A polyaniline nanoprobe and its preparation method and application

Abstract

The present invention belongs to the field of probe technology, and discloses a polyaniline nanoprobe and its preparation method and application. The polyaniline nanoprobe comprises a core polyaniline and a phospholipid-polyethylene glycol-carboxyl group wrapped in the outer layer of the polyaniline. The present invention wraps the prepared polyaniline in the PEG core by self-assembly of the amphiphilic reagent DSPE-PEG-COOH in an aqueous solution to obtain a water-soluble nanoparticle probe. The obtained nanoprobe can be used for dual-wavelength (780 / 1064nm) ratio photoacoustic imaging, and has good acid response ratio imaging characteristics, can realize accurate imaging based on acid response in the tumor microenvironment, and is applied to tumor detection.

Description

Technical Field

[0001] The invention belongs to the technical field of probes, and in particular relates to a polyaniline nanoprobe and a preparation method and application thereof. Background Art

[0002] During the growth and evolution of tumors, the most important feature of the tumor microenvironment (TME) is the change in the acid environment. Since tumor cells usually grow much faster than normal cells, normal nutrients and blood oxygen content cannot meet the growth needs. Therefore, tumor cells survive by generating energy through glycolysis. Based on this metabolic mode, tumor cells produce a large amount of lactic acid and adenosine triphosphate hydrolysis products, as well as some excess CO2 and H + , resulting in increased acidity in the tumor site and a lower pH value than normal. Normally, the pH value of normal human tissue cells is about 7.4, while the pH value of tumor tissue is about 6.0-7.0. Therefore, the diagnostic signal stimulated by this special acidic TME can further reflect the changes in the physiological parameters of tumor cells / tissues and provide clinically valuable information for the formulation of treatment and diagnostic strategies.

[0003] Photoacoustic imaging (PAI) is a new imaging technology with high optical resolution and large acoustic penetration depth. It can visualize the anatomy, oxygen metabolism, hemodynamics and other information of living organisms, and has been widely used in the detection of various diseases. Photoacoustic molecular imaging (PMI) is a biological imaging technology based on photoacoustic imaging, which combines molecular probes with high sensitivity, high specificity and strong optical signals with photoacoustic imaging equipment with excellent performance.

[0004] Polyaniline is a kind of polymer. After reacting with an acid, its absorption at 780 nm in the doped state increases significantly, and it can be prepared into an acid-responsive photoacoustic probe for the diagnosis and treatment of related diseases. Some researchers developed and synthesized a nano-probe based on the response of glutathione (GSH) in the tumor microenvironment using polyaniline as the raw material (Wang S, Zhang L, Zhao J, et al. A tumor microenvironment-induced absorption red-shifted polymer nanoparticle for simultaneously activated photoacoustic imaging and photothermal therapy[J]. Sci Adv, 2021, 7(12).), which can detect the tumor microenvironment through single-wavelength photoacoustic imaging technology. In this technology, the photoacoustic imaging detection uses an 808-nm single-wavelength laser. Since blood in the living body has a strong background photoacoustic signal, it will interfere with the signal of the detection probe itself in the single-wavelength mode, resulting in inaccurate photoacoustic signals of the probe actually measured; in addition, the photoacoustic imaging based on a single wavelength is easily interfered by the concentration of the body itself and cannot accurately reflect the real changes in the tumor microenvironment.

[0005] In addition, the state change of polyaniline from emeraldine base (EB) to emeraldine salt (ES) requires a strong acid environment with pH < 4, which is much lower than the tumor microenvironment (6.0 < pH < 7.0), so it is difficult to be used as a nano-probe responsive to the acidic microenvironment of tumors; and due to the extremely poor water solubility of polyaniline itself, it is difficult to be applied to the detection of biological living bodies, and it needs to be prepared into a water-soluble probe. Based on this, it is of great significance to prepare a water-soluble nano-probe of polyaniline that is sensitive to the acidic environment of tumors.

[0006] Therefore, there is an urgent need to provide a nano-probe with high accuracy and high sensitivity that can achieve accurate imaging based on the acid response in the tumor microenvironment. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a polyaniline nano-probe, its preparation method and application. The polyaniline nano-probe provided by the present invention is a nano-probe with high accuracy and high sensitivity that can achieve accurate imaging based on the acid response in the tumor microenvironment.

