Synthesis path calculation and preparation method of quantum dot molecularly imprinted material
By determining the synthesis pathway of quantum dot molecularly imprinted materials through molecular simulation calculations and selecting the optimal functional monomers and their reaction ratios, the time-consuming and labor-intensive problems of traditional methods are solved, and efficient and low-cost CML detection is achieved, which is applicable to food, biological and chemical detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-03-13
AI Technical Summary
Existing technologies for detecting carboxymethyl lysine (CML) suffer from problems such as high detection difficulty, high cost, and long time consumption, especially in the detection of foodborne CML where accuracy is limited. Furthermore, the preparation process of traditional fluorescent molecular imprinting materials consumes a lot of resources and manpower.
By using molecular simulation calculations and a semi-empirical method based on quantum mechanics, the synthetic route of carboxymethyl lysine quantum dot molecular imprinted materials was determined. The optimal functional monomer and its best reaction ratio with the template molecule were selected to prepare quantum dot molecular imprinted materials, simplifying the preparation process and improving detection performance.
It achieves efficient and low-cost CML detection, with uniform material particles, highly selective identification and adsorption of CML, strong detection stability, and is suitable for food, biological and chemical detection fields.
Smart Images
Figure CN121662239A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of molecular simulation calculation and molecular imprinted material preparation technology, specifically relating to a synthesis path calculation and preparation method for quantum dot molecular imprinted materials. Background Technology
[0002] Carboxymethyl lysine, English name N ɛ -carboxymethyllysine, or CML for short, is the most studied late-stage glycosylation terminator (AGEs) and is often used as a marker to measure the content of AGEs in organisms and foods. CML is very stable and is usually formed by the Maillard reaction between reducing sugars and proteins, lipids, or nucleic acids. CML in the human body is divided into endogenous and dietary sources. When foods rich in CML are ingested, about 10% of CML enters the bloodstream as small molecules. About two-thirds of this CML accumulates in different tissues and organs, affecting cell and tissue function and causing various diseases, including diabetes and kidney disease, thus harming human health.
[0003] CML itself lacks both cross-linking and fluorescence, making detection challenging. Current detection methods for CML primarily include instrumental analysis and immunochemical methods. Instrumental analysis can accurately detect CML residues, but sample pretreatment is complex, time-consuming, and costly, requiring specialized personnel and expensive large-scale equipment, hindering real-time detection. Enzyme-linked immunosorbent assay (ELISA) is the most commonly used immunoassay method for CML detection, offering advantages such as high sensitivity, good specificity, simple operation, and easy result observation. However, it is mainly used for detecting endogenous CML, limiting its application in detecting foodborne CML. This is because the accuracy of ELISA is significantly affected by the matrix; foodborne CML is typically in a bound state with a complex matrix, making the preparation of standard monoclonal antibodies very difficult, resulting in high detection costs and limited accuracy. Furthermore, antibody transportation and storage also increase the difficulty of application.
[0004] Quantum dot molecularly imprinted fluorescence sensing technology combines the excellent optical properties of quantum dots with the high selectivity of molecularly imprinted polymers. It has advantages such as simple preparation, good stability, good selectivity, high sensitivity, low cost, and short analysis time. It has broad development potential in food, environmental and biological analysis and is in line with the development trend of detection technology.
[0005] However, traditional methods, after preparing fluorescent molecularly imprinted materials, require characterization of the morphology using scanning electron microscopy and transmission electron microscopy, identification of interacting groups between compounds using Fourier transform infrared spectroscopy, and further evaluation of their overall detection performance by obtaining fluorescence spectra, specificity, time stability, pH stability, and optimal reaction time. This experimental process not only consumes a large amount of reagents and uses expensive equipment, but also requires significant time and manpower costs. Summary of the Invention
[0006] To address the aforementioned technical problems, this invention provides a method for calculating the synthesis path and preparing quantum dot molecularly imprinted materials.
[0007] The key to quantum dot molecular imprinted fluorescence sensing technology lies in determining the synthesis route of fluorescent molecular imprinted materials, including the optimal functional monomers and their best reaction ratio with template molecules, in order to improve detection performance.
[0008] The method of this invention utilizes a semi-empirical approach based on quantum mechanics to simulate template molecules and functional monomers through molecular simulation technology. It selects the optimal functional monomer and its best reaction ratio with carboxymethyl lysine, determines the synthesis pathway of carboxymethyl lysine quantum dot molecularly imprinted materials, and further prepares carboxymethyl lysine quantum dot molecularly imprinted materials. This solves the problems of traditional methods, which require repeated preparation of fluorescent molecularly imprinted materials and then use various complex characterization and detection methods to judge the performance of the prepared materials, resulting in huge time and labor costs.
[0009] To achieve the above objectives, the technical solution of the present invention is as follows.
