Electrochemiluminescence reagent based on molybdenum disulfide quantum dots, preparation method and application

Abstract

This invention discloses an electrochemiluminescence agent enhanced by molybdenum disulfide quantum dots, its preparation method, and its application, belonging to the field of electrochemiluminescence analysis technology. Addressing the problems of existing electrochemiluminescence detection of dopamine, such as the need for electrode modification, cumbersome operation, and high toxicity of co-reactants, this invention proposes using a mixture of molybdenum disulfide quantum dots and ruthenium terpyridine as the electrochemiluminescence agent. This agent requires no electrode modification and can be directly added to the test solution for rapid dopamine detection. The mechanism lies in the homogeneous catalysis of the oxidation reaction of ruthenium terpyridine by molybdenum disulfide quantum dots in aqueous solution, while its surface amino groups act as co-reactants. Through the dual synergistic effect of catalytic oxidation and co-reaction, the electrochemiluminescence signal is significantly enhanced. This invention successfully establishes an electrochemiluminescence method for determining dopamine, with a detection range of 10 nM to 50 μM and a detection limit of 5.48 nM; this system provides a promising detection platform for dopamine in urine.

Description

Technical Field

[0001] This invention relates to the field of electrochemiluminescence technology, and in particular to electrochemiluminescent agents enhanced by molybdenum disulfide quantum dots, their preparation methods, and applications. Background Technology

[0002] Dopamine (DA) is an important catechol neurotransmitter in the brain, involved in the regulation of various activities in the central nervous system. DA dysregulation can lead to Parkinson's disease, schizophrenia, depression, and other conditions. Therefore, accurate DA analysis is crucial for disease diagnosis and pathological research. To date, various analytical methods, including electrochemical, chemiluminescence, and chromatography, have been employed to selectively detect DA in complex samples. However, these techniques suffer from drawbacks such as complex synthesis protocols and high costs, making the development of a selective, sensitive, reliable, and economical sensor a challenge.

[0003] Electrochemiluminescence (ECL) is a powerful clinical diagnostic analytical technique that has attracted increasing attention due to its low background interference, high sensitivity, wide detection range, and good controllability. Among various luminescent agents, ruthenium terpyridine (Ru(bpy)3) is particularly promising. 2+ Due to its superior performance in aqueous solutions, it has become the only commercially viable option. Based on Ru(bpy)3 2+ The ECL system has been explored with a variety of reactants, including oxalic acid (H2C4O4), potassium persulfate (K2S2O8), and tripropylamine (TPrA), among which TPrA has become the most popular commercial choice due to its high efficiency. Unfortunately, despite the great success of TPrA, it is still subject to some limitations, including high toxicity, volatility, and corrosiveness. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, this invention proposes an electrochemiluminescent agent enhanced by molybdenum disulfide quantum dots, its preparation method, and the mechanism and application of dual synergistic enhancement of electrochemiluminescence, providing a promising detection platform for the detection of dopamine in urine.

[0005] This invention proposes an electrochemiluminescent agent based on molybdenum disulfide quantum dots, wherein the electrochemiluminescent agent is a mixture of molybdenum disulfide quantum dots and ruthenium terpyridine, which does not require electrode modification and satisfies the requirement for rapid detection of dopamine; Molybdenum disulfide quantum dots synergistically enhance the electrochemiluminescence of ruthenium terpyridine through a dual mechanism of catalytic oxidation and co-reaction; wherein the catalytic oxidation of ruthenium terpyridine by the molybdenum disulfide quantum dots is a homogeneous catalytic oxidation in a mixed solution (such as an aqueous solution).

[0006] The present invention proposes a method for preparing an electrochemiluminescent agent based on molybdenum disulfide quantum dots, the method steps are as follows: molybdenum disulfide quantum dots and ruthenium terpyridine are dispersed in a solvent to obtain an electrochemiluminescent agent.

[0007] Preferably, the preparation method of the molybdenum disulfide quantum dots is as follows: a molybdenum source and L-cysteine ​​are mixed and reacted hydrothermally to obtain molybdenum disulfide quantum dots.