[0008] The present invention provides a polyaniline nano-probe.

[0009] Specifically, a polyaniline nano-probe includes a core of polyaniline and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethylene glycol-carboxyl (DSPE-PEG-COOH) wrapped around the outer layer of the polyaniline.

[0010] The polyaniline nanoprobe is in a granular form, and the particle size of the polyaniline nanoprobe is 80-100 nm.

[0011] The invention also provides a method for preparing the polyaniline nanoprobe.

[0012] Specifically, the method for preparing the polyaniline nanoprobe comprises the following steps:

[0013] Dissolving aniline and acid in water to obtain aniline solution;

[0014] Mixing and dissolving the phospholipid-polyethylene glycol-carboxyl group and the trivalent iron salt to obtain a mixed solution;

[0015] The aniline solution is mixed with the mixed solution, stirred at 0-4° C. to self-assemble into nanoparticles, and then impurities are removed to prepare polyaniline nanoprobes.

[0016] In some embodiments of the present invention, the acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0017] In some embodiments of the present invention, the molecular weight of the phospholipid-polyethylene glycol-carboxyl (DSPE-PEG-COOH) is 1500-4000, such as 2000.

[0018] In some embodiments of the present invention, the mass ratio of the aniline to the phospholipid-polyethylene glycol-carboxyl group is (1-5):1; preferably, the mass ratio of the aniline to the phospholipid-polyethylene glycol-carboxyl group is (3-4):1.

[0019] In some embodiments of the present invention, the acid solution is concentrated hydrochloric acid, and the mass ratio of the concentrated hydrochloric acid to the aniline is (0.8-1.2):1.

[0020] In some embodiments of the present invention, the trivalent iron salt is one of ferric chloride, ferric sulfate and ferric nitrate.

[0021] In some embodiments of the present invention, the trivalent iron salt is ferric chloride; preferably, the mass ratio of the ferric chloride to the phospholipid-polyethylene glycol-carboxyl group is (0.5-1.5):1; further preferably, the mass ratio of the ferric chloride to the phospholipid-polyethylene glycol-carboxyl group is (1.0-1.5):1.

[0022] In some embodiments of the present invention, the process of removing impurities is: placing the reaction solution stirred to self-assemble into nanoparticles in a dialysis bag with a molecular weight of MW1000-8000, and dialyzing at room temperature (5-35° C.) for 1-10 hours.

[0023] The invention also provides application of the polyaniline nanoprobe.

[0024] Specifically, the polyaniline nanoprobe is used in the preparation of a tumor detection kit.

[0025] The invention also provides a tumor detection kit.

[0026] Specifically, a tumor detection kit includes the above-mentioned polyaniline nanoprobe.

[0027] In the polyaniline nanoprobe provided by the present invention, the carboxyl group of DSPE-PEG-COOH reacts with polyaniline to cause a self-doping effect, which can improve the sensitivity of the nanoprobe to pH; and the polyaniline nanoprobe has a dual-wavelength (780 / 1064nm) ratio imaging characteristic of pH response. Compared with traditional inert probes, that is, they emit a non-specific signal that is "always on" and generate photoacoustic signals before and after entering the tumor, the nanoprobe designed by the present invention adopts a strategy of dual-wavelength ratio imaging combined with the acid response of the tumor microenvironment, which can effectively overcome the strong photoacoustic background signal of blood in photoacoustic live tumor imaging, resulting in insufficient specificity of tumor signals obtained under a single wavelength, improve tumor detection specificity and sensitivity, and can detect changes in the tumor acid environment more sensitively and accurately.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention encapsulates the polyaniline in the PEG core by self-assembly of the amphiphilic reagent DSPE-PEG-COOH in an aqueous solution to obtain a water-soluble DPC-PANI nanoparticle probe. The obtained nanoprobe is a dual-wavelength (780 / 1064nm) ratiometric photoacoustic imaging and has good acid response ratio imaging characteristics, which can achieve precise imaging based on acid response in the tumor microenvironment.

