substrate. On the other hand, on the paper substrate containing gold nanoparticles (Example 1 and Comparative Example 4) or on the gold thin film, the Raman signal of a significantly increased intensity could be detected by the Raman signal enhancement effect by the substrate. In particular, when the substrate of Example 1 was used, the intensity was 1.5 to 4.8 times higher than that of Comparative Example 4 produced by screen printing the gold nanoparticle solution. According to the number of wafers, the intensity was 1.5 to 4.8 times higher than that of the gold thin film. Raman signals of high intensity ranging from 2.4 times to 13.9 times were shown. This indicates that when the appropriate wave number is selected, detection using the substrate of the present invention can be performed about 14 times more sensitive than when the gold thin film is used as the substrate.

Experimental Example  3: Raman intensity change of Raman active molecule according to kinds of substrate

In the surface enhanced Raman scattering substrate in which the gold nanoparticles were distributed on the surface prepared by the continuous chemical reaction method, in order to confirm the difference in surface enhancement Raman scattering effect depending on the material of the base material, 1 to 3, each of gold nanoparticles, aluminum foil, glass, and PET film was coated with RhB at a concentration of 1 mM and Raman spectrum was measured and shown in FIG.

 As shown in Fig. 5, a significantly increased Raman signal measurement was possible in the surface-enhanced Raman scattering substrate prepared by applying a continuous chemical reaction method on a paper substrate compared to other substrates.

Experimental Example  4: Reproducibility of Raman signal measurement according to substrate type

To confirm the reproducibility of signals by repetitive measurement, RhB was applied at a concentration of 1 mM to the substrate prepared according to Example 1, Comparative Example 1 and Comparative Example 2, and the intensity with respect to the Raman shift wave number was observed. The measurement was repeated five times under the same conditions as in Experimental Example 3, and the graphs obtained from the respective measurements were superimposed on each other and shown in FIG.

As shown in Fig. 6, when the base material (indicated by Paper in Fig. 6) according to Example 1 was used, a constant peak intensity was obtained even when measured repeatedly. However, when the base materials of Comparative Examples 1 and 2 were used Al foil and Glass). It can be confirmed that there is a large variation in measured intensity in each measurement. This is consistent with the formation of gold nanoparticles on the aluminum foil and glass substrate identified in Fig. 3 in a non-uniform distribution. That is, since the gold nanoparticles capable of exhibiting the surface enhanced Raman scattering effect are unevenly distributed on the substrate, the surface enhancement Raman from the substrate produced according to the manufacturing sequence, even in the same substrate, This shows that reproducible analysis is impossible because the scattering effect is different.

Experimental Example  5: Raman signal enhancement effect according to the number of repetition of continuous chemical reaction method

The Raman signal was measured using a paper-based surface enhanced Raman scattering substrate containing silver nanoparticles prepared by increasing the number of repetitions of the continuous chemical reaction method prepared in Example 2 five times to 20 times, The results are shown in Fig. As shown in FIG. 7, it was confirmed that the measured Raman intensity increases as the number of repetitions increases. It was also confirmed that the increase pattern was different according to the measured wave number. This means that it is possible to search conditions that maximize the rate of increase of the signal by adjusting the number of repetitions according to the wave number to be measured. That is, the optimum conditions for maximizing the Raman signal enhancement effect can be found by appropriately combining the measured wave number and the number of iterations of the continuous chemical reaction method.

Example  3: Double metal nanoparticles (bimetallic nanoparticle, Au @ AgNP) adsorbed on paper Surface enhanced Raman scattering  Manufacture of substrate

Silver nanoparticles were formed on a paper substrate in the same manner as in Example 1 by using a 20 mM aqueous solution of AgNO ₃ as a precursor and a NaBH ₄ solution as a reducing agent. The silver nanoparticles were grown to have a predetermined size by repeating the procedure of immersing and washing in each solution for 30 seconds six times. Thereafter, silver nanoparticles and complex double metal nanoparticles formed on the paper substrate were formed using a 1 mM aqueous solution of HAuCl ₄ as a gold precursor. Silver nanoparticles were immersed in each solution for 30 seconds to adsorb and reduce gold precursor ions to form gold nanoparticles. Each of the gold nanoparticles was repeated 1 to 5 times to prepare five samples. As a control, a substrate containing only silver nanoparticles not treated with a gold precursor solution and a reducing agent was used.