[0008] Preferably, the molybdenum source is one or more of sodium molybdate, ammonium molybdate, and ammonium tetrathiomolybdate.

[0009] Preferably, the molar ratio of molybdenum source to L-cysteine ​​is 1:3-5.

[0010] Preferably, the hydrothermal reaction conditions are: temperature 180-220℃, time 12-48h.

[0011] Preferably, the mass ratio of molybdenum disulfide quantum dots to ruthenium terpyridine is 1:2-3.

[0012] Preferably, the solvent is water.

[0013] This invention proposes the application of an electrochemiluminescent agent enhanced by molybdenum disulfide quantum dots in the detection of dopamine, wherein the electrochemiluminescent agent is as described above.

[0014] The present invention proposes an electrochemiluminescence sensor comprising the above-mentioned electrochemiluminescent agent, wherein the electrochemiluminescence sensor can be used for the detection of dopamine.

[0015] Beneficial technical effects of the present invention: (1) The electrochemiluminescent agent of the present invention is a homogeneous mixture, which does not require any electrode modification steps, is simple to operate, has good reproducibility, and is suitable for rapid on-site detection.

[0016] (2) The molybdenum disulfide quantum dots of the present invention enhance the electrochemiluminescence signal through catalytic oxidation of ruthenium terpyridine and synergistic co-reaction mechanism, resulting in high sensitivity and a detection limit for dopamine at the nanomolar level.

[0017] (3) The method for preparing molybdenum disulfide quantum dots provided by the present invention uses L-cysteine ​​as a sulfur source and reducing agent, and performs hydrothermal synthesis in one step. The product has good water solubility and high quantum yield.

[0018] (4) The electrochemiluminescent agent of the present invention can be directly used for rapid detection of dopamine in complex biological samples such as urine. It has a short response time, good selectivity, and broad clinical application prospects. Attached Figure Description

[0019] Figure 1The following are characterization diagrams of MoS2QDs proposed in this invention: (a) is the TEM spectrum of MoS2QDs (with a particle size distribution inside), (b) is the HRTEM spectrum of MoS2QDs, (c) is the optical image and blue fluorescence image of the aqueous solution of MoS2QDs, (d) is the fine XPS spectrum of Mo 3d of MoS2QDs, and (e) is the fine XPS spectrum of S2p of MoS2QDs. Figure 2 The following are the fluorescence spectra of MoS2QDs under different excitation wavelengths proposed in this invention; Figure 3 The infrared spectrum of the MoS2QDs aqueous solution proposed in this invention; Figure 4 The Ru(bpy)3 proposed in this invention 2+ / ECL performance diagram of MoS2QDs system; where (a) is the performance diagram of MoS2QDs and Ru(bpy)3. 2+ Ru(bpy)3 2+ ECL intensity-voltage plot of +MoS2QDs (inner plot shows Ru(bpy)3) 2+ (enlarged ECL intensity-voltage diagram), (b) is Ru(bpy)3 2+ ECL stability plot of the +MoS2QDs system; Figure 5 The Ru(bpy)3 proposed in this invention 2+ / TPrA and Ru(bpy)3 2+ Comparison of ECL efficiency of the / MoS2QDs system; Figure 6 This invention proposes Ru(bpy)3 at different scan rates 2+ Electrochemical and luminescent response diagrams of the / MoS2QDs system; where (a) is the CV curve, (b) is the ECL curve, and (c) is the oxidation current versus ν. 1 / 2 The relationship between ECL intensity and ν, (d) is the relationship between ECL intensity and ν. 1 / 2 The relationship between them; Figure 7 The Ru(bpy)3 proposed in this invention 2+ / Schematic diagram of the MoS2QDs system mechanism; where (a) represents MoS2QDs and Ru(bpy)3 2+ Ru(bpy)3 2+ UV plots of +MoS2QDs, (b) shows the UV plots of MoS2QDs and Ru(bpy)3 at an excitation wavelength of 365 nm. 2+ Ru(bpy)3 2+ FL plots of +MoS2QDs, (c) shows the bare electrode on MoS2QDs and Ru(bpy)3. 2+Ru(bpy)3 2+ CV cycling curves in MoS2QDs solution, (d) shows the bare electrode in PBS, MoS2QDs, and Ru(bpy)3 solutions. 2+ Ru(bpy)3 2+ DPV plot in +MoS2QDs solution, (e) shows the potentiostatic measurement of the bare electrode in Ru(bpy)3. 2+ The voltage versus ECL intensity relationship in the +MoS2QDs solution system, (f) shows the bare electrode in Ru(bpy)3 2+ ECL strength of the +MoS2QDs solution system at different pH values; Figure 8 The MoS2QDs and precursor L-cys proposed in this invention are for Ru(bpy)3 2+ Enhanced performance comparison chart; Figure 9 To enhance Ru(bpy)3 using MoS2QDs proposed in this invention 2+ ECL mechanism diagram; Figure 10 The diagram shows the quenching of dopamine and its fitting plot proposed in this invention; where (a) is the electroluminescence intensity of dopamine at different concentrations, and (b) is the linear relationship between the ECL quenching ratio and the common logarithm of dopamine concentration. Figure 11 The sensor proposed in this invention is selective for dopamine. Detailed Implementation

