A method for preparing peg-da modified magnetic iron oxide nanoparticles

Abstract

The application discloses a preparation method of PEG-DA modified magnetic iron oxide nanoparticles, and comprises the following steps: synthesizing small-size Fe2O3 nanoparticles by adopting a thermal decomposition method; and modifying the Fe2O3 nanoparticles by PEG-DA. The Fe2O3 nanoparticles synthesized by the thermal decomposition method are easy to control in shape and size, have high crystallinity, high controllability in size, and small aggregation trend, and the method is more advanced in synthesizing iron oxide nanoparticles with higher performance. The Fe2O3 nanoparticles modified by PEG-DA (polyethylene glycol-dopamine) can increase hydrophilicity and improve biocompatibility, and the obtained Fe2O3@PEG-DA nanoparticles are good in stability and have good T1 performance.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to a method for preparing PEG-DA modified magnetic iron oxide nanoparticles. Background Technology

[0002] Magnetic nanoparticles are fundamental to MRI contrast agent research. Currently, the most widely studied magnetic nanoparticles include gadolinium-based nanoparticles, manganese-based nanoparticles, and iron-based nanoparticles. Each of these magnetic nanoparticles has its own advantages and disadvantages.

[0003] Gadolinium-based nanoparticles are currently the most widely used in clinical practice; however, current research indicates that gadolinium-based contrast agents carry the risk of causing renal fibrosis and brain deposition. Manganese is an essential trace element for the human body, participating in various enzymatic reactions, and its physiological safety is higher than that of gadolinium. However, manganese-based nanoparticles typically have a low relaxation rate, and some manganese-based materials may undergo oxidative decomposition in vivo, affecting relaxation efficiency and increasing the risk of toxicity.

[0004] Iron is naturally present in the human body, primarily in hemoglobin and ferritin. Compared to gadolinium and manganese, iron has higher biocompatibility. Currently, iron-based nanoparticles, especially iron oxide nanoparticles, are the most studied in magnetic resonance imaging (MRI), primarily including Fe3O4 and γ-Fe2O3. Fe3O4 nanoparticles are easily oxidized in vivo, inducing higher levels of reactive oxygen species (ROS) and participating in the Fenton reaction to produce highly toxic hydroxyl radicals, leading to increased cytotoxicity and in vivo toxicity. In contrast, Fe2O3 nanoparticles have better chemical stability, reducing the toxicity caused by the instability of Fe3O4 nanoparticles and exhibiting good biocompatibility.

[0005] There are various methods for synthesizing iron oxide nanoparticles, including aqueous / solvothermal synthesis, green synthesis, electrochemical reaction, microemulsion method, coprecipitation method and thermal decomposition method.

[0006] The aqueous / solvothermal synthesis method uses water / organic solvent as a solvent and typically involves heating an autoclave to create a high-temperature, high-pressure environment, resulting in the crystallization of iron oxide nanoparticles. The advantage of this method is that the shape of the iron oxide nanoparticles is easily controlled, and the size distribution is narrow. However, the synthesis process requires high temperature and pressure, carries a high risk factor, and involves multiple steps, a slow reaction rate, and a long synthesis time.

[0007] Green synthesis typically employs environmentally friendly solvent systems and is carried out under relatively mild conditions. Compared to traditional methods, it significantly reduces environmental pollution and lowers the environmental risks associated with the synthesis process. However, due to the mild reaction conditions, the reaction rate is relatively slow, the synthesis time is long, and the product purity is not high.

[0008] Electrochemical reactions produce iron oxide nanoparticles through redox reactions in an electrolyte. The advantages include precise control over particle size, morphology, and crystallinity by adjusting electrochemical parameters, resulting in nanoarrays with well-defined three-dimensional structures that are easy to process and inexpensive. The disadvantages include the need for removal from the matrix, leading to poor reproducibility.

[0009] The microemulsion method is a technique for synthesizing iron oxide nanoparticles using nanoscale droplets as reactors. The advantages of this method are uniform particle size and good dispersibility. However, it requires surfactants, which can easily remain on the synthesized particles, significantly affecting their performance.

[0010] The coprecipitation method typically involves preparing an iron precursor solution by mixing ferric and ferrous salt solutions in a specific ratio. This solution is then heated to a certain temperature, and iron oxide nanoparticles are synthesized through a coprecipitation reaction under alkaline conditions. Its advantages include simple operation and low cost. However, its disadvantages include irregular shapes, a wide size distribution, and a significant tendency to aggregate in the synthesized iron oxide nanoparticles.

[0011] Thermal decomposition is a method that decomposes iron precursors at high temperatures by adding reducing agents and stabilizers to a solvent medium. Thermal decomposition effectively overcomes the shortcomings of the methods mentioned above. The synthesized iron oxide nanoparticles exhibit easily controllable shape and size, high crystallinity, a small size distribution range, and a significantly lower aggregation tendency compared to co-precipitation methods. Therefore, the use of thermal decomposition has profound significance in the synthesis of iron oxide nanoparticles.