[0010] The first aspect of this invention provides a method for calculating the synthesis pathway of quantum dot molecularly imprinted materials, comprising the following steps: Using carboxymethyl lysine as a template molecule, we identified several functional monomers that can form hydrogen bonds with the template molecule, as well as the lowest energy configuration of the template molecule.
[0011] Based on the lowest energy configurations of the functional monomer and the template molecule, the Mulliken charge and single-point energy of the template molecule and the functional monomer are calculated to determine the interaction sites where hydrogen bonds can form between the template molecule and the functional monomer. The complex of the template molecule and the functional monomer is then constructed, and the lowest energy conformation of the complex is determined.
[0012] Based on the lowest energy conformation of the complex, the single-point energy of the complex is calculated. Substituting the single-point energies of the template molecule, functional monomer, and complex into the binding energy calculation formula, the binding energy between the template molecule and the functional monomer is obtained. The functional monomer with the largest absolute value of binding energy is selected as the optimal functional monomer.
[0013] The lowest energy conformation of the complex of the template molecule and the optimal functional monomer at different molar ratios is determined, and the binding energy of the complex of the template molecule and the optimal functional monomer at different molar ratios is calculated. The molar ratio of the template molecule and the optimal functional monomer with the largest absolute value of binding energy is then selected as the optimal reaction ratio.
[0014] Preferably, the functional monomers are methacrylic acid, acrylamide, and 3-aminopropyltriethoxysilane.
[0015] The preferred formula for calculating the binding energy is as follows: Δ E = E complex -( E template + nE monomer ); Where, Δ E This represents the binding energy between the template molecule and the functional monomer; E complex Indicates the energy of the complex; E template This represents the energy of the template molecule; E monomer This represents the energy of a functional monomer. n This indicates the molar ratio of the functional monomer to the template molecule in the complex.
[0016] Preferably, the complex of the template molecule and the functional monomer is constructed at a molar ratio of 1:1 between the template molecule and the functional monomer.
[0017] Preferably, the most suitable functional monomer is 3-aminopropyltriethoxysilane.
[0018] The preferred method for selecting the molar ratio of the template molecule with the largest absolute value of binding energy to the optimal functional monomer is as follows: Construct complexes of template molecules and optimal functional monomers in different molar ratios.
[0019] Based on the Mulliken charge of the template molecule and the optimal functional monomer, as well as the complexes of the template molecule and the optimal functional monomer at different molar ratios, the range of molar ratios in which the template molecule and the optimal functional monomer can interact is determined.
[0020] The lowest energy conformation of the complex within the molar ratio range in which the template molecule and the optimal functional monomer can interact is determined. The single-point energy of the complex within the molar ratio range in which the template molecule and the optimal functional monomer can interact is calculated. Substitute these values into the binding energy calculation formula to calculate the binding energy within the molar ratio range in which the template molecule and the optimal functional monomer can interact. The molar ratio of the template molecule to the optimal functional monomer with the largest absolute value of binding energy is selected as the optimal reaction ratio of the template molecule and the optimal functional monomer.
[0021] Preferably, the molar ratio in which the template molecule and the optimal functional monomer can interact is in the range of 1:1 to 4; based on the molar ratio of CML to APTES, the optimal reaction ratio of the template molecule and the optimal functional monomer is 1:4.
[0022] A second aspect of this invention provides a method for preparing quantum dot molecularly imprinted materials, comprising the following steps: Using carboxymethyl lysine as a template molecule, the optimal functional monomer and the optimal reaction ratio between the template molecule and the optimal functional monomer were screened using the synthetic pathway calculation method for quantum dot molecularly imprinted materials described in the first aspect. Using CdSe / ZnS quantum dots as the fluorescent material core, a CdSe / ZnS quantum dot solution was formed by mixing solvent, surfactant, and co-surfactant with CdSe / ZnS quantum dots. The solution was then polymerized with a crosslinking agent, initiator, template molecule, and optimal functional monomer under stirring conditions to obtain a molecularly imprinted polymer precursor. The template molecule in the molecularly imprinted polymer precursor was removed using an extractant, and after drying, the quantum dot molecularly imprinted material was obtained.
[0023] Preferably, the solvent is cyclohexane; the surfactant is Triton X-100; the co-surfactant is n-hexanol; the crosslinking agent is tetraethoxysilane; the initiator is ammonia; and the extractant is a mixed solution of ethanol and acetic acid in a volume ratio of 8:2.
[0024] The beneficial effects of this invention are: 1. This invention uses molecular simulation calculations and a semi-empirical method based on quantum mechanics to determine the synthesis path of carboxymethyl lysine quantum dot molecularly imprinted materials, predicts the experimental phenomena in the preparation of the materials, provides a feasible experimental scheme, enhances the interaction force between functional monomers and template molecules CML, thereby optimizing the fluorescence detection performance of the materials, laying a theoretical foundation for the experiment, and significantly reducing the consumption of manpower and material resources in the experimental process compared with traditional methods.