[0020] The present invention will be further explained below with reference to specific embodiments.

[0021] In the embodiments of this invention, sodium molybdate dihydrate (Na2MoO4•2H2O), L-cysteine ​​(L-cys), and ruthenium tripyridine chloride hexahydrate (Ru(bpy)3Cl2•6H2O) were purchased from Sinopharm Chemical Reagent Co., Ltd., and were all analytical grade, requiring no further purification before use. PBS buffer solution was purchased from Pinggen Technology Co., Ltd., and ultrapure water (18.2 MΩ·cm) was used throughout the experiment. Dialysis bags (1000D) were purchased from Shanghai Bioengineering Co., Ltd. Transmission electron microscopy and high-resolution electron microscopy were performed on a FEITEI Tecnai F20 from FEI Corporation, USA. Fourier transform infrared (FTIR) spectra and XPS spectra were obtained on a Thermo Fisher Scientific Fourier transform infrared spectrometer and an X-ray photoelectric self-energy spectrometer, respectively. Fluorescence spectra and ultraviolet-visible (UV-vis) spectra were recorded on a Hitachi F-4600 spectrometer and a Shimadzu UV-3600i Plus spectrometer, respectively. Electrochemiluminescence measurements were performed using an MPI-E type electrochemiluminescence analyzer (Xi'an Mindray Analytical Instrument Co., Ltd.), with the photomultiplier tube voltage set to 600V during detection.

[0022] Example 1 Dissolve 0.13 g of sodium molybdate in 40 mL of ultrapure water, add 0.26 g of L-cys, stir well, adjust the pH to 6.5 with 0.1 M hydrochloric acid, and perform a hydrothermal reaction at 200 °C for 36 hours. After natural cooling, centrifuge to collect the supernatant. Dialyze the supernatant in a dialysis bag for 6 hours, and freeze-dry to obtain molybdenum disulfide quantum dots.

[0023] Weigh 60 μg of terpyridine ruthenium chloride hexahydrate and 24 μg of molybdenum disulfide quantum dot solution, and sonicate them in PBS buffer to form a luminescent agent.

