A pll / mwcnts-nh2 electrode-based electrode material, a preparation method and application thereof

Abstract

The application relates to the technical field of biological detection, in particular to an electrode based on a PLL / MWCNTs-NH2 electrode modification material and a preparation method and application thereof. A glass carbon electrode (GCE) is taken as a substrate, and polylysine (PLL) and amino-modified multi-walled carbon nanotubes (MWCNTs-NH2) are sequentially modified. By optimizing detection conditions such as pH, scanning speed and PBS concentration, the sensor has a good linear response to 8-OHdG in the range of 0.0044 muM to 14.12 muM, and the detection limit is as low as 0.2 nM. The sensor has strong anti-interference ability, can effectively eliminate the influence of interference substances such as uric acid, and has good stability and repeatability. In actual urine sample detection, the detection result is similar to that of an ELISA method, and the sensor has wide application prospects.

Description

Technical Field

[0001] This invention relates to the field of biodetection technology, specifically to an electrode based on PLL / MWCNTs-NH2 electrode modification material, its preparation method, and its application. Background Technology

[0002] 8-Hydroxy-2'-deoxyguanosine (8-OHdG) is an important biomarker of DNA oxidative damage, and its levels in organisms are closely related to the occurrence and development of various diseases, such as cancer and neurodegenerative diseases. Accurate detection of 8-OHdG levels in biological samples is of great significance for early disease diagnosis, disease monitoring, and evaluation of treatment effectiveness.

[0003] Currently, methods for detecting 8-OHdG mainly include high-performance liquid chromatography (HPLC) and mass spectrometry. However, these methods suffer from drawbacks such as expensive equipment, complex operation, and long detection cycles, limiting their application in clinical and field testing. Electrochemical sensors, on the other hand, offer advantages such as low cost, high sensitivity, fast response, and ease of operation, demonstrating significant application potential in the field of biomolecular detection. However, existing electrochemical sensors still suffer from insufficient sensitivity and poor anti-interference capabilities when detecting 8-OHdG, requiring further improvement. Summary of the Invention

[0004] In view of the above situation and to overcome the defects of the prior art, the present invention provides an electrode based on PLL / MWCNTs-NH2 electrode modification material, its preparation method and application, which makes up for the shortcomings of the existing detection methods and achieves high sensitivity, high selectivity and rapid detection of 8-OHdG.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an electrode based on PLL / MWCNTs-NH2 electrode modification material, with a glassy carbon electrode as the substrate, and the surface of the glassy carbon electrode sequentially modified with polylysine and aminated multi-walled carbon nanotubes.

[0006] A method for preparing an electrode,

[0007] (1) Preparation of PLL (polylysine) deposition solution:

[0008] Lysine was dissolved in phosphate buffer (PBS), and after thorough dissolution and mixing, the PLL deposition solution was obtained.

[0009] (2) Preparation of MWCNTs-NH2 suspension:

[0010] Dissolve MWCNTs-NH2 in deionized water and stir for 12 hours. After stirring, place the mixture in an ultrasonic instrument and sonicate for 30 minutes.

[0011] (3) Electrode modification:

[0012] Pre-treat the bare glassy carbon electrode;

[0013] Take out the PLL deposition solution from (1), scan for 8 cycles under -1.5V-2.5V conditions, and obtain a PLL deposition layer on the surface of the glassy carbon electrode (GCE); take the MWCNTs-NH2 suspension from (2) and drop it onto the PLL deposition layer modified electrode, and let it dry naturally to obtain a PLL / MWCNTs-NH2 electrode.

[0014] Furthermore, the PBS in (1) is 0.1M, pH 9.0.

[0015] Furthermore, the concentration of lysine was 10 mM.

[0016] Furthermore,

[0017] The concentration of MWCNTs-NH2 in (2) is 1 mg / mL.

[0018] Furthermore,

[0019] The pretreatment of the bare glassy carbon electrode in (3) is as follows: the bare glassy carbon electrode is polished with 0.3μm and 0.05μm alumina slurry respectively, and then ultrasonically washed in nitric acid (1:1), ethanol and deionized water for 3 min respectively.