[0012] Existing methods for synthesizing iron oxide nanoparticles often result in products that tend to aggregate due to their large specific surface area and high surface tension. Furthermore, these nanoparticles have low size controllability and low crystallinity, making it difficult to control their performance.

[0013] Therefore, it is necessary to propose a method for preparing PEG-DA modified magnetic iron oxide nanoparticles to solve the above problems. Summary of the Invention

[0014] This invention addresses the problem that existing methods for synthesizing iron oxide nanoparticles often result in products that tend to aggregate, have low size controllability, low crystallinity, and therefore poor performance control. It proposes a method for preparing PEG-DA modified magnetic iron oxide nanoparticles.

[0015] The method for preparing PEG-DA modified magnetic iron oxide nanoparticles includes the following steps:

[0016] S1. Synthesis of small-sized Fe2O3 nanoparticles: Fe2O3 nanoparticles were synthesized by thermal decomposition.

[0017] S2, PEG-DA modified Fe2O3 nanoparticles: Take an aqueous solution of Fe2O3 nanoparticles, add 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS), mix well, and place the mixture in an oven at 37°C for 30 min; then add PEG-DA (Mn=2kDa), stir magnetically for 24 h, centrifuge and wash to remove large particles; after centrifugation and washing, dialyze the solution for 48 h to obtain Fe2O3@PEG-DA nanoparticles.

[0018] In a preferred embodiment of the present invention, the synthesis method of small-sized Fe2O3 nanoparticles in S1 is as follows: First, 0.1 g of sodium citrate dihydrate and 0.045 g of FeCl3·6H2O are weighed and ultrasonically dissolved in 100 mL of deionized water. The mixture is placed in a 250 mL three-necked flask and stirred vigorously under N2 protection; 0.1 mol L... -1 The pH of the sodium hydroxide solution was adjusted to 5.8; then 0.024 g of urea was added, and the mixture was heated to 100 °C and refluxed for 24 h; after the solution was naturally cooled to room temperature, the cooled solution was dialyzed for 24 h and then freeze-dried and weighed to obtain aqueous Fe2O3 nanoparticles, which were golden yellow in color and prepared to a concentration of 1 mg / mL.

[0019] In a preferred embodiment of the present invention, the method for modifying Fe2O3 nanoparticles with PEG-DA in S2 is as follows: Take 10-20 mL of 0.5-2 mg / mL Fe2O3 nanoparticle aqueous solution, add 5-20 mg of EDC and 10-25 mg of NHS, mix well, and place the mixture in an oven at 25-40°C for 15-60 min; then add 30-100 mg of PEG-DA, stir magnetically at room temperature for 12-48 h, centrifuge and wash to remove large particles; after centrifugation and washing, dialyze the solution for 24-72 h to obtain Fe2O3@PEG-DA nanoparticles.

[0020] In a preferred embodiment of the present invention, the specific method for modifying Fe2O3 nanoparticles with PEG-DA in S2 is as follows: Take 15 mL of Fe2O3 nanoparticle aqueous solution with 1 mg / mL, add 10 mg of EDC and 15 mg of NHS, mix well, place the mixture in an oven at 37°C and react for 30 min; then add 50 mg of PEG-DA, stir magnetically for 24 h, centrifuge and wash to remove large particles; after centrifugation and washing, dialyze the solution for 48 h to obtain Fe2O3@PEG-DA nanoparticles.

[0021] Implementing the embodiments of the present invention has the following beneficial effects:

[0022] Compared with other synthesis methods, the Fe2O3 nanoparticles synthesized by the thermal decomposition method of this invention have easily controllable shape and size, high crystallinity, high size controllability, and less tendency to aggregate. This method is more advanced in the synthesis of higher performance iron oxide nanoparticles.

[0023] This invention uses PEG-DA (polyethylene glycol-dopaamide) to modify Fe2O3 nanoparticles, which can increase hydrophilicity and improve biocompatibility. The resulting Fe2O3@PEG-DA nanoparticles have good stability and good T1 performance. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 Image of Fe2O3 nanoparticle sample;

[0026] Figure 2 A schematic diagram illustrating the synthesis of PEG-DA modified Fe2O3 nanoparticles;

[0027] Figure 3 TEM image of Fe2O3 nanoparticles;

[0028] Figure 4 A bar chart showing the size distribution of Fe2O3 nanoparticles;

[0029] Figure 5 The image shows an in vitro magnetic resonance imaging (MRI) image of Fe2O3 nanoparticles under a magnetic field strength of 0.5T and its corresponding pseudo-color image.

[0030] Figure 6 The curves show the relationship between the reciprocal of the relaxation time of Fe2O3 nanoparticles under a magnetic field strength of 0.5T and the iron concentration for T1(a) and T2(b).