[0030] (2) In the acid-responsive ratiometric photoacoustic detection nanoprobe that can be applied to photoacoustic imaging provided by the present invention, the photoacoustic intensity at two wavelengths of 780 / 1064nm is measured, and the ratio thereof is used as a characterization parameter to determine the pH value of the tumor tissue. Compared with traditional acid-responsive photoacoustic detection probes, it has higher accuracy and sensitivity and has good clinical application prospects. Compared with traditional single-wavelength imaging, the dual-wavelength ratio imaging nanoprobe provided by the present invention can reduce the changes in photoacoustic signal intensity caused by interference from other factors, thereby obtaining imaging results with higher specificity. Using dual-wavelength ratiometric photoacoustic imaging in combination with specific acid-responsive probes to visualize tumors from the tumor microenvironment level helps to understand the evolution and changes of tumors and achieve accurate visualization of tumor boundaries. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the acid response of the polyaniline nanoprobe prepared in an embodiment of the present invention;

[0032] Figure 2 The absorption spectrum of the polyaniline nanoprobe prepared in Example 1;

[0033] Figure 3 This is the absorption spectrum of the polyaniline nanoprobe prepared in Example 2;

[0034] Figure 4 This is the absorption spectrum of the polyaniline nanoprobe prepared in Example 3;

[0035] Figure 5 This is a scanning electron microscope image of the polyaniline nanoprobe prepared in Example 1;

[0036] Figure 6 This is the particle size distribution diagram of the polyaniline nanoprobe prepared in Example 1;

[0037] Figure 7 The spectra of the polyaniline nanoprobe prepared in Example 1 at different pH values;

[0038] Figure 8 Photoacoustic spectra of the polyaniline nanoprobe prepared in Example 1 at different pH values;

[0039] Fig. 9 This is a white light photograph of the chicken breast prepared in the experiment;

[0040] Fig.10 Photoacoustic imaging images of the polyaniline nanoprobe prepared in Example 1 at different depths;

[0041] Fig.11 White light photos of polyaniline nanoprobes mixed with different solutions at different pH values;

[0042] Fig.12 is the absorption value of polyaniline nanoprobe after mixing with different solutions at different pH;

[0043] Fig.13 Photoacoustic images of polyaniline nanoprobes mixed with different solutions at different pH values;

[0044] Fig.14 is the photoacoustic signal value after the polyaniline nanoprobe was mixed with different solutions at different pH;

[0045] Fig.15 Photoacoustic images of polyaniline nanoprobes at different pH values;

[0046] Fig.16 PA780 / PA1064 signal ratio diagram of polyaniline nanoprobe at different pH values;

[0047] Fig.17 The survival rate of Hep G2 cells under the action of different concentrations of polyaniline nanoprobes;

[0048] Fig.18 The survival rate of HCCLM3 cells under the action of different concentrations of polyaniline nanoprobes;

[0049] Fig.19 The survival rate of LO2 cells under the action of different concentrations of polyaniline nanoprobes. DETAILED DESCRIPTION

[0050] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0051] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0052] Example 1

[0053] A method for preparing a polyaniline nanoprobe comprises the following steps:

[0054] At room temperature, 190 μL (194 mg) of aniline, 190 μL of hydrochloric acid and 5 mL of deionized water were mixed and placed in an ultrasonic cleaning instrument for 40 min to fully dissolve the aniline solution. Then, 50 mg of DSPE-PEG-COOH (phospholipid-polyethylene glycol-carboxyl, molecular weight 2000) powder was weighed and added to 0.666 mL of 100 mg / mL FeCl3 solution, and placed in an ultrasonic cleaning instrument for 40 min to fully dissolve and mix the mixture to obtain a mixed solution.

[0055] The two solutions were mixed and placed in an ice bath (0-4°C) and stirred for 8 hours to allow them to be fully mixed and self-assembled into nanoparticles until the color changed from bright yellow to dark blue. The resulting solution was placed in a dialysis bag with a molecular weight of MW1000-8000 and dialyzed at room temperature for 6 hours to remove impurities, thereby obtaining a photoacoustic ratio nanoprobe with the component of DPC-PANI.

