CN112461818B

CN112461818B - Gold nanocluster with multiple optical signal channels

Info

Publication number: CN112461818B
Application number: CN202011304909.8A
Authority: CN
Inventors: 高凌峰; 李伟; 何池洋; 桂云云; 杨雅雯
Original assignee: Wuhan Textile University
Current assignee: Wuhan Textile University
Priority date: 2020-11-13
Filing date: 2020-11-13
Publication date: 2022-06-24
Anticipated expiration: 2040-11-13
Also published as: CN112461818A

Abstract

The invention discloses a gold nanocluster with multiple optical signal channels, belongs to the technical field of functionalized nano material detection, and relates to a gold nanocluster for selectively distinguishing and detecting multiple optical signals of multiple heavy metal ions. The gold nanoclusters synthesized by the method are uniform in size and have good chemiluminescence and fluorescence characteristics, and the method has the advantages of being simple, rapid and low in cost. The gold nanoclusters can be used for selectively distinguishing various heavy metal ions. The gold nanocluster with the multiple optical signal channels has wide application prospects in the fields of biological analysis and biological imaging.

Description

Gold nanocluster with multiple optical signal channels

Technical Field

The invention relates to the field of gold nanoclusters, in particular to a gold nanocluster with multiple optical signal channels, a preparation method of the gold nanocluster and application of the gold nanocluster in selective detection of heavy metal ions.

Background

Metal nanoclusters having luminescence properties, such as gold and silver nanoclusters, are very close in size to the fermi wavelength of electrons and thus may exhibit characteristics similar to discrete electronic states of molecules. The ultrafine gold nanoclusters are composed of several gold atoms, have phosphorescence and fluorescence properties related to the size, and due to good light stability and biocompatibility, the gold nanoclusters with the luminescence property are deeply applied to the aspects of in vivo and in vitro imaging, metal ion sensing, biosensor construction and the like in recent years. In the past decades, many methods have been developed to synthesize gold nanoclusters, for example, gold nanoclusters using polyamide dendrimers as protective agents may have various emission wavelengths from far ultraviolet to near infrared.

The chemical nose/tongue detection strategy simulates the olfactory system of mammals, and the chemical nose/tongue detection strategy is developed rapidly since the application of nano materials in the field. A chemical nasal/lingual detection sensor is generally defined as an array detection sensing system that can produce different responses to different target analytes. The existing detection strategy establishes an array detection method based on green fluorescent protein and different functionalized nano materials, and can successfully distinguish and identify different proteins. However, the ability of the array detection sensor to identify and distinguish is closely related to the number of sensing elements. Most of the reported array detection sensing strategies are based on a single signal pathway, such as a fluorescent signal. If more signal paths can be introduced, the sensing capability of the sensor should be improved.

One solution is to design a nanomaterial with multiple optical signal channels. A number of nanomaterials and compounds have been developed with a variety of signals and are referred to as molecular or nano-material laboratories. Such as: carbon nitride nano material (g-C) with multiple signal channels₃N₄) The photoluminescence signal, rayleigh scattering signal and uv-visible signal are used to distinguish the proteins. However, these array detection strategies extract only one signal parameter from each optical signal, which increases the complexity of detection, the detection time, and wastes signal resources. Another way to enhance the detection of the array is to extract multiple valid parameters from a single signal source.