[0020] Furthermore,

[0021] The volume ratio of PLL sediment to MWCNTs-NH2 suspension is 500:1.

[0022] An electrode is used as a sensor for detecting 8-OHdG, wherein the electrode is prepared by the method described above.

[0023] Application of a sensor in environmental monitoring for the detection of 8-hydroxy-2'-deoxyguanosine.

[0024] Furthermore, the sensor's detection conditions were as follows: a three-electrode system was used, with the working electrode, reference electrode, and counter electrode being a glassy carbon electrode modified with experimental materials, a silver chloride electrode soaked in saturated potassium chloride, and a platinum electrode, respectively; the electrolyte solution was 0.1M PBS containing 8-OHdG at pH 7.0; the cyclic voltammetry (CV) testing conditions were a scan voltage of 0.1V-0.65V and a scan rate of 100mV / s; the differential pulse voltammetry (DPV) testing conditions were a scan voltage of 0.1V-0.65V, an amplitude of 50mV, a pulse width of 50ms, and a scan rate of 50mV / s.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] The polylysine (PLL) of this invention exhibits excellent biocompatibility and film-forming properties, providing stable support for the loading of aminated multi-walled carbon nanotubes (MWCNTs-NH2). MWCNTs-NH2, with its large specific surface area and excellent conductivity, forms a PLL / MWCNTs-NH2 composite material that significantly improves the electron transfer efficiency and sensitivity of the sensor. Furthermore, the structure of PLL matches the spatial conformation of 8-OHdG, enhancing recognition specificity; MWCNTs-NH2, on the other hand, strengthens the conductivity of the electrodes. The two components bind through electrostatic interactions, resulting in a composite with the strongest electroactivity towards 8-OHdG. The composite material's large specific surface area, multiple active sites, and synergistic effects among its components contribute to the sensor's superior performance. Attached Figure Description

[0027] Figure 1 The CV curves of the bare GCE electrode, MWCNTs-NH2, PLL, and PLL / MWCNTs-NH2 modified electrode of this invention in 0.1M PBS (pH 7.0) containing 7.06 μM 8-OHdG are shown.

[0028] Figure 2 A is the CV diagram of the PLL / MWCNTs-NH2 modified electrode of the present invention at different pH values;

[0029] Figure 2 B is the peak current calibration curve of the oxidation peak potential of the PLL / MWCNTs-NH2 modified electrode of the present invention at different pH values;

[0030] Figure 3 A is the CV diagram of the PLL / MWCNTs-NH2 modified electrode of the present invention at different scan rates;

[0031] Figure 3 B is the calibration curve of the oxidation peak current of the PLL / MWCNTs-NH2 modified electrode of the present invention at different scan rates;

[0032] Figure 4 The oxidation peak current variation of the PLL / MWCNTs-NH2 modified electrode of this invention in PBS with different concentrations;

[0033] Figure 5 The oxidation peak current variation of the PLL under different deposition conditions in this invention;

[0034] Figure 6 The oxidation peak current variation of the PLL / MWCNTs-NH2 modified electrode under different MWCNTs-NH2 drop coating amounts according to the present invention;

[0035] Figure 7The oxidation peak current variation of the PLL / MWCNTs-NH2 modified electrode of this invention under different incubation times;

[0036] Figure 8 The DPV diagrams and calibration curves of the PLL / MWCNTs-NH2 modified electrode of this invention in PBS solutions of different concentrations of 8-OHdG are shown.

[0037] Figure 9 This invention relates to the change in the current signal of 8-OHdG in the presence of interfering substances;

[0038] Figure 10 A is the CV diagram of UA and 8-OHdG in this invention.

[0039] Figure 10 B is the CV diagram of UA, 8-OHdG and uricase in this invention;

[0040] Figure 11 These are the results of the anti-interference test of this invention;

[0041] Figure 12 This is the result of the stability test of the present invention. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0043] Example 1:

[0044] An electrode based on PLL / MWCNTs-NH2 electrode modification material, with a glassy carbon electrode as the substrate, wherein polylysine and aminated multi-walled carbon nanotubes are sequentially modified on the surface of the glassy carbon electrode.