[0025] The carboxymethyl lysine quantum dot molecularly imprinted material synthesized in this invention has uniform particle size, can efficiently and selectively recognize and adsorb CML, and has strong detection stability. It provides a reference technology for the fields of food, biology and chemical detection in my country and has important practical value. Attached Figure Description
[0026] Figure 1 This is a flowchart of the molecular simulation calculation for the synthesis pathway of the carboxymethyl lysine quantum dot molecularly imprinted material of the present invention.
[0027] Figure 2 This is the lowest energy configuration diagram of CML in this invention.
[0028] Figure 3 This is the lowest energy configuration diagram of MAA in this invention.
[0029] Figure 4 This is the lowest energy configuration diagram of AM in this invention.
[0030] Figure 5 This is the lowest energy configuration diagram of APTES in this invention.
[0031] Figure 6 This is the lowest energy conformation diagram of CML-MAA in this invention.
[0032] Figure 7 This is the lowest energy conformation diagram of CML-AM in this invention.
[0033] Figure 8 This is the lowest energy conformation diagram of CML-APTES in this invention.
[0034] Figure 9 This is a flowchart illustrating the preparation process of the carboxymethyl lysine quantum dot molecularly imprinted material in this invention.
[0035] Figure 10 This is a scanning electron microscope image of the carboxymethyl lysine quantum dot molecularly imprinted material in this invention.
[0036] Figure 11 The images shown are transmission electron microscope (TEM) images of the carboxymethyl lysine quantum dot molecularly imprinted material of this invention. (a) is a TEM image of the carboxymethyl lysine quantum dot molecularly imprinted material; (b) is a magnified view of a portion of (a).
[0037] Figure 12 This is the Fourier transform infrared spectrum of the carboxymethyl lysine quantum dot molecularly imprinted material in this invention.
[0038] Figure 13 The fluorescence spectra of the carboxymethyl lysine quantum dot molecularly imprinted material and CdSe / ZnS quantum dots in this invention are shown.
[0039] Figure 14 This is a fluorescence intensity diagram of the carboxymethyl lysine quantum dot molecularly imprinted material of this invention over 20 consecutive days.
[0040] Figure 15This is a fluorescence intensity diagram of the carboxymethyl lysine quantum dot molecularly imprinted material in this invention within the pH range of 2.0 to 12.0.
[0041] Figure 16 The diagram shows the dynamic adsorption characteristics of the carboxymethyl lysine quantum dot molecularly imprinted material and the quantum dot non-imprinted material prepared by the same method in this invention.
[0042] Figure 17 The fluorescence spectra of the carboxymethyl lysine quantum dot molecularly imprinted material of this invention in CML solutions of different concentrations are shown.
[0043] Figure 18 This is a linear graph showing the fluorescence intensity of the carboxymethyl lysine quantum dot molecularly imprinted material in this invention in response to CML solutions of different concentrations.
[0044] Figure 19 This is a histogram showing the relative quenching amounts of CML, carboxyethyl lysine (CEL), and lysine (Lys) to the carboxymethyl lysine quantum dot molecular imprinted material in this invention. Detailed Implementation
[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0046] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0047] Endogenous CML is produced by the glycation reaction of carbohydrates and proteins in the body, and is particularly prone to formation in cells and plasma tissues of people with hyperglycemia and renal failure. Food-derived CML refers to CML ingested from external sources, generally CML contained in food.
[0048] Carboxymethyl lysine, English name N ɛ -carboxymethyllysine, abbreviated as CML.
[0049] The full name of methacrylic acid is methacrylic acid, abbreviated as MAA.
[0050] Acrylamide is abbreviated as AM.
[0051] The full English name of 3-aminopropyltriethoxysilane is 3-(Triethoxysilyl)propan-1-amine, abbreviated as APTES, and it is also known as silane coupling agent KH-550.
[0052] The full English name of carboxyethyl lysine is N ε -(1-Carboxyethyl)-L-lysine, abbreviated as CEL.
[0053] The full English name for lysine is L-Lysine, abbreviated as Lys.
[0054] The technical solution of the present invention will be further described below through specific embodiments.
[0055] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.
[0056] Example 1 like Figure 1 A method for calculating the synthesis pathway of quantum dot molecularly imprinted materials, comprising the following steps: Step S1: Using carboxymethyl lysine as a template molecule, determine multiple functional monomers that can form hydrogen bonds with the template molecule and the lowest energy configuration of the template molecule.
[0057] This invention primarily uses carboxymethyl lysine as a template molecule, selecting multiple functional monomers capable of forming hydrogen bonds with the template molecule to establish initial 3D models of both the functional monomers and the template molecule. The selected functional monomers are methacrylic acid, acrylamide, and 3-aminopropyltriethoxysilane. The initial 3D models were established using Chem3D 19.0 software from CambridgeSoft.