Heavy metal contamination is a very serious problem. The source of heavy metal ions is wide, but the analysis is carried out from the actual source channel, the heavy metal ions in the water mainly come from chemical industry, printing textile, inorganic pigment and the like, and the water also comprises domestic sewage, mining wastewater and the like in cities, when the sewage is discharged into the environment and is eaten by peopleWhen the chain propagates, the influence on animals and plants is more serious. Wherein an excessively high concentration of Al³⁺The ions can cause damage to the immune system and the central nervous system of a human body, and cause red blood cell hypopigmentation anemia, reduction of biological enzyme activity, cell decay and the like, so that serious diseases such as Alzheimer disease, Parkinson disease, senile dementia and the like are caused; when Al is present in human brain tissue³⁺When the ion deposition is excessive, the damage to the brain can be caused, and the symptoms of low intelligence, memory decline, slow action and the like are presented; in addition, when the concentration of aluminum ions in human body is too high, the absorption of calcium, phosphorus and other elements and vitamin D in human body is inhibited, and joint pain and skeleton softness are seriously caused. According to the regulations of the world health organization of the United nations, the concentration of aluminum ions in drinking water must not exceed 200mg/L, and the maximum amount of aluminum ingested per week per 1Kg of human body weight must not exceed 7 mg. The cobalt compound is widely distributed in nature, generally, the cobalt content in the soil is 0.05-65.00 mg kg^-1Median value of 8mg kg^-1In human life activities, cobalt is an important component of vitamin B12 and participates in many biochemical reactions. However, excessive intake of Co compounds has been shown to have adverse effects on skin, lungs, thyroid gland, and the like. Studies have shown that co (ii) implanted in artificial joints in humans can transfer to the internal environment of the human body, inducing apoptosis, and thereby inhibiting T lymphocyte expansion, which researchers have observed in hip aspirates and regional lymph nodes where patients are implanted in artificial joints. Many countries make clear regulations on the concentration of cobalt ions in domestic water, for example, the maximum concentration of cobalt in domestic water supply source proposed by China is 0.02mg L^-1(ii) a Chromium is a necessary trace element for the growth of human bodies, animals and plants, has an important effect on maintaining the normal functions of the human bodies, is an indispensable auxiliary component of insulin, can be absorbed by gastrointestinal digestive tracts when entering the human bodies through water and food, and has the effects of carcinogenesis, teratogenesis and mutagenesis after long-term accumulation. In organisms, copper is a catalytic cofactor of a plurality of metalloenzymes and proteins, can participate in a plurality of oxidation-reduction reactions, and has important effects on the metabolic process of organisms, such as Cu-Zn-SOD, DA-beta-hydroxylase and tyrosineAcid enzymes, ceruloplasmin, etc.; copper can participate in iron metabolism, which is beneficial to the synthesis of hemoglobin; can affect the generation and the metastasis of the tumor and inhibit the proliferation of tumor cells; plays a fundamental role in the formation of bone, nervous system, cardiovascular and connective tissue in the field of pathophysiological studies, Zn²⁺Play an irreplaceable role in the catalysis and conversion processes of biological enzymes. When zinc in a human body is deficient, the zinc can cause the disturbance of the immune system of the human body, diarrhea, epilepsy and the like; if the zinc is excessively ingested, the human body can be harmed, and various diseases can be caused, such as Parkinson's disease, Alzheimer's disease and the like³⁺，Co²⁺，Cr³⁺，Cu²⁺And Zn²⁺And (3) a detection method.

The prior art luminol modified gold nano-material (CN102191034A, CN101900723A, CN102021226A, CN104371705A and the like) has the particle size of more than or equal to 10nm, has chemiluminescence property due to the modification of the luminol, but does not have fluorescence property, is applied to pesticide detection, immunoassay such as detection of antibody, antigen or protein and detection of nucleic acid such as DNA, RNA and aptamer molecules, and is not applied to detection of heavy metal.

In addition, in the prior art, gold nanoclusters are used for detecting heavy metals, but only one signal of fluorescence or chemiluminescence can be generally used for detecting single metal ions, and more than two different types of heavy metal ions cannot be detected simultaneously.

The chemiluminescence and fluorescence-based analysis technology has the advantages of simple instrument and device, rapid analysis, high sensitivity, wide linear range and the like, and is widely applied to the fields of clinical diagnosis, food safety, environmental monitoring and the like. In the traditional detection strategy, chemiluminescence and fluorescence spectrum also only extract a valid signal to detect the target. In fact, other effective parameters in the spectrum are ignored and not effectively utilized, such as chemiluminescence signals at different times, integrated values of the luminescence signals, and fluorescence signals at different peak positions.

There is an urgent need to develop a gold nanocluster prepared by a one-pot method and having multiple optical signal paths, wherein the gold nanocluster simultaneously has a chemiluminescent signal and a fluorescent signal so as to construct a heavy metal ion sensing detection array, and the detection array can successfully distinguish different heavy metal ions and different metal ion concentrations.