[0056] Example 2

[0057] A method for preparing a polyaniline nanoprobe comprises the following steps:

[0058] At room temperature, 47.5 μL of aniline, 47.5 μL of hydrochloric acid and 5 mL of deionized water were mixed and placed in an ultrasonic cleaning instrument for 40 min to fully dissolve the aniline solution. Then, 50 mg of DSPE-PEG-COOH (phospholipid-polyethylene glycol-carboxyl, molecular weight 2000) powder was weighed and added to 0.666 mL of 100 mg / mL FeCl3 solution, and placed in an ultrasonic cleaning instrument for 40 min to fully dissolve and mix the mixture to obtain a mixed solution.

[0059] The two solutions were mixed and placed in an ice bath (0-4°C) and stirred for 8 hours to allow them to be fully mixed and self-assembled into nanoparticles until the color changed from bright yellow to dark blue. The resulting solution was placed in a dialysis bag with a molecular weight of MW1000-8000 and dialyzed at room temperature for 6 hours to remove impurities, thereby obtaining a photoacoustic ratio nanoprobe with the component of DPC-PANI.

[0060] Example 3

[0061] A method for preparing a polyaniline nanoprobe comprises the following steps:

[0062] At room temperature, 190 μL of aniline, 190 μL of hydrochloric acid and 5 mL of deionized water were mixed and placed in an ultrasonic cleaning instrument for 40 min to fully dissolve the aniline solution. Then 50 mg of DSPE-PEG-COOH (phospholipid-polyethylene glycol-carboxyl, molecular weight 2000) powder was weighed and added to 0.333 mL of 100 mg / mL FeCl3 solution, and placed in an ultrasonic cleaning instrument for 40 min to fully dissolve and mix the mixture to obtain a mixed solution.

[0063] The two solutions were mixed and placed in an ice bath (0-4°C) and stirred for 8 hours to allow them to be fully mixed and self-assembled into nanoparticles until the color changed from bright yellow to dark blue. The resulting solution was placed in a dialysis bag with a molecular weight of MW1000-8000 and dialyzed at room temperature for 6 hours to remove impurities, thereby obtaining a photoacoustic ratio nanoprobe with the component of DPC-PANI.

[0064] The present invention wraps the prepared polyaniline in the PEG core by self-assembly of the amphiphilic reagent DSPE-PEG-COOH in aqueous solution to obtain a water-soluble DPC-PANI nanoparticle probe. The obtained nanoprobe is a dual-wavelength (780 / 1064nm) ratio photoacoustic imaging, and has good acid response ratio imaging characteristics, which can achieve accurate imaging based on acid response in the tumor microenvironment. Figure 1 Schematic diagram of the acid response of polyaniline nanoprobe.

[0065] Product effect testing

[0066] By adjusting the ratio of DSPE-PEG-COOH to FeCl3, DPC-PANI probes with different acid response sensitivities can be obtained. Table 1 is a table of raw material ratios in the synthesis of polyaniline nanoprobes in Examples 1-3.

[0067] Table 1

[0068]

[0069]

[0070] Three polyaniline nanoprobes with different component ratios were obtained in Examples 1 to 3. After the polyaniline nanoprobes provided in each Example were incubated with buffer solutions of different pH values ​​at equal concentrations, their absorption spectra were measured. Figure 2 , Figure 3 , Figure 4 The absorption spectra of the polyaniline nanoprobes prepared in Examples 1-3 are shown in Figures 1-3. Figure 2-Figure 4 It can be seen that the polyaniline nanoprobe prepared in Example 1 has the best sensitivity, followed by Example 3.

[0071] The polyaniline nanoprobe prepared in Example 1 was morphologically characterized. Figure 5 This is an electron scanning micrograph of the polyaniline nanoprobe prepared in Example 1. The result shows that the polyaniline nanoparticles are uniform particles with good dispersion. Figure 6 is the particle size distribution of polyaniline nanoprobes. The results show that the average particle size of the polyaniline nanoprobes is 80-100nm.