[0058] Step S2: Based on the lowest energy configuration of the functional monomer and the template molecule, calculate the Mulliken charge and single-point energy of the template molecule and the functional monomer, determine the interaction sites where hydrogen bonds can form between the template molecule and the functional monomer, construct the complex of the template molecule and the functional monomer, and determine the lowest energy conformation of the complex.
[0059] Step S2.1: Calculate the single-point energies of the template molecule and the functional monomer based on the lowest energy configuration of the functional monomer and the template molecule.
[0060] This invention optimizes the lowest energy configuration of the template molecule and the functional monomer separately, and calculates the single-point energy. In this invention, the optimization of the lowest energy configuration and the calculation of the single-point energy are performed using Hyperchem 8.0 software from Hypercube Systems, Inc., employing the PM3 algorithm in Semi-Empirical and selecting the RHF self-consistent field model. Figures 2 to 5The lowest energy configuration diagrams of CML, MAA, AM, and APTES are shown respectively.
[0061] Step S2.2: Calculate the Mulliken charge of the template molecule and the functional monomer, analyze the possible interaction sites between the template molecule and the functional monomer, and construct the complex of the template molecule and the functional monomer accordingly.
[0062] Table 1. Mulliken charge distribution in CML Table 2. Mulliken charge distribution of MAA Table 3. Mulliken charge distribution of AM Table 4 Mulliken charge distribution of APTES Note: "-" indicates no data.
[0063] As can be seen from Tables 1 to 4, both CML and the functional monomer contain atoms with high electronegativity that are connected to H, suggesting that CML and the functional monomer are connected through hydrogen bonding.
[0064] Based on the Mulliken charges of each atom, hydrogen bond donors and acceptors in CML and functional monomers are inferred as possible interaction sites between the template molecule and the functional monomer. CML can provide four hydrogen bond acceptors: 1O, 11O, 12O, and 13O; and five hydrogen bond donors: 15H, 25H, 28H, 29H, and 30H.
[0065] MAA can provide two hydrogen bond acceptors, 5O and 6O, and one hydrogen bond donor, 12H.
[0066] AM can provide one hydrogen bond acceptor, 5O; and two hydrogen bond donors, 7H and 8H.
[0067] APTES can provide three hydrogen bond acceptors, namely 3O, 4O and 5O; and two hydrogen bond donors, namely 21H and 22H.
[0068] In summary, hydrogen bond interactions can be easily formed between CML and these hydrogen bond donors and acceptors in the functional monomers, and the complex structure of CML and functional monomers can be constructed accordingly.
[0069] Step S3: Calculate the single-point energy of the complex based on its lowest energy conformation.
[0070] The main purpose of this invention is to obtain the lowest energy conformation of the complex based on the constructed template molecule and functional monomer, and to calculate the single-point energy of the complex. In this invention, when optimizing the lowest energy conformation and calculating the single-point energy, Hyperchem 8.0 software from Hypercube Systems, Inc., is used, employing the PM3 algorithm in Semi-Empirical, and selecting the RHF self-consistent field model.
[0071] Specifically, when constructing the complex of the template molecule and the functional monomer, the molar ratio of the template molecule to the functional monomer is 1:1. That is, 1 mol of CML corresponds to 1 mol of functional monomer.
[0072] according to Figures 6 to 8 The lowest energy conformations of CML-MAA, CML-AM, and CML-APTES are shown respectively.
[0073] Step S4: Substitute the single-point energies of the template molecule, functional monomer, and complex into the binding energy calculation formula to obtain the binding energy between the template molecule and the functional monomer, and screen out the functional monomer with the largest absolute value of binding energy as the optimal functional monomer.
[0074] The embodiments of the present invention are mainly based on the binding energy Δ E The calculation formula is used to calculate the binding energy Δ between the template molecule and the functional monomer. E To select the most suitable functional monomer. Binding energy Δ E The formula for calculating Δ is: E = E complex -( E template + nE monomer ); where Δ E This represents the binding energy between the template molecule and the functional monomer; E complex Indicates the energy of the complex; E template This represents the energy of the template molecule; E monomer This represents the energy of a functional monomer. n This indicates the molar ratio of the functional monomer to the template molecule in the complex.
[0075] It should be noted that the binding energy Δ E The larger the absolute value, the stronger the interaction force between the template molecule and the functional monomer, the stronger the ability of the synthesized material to capture carboxymethyl lysine, and the better the fluorescence quenching performance.
[0076] Table 5 Single-point energies of CML with functional monomers and their complexes, in kcal / mol As can be seen from Table 5, the binding energy Δ of CML-APTES E The largest absolute value indicates the strongest interaction between CML and APTE, resulting in the most stable complex and the strongest adsorption of CML. Therefore, based on molecular simulation calculations, APTES was selected as the optimal functional monomer.