Disclosure of Invention

The invention aims to provide a double-signal functionalized gold nanocluster with chemiluminescence and fluorescence signals, a preparation method thereof and application thereof in heavy metal ion array detection and analysis, wherein the content comprises the following aspects:

gold nanoclusters AuNCs having a chemiluminescent and fluorescent multiple light signal channel with luminol and undecament undecanoic acid (MUA) attached to their surfaces are provided, having a particle size of less than about 10 nm.

The gold nanoclusters AuNCs are formed by using 11-mercaptoundecanoic acid (MUA) as a blocking agent and chloroauric acid to form Au (I) -thiol complexes, and introducing luminol as a reducing agent to reduce the Au (I) -thiol complexes.

The particle size of the gold nanoclusters AuNCs is less than about 10nm, or less than about 5nm, or less than about 3nm, and preferably the particle size is about 2nm, and the gold nanoclusters AuNCs have both fluorescence and chemiluminescence properties.

The preparation method of the gold nanoclusters AuNCs comprises the following steps: (1) dissolving undecamydryl undecanoic acid (MUA) in a NaOH solution, and mixing with a chloroauric acid aqueous solution under a stirring state to obtain a mixed solution;

(2) dropwise adding NaOH under the stirring state until the solution becomes clear, and stirring the solution to obtain an Au (I) -thiol complex formed by MUA and gold;

(3) and (3) heating the solution under a stirring state, adding the luminol aqueous solution into the solution obtained in the step (2), and continuously stirring to obtain the gold nanocluster AuNCs.

The amount of the substance of the undecamydryl undecanoic acid (MUA) in the undecamydryl undecanoic acid (MUA) solution in the step (1) is 3 to 6 times of the amount of the substance of the chloroauric acid in the aqueous chloroauric acid solution, and preferably the amount of the substance of the undecamydryl undecanoic acid (MUA) in the undecamydryl undecanoic acid (MUA) solution is 4 times of the amount of the substance of the chloroauric acid in the aqueous chloroauric acid solution.

And (3) stirring the solution in the step (2) for 10-30 minutes to obtain an Au (I) -thiol complex formed by the undecamydryl undecanoic acid (MUA) and the gold, and preferably stirring the solution for 20 minutes to obtain an Au (I) -thiol complex formed by the undecamydryl undecanoic acid (MUA) and the gold.

In the step (3), the solution is heated to 20-120 ℃, preferably 50-100 ℃, and more preferably 60 ℃ under the stirring state, the amount of the luminol in the luminol aqueous solution is 0.40-2.67 times of the amount of the chloroauric acid in the chloroauric acid aqueous solution in the step (1), the continuous stirring time is preferably 5-24h, more preferably 7-10h, and more preferably 8 h.

Gold nanoclusters AuNCs having a chemiluminescent and fluorescent multiple-optical signal channel are provided, and are formed by forming an Au (I) -thiol complex with Au (I) by using 11-mercaptoundecanoic acid (MUA) as a capping agent, and then introducing luminol as a reducing agent to reduce the Au (I) -thiol complex to form AuNC, wherein the luminol is connected to the surface of the gold nanoclusters through a covalent bond Au-N bond and has a particle size of about 2.0 +/-0.5 nm.

The gold nanoclusters AuNCs have a chemiluminescence characteristic, and the gold nanoclusters AuNCs react with hydrogen peroxide to generate chemiluminescence.

The gold nanoclusters AuNCs have fluorescence characteristics, and have fluorescence emission peaks at 424nm and 598 nm.

The preparation method of the gold nanocluster AuNCs comprises the following steps: (1) dissolving 11-mercaptoundecanoic acid (MUA) in NaOH solution, and mixing with chloroauric acid aqueous solution under stirring to obtain mixed solution; the amount of MUA species in the aqueous MUA solution is 4 times the amount of chloroauric acid species in the aqueous chloroauric acid solution;

(2) dropwise adding NaOH under stirring until the solution becomes clear, and stirring the solution for 20 minutes to obtain an Au (I) -thiol complex formed by 11-mercaptoundecanoic acid (MUA) and gold;

(3) heating the solution to 60 ℃ under the stirring state, adding the luminol water solution into the solution obtained in the step (2), and continuously stirring for 8 hours to obtain gold nanoclusters, namely AuNCs; the amount of the luminol substance in the luminol water solution is 0.40-2.67 times that of the chloroauric acid substance in the chloroauric acid water solution in the step (1).