[0045] A method for preparing an electrode,

[0046] (1) Synthesis of PLL: Prepare 0.1M PBS (pH 9.0), and dissolve 0.01462g of lysine in the PBS to make the concentration of lysine 10mM. After thorough dissolution and mixing, the PLL precipitation solution is obtained and stored in a refrigerator at 4℃ for later use.

[0047] (2) Preparation of MWCNTs-NH2 suspension: Take 8 mg of MWCNTs-NH2, dissolve it in 8 mL of deionized water, add magnetic beads to the mixed solution, place it on a magnetic stirrer and stir for 12 h. After stirring, place it in an ultrasonic instrument and sonicate for 30 min. After ultrasonic treatment, place it in a 4℃ refrigerator for later use.

[0048] (3) Construction of electrochemical sensor interface

[0049] Before electrode modification, bare GCEs were polished with 0.3 μm and 0.05 μm alumina pastes, respectively. Then, the electrodes were ultrasonically washed for 3 min each in nitric acid (1:1), ethanol, and deionized water. The pre-prepared PLL deposition solution was then taken out and scanned 8 times under -1.5V to 2.5V conditions to obtain PLL on the electrode surface. Subsequently, MWCNTs-NH2 nanomaterials were thoroughly mixed using a vortex mixer, and 10 μL of the MWCNTs-NH2 nanomaterial suspension was drop-coated onto the PLL-modified electrode. After natural drying, a PLL / MWCNTs-NH2 electrode was obtained, with a PLL deposition solution to MWCNTs-NH2 suspension volume ratio of 500:1. Subsequently, PLL and MWCNTs-NH2 were modified on the electrode surface using the same method as control experiments.

[0050] Example 2:

[0051] An electrode is used as a sensor for the detection of 8-OHdG, wherein the electrode is prepared by the method of Example 1.

[0052] The detection principle is as follows: When the PLL / MWCNTs-NH2 modified electrode is placed in an electrolyte containing 8-OHdG, the PLL structure matches the spatial conformation of 8-OHdG, allowing 8-OHdG to specifically adsorb onto the electrode surface. Simultaneously, the excellent conductivity of MWCNTs-NH2 provides a good channel for electron transfer. Upon applying a certain potential, 8-OHdG undergoes an oxidation reaction on the electrode surface, with specific groups in its molecular structure (such as hydroxyl groups) losing electrons, generating an oxidation current. This oxidation current is detected by differential pulse voltammetry (DPV). Within a certain concentration range, the oxidation peak current shows a linear relationship with the concentration of 8-OHdG. Therefore, based on the detected oxidation peak current value, the concentration of 8-OHdG can be quantitatively analyzed using a pre-established linear equation.

[0053] Application of a sensor in environmental monitoring for the detection of 8-hydroxy-2'-deoxyguanosine.

[0054] Differential pulse voltammetry (DPV) was used for detection. The modified sensor was placed in 0.1M PBS (pH 7.0) containing 8-OHdG, and scanning was performed under optimized detection conditions to record the oxidation peak current. The oxidation peak current showed a good linear relationship with the concentration of 8-OHdG in the ranges of 0.0044μM-0.0706μM, 0.0706μM-3.53μM, and 3.53μM-14.12μM, allowing for quantitative analysis of the 8-OHdG concentration based on the linear equation.

[0055] 1. Characterization of the PLL / MWCNTs-NH2 electrochemical sensor interface

[0056] (1) Electrochemical testing system

[0057] Characterization was performed using an electrochemical workstation, employing a traditional three-electrode system consisting of a working electrode, a reference electrode, and a counter electrode, corresponding to the glassy carbon electrode modified with the experimental materials, the silver chloride electrode soaked in saturated potassium chloride, and the platinum electrode, respectively. The electrolyte solution was 0.1M PBS (pH 7.0) containing 7.06 μM 8-OHdG. CV testing conditions: scan voltage: 0.1V–0.65V; scan rate: 100 mV / s. DPV testing conditions: scan voltage: 0.1V–0.65V; amplitude: 50 mV; pulse width: 50 ms; scan rate: 50 mV / s.