[0077] Step S5: Determine the lowest energy conformation of the complex of the template molecule and the optimal functional monomer at different molar ratios, calculate the binding energy of the complex of the template molecule and the optimal functional monomer at different molar ratios, and screen out the molar ratio of the template molecule and the optimal functional monomer with the largest absolute value of binding energy as the optimal reaction ratio.
[0078] Step S5.1: Based on the Mulliken charges of the template molecule and the optimal functional monomer, analyze the possible reaction ratios of the template molecule and the optimal functional monomer, optimize the lowest energy conformation of the complex with different reaction ratios, and calculate the single-point energy of the complex with different reaction ratios.
[0079] According to Tables 1 to 4, CML provides four hydrogen bond acceptors: 1O, 11O, 12O, and 13O; and five hydrogen bond donors: 15H, 25H, 28H, 29H, and 30H. APTES provides three hydrogen bond acceptors: 3O, 4O, and 5O; and two hydrogen bond donors: 21H and 22H. This shows that CML provides more hydrogen bond binding sites than APTES, and APTES has greater steric hindrance, making it difficult to fully utilize the hydrogen bond binding sites. Therefore, the reaction ratio is chosen to be a molar ratio of CML to APTES of 1:n; where n is a positive integer, taking values of 1, 2, 3, ...
[0080] Table 6. Charge distribution of CML in the complex under different reaction ratios Note: 1:1, 1:2, 1:3 and 1:4 are different molar ratios of CML to APTES.
[0081] As can be seen from Table 6, when n=1, the charge of 28H is 0.228 before the interaction between CML and APTES. After the interaction between CML and APTES, the charge of 28H in CML becomes 0.256, and the charge increases by 0.028. This indicates that charge transfer occurs between CML and APTES, that is, an interaction occurs between CML and APTES.
[0082] As shown in Table 6, when n=2, before the interaction between CML and APTES, the charge of 28H is 0.228 and the charge of 15H is 0.228; while after the interaction between CML and APTES, the charge of 28H in CML becomes 0.264, an increase of 0.036, and the charge of 15H becomes 0.248, an increase of 0.02. This indicates that compared with n=1, an additional interaction site is added between CML and APTES, and the interaction force between CML and APTES is enhanced.
[0083] As shown in Table 6, when n=3, before the interaction between CML and APTES, the charge of 28H is 0.228, the charge of 15H is 0.228, and the charge of 11O is -0.302. After the interaction between CML and APTES, the charge of 28H in CML becomes 0.275, an increase of 0.047; the charge of 15H becomes 0.248, an increase of 0.02; and the charge of 11O becomes -0.341, a decrease of 0.039. This indicates that compared to when n=2, further increasing the number of APTES adds another interaction site between CML and APTES, and the interaction force between CML and APTES continues to strengthen.
[0084] As shown in Table 6, when n=4, before the interaction between CML and APTES, the charge of 1O is -0.305, the charge of 12O is -0.395, and the charge of 15H is 0.228. After the interaction between CML and APTES, the charge of 1O in CML becomes -0.353, a decrease of 0.048; the charge of 12O becomes -0.436, a decrease of 0.041; and the charge of 15H becomes 0.260, a decrease of 0.032. This indicates that compared to when n=3, the interaction sites between CML and APTES have changed, but the amount of charge transfer has increased, indicating that the interaction force between CML and APTES continues to strengthen.
[0085] After multiple optimization calculations, it was found that when n=5, there was always one APTES molecule in the calculated complex that did not interact with CML. Therefore, n=1, 2, 3 and 4 were selected.
[0086] Step S5.2, based on the binding energy Δ E The calculation formula is used to calculate the binding energy Δ between the template molecule and the optimal functional monomer for different reaction ratios. E To determine the optimal reaction ratio between the template molecule and the most suitable functional monomer.
[0087] Table 7. Binding energy Δ of the complex under different reaction ratios E Unit: kcal / mol Note: The reaction ratio indicates the molar ratio of CML to APTES.
[0088] Table 7 shows that the binding energy of the complex is the largest when the reaction ratio is 1:4 (CML to APTES molar ratio). The quantum dot molecularly imprinted material synthesized under this reaction ratio has the strongest ability to capture CML. Therefore, the optimal reaction ratio is 1:4 (CML to APTES molar ratio), that is, 1 mol of CML corresponds to 4 mol of APTES.
[0089] Example 2 Based on the optimal functional monomer and the optimal reaction ratio between the template molecule and the optimal functional monomer determined by the above method, quantum dot molecular imprinted materials were prepared using CdSe / ZnS quantum dots as the fluorescent material core, CML as the template molecule, APTES as the functional monomer, tetraethoxysilane as the crosslinking agent, and ammonia as the initiator.