[0072] The absorption spectra of the polyaniline nanoprobe prepared in Example 1 and prepared with different pH buffers were detected. The samples were ultrasonically vibrated for 5 minutes to make them dispersed evenly. Deionized water was added to the cuvette as the test baseline. After calibrating the baseline, each sample was added to the cuvette one by one and placed in the sample cell of the spectrophotometer for test recording. Figure 7 The spectra of the polyaniline nanoprobe prepared in Example 1 in buffer solutions with different pH values. Figure 7 The results showed that the polyaniline nanoprobe had good pH response ability. In buffer solutions with different pH values, the probe absorption spectrum showed regular changes. As the pH value gradually decreased, the absorption peak at 780nm gradually increased, and the absorption value gradually increased. At the same time, the absorption curve at 1064nm remained basically unchanged. Figure 8 This is the photoacoustic spectrum of the polyaniline nanoprobe prepared in Example 1 in buffer solutions with different pH values. Figure 8 The results showed significant differences in photoacoustic signals at a wavelength of 780nm and basically consistent photoacoustic signal intensities at a wavelength of 1064nm.

[0073] The polyaniline nanoprobe was subjected to in vivo photoacoustic imaging at different depths. The in vitro in vivo imaging test can reflect the in vivo photoacoustic imaging potential of the polyaniline nanoprobe. The specific research method is as follows: fresh chicken breast meat was used to make a phantom, cut into 2.5cm×2.5cm×4cm cubes, and the chicken breast meat was bluntly separated at different depths (0.5cm, 0.75cm, 1.25cm, 1.5cm). A transparent plastic tube encapsulated with the same concentration of probes was horizontally inserted into the chicken breast meat ( Fig. 9 The white light photo of the chicken breast prepared in the experiment). The imaging experiment was carried out using the PACT photoacoustic system. The prepared phantom was placed on the stage, coupling glue was applied to the surface of the phantom, and bubbles were removed with a syringe. The laser wavelength was adjusted to 780nm, and imaging and quantitative analysis were performed on two groups of probe samples with different pH values. Fig.10 The photoacoustic imaging images of the polyaniline nanoprobe prepared in Example 1 at different depths are shown, wherein: Fig.10 A in the middle is the photoacoustic image of polyaniline nanoprobe in the phantom after incubation at different pH values ​​under 780nm laser; Fig.10 B is the quantitative result of photoacoustic intensity of A. Fig.10 It can be seen that in the chicken breast biomimetic, both pH 7.4 and pH 6.5 probes can detect probe photoacoustic signals at four different depths under 780nm excitation, and the deepest can reach 1.5cm; in addition, in the pH 6.5 buffer, the 780nm absorption of the probe is significantly enhanced due to the protonation of the probe, and the photoacoustic signal intensity at different depths is significantly enhanced compared with pH 7.4.

[0074] Further evaluation of the polyaniline nanoprobe on H + In order to investigate the specific response of the polyaniline nanoprobes, the polyaniline nanoprobes in different pH buffers were mixed with KCl, NaCl, MgSO4, Glucose and PBS for 10 min, and the color changes of the solutions were observed. The absorption values ​​and photoacoustic signal intensities of each group were tested. Fig.11 White light photos of polyaniline nanoprobes mixed with different solutions at different pH values. Fig.12 is the absorption value of polyaniline nanoprobe mixed with different solutions at different pH. Fig.11 , 12 It can be seen that the color of the solution between the groups remained basically unchanged after the polyaniline nanoprobes in different pH buffers were mixed with KCl, NaCl, MgSO4, Glucose and PBS, and no obvious special changes were observed. The absorption values ​​of each group of solutions were measured separately, and it can be seen that the absorption value of 780nm between the same pH buffers remained unchanged, and the absorption value of 780nm increased as the pH value of the buffer decreased. The above-mentioned groups of solutions were further subjected to photoacoustic imaging tests to collect photoacoustic signal values, and similar results were obtained. Fig.13 , Fig.14The photoacoustic images and photoacoustic signal values ​​of polyaniline nanoprobes after mixing with different solutions at different pH values ​​are shown in Figure 2. The results show that in the three groups of buffer solutions at pH 7.4, pH 7.0 and pH 6.5, the photoacoustic intensity of the polyaniline nanoprobe is not affected by each electrolyte solution and remains unchanged. The above absorption values ​​and photoacoustic imaging prove that the polyaniline nanoprobe has the ability to target H + Sensitive and specific response, without interference from the above substances.