[0024] The MoS2QDs synthesized in this embodiment were structurally characterized, from Figure 1 As shown in part (a), MoS₂QDs are uniformly dispersed. The inset is a histogram of the particle size distribution of MoS₂QDs, which shows that the particle size distribution is between 2-3 nm, with an average particle size of 2.4 nm, basically satisfying a normal distribution. Figure 1 Part (b) clearly shows the lattice fringes of MoS2QDs, revealing the interplanar spacing of MoS2QDs, which is calculated to be 0.23 nm, corresponding to the (103) crystal plane of MoS2QDs. Figure 1 As shown in section (c), the MoS₂QDs solution is a pale yellow liquid (left image). Under 365 nm UV light irradiation, MoS₂QDs exhibit bright blue fluorescence (right image). Figure 2 As shown, MoS2QDs exhibit excitation dependence, with a maximum emission peak at 419 nm. Figure 3The Fourier transform infrared spectrum of MoS2QDs is shown at 466.96 cm⁻¹. -1 There is a weak peak at 1634.34 cm⁻¹, which is caused by Mo-S vibration. -1 The absorption peak appearing at 3268.87 cm⁻¹ is the NH bending vibration peak of -NH₂. -1 The peak at that point is caused by the -OH vibration. For example... Figure 1 As shown in section (d), the Mo 3d spectrum is deconvoluted into five singlets: 226.35 eV, 228.31 eV, and 232.03 eV correspond to S 2s, Mo 3d5 / 2, and Mo 3d3 / 2, respectively; 225.68 eV and 227.73 eV correspond to S 2O 3, respectively. 2- and S2 2- or polysulfides S n 2- .like Figure 1 As shown in section (e), the peaks at 163.5 eV and 164.7 eV for S 2p are attributed to the Mo-S bond, while the peaks at 168.1 eV and 169.4 eV are likely due to SO. x These characterization results demonstrate the successful synthesis of MoS2QDs.

[0025] Furthermore, the ECL properties of the MoS2QDs synthesized in this embodiment were analyzed to evaluate their potential as co-reactants and electrocatalysts. Notably, the MoS2QDs did not exhibit an ECL signal, indicating that they are not an ECL release source. Instead, they showed a similar signal to Ru(bpy)3 alone. 2+ In comparison, Ru(bpy)3 2+ The ECL intensity of the / MoS2QDs system is significantly enhanced (approximately 50-fold). The ECL signal indicates that Ru(bpy)3 2+ The / MoS2QDs system exhibits a strong ECL signal at 1.05V, with a peak voltage of 1.15V, which is similar to Ru(bpy)3. 2+ The ECL behavior is consistent with that of Ru(bpy)3, indicating that the anodic ECL signal in this system originates from Ru(bpy)3. 2+ And enhanced by MoS2QDs ( Figure 4 (Part (a)). Furthermore, the system retained over 95% of its initial signal strength (2700 a.u. → 2579 a.u.) after 20 cycles, with an RSD of 8.76%, indicating good stability. Figure 4 (b) of the text. (The text then abruptly shifts to a discussion of Ru(bpy)3, mentioning its part.) 2+ Compared to the / TPrA system, Ru(bpy)3 2+ The ECL efficiency of the / MoS2QDs system is 89.4% ( Figure 5 This indicates that in enhancing Ru(bpy)32+ In terms of ECL, it exhibits performance comparable to TPRA. Further analysis shows ( Figure 6 ), in Ru(bpy)3 2+ In the / MoS2QDs system, the ECL intensity and peak current are related to the square root of the scan rate (v). 1 / 2 A linear relationship exists between them, indicating that this is a diffusion-controlled process. These suggest that MoS2QDs can act as enhancers for Ru(bpy)3. 2+ ECL nanomaterials, Ru(bpy)3 2+ The / MoS2QDs system shows promising application prospects in ECL detection.

[0026] Further research on MoS2QDs enhancing Ru(bpy)3 2+ The ECL mechanism was studied, focusing on electron interactions and the ECL process. The ultraviolet-visible (UV) spectrum of the combined system was also investigated. Figure 7 Part (a) is the sum of the individual spectra of each component, indicating minimal ground-state interactions. However, the fluorescence spectrum ( Figure 7 Part (b) shows Ru(bpy)3 2+ The presence of quenching reactions in the / MoS2QDs system implies an interaction between the excited states of the two molecules, promoting the transformation of MoS2QDs into Ru(bpy)3. 2+ Energy transfer, thereby promoting Ru(bpy)3 2+ Oxidation and subsequent ECL emission.

