CN110961657B

CN110961657B - Gold nanoparticles and preparation method thereof

Info

Publication number: CN110961657B
Application number: CN201911387490.4A
Authority: CN
Inventors: 陈榕
Original assignee: Hainan Medical College
Current assignee: Hainan Medical College
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2023-01-31
Anticipated expiration: 2039-12-27
Also published as: CN110961657A

Abstract

The invention discloses a preparation method of gold nanoparticles, which comprises the following steps: reacting the chlorogenic acid solution with the chloroauric acid solution at the temperature of 80-100 ℃ to obtain the gold nanoparticles. According to the green preparation method of the gold nanoparticles, the reducing agent chlorogenic acid (CGA) with biological activity is adopted, the use of the reducing agent sodium borohydride with high toxicity is avoided, an additional stabilizing agent or a protective agent is not required, the reaction condition is simple, rapid and environment-friendly, the surface coating functionalization of the CGA to AuNPs is completed in one step, the prepared CGA-AuNPs have a good scavenging effect on free radical DPPH, the oxidation resistance of the AuNPs is improved, and the method has potential medical application.

Description

Gold nanoparticles and preparation method thereof

Technical Field

The invention relates to a nano particle, in particular to a gold nano particle and a preparation method thereof.

Background

AuNPs show unique physical and chemical properties, such as surface plasmon resonance absorption (SPR), raman Scattering (RS) and the like, and the unique properties of gold nanoparticles depend on the change of the size and the appearance of the gold nanoparticles to a great extent, and the unique optical and electrical properties of the AuNPs enable the AuNPs to have wide application in the fields of biomedicine and the like, including medical imaging, such as X-ray imaging, fluorescence imaging, surface Enhanced Raman Scattering (SERS) imaging and the like; disease treatment, such as drug delivery, nucleic acid transport, photothermal therapy, and radiation therapy; disease diagnosis such as nucleic acid and protein detection, etc.

Multifunctional nanomaterials usually require surface modification and bioconjugation reactions to introduce various functional groups and bioactive molecules for better disease diagnosis and treatment. The gold nanoparticles are easy to realize surface modification or biological coupling reaction, can introduce antibodies, polypeptides, ligands, medicines and genes, improve the targeting property and specificity of AuNPs, and provide a beneficial means for deeply exploring various biological activities of the AuNPs, so that the gold nanoparticles become a research hotspot in the field of nano biomedicine.

Sodium borohydride, a strong reducing agent, required in the common method for preparing gold nanoparticles is highly toxic and can strongly stimulate the upper respiratory tract, eyes and skin, and the reagent is harmful to human bodies when inhaled or contacted with the skin. And surface modification or bioconjugation needs to be performed stepwise.

In view of the above important applications and problems of AuNPs, there is a need to develop a simple green method for synthesizing nanoparticles, which avoids the use of toxic chemicals, is more environmentally friendly, and facilitates the completion of surface modification or bioconjugation.

Disclosure of Invention

Based on the above, the present invention aims to overcome the disadvantages of the prior art and provide a method for preparing gold nanoparticles. The AuNPs green synthesis method uses plant extracts or biological active substances such as microorganisms and the like as reactants to synthesize an AuNPs structure, except for environmental friendliness brought by using green reagents to replace chemical reagents, the green synthesis method can improve the biocompatibility of products, simplify reaction steps and facilitate large-scale production, and the green reagents are combined with AuNPs to possibly generate synergistic biological activity.

According to the green preparation method of the gold nanoparticles, the reducing agent chlorogenic acid with biological activity is adopted, the use of the reducing agent sodium borohydride with high toxicity is avoided, an additional stabilizing agent or a protective agent is not required, the reaction condition is simple, rapid and environment-friendly, the surface coating functionalization of the CGA to AuNPs is completed in one step, the prepared CGA-AuNPs have a good scavenging effect on free radical DPPH, the oxidation resistance of the AuNPs is improved, and the method has potential medical application.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: reacting the chlorogenic acid solution with the chloroauric acid solution at the temperature of 80-100 ℃ to obtain the gold nanoparticles.

Preferably, the reaction temperature is 90-100 ℃.

More preferably, the reaction temperature is 100 ℃. In the preferable temperature range, the reaction speed is high, the energy consumption is low, and the gold nanoparticles with good dispersity and no agglomeration can be prepared.

Preferably, the reaction molar ratio of the chloroauric acid to the chlorogenic acid is 1:1-1:4. When the molar ratio of the two is 1:1-1:2, preparing spherical gold nanoparticles, wherein the nano sol is wine red; when the molar ratio of the two (chloroauric acid/chlorogenic acid) is 1:2-1:4, the dropping speed is controlled to prepare the gold nanoparticles with larger irregular sizes formed by stacking small gold nanoparticles, and the nano sol is purple or blue.