[0090] like Figure 9 A method for preparing quantum dot molecularly imprinted materials includes the following steps: Step 1: Add 7.5 mL of cyclohexane as solvent, 1.82 g of Triton X-100 as surfactant, and 0.4 mL of n-hexanol as co-surfactant to a flask. Stir at 800 rpm for 20 min at 25 °C. Add 75 μL of a 25 mg / mL CdSe / ZnS quantum dot solution (purchased from Suzhou Xingshuo Nanotechnology Co., Ltd.) to the flask. After 10 min, add 75 μL of tetraethoxysilane and 100 μL of 25 wt% ammonia solution while stirring. Stir again for 2.0 h. Then add 20 μL of APTES and 4.2 mg of CML, and stir at 800 rpm for 24 h to complete the polymerization reaction.
[0091] After the polymerization reaction was completed, 10 mL of acetone was added to the reaction solution, and the mixture was centrifuged at 2000 rpm for 20 min to remove the supernatant. The precipitate was washed with 10 mL of acetone, and centrifuged again at 2000 rpm for 20 min to remove the supernatant. The product was dried at 50 °C for 24 h to obtain the molecularly imprinted polymer precursor.
[0092] Step 2: Using a mixed solution of ethanol and acetic acid in a volume ratio of 8:2 as the extraction agent, the template molecule CML in the molecularly imprinted polymer precursor is extracted until no carboxymethyl lysine template molecule is found in the molecularly imprinted polymer. After drying, the quantum dot molecularly imprinted material is obtained, denoted as CdSe@SiO2@MIP.
[0093] MIP stands for Molecularly Imprinted Polymer.
[0094] Comparative Example 1 A method for preparing a quantum dot non-molecular imprinted material CdSe@SiO2@NIP is carried out according to the preparation method of quantum dot molecular imprinted material in Example 2, except that the template molecule CML is not added in step 1.
[0095] NIP stands for Non-Imprinted Polymer, which is a control polymer prepared without template molecules and used to compare the performance of molecularly imprinted polymers (MIP).
[0096] Test 1: Characterization of the quantum dot molecular imprinted material prepared in Example 2.
[0097] A small amount of CdSe@SiO2@MIP powder prepared in Example 2 was dispersed on a conductive adhesive, excess powder was blown off, gold was sputtered onto the surface, and the morphology of the sample was observed using a GeminiSEM 500 scanning electron microscope. Figure 10 As shown, the particle size of more than 50 CdSe@SiO2@MIP particles in these microspheres is approximately 130 nm, and the distribution is relatively uniform.
[0098] A small amount of CdSe@SiO2@MIP powder prepared in Example 2 was dissolved in an ethanol solution, ultrasonically dispersed, and 10 μL was dropped onto a copper grid. The sample was dried under UV light and observed using a JEM-2100Plus transmission electron microscope. Figure 11 As shown, all CdSe@SiO2@MIPs exhibit a uniform core-shell structure, with the CdSe / ZnS quantum dots located in the center of the silicon spheres, displaying monodisperse characteristics. This unique core-shell structure is formed during the hydrolysis of tetraethoxysilane, resulting in a negatively charged silicon intermediate. This intermediate interacts electrostatically with the negatively charged CdSe / ZnS quantum dots, ultimately creating a uniform silicon dioxide shell on the surface of the CdSe / ZnS quantum dots.
[0099] A small amount of dried CdSe@SiO2@MIP powder prepared in Example 2 was pressed into tablets using potassium bromide. The infrared spectrum was then measured using a Thermo Fisher Nicolet iS10 Fourier transform infrared spectroscopy system with a wavenumber resolution of 1 cm⁻¹. -1 Wavenumber range 4000cm -1 ~600cm -1 ,like Figure 12 As shown, at 1034cm -1 and 786cm -1The peaks on the left and right are antisymmetric stretching peaks of Si-O-Si, indicating that TEOS was successfully wrapped around the quantum dot to form a silicon dioxide cladding; at 1557 cm⁻¹ -1 The peaks on the left and right are the bending vibration peaks of NH, indicating that APTES was successfully connected to CdSe@SiO2@MIP; at 2933 cm⁻¹ -1 The peaks to the left and right are the stretching vibration peaks of CH. These results show that APTES and TEOS were successfully synthesized onto the surface of CdSe / ZnS quantum dots, generating quantum dot molecularly imprinted polymers.
[0100] Test 2: Fluorescence detection performance.
[0101] All fluorescence detections were performed under the same conditions: the slit width for excitation and emission was 5 nm, the excitation wavelength was set to 450 nm, the emission wavelength scanning range was set to 600 nm to 660 nm, and the emission scanning speed was 1 nm / 0.1 s.