[0027] Further investigation of the ECL process was conducted. Cyclic voltammetry (CV) analysis showed that... Figure 7 (c) part), Ru(bpy)3 2+ An oxidation peak was observed at 1.1 V in the / MoS2QDs system, corresponding to Ru(bpy)3. 2+ Oxidation in solution is consistent, differential pulse voltammetry (PDV) (Figure) Figure 7 The (d) part confirms the existence of this oxidation peak, while the shoulder peak at 0.1V ( Figure 7 The inner inset of part (d) is due to the oxidation of MoS2QDs. Interestingly, with the addition of MoS2QDs, Ru(bpy)3 2+ The oxidation peak current at 1.1V increased significantly (approximately 4 times), and Ru(bpy)3 2+ The initial oxidation potential decreased from 0.95 V to 0.75 V. This indicates that MoS2QDs affect Ru(bpy)3. 2+ The oxidation of [a substance] exhibits electrocatalytic activity. The ECL emission of this system at different potentials was tested using a potentiostatic method. Figure 7(e) indicates that electrochemiluminescence occurs in Ru(bpy)3 2+ Following oxidation by MoS2QDs, to gain a deeper understanding, we evaluated the effect of pH on Ru(bpy)3. 2+ The effect of the / MoS2QDs system on Ru(bpy)3 as pH increases from 6.0 to 10.0. 2+ The ECL strength of the / MoS2QDs system gradually increases. Figure 7 (f) This indicates that amino deprotonation on the MoS2QDs surface plays a crucial role in the ECL process, leading to the observed ECL enhancement. Furthermore, amino-containing L-cys affect Ru(bpy)3 2+ The ECL has an enhancing effect, but the catalytic oxidation provided by MoS2QDs and the amino groups on its surface have a greater effect on Ru(bpy)3. 2+ The ECL enhancement is more significant ( Figure 8 Based on the results of the differential pulse voltammetry ( Figure 7 (d) part), Ru(bpy)3 2+ The possible luminescence mechanism of the / MoS2QDs system is as follows ( Figure 9 First, MoS₂QDs are electrochemically oxidized to MoS₂QDs(Ox), and MoS₂QDs(Ox) catalyzes Ru(bpy)₃. 2+ Electrochemical oxidation to produce Ru(bpy)3 3+ On the other hand, MoS2QDs(-NH2) are electrochemically oxidized to MoS2QDs(-NH2). +• Then MoS2QDs(-NH2) +• The deprotonation reaction occurs to generate MoS2QDs(-NH2) • ) free radicals. Then, MoS2QDs(-NH2) • Free radicals and Ru(bpy)3 3+ The reaction produces Ru(bpy)3. 2+* Finally, the excited state Ru(bpy)3 2+* Return to ground state and emit ECL.

[0028] Because Ru(bpy)3 2+ The ECL signal of the / MoS2QDs system is stable and strong, making it highly likely to be applied in ECL sensing systems. Because the DA in Ru(bpy)3... 2+ The quenching effect in the ECL process, therefore, constructing Ru(bpy)3 2+ / MoS2QDs DA model ECL detection system. For example... Figure 10As shown in section (a), the ECL decreased slightly after the addition of 10 nM DA compared to the blank state. With increasing DA concentration, the ECL intensity gradually decreased, exhibiting a strong quenching effect; the ECL signal was almost completely quenched when the concentration in the system reached 50 μM. The ECL quenching ratio (Y = (I0 - I) / I0; where I0 and I are the ECL intensities with and without dopamine, respectively) showed a linear relationship with the common logarithm of dopamine concentration (lgC / M), with a linear regression equation of Y = 1.927 + 0.236x. The linear range was 10 nM to 50 μM, and the detection limit was 5.48 nM (δ = 3). 2+ The / MoS2QDs system exhibits a lower detection limit and a wider detection range for DA compared to previously reported ECL sensors with complex modifications (Table 1).