The method further comprises a step of purifying the functionalized gold nanoclusters by centrifugation.

The functionalized gold nanoclusters may be centrifuged under the following conditions: the initially synthesized gold nanoclusters are mixed with acetonitrile in a volume ratio of 1: 2 and centrifuged at 12000rpm for 5 minutes, and then the precipitate is dissolved with distilled or deionized water or ultrapure water.

The method for distinguishing the array of the heavy metal ions is developed based on the functionalized gold nanoclusters.

The heavy metal ions are Al³⁺，Co²⁺，Cr³⁺，Cu²⁺And Zn²⁺And the gold nanoclusters are selectively distinguished through different influences of the heavy metal ions on chemiluminescence spectrums and fluorescence spectrums of the gold nanoclusters AuNCs.

The invention develops a one-pot method for preparing gold nanoclusters with multiple optical signal paths, wherein the gold nanoclusters have chemiluminescent signals and fluorescent signals. The AuNCs prepared are analyzed by a high-resolution transmission electron microscope and X photoelectron spectroscopy, and chemiluminescence and fluorescence signals of the AuNCs are researched. In order to fully utilize the chemiluminescence and fluorescence signal channels, five effective parameters are extracted from the chemiluminescence spectrum and the fluorescence spectrum and are used for constructing a heavy metal ion sensing detection array. The detection array can successfully distinguish different heavy metal ions and different metal ion concentrations.

Compared with the prior art, the invention has the following advantages:

(1) the gold nanocluster has the size of less than 10nm, 11-mercaptoundecanoic acid (MUA) is used as a stabilizer to enable the gold nanocluster to have the size of less than 10nm, preferably 2m, so that a chemiluminescence signal and a fluorescence signal can be simultaneously obtained, a heavy metal ion sensing detection array can be further constructed, multiple heavy metal ions can be simultaneously selected and distinguished, and the heavy metal ions are Al³⁺，Co²⁺，Cr³⁺，Cu²⁺And Zn²⁺And e.g. Hg²⁺，Pb²⁺The equal-heavy metal ions are obviously distinguished on signals, the gold nanocluster with the multiple optical signal channels has wide application prospects in the fields of biological analysis and biological imaging, the defect that a plurality of different detection reagents need to be replaced in actual detection application is overcome, and the instantaneity and the convenience are improved.

(2) The gold nanoclusters synthesized by the one-pot method are uniform in size and have good chemiluminescence and fluorescence characteristics, and the method has the advantages of being simple, rapid and low in price.

(3) The gold nanoclusters can simultaneously select and distinguish various heavy metal ions through different influences of the heavy metal ions on chemiluminescence spectrums and fluorescence spectrums of the gold nanoclusters AuNCs.

Drawings

FIG. 1 is a high-resolution transmission electron microscope of gold nanoclusters AuNCs with multiple optical signal channels for chemiluminescence and fluorescence;

FIG. 2 is an X-ray photoelectron spectrum of gold nanoclusters AuNCs having multiple optical signal channels for chemiluminescence and fluorescence; FIG. 3 is a graph of the relative chemiluminescence kinetics of gold nanoclusters AuNCs with multiple optical signal channels for chemiluminescence and fluorescence;

FIG. 4 is a conditional screening of gold nanoclusters AuNCs having multiple optical signal channels for chemiluminescence and fluorescence, wherein FIG. 4A is a synthesis conditional screening;

FIG. 4B is a screening of the concentration of sodium hydroxide in the assay conditions; FIG. 4C is a screening of the concentration of hydrogen peroxide in the assay conditions;

FIG. 5 is a fluorescence signal characteristic diagram of gold nanoclusters AuNCs with a multi-optical signal channel for chemiluminescence and fluorescence;

FIG. 6 is Al³⁺，Co²⁺，Cr³⁺，Cu²⁺，Hg²⁺，Pb²⁺And Zn²⁺The chemiluminescence and fluorescence signal influence on gold nanocluster AuNCs with a multi-optical signal channel of chemiluminescence and fluorescence.