[0102] like Figure 13 The image shows the fluorescence spectra of CdSe / ZnS quantum dots and CdSe@SiO2@MIP prepared in Example 2 under 450 nm excitation. Compared with CdSe / ZnS quantum dots, the fluorescence emission spectrum of CdSe@SiO2@MIP prepared in Example 2 under 450 nm excitation is red-shifted. The reason is that the outer layer of CdSe / ZnS quantum dots is coated with silicon dioxide, which affects the emission peak of CdSe / ZnS quantum dots.
[0103] The CdSe@SiO2@MIP prepared in Example 2 and the CdSe@SiO2@NIP prepared in Comparative Example 1 were dispersed in ultrapure water to obtain stock solutions with a concentration of 4 mg / mL, which were stored at room temperature and protected from light. The CML stock solution, with a concentration of 1000 mg / L, was dissolved in water and stored at -20°C until use.
[0104] During the test, the stock solutions of CdSe@SiO2@MIP and CdSe@SiO2@NIP and a known concentration of CML standard solution were added to a test tube, followed by the addition of ultrapure water to 4 mL. The solution was then ultrasonically dispersed and mixed, allowed to stand for a period of time, and a portion of the solution was transferred to a cuvette for fluorescence measurement.
[0105] The fluorescence intensity of the same CdSe@SiO2@MIP solution was measured within 20 days to examine its fluorescence stability. Figure 14 As shown, the fluorescence intensity of CdSe@SiO2@MIP remained relatively stable during 16 measurements over 20 days, indicating that the quantum dot molecularly imprinted polymer of Example 2 has good fluorescence stability.
[0106] The pH of the CdSe@SiO2@MIP solution was adjusted using hydrochloric acid and sodium hydroxide solution. The fluorescence intensity of the CdSe@SiO2@MIP solution was measured within the pH range of 2.0–12.0. Figure 15 As shown, the fluorescence intensity of CdSe@SiO2@MIP is relatively stable when the pH is in the range of 3.0 to 8.0. pH=7 was selected as the optimal pH condition.
[0107] CdSe@SiO2@MIP solution, CdSe@SiO2@NIP solution and CML standard solution of known concentration were mixed and ultrasonically dispersed. The concentrations of CdSe@SiO2@MIP and CdSe@SiO2@NIP were 1 mg / mL and the concentration of CML was 1 mg / L. After standing for a period of time, the fluorescence intensity was recorded at different time intervals.
[0108] like Figure 16 As shown, the fluorescence intensity of CdSe@SiO2@NIP and CdSe@SiO2@MIP decreases with increasing reaction time, reaching its lowest value at 2 hours. This indicates that MIP is completely adsorbed within 2 hours. Therefore, the optimal reaction time for CdSe@SiO2@MIP and CML is 2 hours.
[0109] like Figure 16 Fluorescence images of CdSe@SiO2@MIP and CdSe@SiO2@NIP show that CdSe@SiO2@NIP exhibits non-specific adsorption, and the decrease in fluorescence intensity of CdSe@SiO2@NIP is less than that of CdSe@SiO2@MIP.
[0110] CdSe@SiO2@MIP solutions were mixed with CML standard solutions of known concentrations, and then ultrasonically dispersed and mixed thoroughly. The concentration of CdSe@SiO2@MIP was 1 mg / mL, and the concentrations of CML were 0 μg / L, 100 μg / L, 300 μg / L, 500 μg / L, and 700 μg / L. The fluorescence intensity of the mixed solutions was detected under optimal conditions. Figure 17 As shown. Figure 18 As shown, by fitting a standard curve with the fluorescence intensity peak area between 600 nm and 660 nm as the ordinate and the CML concentration as the abscissa, it can be found that the fluorescence intensity of the solution has a linear relationship with the CML concentration, y = -529.9x + 1631440, R 2 =0.96448. This indicates that the CdSe@SiO2@MIP prepared in Example 2 has good detection performance and can detect CML within a certain concentration range.
[0111] CdSe@SiO2@MIP and CdSe@SiO2@NIP solutions were mixed with known concentrations of CML, carboxyethyl lysine (CEL), and lysine (Lys) standard solutions, respectively, and ultrasonically dispersed. The concentration of CdSe@SiO2@MIP was 1 mg / mL, and the concentrations of CML, CEL, and lysine were all 1 mg / L. The fluorescence intensity of the mixed solutions was measured under optimal conditions. The ratio of initial fluorescence intensity to fluorescence intensity after 2 hours of reaction, F0 / F, was plotted on the ordinate, and the sample type on the abscissa to observe the degree of fluorescence quenching in different samples. Figure 19 As shown, CdSe@SiO2@MIP exhibits the greatest quenching degree for CML, while the quenching degree of CEL and Lys by CdSe@SiO2@MIP is similar to that of CEL and Lys by CdSe@SiO2@NIP. This indicates that the CdSe@SiO2@MIP prepared in Example 2 has good specific recognition ability for CML.