[0058] (2) Characterization of the electrochemical sensor interface

[0059] Bare GCE electrodes and electrodes modified with different materials PLL, MWCNTs-NH2, and PLL / MWCNTs-NH2 were placed in an electrolyte containing 7.06 μM 8-OHdG in 0.1 M PBS (pH 7.0) for CV scanning to compare the electrochemical responses of different materials to 8-OHdG. Figure 1 As shown, the results indicate that the bare GCE electrode (curve a) exhibits a weak irreversible oxidation peak in the presence of 8-OHdG, while the MWCNTs-NH2 (curve b) and PLL (curve c) modified electrodes both show obvious oxidation peaks. The PLL / MWCNTs-NH2 (curve d) modified electrode exhibits the highest oxidation peak current.

[0060] 2. Optimization of detection conditions for electrochemical sensors

[0061] (1) Testing the effect of different pH values ​​on the detection of 8-OHdG

[0062] PBS solutions with pH values ​​of 6.0, 6.5, 7.0, 7.5, 8.0, and 9.0 were prepared. 8-OHdG was added to each pH solution, and the final concentration of 8-OHdG was quantified to be 7.06 μM. The PLL / MWCNTs-NH2 modified electrode was then subjected to CV scanning in the PBS solutions to obtain different CV curves, which were then analyzed. The experimental results... Figure 2 As can be seen from A, the oxidation peak current of 8-OHdG is in the pH range of 6.0-9.0, and the oxidation peak current reaches its highest at pH 7.0. Therefore, pH 7.0 is selected as the optimal pH value. Figure 2B is the calibration curve of pH value versus 8-OHdG oxidation peak potential (Epa), showing that as the pH value increases, the oxidation peak potential of 8-OHdG decreases continuously, and the two are linearly correlated (R). 2 =0.999), indicating that the proton participated in the oxidation process of 8-OHdG.

[0063] (2) Testing the effect of different scan rates on the detection of 8-OHdG

[0064] The PLL / MWCNTs-NH2 modified electrode was placed in 0.1M PBS (pH 7.0) containing 7.06 μM 8-OHdG for electrochemical testing. Scan rates of 5 mV / s, 30 mV / s, 50 mV / s, 80 mV / s, 100 mV / s, 120 mV / s, 150 mV / s, 200 mV / s, 250 mV / s, 300 mV / s, and 350 mV / s were varied to obtain and analyze different CV curves. Figure 3 As can be seen from A, the oxidation peak current of 8-OHdG gradually increases with the increase of scan rate between 5-350 mV / s. However, considering that the background current should not be too large, the subsequent experiments were finally carried out under the condition of 100 mV / s. Figure 3 B is the calibration curve of scan rate versus 8-OHdG oxidation peak current. The results show that as the scan rate increases, the 8-OHdG oxidation peak current increases, and the two show a linear correlation (R0). 2 =0.992), indicating that the oxidation of 8-OHdG on GCE / PLL / MWCNTs-NH2 is an adsorption-controlled electrode process.

[0065] (3) Testing the effect of different PBS concentrations on the detection of 8-OHdG

[0066] PBS solutions of 0.025M, 0.05M, 0.1M, 0.15M, and 0.2M were prepared, and specific volumes of 8-OHdG were added to each PBS solution to ensure that each PBS contained 7.06 μM of 8-OHdG. A PLL / MWCNTs-NH2 modified electrode was then subjected to CV scanning in the PBS solutions to obtain different CV curves, and the optimal PBS concentration was analyzed. Figure 4 It can be seen that within the range of 0.025M-0.1M, the oxidation current of 8-OHdG gradually increases with the increase of PBS concentration. Between 0.1M-0.2M, the oxidation current of 8-OHdG gradually decreases with the increase of PBS concentration. The oxidation peak current reaches the highest value and has the best peak shape at 0.1M PBS. Therefore, 0.1M PBS is selected as the optimal electrolyte concentration.