FIG. 7 shows Al³⁺，Co²⁺，Cr³⁺，Cu²⁺，Hg²⁺，Pb²⁺And Zn²⁺Array detection of the images at a single concentration;

FIG. 8 shows Al³⁺，Co²⁺，Cr³⁺，Cu²⁺，Hg²⁺，Pb²⁺And Zn²⁺The images were detected on an array at different concentrations.

Detailed Description

Example 1 Synthesis of gold nanoclusters AuNCs with multiple optical signaling channels for chemiluminescence and fluorescence.

And (3) reagent sources: chloroauric acid, acetonitrile, heavy metal ions, and hydrogen peroxide were obtained from Shanghai reagent, luminol was obtained from TCI reagent, and 11-mercaptoundecanoic acid (MUA) was obtained from Anyiji reagent.

The AuNCs are prepared by the following steps: 0.0131g of 11-mercaptoundecanoic acid (MUA) was dissolved in 18mL of ultrapure water containing NaOH, followed by addition of 10mM of 1.5mL chloroauric acid solution, followed by dropwise addition of NaOH solution to make the originally turbid solution clear. After the solution was stirred for 20 minutes, 0.9mL of 10mM luminol solution was added dropwise and the mixture was heated and stirred at 60 deg.C for 8 hours. Finally the excess was separated by adding acetonitrile (mixed with nanomaterial at a volume ratio of 2: 1) and centrifuging (12000 rpm). The prepared AuNCs were redispersed in water and stored at 4 degrees Celsius for use.

The characterization is shown in FIG. 1: the high-resolution transmission electron microscope shows that the 11-mercaptoundecanoic acid (MUA) is modified on the surface of AuNCs, so that the aggregation of gold nanoclusters is effectively inhibited, and the dispersibility of AuNCs is good. The size distribution range of the gold nanoclusters is relatively small, and the size is 2.0 +/-0.5 nm.

Example 2 Synthesis of gold nanoclusters AuNCs with multiple optical signaling channels for chemiluminescence and fluorescence.

The AuNCs are prepared by the following steps: 0.0131g of 11-mercaptoundecanoic acid (MUA) was dissolved in 18mL of ultrapure water containing NaOH, followed by addition of 10mM of 1.5mL of chloroauric acid solution, followed by dropwise addition of NaOH solution to bring the originally turbid solution into a clear state. After the solution was stirred for 20 minutes, 0.9mL of 10mM luminol solution was added dropwise and the mixture was heated and stirred at 100 deg.C for 5.5 hours. Finally the excess was separated by adding acetonitrile (mixed with nanomaterial at a volume ratio of 2: 1) and centrifuging (12000 rpm). The prepared AuNCs were redispersed in water and stored at 4 degrees Celsius for use.

Example 3 Synthesis of gold nanoclusters AuNCs with multiple optical signaling channels for chemiluminescence and fluorescence.

The AuNCs are prepared by the following steps: 0.0131g of 11-mercaptoundecanoic acid (MUA) was dissolved in 18mL of ultrapure water containing NaOH, followed by addition of 10mM of 1.5mL of chloroauric acid solution, followed by dropwise addition of NaOH solution to bring the originally turbid solution into a clear state. After the solution was stirred for 20 minutes, 0.9mL of 10mM luminol solution was added dropwise and the mixture was heated and stirred at 80 deg.C for 24 hours. Finally the excess was separated by adding acetonitrile (mixed with nanomaterial at a volume ratio of 2: 1) and centrifuging (12000 rpm). The prepared AuNCs were redispersed in water and stored at 4 degrees Celsius for use.

Example 4.