The morphology of the gold-silver composite double metal nanoparticles adsorbed on the paper substrate was observed by TEM, and the crystallinity was analyzed by SAED, and the results are shown in Fig. As shown in FIG. 8, it was confirmed that the gold-silver composite double metal nanoparticles have a relatively small size of gold nanoparticles on the silver nanoparticles and thus have a raspberry-like shape. At this time, it was confirmed that the gold and silver particles had a lattice spacing of 0.147 nm (Au 220 grating) and 0.144 nm (Ag 220 grating), respectively. Further, the SAED analysis results also confirmed that the silver formed by the continuous chemical reaction method according to the present invention Indicating that the nanoparticles have a well-defined crystal structure.

Also, the binding of the gold-silver composite double metal nanoparticles on the paper substrate was confirmed by XPS analysis, and the results are shown in Figs. 9A and 9B. The XRD analysis showed that the crystal structure of each component of the gold- Again, the results are shown in Figure 9C.

Experimental Example  6: Raman signal enhancement effect by double metal nanoparticles

The rhodamine 6G (rhodamine 6G, R6G) used as the SERS probe was prepared for each concentration from 1 fM (1 x 10 ^-15 M) to 1 mM (1 x 10 ^-3 M) Based surface enhanced Raman scattering substrate comprising complex double metal nanoparticles and measuring the Raman signal and the results are shown in Figures 10A-C from which the enhancement factor (EF), a measure of the SERS effect, Respectively. As shown in FIGS. 10B and 10C, when the Raman signal was measured on a paper-based surface enhanced Raman scattering substrate containing gold-silver composite double metal nanoparticles according to the present invention, it was confirmed that detection was possible up to 1 fM level, EF is about 10 < ^{12 &} gt ;, indicating that the SERS effect by the paper-based surface enhanced Raman scattering substrate comprising gold-silver composite double metal nanoparticles according to the present invention is excellent.

In order to confirm the stability of the paper-based surface enhanced Raman scattering substrate comprising the gold-silver composite double metal nanoparticles according to the present invention, the substrate was kept in air for up to 30 days, , 7 days, 15 days and 30 days, respectively. As a control group, a single silver nanoparticle-adsorbed substrate was used. Raman spectra were measured at each of the above points and are shown in Figs. 10D to 10F. As shown in Figures 10D-F, the paper-based surface enhanced Raman scattering substrate comprising gold-silver composite double metal nanoparticles according to the present invention exhibits significantly higher Raman intensity at the point of full measurement than the substrate comprising silver nanoparticles Respectively. Particularly, in the case of a substrate containing silver nanoparticles, the intensity of the Raman signal measured with the lapse of time has been drastically decreased as the Raman signal measured at less than half of the three days after the production is decreased. However, When the paper-based surface enhanced Raman scattering substrate containing the double metal nanoparticles was used, little decrease in the intensity of the measured signal was observed even after a lapse of 30 days. This indicates that the use of gold - silver composite double metal nanoparticles can overcome disadvantages of silver which is susceptible to oxidation as well as synergistic SERS effect.

In Example 3, R6G was treated on five samples prepared by varying the number of repetition times of the control group and the gold nanoparticle forming process, and the intensity of the Raman signal was measured at 1361 cm ^-1 . The results are shown in FIG. 11 . As shown in FIG. 11, gold nanoparticles were formed at an appropriate density and size when gold nanoparticles were formed two to three times. As a result, it was confirmed that the maximum SERS effect was exhibited.