[0067] (4) Testing the effect of different PLL deposition conditions on the detection of 8-OHdG

[0068] A lysine solution with pH 9.0 was prepared. The deposition potential was varied, with scans performed at -1.0V to 2.2V for 7 cycles, -1.5V to 2.5V for 8 cycles, -1.0V to 2.2V for 8 cycles, and -1.5V to 2.5V for 8 cycles. The resulting electrode was then subjected to CV testing in 0.1M PBS (pH 7.0) containing 7.06 μM 8-OHdG. Different CV curves were obtained to screen for the optimal PLL deposition conditions. Figure 5 It can be seen that the oxidation peak current is the highest when scanning 8 times from -1.5V to 2.5V, which is the optimal deposition condition.

[0069] (5) Effect of test drop volume on 8-OHdG detection

[0070] 2 μL, 4 μL, 6 μL, 8 μL, 10 μL, 12 μL, 14 μL, and 16 μL of MWCNTs-NH2 nanomaterials were drop-coated onto a PLL-modified electrode, respectively. CV scanning was performed in 0.1 M PBS (pH 7.0) containing 7.06 μM 8-OHdG to analyze the optimal drop-coating volume. Figure 6 It can be seen that the oxidation peak current gradually increases with the increase of the nanomaterial coating amount. The increase of oxidation peak current reaches its maximum when the coating amount is 8μL-10μL, and the increase decreases with further increase of coating amount. Since the peak current increase is the largest and the peak shape is the best when the coating amount is 10μL, the coating amount of 10μL was finally selected.

[0071] (6) Testing the effect of different pre-concentration conditions on the detection of 8-OHdG

[0072] Electrochemical tests were performed on the PLL / MWCNTs-NH2 electrode in 0.1M PBS (pH 7.0) containing 7.06 μM 8-OHdG. The incubation time of the modified electrode in the electrolyte solution was varied to 4 min, 6 min, 8 min, 10 min, 12 min, 14 min, and 16 min, and different CV curves were obtained and analyzed to select the optimal incubation time. Figure 7 It can be seen that within the range of 4 min to 16 min, the oxidation current of 8-OHdG increases continuously with the increase of incubation time. The oxidation peak current increases the most in the range of 8 min to 10 min, while the increase of oxidation current of 8-OHdG decreases in the range of 10 min to 16 min. Therefore, 10 min is selected as the optimal incubation time.

[0073] 3. Performance Analysis of Electrochemical Sensors

[0074] (1) Linear range and LOD of the electrochemical sensor for 8-OHdG

[0075] PBS solutions containing 0.0044 μM, 0.0176 μM, 0.0235 μM, 0.0353 μM, 0.0706 μM, 0.176 μM, 0.353 μM, 0.706 μM, 1.02 μM, 1.76 μM, 2.65 μM, 3.53 μM, 5.3 μM, 7.06 μM, 10.6 μM, and 14.12 μM 8-OHdG were prepared. DPV scans were performed on the PLL / MWCNTs-NH2 electrode in these electrolytes, and different DPV curves were obtained and analyzed. Figure 8 As shown in A, the oxidation peak current increases with increasing 8-OHdG concentration, and the 8-OHdG oxidation peak current value shows a good linear relationship with the 8-OHdG concentration in the ranges of 0.0044μM-0.0706μM, 0.0706μM-3.53μM, and 3.53μM-14.12μM (e.g., ...). Figure 8 (As shown in B, 8C, and 8D), their linear equations are: Ipa(μA)=37.35+74.03C(μM), R 2 =0.999; Ipa(μA)=42.13+18.31C(μM), R 2 =0.993; Ipa(μA)=92.18+3.61C(μM), R 2 =0.994, and the limit of detection (LOD) is 0.2 nM.