Preferably, in the preparation method, the chlorogenic acid solution is heated to 80-100 ℃, and then chloroauric acid is dropwise added and the heating is continued for 5-60 s. This option allows the reduction reaction to be completed quickly.

Preferably, the reaction concentration of the chlorogenic acid solution is 0.1-0.45 mmol/L.

Preferably, the reaction concentration of the chloroauric acid solution is 0.06-0.2 mmol/L. In the preferable concentration range, the prepared gold nanoparticles have good dispersibility and are not easy to agglomerate.

Meanwhile, the invention also provides the gold nanoparticles prepared by the preparation method. The prepared gold nanoparticles have a good effect of removing free radicals DPPH, improve the oxidation resistance of AuNPs, and have potential medical application.

Compared with the prior art, the invention has the beneficial effects that:

Drawings

FIG. 1 is a transmission electron microscope image of gold nanoparticles obtained in example 1 of the present invention;

FIG. 2 is a transmission electron microscope image of gold nanoparticles obtained in example 1 of the present invention;

FIG. 3 is a transmission electron microscope image of gold nanoparticles obtained in example 1 of the present invention;

FIG. 4 is an IR spectrum of gold nanoparticles obtained in example 1 of the present invention;

FIG. 5 is an EDS energy spectrum of gold nanoparticles obtained in example 1 of the present invention;

FIG. 6 is a transmission electron microscope image of gold nanoparticles obtained in example 3 of the present invention;

FIG. 7 is a transmission electron micrograph of gold nanoparticles obtained in example 3 of the present invention;

FIG. 8 is a transmission electron micrograph of gold nanoparticles obtained in example 3 of the present invention;

FIG. 9 is a graph comparing the oxidation resistance of gold nanoparticles obtained in the present invention;

FIG. 10 is a transmission electron micrograph of gold nanoparticles obtained in example 4 of the present invention;

FIG. 11 is a transmission electron micrograph of gold nanoparticles obtained in example 4 of the present invention;

FIG. 12 is a transmission electron micrograph of gold nanoparticles obtained in example 4 of the present invention.

Detailed Description

To better illustrate the objects, aspects and advantages of the present invention, the present invention will be further described with reference to the accompanying drawings and specific embodiments.

Example 1

In an embodiment of the gold nanoparticles of the present invention, the gold nanoparticles of this embodiment are prepared as follows:

experimental materials chlorogenic acid (25 mmol/L), chloroauric acid (20 mmol/L)

The experimental process comprises the following steps:

(1) Respectively taking 100 mu L of each of chlorogenic acid and chloroauric acid, diluting the chlorogenic acid to 10ml (the concentration is 0.25 mmol/L), and diluting the chloroauric acid to 2ml (the concentration is 1 mmol/L);

(2) Preheating a hot plate for 30min, putting a sample bottle filled with 2400 mu l of chlorogenic acid solution on the hot plate, heating for 2min, then adding 600 mu l of chloroauric acid solution, continuously heating for 1min, taking down, wherein the reaction temperature is 80-90 ℃, the reaction concentration ratio is 1:1, the color changes (dark purple is obtained when the dripping is finished, and the color changes from purple to red and finally to wine red in the heating process), and obtaining gold nanoparticles after the reaction is finished; the transmission electron microscope images are shown in attached figures 1-3, the infrared spectrogram is shown in figure 4, and the EDS energy spectrogram is shown in figure 5;

as can be seen from the attached drawings 1-3, the gold nanoparticles are mainly spherical, have good dispersibility and are not agglomerated, which indicates that chlorogenic acid is simultaneously used as a reducing agent and a stabilizing agent, an organic thin layer can be observed around the gold nanoparticles, which indicates that the chlorogenic acid has a stabilizing effect by coating the gold nanoparticles, and the measured average particle size of the gold nanoparticles is 38.81nm. As can be seen from fig. 4, chlorogenic acid-gold nanoparticles formation is illustrated by the characteristic peak of-OH; as can be seen from fig. 5, the Au characteristic peak of EDS illustrates the successful synthesis of gold nanoparticles.

Example 2

In an embodiment of the gold nanoparticles of the present invention, the parameters related to the preparation process of the gold nanoparticles are specifically studied and analyzed.

1. Influence of chlorogenic acid concentration on gold Sol Synthesis

The experimental method comprises the following steps: mixing chlorogenic acid solution (25 mmol/L) with water, heating to boil under stirring in a heater, adding chloroauric acid solution (20 mmol/L), heating to boil, and taking off.