[0112] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for calculating the synthesis pathway of quantum dot molecularly imprinted materials, characterized in that, Includes the following steps: Using carboxymethyl lysine as a template molecule, we identified several functional monomers that can form hydrogen bonds with the template molecule and the lowest energy configuration of the template molecule. Based on the lowest energy configuration of the functional monomer and the template molecule, the Mulliken charge and single-point energy of the template molecule and the functional monomer are calculated, the interaction sites that can form hydrogen bond interactions between the template molecule and the functional monomer are determined, and the complex of the template molecule and the functional monomer is constructed to determine the lowest energy conformation of the complex. Based on the lowest energy conformation of the complex, calculate the single-point energy of the complex; substitute the single-point energies of the template molecule, functional monomer, and complex into the binding energy calculation formula to obtain the binding energy between the template molecule and the functional monomer, and screen out the functional monomer with the largest absolute value of binding energy as the optimal functional monomer. The lowest energy conformation of the complex of the template molecule and the optimal functional monomer at different molar ratios is determined, and the binding energy of the complex of the template molecule and the optimal functional monomer at different molar ratios is calculated. The molar ratio of the template molecule and the optimal functional monomer with the largest absolute value of binding energy is then selected as the optimal reaction ratio.
2. The method for calculating the synthesis path of quantum dot molecularly imprinted materials according to claim 1, characterized in that, The functional monomers are methacrylic acid, acrylamide and 3-aminopropyltriethoxysilane.
3. The method for calculating the synthesis path of quantum dot molecularly imprinted materials according to claim 1, characterized in that, The formula for calculating binding energy is as follows: D E = E complex -( E template + nE monomer ); Where, Δ E This represents the binding energy between the template molecule and the functional monomer; E complex Indicates the energy of the complex; E template This represents the energy of the template molecule; E monomer This represents the energy of a functional monomer. n This indicates the molar ratio of the functional monomer to the template molecule in the complex.
4. The method for calculating the synthesis path of quantum dot molecularly imprinted materials according to claim 1, characterized in that, The complex of the template molecule and the functional monomer was constructed with a molar ratio of template molecule to functional monomer of 1:
1.
5. The method for calculating the synthesis path of quantum dot molecularly imprinted materials according to claim 1, characterized in that, The most suitable functional monomer is 3-aminopropyltriethoxysilane.
6. The method for calculating the synthesis path of quantum dot molecularly imprinted materials according to claim 1, characterized in that, The specific method for selecting the molar ratio of the template molecule with the largest absolute value of binding energy to the optimal functional monomer is as follows: Construct complexes of template molecules and optimal functional monomers in different molar ratios; Based on the Mulliken charge of the template molecule and the optimal functional monomer, as well as the complexes of the template molecule and the optimal functional monomer at different molar ratios, the range of molar ratios in which the template molecule and the optimal functional monomer can interact is determined. The lowest energy conformation of the complex within the molar ratio range in which the template molecule and the optimal functional monomer can interact is determined. The single-point energy of the complex within the molar ratio range in which the template molecule and the optimal functional monomer can interact is calculated. Substitute these values into the binding energy calculation formula to calculate the binding energy within the molar ratio range in which the template molecule and the optimal functional monomer can interact. The molar ratio of the template molecule to the optimal functional monomer with the largest absolute value of binding energy is selected as the optimal reaction ratio of the template molecule and the optimal functional monomer.
7. The method for calculating the synthesis path of quantum dot molecularly imprinted materials according to claim 1, characterized in that, The molar ratio in which the template molecule and the optimal functional monomer can interact is in the range of 1:1 to 4; Based on the molar ratio of CML to APTES, the optimal reaction ratio of template molecule to the most suitable functional monomer is 1:
4.
8. A method for preparing quantum dot molecularly imprinted materials, characterized in that, Includes the following steps: Using carboxymethyl lysine as a template molecule, the optimal functional monomer and the best reaction ratio between the template molecule and the optimal functional monomer were screened using the synthesis pathway calculation method of the quantum dot molecular imprinted material described in claim 1. Using CdSe / ZnS quantum dots as the core of fluorescent materials, solvents, surfactants and co-surfactants are mixed with CdSe / ZnS quantum dots to form a CdSe / ZnS quantum dot solution. Then, a polymerization reaction is carried out with crosslinking agent, initiator, template molecule and optimal functional monomer under stirring conditions to obtain a molecularly imprinted polymer precursor. Template molecules in the molecularly imprinted polymer precursor are removed using an extractant, and after drying, quantum dot molecularly imprinted materials are obtained.
9. The method for preparing quantum dot molecularly imprinted materials according to claim 8, characterized in that, The solvent was cyclohexane; the surfactant was Triton X-100; the co-surfactant was n-hexanol; the crosslinking agent was tetraethoxysilane; the initiator was ammonia; and the extractant was a mixed solution of ethanol and acetic acid in a volume ratio of 8:2.