[0076] (2) Anti-interference experiment of electrochemical sensor

[0077] The test investigated the effects of potential interfering substances in urine samples on the detection of 8-OHdG under the same conditions, including UA, AA, A, and Na. + Zn 2+ K + The concentrations were set as follows: 8-OHdG concentration was 7.06 μM, UA concentration was 20 μM, AA and A were both 100 μM, and Na... + Zn 2+ K + All were 400 μM. The PLL / MWCNTs-NH2 modified electrode was subjected to CV scanning in the above electrolyte to obtain different CV curves, which were then compared and analyzed. Figure 9 It can be seen that the current signal of 8-OHdG does not change significantly in the presence of interference.

[0078] exist Figure 10In section A, curve (a) represents the CV curve of 7.06 μM 8-OHdG, which shows the electrochemical characteristics of 8-OHdG alone under the current test conditions. Curve (b) represents the CV curve of 7.06 μM 8-OHdG + 20 μM UA. This curve shows that when 7.06 μM 8-OHdG and 20 μM UA are present together, UA exhibits a significant oxidation peak current.

[0079] Given that UA exhibits a significant oxidation peak current when coexisting with 8-OHdG, further investigation was conducted. A PBS solution containing 400 μM UA and 7.06 μM 8-OHdG was prepared for electrochemical testing. Subsequently, different concentrations of uricase were added to this solution, and the reaction was repeated after 30 min. Figure 10 In section B, curve (a) represents the CV curve of 7.06 μM 8-OHdG + 400 μM UA, showing the electrochemical state of the system without the addition of uricase. Curve (b) represents the CV curve of 7.06 μM 8-OHdG + 400 μM UA + 10 μg / mL uricase; after adding 10 μg / mL uricase, the electrochemical signal of the system began to change. Curve (c) represents the CV curve of 7.06 μM 8-OHdG + 400 μM UA + 15 μg / mL uricase; the changes become more apparent with increasing uricase concentration. Curve (d) represents the CV curve of 7.06 μM 8-OHdG + 400 μM UA + 20 μg / mL uricase. From... Figure 10 A series of curve comparisons show that as the concentration of uricase increases from 10-20 μg / mL, the interference of UA gradually decreases. When the concentration of uricase reaches 20 μg / mL, the oxidation peak of UA almost disappears. This fully demonstrates that adding uricase can effectively eliminate the interference of UA in urine.

[0080] (3) Repeatability experiments of electrochemical sensors

[0081] Five groups of PLL / MWCNTs-NH2 modified electrodes were prepared according to the above method. These electrodes were then placed in 0.1M PBS (pH 7.0) containing 7.06 μM 8-OHdG for electrochemical testing. Each electrode was tested in triplicate, and CV curves were obtained and RSD was calculated. Figure 11 The experimental results show that the RSD is calculated to be 2.81%, indicating that the sensor has good repeatability.

[0082] (4) Stability test of electrochemical sensor

[0083] The PLL / MWCNTs-NH2 electrode was stored at 4°C for one week. Electrochemical tests were then performed on the modified electrode in 0.1M PBS (pH 7.0) containing 7.06 μM 8-OHdG. CV curves were obtained, and RSD was calculated. Figure 12 Experimental results show that the oxidation peak current remains above 90% of the original response, indicating that the sensor has good stability.

[0084] 4. Actual Sample Analysis

[0085] The collected urine samples were placed in a 4°C refrigerator for 12 hours to allow impurities to fully precipitate. Then, the supernatant was collected and centrifuged at 12,000 rpm for 15 minutes to further remove impurities. The supernatant was then collected. Next, the urine was diluted five-fold with 0.1M PBS (pH 7.0), and uricase was added at a quantitative concentration of 20 μg / mL. The reaction was allowed to proceed for 30 minutes to eliminate uric acid interference. A DPV scan was performed on the treated urine using a PLL / MWCNTs-NH2 electrode. The content of 8-OHdG in the urine was measured using the standard addition method, and the results were compared with those of ELISA detection to calculate the recovery rate. The experimental results are shown in Table 1. The standard recovery rate of 8-OHdG in the urine samples ranged from 91.72% to 102.97%. 8-OHdG was detected in the urine samples of breast cancer patients, but not in the samples of healthy individuals. Each sample was tested in triplicate, and the RSD was less than 10%. Simultaneously, ELISA kits were used to detect 8-OHdG in the same urine samples. The data obtained from the two methods were compared, as shown in Table 2. The results showed that the detection results were similar. A t-test was used to analyze the difference between the two detection methods. P = 0.907, P > 0.05, indicating that there was no statistically significant difference between the two detection methods.