And (4) experimental conclusion: when the reaction concentration of the chloroauric acid is fixed at 0.1mmol/L, the reaction concentrations of the chlorogenic acid are respectively 0.1mmol/L, 0.2mmol/L, 0.3mmol/L and 0.4mmol/L, and the color of the sol is red, purple and blue along with the increase of the reaction concentration of the chlorogenic acid.

2. Influence of reaction temperature on gold Sol Synthesis

Mixing a chlorogenic acid solution (25 mmol/L) and water in a sample bottle, stirring and heating on a constant-temperature magnetic heater to a condition temperature, adding a chloroauric acid solution (20 mmol/L), heating until the color changes for 1 minute, taking down, and controlling the reaction molar ratio of the chloroauric acid to the chlorogenic acid to be 1:1, wherein the reaction temperatures are respectively room temperature, 40 ℃, 60 ℃, 80 ℃, 90 ℃ and 100 ℃; it is found that clear and transparent wine red gold sol can be synthesized only when the reaction temperature is higher than 80 ℃, and the reaction temperature is below 80 ℃, the synthesized gold sol has a Tyndall phenomenon, but the color is orange yellow and has obvious turbidity. Within the preferable temperature range, the reduction reaction can be more complete and rapid, the energy consumption is low, and the prepared gold nanoparticles have good dispersibility and are not easy to agglomerate.

Example 3

In an embodiment of the gold nanoparticles of the present invention, a method for preparing gold nanoparticles of the present embodiment includes:

mixing 2ml 1mmol/L chlorogenic acid solution and 7ml water in a sample bottle according to a reaction molar ratio (chloroauric acid/chlorogenic acid) of 1:2, stirring and heating to boil on a constant-temperature magnetic heater, controlling the dropping speed, adding 1ml 1mmol/L chloroauric acid solution, continuously heating to boil for 5-10 s, taking down to prepare gold nanoparticles, testing that the average particle size is 40.54nm, and taking out the gold nanoparticles as shown in the TEM pictures of figures 6-8. As can be seen from figures 6-8, the obtained gold nanoparticles are changed in shape, good in dispersity and free from agglomeration, the chlorogenic acid is simultaneously used as a reducing agent and a stabilizing agent, and good coating of the gold nanoparticles by an organic thin layer of the chlorogenic acid can be observed around the gold nanoparticles.

Example 4

In one embodiment of the gold nanoparticles of the present invention, the oxidation resistance of the gold nanoparticles is specifically studied and analyzed.

Mixing and shaking 1ml of the prepared CGA-AuNPs sample and 1ml of DPPH-free radical absolute ethyl alcohol solution (0.2 mmol/L) in a sample bottle, placing the sample bottle in a dark environment for reaction for 30min, and measuring the absorbance of the sample bottle As As at 517nm by taking 1ml of the mixed solution of distilled water and 1ml of absolute ethyl alcohol As a reference; simultaneously, 1ml of sample is taken to be mixed with 1ml of absolute ethyl alcohol to obtain absorbance Ab, 1ml of DPPH-free radical absolute ethyl alcohol solution is taken to be mixed with 1ml of distilled water to obtain absorbance Ac, and the clearance rate is calculated according to the following formula:

the measured clearance of the CGA-AuNPs samples to DPPH.free radical is shown in the attached FIG. 9: as can be seen from FIG. 9, the prepared CGA-AuNPs have a DPPH radical clearance rate of more than 90%, slightly higher than that of CGA, and after the prepared CGA-AuNPs are centrifuged, the supernatant is discarded and redispersed with water, TEM images are as follows, wherein the TEM images are as follows: as can be seen, the CGA coating layer becomes thinner, and the measured clearance rate of DPPH & free radical is reduced from more than 90% to less than 30%, which shows that the AuNPs are coated by the CGA, and the oxidation resistance of the AuNPs is improved.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation method of gold nanoparticles is characterized by comprising the following steps: heating a chlorogenic acid solution to 80-100 ℃, then dropwise adding chloroauric acid, and continuously heating for 5-60 s for reaction to obtain gold nanoparticles;

the reaction molar ratio of the chloroauric acid to the chlorogenic acid is 1 to 2 to 1, the dropping speed is controlled, gold nanoparticles with large random sizes formed by stacking small gold nanoparticles are prepared, and the nano sol is purple or blue.

2. The method for preparing gold nanoparticles according to claim 1, wherein the reaction concentration of the chlorogenic acid solution is 0.1 to 0.45mmol/L.

3. The method for preparing gold nanoparticles according to claim 1, wherein the reaction concentration of the chloroauric acid solution is 0.06 to 0.2mmol/L.

4. Gold nanoparticles prepared by the method of any one of claims 1~3.