The invention makes X-ray photoelectron spectrum to research the valence state of gold atom in the functional gold nanocluster. FIG. 2 shows an X-ray photoelectron spectrum of functionalized Au 4f of gold nanocluster_7/2The binding energy was 84.3eV, which is between the binding energy of Au (0) 84.0eV and Au (i) 85.1eV, indicating that Au (0) and Au (i) coexist in the functionalized gold nanoclusters. Au 4f_7/2And Au 4f_5/2The difference of the spin-orbit splitting energy level of the compound is 3.7eV, which is completely consistent with the report of the prior literature. The gold cluster is surface functionalized with undecamydryl undecanoic acid and RouIn the minox, the energy level peak of C1s was split into four peaks, C1, C2, C3 and C4, which correspond to-CH-, -C-NH-, -CO-NH-, -COO-groups, respectively, and the peak of C1 was also evident due to the presence of undecamyl undecanoic acid. The 1s peak of N is divided into two portions, 400.0eV and 400.8eV respectively, corresponding to the-N-C-and-N-CO-groups of luminol respectively.

To investigate the chemiluminescent performance of the AuNCs prepared, we will use 150mL of 5mM H₂O₂Solution (c)_NaOH0.1M) was injected into 150mL of the prepared AuNCs solution, and a chemiluminescent signal was measured by an RFL-1 type photometer. Under the same detection condition, the chemiluminescence properties of the luminol functionalized gold nano material and the mixture of the gold nanocluster and the luminol solution are detected and compared with a chemiluminescence dynamics curve of AuNCs, and the result shows that the chemiluminescence properties of AuNCs are optimal, which is probably the synergistic catalytic effect of MUA and the gold nanocluster on a luminol hydrogen peroxide chemiluminescence system. In previous work, it has been demonstrated that the enhanced and catalytic mechanism of chemiluminescence is associated with the production of oxygen radicals (including OH)^·，O₂ ^·-And other free radical derivatives) the gold nanomaterial can facilitate the generation of electron transfer free radicals during chemical reactions. Thus, under the catalytic action of gold nanoclusters, H₂O₂Can be cleaved into two OH radicals which can react with HO^2-The luminol anion, thereby promoting O₂ ^·-And the formation of MS-AuNCs functionalized luminol free radicals, thereby accelerating the chemiluminescent reaction. In addition, early studies have shown that carboxyl group-containing substances such as amino acids and phenolic compounds can enhance luminol-H₂O₂-Co²⁺The chemiluminescence intensity of the system. Thus, the enhancement of chemiluminescence may be attributed to the carboxyl groups and O on the MUA molecule₂ ^·-By reaction of formed-CO₄ ^·2-Related, to-CO₄ ^·2-Can react with luminol to promote the generation of luminol free radical, thereby enhancing the chemiluminescence intensity. Therefore, the good chemiluminescence of AuNCs and hydrogen peroxide systems can be attributed to MUA andthe gold nanoclusters promote HO during chemical reactions^·，O₂ ^·-and-CO₄ ^·2-And the gold nanoclusters, as a nano-sized reaction platform, can also promote the generation of radicals for a chemiluminescent reaction, thereby obtaining strong chemiluminescence.

Example 5.

In order to obtain the best chemiluminescence effect, the preparation conditions are optimized, as shown in fig. 4A, the chemiluminescence performance of AuNCs begins to increase along with the increase of the reaction time and the reaction temperature, and the best chemiluminescence effect is obtained at the reaction temperature of 60 ℃ and the reaction time of 8 h.

Test conditions for chemiluminescence:

the chemiluminescent signal was detected on an RFL-1 type luminescence detector (Siamelimei, China) by mixing 150. mu.L of the gold nanoclusters with 150. mu.L of 5mM H₂O₂(0.1M NaOH) mixing produced a chemiluminescent signal. For array sensing detection, gold nanoclusters and different heavy metal ions are mixed in a volume ratio of 9: 1 at corresponding concentrations, incubated at room temperature for 10 minutes, 150 μ L of the mixture is injected into a quartz chemiluminescence detection cell, and 150 μ L of 5mM H₂O₂(0.1M NaOH) was injected into the test cell and the chemiluminescent signal was recorded.

Test conditions for fluorescence:

the fluorescence signal was detected on an F-7000 type fluorescence detector (Xe lamp 150W, Hitachi, light source) with an excitation wavelength of 290nm, by mixing gold nanoclusters and different heavy metal ions at respective concentrations in a volume ratio of 9: 1, incubating at room temperature for 10 minutes, injecting 150. mu.L of the above mixture into a quartz fluorescence detection cell, and recording the fluorescence signal.