[0029] Table 1. Determination of DA using different methods To investigate the selectivity of the ECL sensor in DA detection, several small molecules, including glucose, ascorbic acid (AA), lactic acid, and uric acid (UA), were selected as interfering substances. Figure 11 It can be seen that the interfering substance causes slight changes in ECL, while 10 μM DA can induce significant quenching of ECL, which may be attributed to the excited state of Ru(bpy)3. 2+* Energy transfer between DA and its oxidation products. To evaluate the application of the ECL biosensor in practical applications, DA in urine was detected in Ru(bpy)3. 2+ Urine and different concentrations of DA were added to the / MoS2QDs system. Table 2 shows that the recovery rate of this method ranged from 95.90% to 101.13%. The results indicate that the ECL system can be used to detect DA in real urine samples.

[0030] Table 2. Determination of Real Samples by Spiked Recovery Method Example 2 The hydrothermal reaction at 200℃ for 36 hours was changed to a reaction at 180℃ for 36 hours, while other preparation conditions remained the same as in Example 1, yielding quantum dots with morphology and properties similar to those in Example 1. The luminescent agent was prepared in the same manner as in Example 1. The detection range for dopamine was 10 nM-10 μM, the detection limit was 6.69 nM (δ=3), and the recovery rate was in the range of 94.70-103.13%.

[0031] Example 3 The hydrothermal reaction at 200℃ for 36 hours was changed to a reaction at 200℃ for 24 hours, while other preparation conditions remained the same as in Example 1, yielding quantum dots with morphology and properties similar to those in Example 1. The luminescent agent was prepared in the same manner as in Example 1. The detection range for dopamine was 10 nM-30 μM, the detection limit was 6.23 nM (δ=3), and the recovery rate was in the range of 94.70-98.13%.

[0032] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application. The scope of this application is defined by the appended claims and their equivalents, all of which should be included within the protection scope of this application.

Claims

1. An electrochemiluminescent agent enhanced by molybdenum disulfide quantum dots, characterized in that, The electrochemiluminescent agent is a mixture of molybdenum disulfide quantum dots and ruthenium terpyridine; Molybdenum disulfide quantum dots synergistically enhance the electrochemiluminescence of ruthenium terpyridine through both catalytic oxidation and co-reaction mechanisms. The catalytic oxidation of ruthenium terpyridine by molybdenum disulfide quantum dots is a homogeneous catalytic oxidation in a mixed solution.

2. A method for preparing an electrochemiluminescent agent enhanced by molybdenum disulfide quantum dots, characterized in that, The method steps are as follows: molybdenum disulfide quantum dots and ruthenium terpyridine are dispersed in a solvent to prepare an electrochemiluminescent agent.

3. The preparation method of the electrochemiluminescent agent based on molybdenum disulfide quantum dots according to claim 2, characterized in that, The preparation method of the molybdenum disulfide quantum dots is as follows: a molybdenum source and L-cysteine ​​are mixed and reacted hydrothermally to obtain molybdenum disulfide quantum dots.

4. The preparation method of the electrochemiluminescent agent based on molybdenum disulfide quantum dots according to claim 3, characterized in that, The molybdenum source is one or more of sodium molybdate, ammonium molybdate, and ammonium tetrathiomolybdate.

5. The preparation method of the electrochemiluminescent agent based on molybdenum disulfide quantum dots according to claim 3, characterized in that, The molar ratio of molybdenum source to L-cysteine ​​is 1:3-5.

6. The method for preparing the electrochemiluminescent agent based on molybdenum disulfide quantum dots according to claim 3, characterized in that, The conditions for the hydrothermal reaction are: temperature 180-220℃, time 12-48h.

7. The method for preparing the electrochemiluminescent agent based on molybdenum disulfide quantum dots according to claim 2, characterized in that, The mass ratio of molybdenum disulfide quantum dots to ruthenium terpyridine is 1:2-3.

8. The method for preparing the electrochemiluminescent agent based on molybdenum disulfide quantum dots according to claim 2, characterized in that, The solvent is water.

9. The application of an electrochemiluminescent agent enhanced by molybdenum disulfide quantum dots in the detection of dopamine, characterized in that, The electrochemiluminescent agent is as described in claim 1.

10. An electrochemiluminescence sensor, characterized in that, Containing the electrochemiluminescent agent of claim 1, the electrochemiluminescent sensor can be used for the rapid detection of dopamine.

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