[0075] To further evaluate the feasibility of photoacoustic ratio imaging of polyaniline nanoprobes, according to the absorption spectrum characteristics of polyaniline nanoprobes, the photoacoustic signals of the probes in buffer solutions with different pH values ​​at wavelengths of 780nm and 1064nm were collected, and their ratio images and ratio values ​​were reconstructed and calculated. The specific method is as follows: the probe solution was evenly mixed with buffer solutions with pH values ​​of 3-8, and the samples were added into hollow sample tubes one by one, and the sample tubes were placed in water. The height of the photoacoustic imaging probe was adjusted, and the photoacoustic values ​​at 780nm and 1064nm were collected, respectively, where the wavelength of 780nm was used as the acid response signal, and the wavelength of 1064nm was used as the isosignal point. After collecting the photoacoustic data, the images and signal values ​​of 780nm, 1064nm, and 780 / 1064nm were calculated. The response PA signal value at 780nm was divided by the PA signal value at 1064nm as the ratio, and the fitting equation of pH and photoacoustic ratio value was calculated. Among them, Fig.15 The photoacoustic images of polyaniline nanoprobes at different pH values ​​show that at 780nm, the photoacoustic signal gradually increases with the decrease of pH, while the photoacoustic signal at 1064nm remains basically unchanged. The reconstructed ratio image 780nm / 1064nm is also linearly proportional to the pH value. As the pH value decreases, PA780 / 1064 gradually increases. Fig.16 The PA780 / PA1064 signal ratio diagram of polyaniline nanoprobe at different pH values ​​shows that the pH value can be calculated by reconstructing the ratio of the photoacoustic images collected at two wavelengths (780 / 1064nm).

[0076] The biocompatibility of polyaniline nanoprobes was further evaluated, and the survival rates of HepG2, HCCLM3, and LO2 cells under the action of different concentrations of polyaniline nanoprobes were studied. After incubating polyaniline nanoprobes with different concentrations (50, 100, 200, 300, 300, 400, and 500 μg / mL) and three types of cells (HepG2, HCCLM3, and LO2) for 24 hours, CCK-8 experimental tests were performed. Fig.17 , Fig.18 , Fig.19They are the survival rates of HepG2, HCCLM3, and LO2 cells, respectively. The results show that the polyaniline nanoprobe has good biocompatibility and low toxicity to cells. When the concentration reaches 500 μg / mL, the survival rates of the cell lines are all higher than 90%.

[0077] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A polyaniline nanoprobe, characterized in that: It is composed of a core polyaniline and a phospholipid-polyethylene glycol-carboxyl group wrapped in an outer layer of the polyaniline; The method for preparing the polyaniline nanoprobe comprises the following steps: Dissolve aniline and concentrated hydrochloric acid in water to obtain aniline solution; Mixing and dissolving the phospholipid-polyethylene glycol-carboxyl group and the trivalent iron salt to obtain a mixed solution; The aniline solution is mixed with the mixed solution, and the mixture is stirred at 0-4° C. to self-assemble into nanoparticles, and then impurities are removed to obtain a polyaniline nanoprobe; The mass ratio of the concentrated hydrochloric acid to the aniline is (0.8-1.2): 1; The mass ratio of the aniline to the phospholipid-polyethylene glycol-carboxyl group is (3-4): 1; The trivalent iron salt is ferric chloride; the mass ratio of the ferric chloride to the phospholipid-polyethylene glycol-carboxyl group is (1.0-1.5):

1.

2. The polyaniline nanoprobe according to claim 1, characterized in that: The process of removing impurities is as follows: placing the reaction solution stirred and self-assembled into nanoparticles in a dialysis bag with a molecular weight of MW1000-8000, and dialyzing for 1-10 hours at room temperature.

3. Use of the polyaniline nanoprobe according to claim 1 in preparing a tumor detection kit.

4. A tumor detection kit, characterized in that: It comprises the polyaniline nanoprobe as claimed in claim 1.

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