We also optimized the chemiluminescent reaction conditions, as shown in FIGS. 4B and 4C, with the intensity of chemiluminescence being dependent on H₂O₂The increase in the NaOH concentration of the solution was significant, and when the NaOH concentration was 0.1M, the best chemiluminescence was obtained, after which continued increase in the NaOH concentration resulted in a decrease in the chemiluminescence intensity, probably due to the onset of the increase in the NaOH concentrationIncreasing the pH promotes H₂O₂When the NaOH concentration exceeds 0.1M, the blocking agent MUA starts to fall off from the AuNCs surface, leading to aggregation of AuNCs, resulting in a decrease in the chemiluminescence intensity. When H is present₂O₂The increase in concentration from 0.5mM to 5mM resulted in a significant increase in chemiluminescence intensity, after which continued increase resulted in a decrease in chemiluminescence intensity. Thus, the optimal chemiluminescent reaction condition is 5mM H₂O₂(0.1M，NaOH)。

The fluorescence properties of AuNCs are shown in FIG. 5, and the orange fluorescence of AuNCs solution is visible to the naked eye (corresponding to an emission peak at 598 nm). The emission peak at 424nm corresponds to AuNCs surface-modified luminol. As the excitation peak increases from 270nm to 350nm, the emission peak position of AuNCs hardly shifts, which is likely because the synthesized AuNCs is a single species and thus the excitation spectrum and the emission spectrum are both fixed. The fluorescence intensity at 598nm reaches a maximum when the excitation wavelength is 290 nm.

Example 6 Selective Distinguishing detection of heavy Metal ions

The detection method comprises the following steps: in order to explore the application of the AuNCs material in the aspect of heavy metal ion detection arrays, the influence of different heavy metal ions on chemiluminescence signals and fluorescence signals of AuNCs is researched. Detection of Fe³⁺、Sn²⁺、Ni²⁺、Mn²⁺、Ag⁺、Fe²⁺、Al³⁺，Co²⁺，Cr³⁺，Cu²⁺，Hg²⁺，Pb²⁺And Zn²⁺And 7 heavy metal ions with relatively strong chemiluminescence signals and fluorescence signals are preliminarily screened from the heavy metal ions as detection targets (namely Fe)³⁺、Sn²⁺、Ni²⁺、Mn²⁺、Ag⁺、Fe²⁺Weak signal) including Al³ ⁺，Co²⁺，Cr³⁺，Cu²⁺，Hg²⁺，Pb²⁺And Zn²⁺And screening again to find Al³⁺，Co²⁺，Cr³⁺，Cu²⁺And Zn²⁺Can be mixed with Hg²⁺，Pb²⁺And (4) directly distinguishing. To fully utilize the AuNCs' optical signal path, IWe extracted 5 effective parameters from the chemiluminescence spectrum and the fluorescence spectrum, and studied the effects of heavy metal ions on the integrated intensity of chemiluminescence 60s, the peak intensity, the intensity at 60s, the intensity of fluorescence at 598nm, and the intensity value of fluorescence at 424 nm. After adding different heavy metal ions to AuNCs respectively, AuNCs produce different signal changes under the influence of the heavy metal ions, as shown in FIG. 6. Therefore, the five parameters of the cumulative intensity of chemiluminescence 60s, the peak intensity, the intensity at 60s, the intensity of fluorescence at 598nm and the intensity value of fluorescence at 424nm are used for establishing a heavy metal ion sensing detection array.

The detection results are shown in fig. 7: principal component analysis is a means of processing complex, high-dimensional data, and can simplify data while preserving data trend characteristics. Therefore, it is an effective tool for processing experimental data, and can be used to process the signal response data generated by heavy metal ions to AuNCs, including the cumulative intensity of chemiluminescence 60s, peak intensity, intensity at 60s, intensity of fluorescence at 598nm, and intensity value of fluorescence at 424 nm. Each heavy metal ion was measured three times to obtain five characteristic signals of chemiluminescence and fluorescence of AuNCs, and then the data was subjected to principal component analysis. The first three main classified data obtained by analysis are used for establishing a three-dimensional data chart, each point represents the response result of the heavy metal ion sample to the detection array, and the result shows that the detection array can successfully distinguish different heavy metal ions.