As a result, the paper-based surface-enhanced Raman scattering substrate produced by the continuous chemical reaction method according to the present invention not only exhibits a remarkable Raman signal enhancing effect but also can provide a reproducible signal, so that it can be used as an analytical substrate using Raman spectroscopy Can be usefully used.

Claims (17)

A first step of immersing the paper substrate in the first metal precursor solution to adsorb the first metal precursor on the substrate;
A second step of immersing the paper base material adsorbed on the first metal precursor in the first buffer solution to wash the first metal precursor that has not been adsorbed;
A third step of immersing the cleaned paper substrate in a reducing agent solution to form first metal nanoparticles; And
And a fourth step of dipping the paper substrate on which the first metal nanoparticles are grown in a first buffer to wash the reducing agent solution.
2. The method of claim 1, wherein the first to fourth steps are repeated two to ten times.
The method of claim 1, further comprising: a first step of immersing the paper substrate obtained in the fourth step in a second metal precursor solution to adsorb a second metal precursor on the substrate;
A second step of immersing the paper base material adsorbed on the second metal precursor in a second buffer solution to be washed;
A third step of immersing the cleaned paper substrate in a reducing agent solution to form second metal nanoparticles; And
Further comprising a fourth step of immersing the paper substrate on which the second metal nanoparticles have been grown in a second buffer to wash the paper base surface-enhanced Raman scattering substrate.
4. The method of claim 3, wherein the first to fourth steps are repeated two to five times.
The method of claim 1 or 2, wherein the first step is performed independently for 10 seconds to 120 seconds.
The method of claim 1 or 2, wherein the third step is performed for 10 seconds to 120 seconds.
5. The paper-based surface enhanced Raman scattering material according to any one of claims 1 to 4, wherein the paper base material has a pattern formed by treating a portion other than the surface enhanced Raman scattering active portion to be formed with a hydrophobic substance Gt;
The method of claim 3 or 4, wherein the first metal and the second metal are different from each other and each independently selected from gold, silver, platinum, aluminum, iron, zinc, copper, tin, bronze, brass, Based surface enhanced Raman scattering substrate.
5. The method of claim 3 or 4 wherein the first metal precursor solution and the second metal precursor solution are different from each other and are aqueous solutions comprising a first metal and a second metal in ionic form, A method for producing a scattering substrate.
11. The method of claim 9, production of the first metal precursor solution and the second metal precursor solution are each independently selected from HAuCl _4, NaAuCl ₄ or AgNO ₃ aqueous solution to the paper-based surface enhanced Raman scattering substrate.
The method according to any one of claims 1 to 4, wherein the reducing agent solution is sodium borohydride (NaBH _4), trioctyl phosphine oxide (TOPO), sodium citrate, hexadecyl trimethyl ammonium chloride (HTAC), cetyl Wherein the aqueous solution is an aqueous solution comprising trimethyl ammonium bromide (CTAB), NH ₄ OH, or a combination thereof.
The method of claim 1 or 2, wherein the first buffer and the first 'buffer are both water.
A paper-based surface enhanced Raman scattering substrate produced by the manufacturing method of claim 1, comprising metal nanoparticles having a diameter of 1 to 100 nm adsorbed uniformly in a designed pattern.
14. The paper-based surface enhanced Raman scattering substrate of claim 13, wherein the metal nanoparticles are composite metal nanoparticles comprising two or more different metals.
15. The paper-based surface enhanced Raman scattering substrate according to claim 14, wherein the composite metal nanoparticle is one in which one metal nanoparticle is adsorbed on one or more other metal nanoparticles.
A field diagnostic kit comprising the paper-based surface enhanced Raman scattering substrate of claim 13.
17. The field diagnostic kit of claim 16, wherein the addition of additional Raman active material exhibits a synergistic signal enhancement effect.

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