[0086] Table 1. Results of 8-OHdG detection in urine based on PLL / MWCNTs-NH2 sensor.

[0087]

[0088] Table 2 shows the results of detecting 8-OHdG in urine using two methods: a PLL / MWCNTs-NH2 sensor and an ELISA kit.

[0089]

[0090]

[0091] In summary, this invention successfully constructed an 8-OHdG electrochemical sensor based on a PLL / MWCNTs-NH2 modified electrode by optimizing the preparation process and detection conditions. This sensor possesses advantages such as high sensitivity, wide linear range, strong anti-interference capability, good stability, and repeatability. In actual urine sample detection, it exhibits detection results similar to those of traditional ELISA methods, demonstrating promising application prospects and the potential to play an important role in fields such as biomedical detection and environmental monitoring.

[0092] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for detecting 8-hydroxy-2'-deoxyguanosine, characterized in that: Using a PLL / MWCNTs-NH2 electrode as the working electrode, the preparation method of the PLL / MWCNTs-NH2 electrode is as follows: (1) Preparation of polylysine (PLL) deposition solution: Polylysine (PLL) was dissolved in PBS and thoroughly mixed to obtain a polylysine (PLL) deposition solution. (2) Preparation of MWCNTs-NH2 suspension: Dissolve MWCNTs-NH2 in deionized water and stir for 12 h. After stirring, place the mixture in an ultrasonic instrument and sonicate for 30 min. (3) Electrode modification: Pre-treat the bare glassy carbon electrode; Take out the polylysine (PLL) deposition solution from (1), scan for 8 cycles under -1.5 V - 2.5 V conditions, and obtain a polylysine (PLL) deposition layer on the surface of the glassy carbon electrode; take the MWCNTs-NH2 suspension from (2) and drop it onto the polylysine (PLL) deposition layer modified electrode, and let it dry naturally to obtain a PLL / MWCNTs-NH2 electrode; The PBS in (1) is 0.1 M, pH 9.0; The concentration of MWCNTs-NH2 in (2) is 1 mg / mL; The volume ratio of polylysine (PLL) precipitation solution to MWCNTs-NH2 suspension was 500:

1.

2. The detection method according to claim 1, characterized in that: The concentration of polylysine (PLL) was 10 mM.

3. The detection method according to claim 1, characterized in that: The pretreatment of the bare glassy carbon electrode in (3) is as follows: the bare glassy carbon electrode is polished with 0.3 µm and 0.05 µm alumina paste respectively, and then ultrasonically washed for 3 min in nitric acid aqueous solution, ethanol and deionized water with a volume ratio of 1:1 respectively.

4. The detection method according to claim 1, characterized in that: The detection method is used for environmental monitoring.

5. The detection method according to claim 1, characterized in that: The detection conditions were as follows: a three-electrode system was used, with the working electrode, reference electrode, and counter electrode being a PLL / MWCNTs-NH2 electrode, a silver chloride electrode soaked in saturated potassium chloride, and a platinum electrode, respectively; the electrolyte solution was 0.1 M PBS containing 8-OHdG at pH 7.0; the cyclic voltammetry (CV) test conditions were a scan voltage of 0.1 V - 0.65 V and a scan rate of 100 mV / s; the DPV test conditions were a scan voltage of 0.1 V - 0.65 V, an amplitude of 50 mV, a pulse width of 50 ms, and a scan rate of 50 mV / s.

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