We also investigated the discrimination of heavy metal ions at different concentrations. It was found that 7 heavy metal ions were well differentiated in the detection sensor array at two different concentrations (1. mu.g/mL and 0.5. mu.g/mL). The results are shown in FIG. 8, from which FIG. 8 we can distinguish Al at the same time³⁺，Co²⁺，Cr³⁺，Cu²⁺And Zn²⁺And the respective concentrations thereof were determined.

In the invention, a mild one-pot method is provided for preparing AuNCs with the size of 2.0 +/-0.5 nm. The synthesized AuNCs have excellent chemiluminescence and fluorescence properties, and based on chemiluminescence and fluorescence signals of AuNCs materials, a detection array sensing method capable of distinguishing different heavy metal ions and different concentrations of heavy metal ions is established. The work synthesizes a multi-signal functionalized gold nanocluster for the first time, and the multi-signal functionalized gold nanocluster has potential application prospects in the fields of biological analysis and biological imaging.

Claims

1. Gold nanoclusters AuNCs with multiple chemiluminescent and fluorescent light signal channels are characterized in that luminol and 11-mercaptoundecanoic acid are connected to the surfaces of the gold nanoclusters AuNCs, the particle size of the gold nanoclusters AuNCs is smaller than 10nm, the gold nanoclusters AuNCs are prepared by forming an Au (I) -thiol complex with chloroauric acid by using the 11-mercaptoundecanoic acid as a blocking agent, and then introducing the luminol as a reducing agent to reduce the Au (I) -thiol complex to form the gold nanoclusters AuNCs;

the gold nanoclusters AuNCs are prepared by a preparation method, wherein the preparation method comprises the following steps: (1) dissolving 11-mercaptoundecanoic acid in NaOH solution, and mixing with chloroauric acid aqueous solution under stirring to obtain mixed solution;

(2) under the stirring state, NaOH is dripped until the solution turns clear, and the solution is stirred to obtain an Au (I) -mercaptan compound formed by 11-mercaptoundecanoic acid and gold;

(3) and (3) heating the solution to 50-100 ℃ under the stirring state, adding the luminol water solution into the solution obtained in the step (2), and continuously stirring to obtain the gold nanocluster AuNCs.

2. The gold nanoclusters AuNCs of claim 1 having fluorescent and chemiluminescent properties.

3. The gold nanoclusters AuNCs of claim 1, having a particle size of less than 5 nm.

4. The gold nanoclusters AuNCs of claim 1, having a particle size of less than 3 nm.

5. The gold nanoclusters AuNCs of claim 1, having a particle size of about 2 nm.

6. The gold nanoclusters AuNCs according to any one of claims 1 to 5, wherein the amount of species of 11-mercaptoundecanoic acid in the 11-mercaptoundecanoic acid solution in step (1) is 3 to 6 times the amount of species of chloroauric acid in the aqueous chloroauric acid solution.

7. The gold nanoclusters AuNCs of claim 6, wherein the amount of species of 11-mercaptoundecanoic acid in the 11-mercaptoundecanoic acid solution is 4 times the amount of species of chloroauric acid in the aqueous chloroauric acid solution.

8. The gold nanoclusters AuNCs according to any one of claims 1 to 5, wherein the Au (I) -thiol complex formed by 11-mercaptoundecanoic acid and gold is obtained after stirring the solution in step (2) for 10 to 30 minutes.

9. The gold nanoclusters AuNCs of claim 8, wherein the Au (I) -thiol complex formed by 11-mercaptoundecanoic acid and gold is obtained after stirring the solution in step (2) for 20 minutes.

10. The gold nanoclusters AuNCs of claim 8, wherein in step (3) the solution is heated to 60 ℃ under stirring, and the amount of the substance of the luminol in the aqueous solution of the luminol is 0.40 to 2.67 times the amount of the substance of the chloroauric acid in the aqueous solution of the chloroauric acid in step (1).