[0031] Figure 7 HRTEM image of Fe2O3@PEG-DA nanoparticles;

[0032] Figure 8 Full-scan XPS spectra of PEG-DA modified Fe2O3 nanoparticles;

[0033] Figure 9 Fe2p spectra of PEG-DA modified Fe2O3 nanoparticles;

[0034] Figure 10In vitro magnetic resonance imaging of PEG-DA modified Fe2O3 nanoparticles and their corresponding pseudo-color images;

[0035] Figure 11 The curves show the relationship between the reciprocal of the relaxation time of PEG-DA modified Fe2O3 nanoparticles under a magnetic field strength of 0.5T and the iron concentration for T1(a) and T2(b). Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0037] The method for preparing PEG-DA modified magnetic iron oxide nanoparticles includes the following steps:

[0038] S1. Synthesis of small-sized Fe2O3 nanoparticles: First, weigh 0.1 g of sodium citrate dihydrate and 0.045 g of FeCl3·6H2O and dissolve them in 100 mL of deionized water using ultrasonication. Place the mixture in a 250 mL three-necked flask and stir vigorously under N2 protection; add 0.1 mol L... -1 The sodium hydroxide solution was adjusted to pH 5.8; then 0.024 g of urea was added, and the mixture was heated to 100°C and refluxed for 24 h. After the solution cooled naturally to room temperature, it was dialyzed for 24 h, then lyophilized and weighed to obtain aqueous Fe₂O₃ nanoparticles, which were golden yellow in color, and prepared to a concentration of 1 mg / mL. Please refer to [link to relevant documentation]. Figure 1 , Figure 1 Image of Fe2O3 nanoparticle sample.

[0039] S2. PEG-DA Modified Fe2O3 Nanoparticles: Take 15 mL of a 1 mg / mL Fe2O3 nanoparticle aqueous solution, add 10 mg of EDC and 15 mg of NHS, mix well, and place the mixture in a 37℃ oven for 30 min. Then add 50 mg of PEG-DA, stir magnetically for 24 h, centrifuge and wash to remove large particles. After centrifugation and washing, dialyze the solution for 48 h to obtain Fe2O3@PEG-DA nanoparticles. Please participate. Figure 2 , Figure 2 This is a schematic diagram of the synthesis of PEG-DA modified Fe2O3 nanoparticles.

[0040] Compared to gadolinium-based and manganese-based nanoparticles, iron oxide nanoparticles exhibit better biocompatibility and greater potential for clinical applications. Among iron oxide nanoparticles, Fe2O3 is less prone to oxidation than γ-Fe2O3, resulting in better biocompatibility. However, its size is difficult to control, and it is prone to aggregation, affecting performance. Therefore, a thermal decomposition method was used to synthesize Fe2O3 nanoparticles with uniform size distribution, and PEG-DA (polyethylene glycol-dopamide) functionalization was employed to effectively improve dispersibility and relaxation properties.

[0041] Performance characterization:

[0042] Transmission electron microscopy analysis of Fe2O3 nanoparticles:

[0043] The precipitated diluted particle suspension (5 μL) was dropped onto a carbon-coated copper grid and air-dried. The morphology and particle size distribution of Fe2O3 nanoparticles were then observed using a transmission electron microscope manufactured by Hitachi High Technology Corporation.

[0044] Please see Figure 3-4 , Figure 3 TEM image of Fe2O3 nanoparticles; Figure 4 The bar chart shows the size distribution of Fe2O3 nanoparticles; the Fe2O3 nanoparticles have regular morphology, are uniformly distributed, and have a size distribution of 13.82±3.46 nm.

[0045] Relaxation rate analysis of Fe2O3 nanoparticles:

[0046] In vitro MRI imaging of Fe2O3 nanoparticle aqueous solution was performed using a 0.5 T MesoMR23-060-I nuclear magnetic resonance analyzer. First, the Fe2O3 nanoparticle aqueous solution was diluted with deionized water to prepare iron ion standard solutions with concentration gradients (5, 10, 20, 40, 80 μg / mL). Then, the iron ion standard solutions were arranged in ascending order of concentration for longitudinal and transverse relaxation characterization. The parameters used for T1-weighted in vitro MRI were: SF = 21 MHz, O1 = 232246 Hz, RFA90° = 2.6, RFA180° = 3.9, TR = 300 ms, TE = 20 ms, Slice width (mm) = 3, Slices = 1, Average = 4, Read Size = 256, Phase Size = 256. The parameters used for T2-weighted in vitro magnetic resonance imaging were: SF=21MHz, O1=232246Hz, RFA90°=2.6, RFA180°=3.9, TR=2000ms, TE=60ms, Slice width (mm)=3, Slices=1, Average=4, Read Size=256, Phase Size=256.

[0047] T1WI and T2WI of Fe2O3 nanoparticles at different iron ion concentrations are as follows: Figure 5 As shown. From Figure 5 It can be observed that with the increase of iron ion concentration, the T1WI signal intensity does not change significantly, while the T2WI signal intensity decreases significantly. The values ​​of r1 and r2 of Fe2O3 nanoparticles were calculated through the linear relationship between iron ion concentration and relaxation rate. Different iron ion concentrations and their corresponding relaxation rates exhibit an excellent linear relationship, such as... Figure 6 As shown, the r1 value of the Fe2O3 nanoparticles is 0.4 mM. -1 s -1 r2 = 4.048 mM -1 s -1 r2 / r1 = 10.12.

[0048] Characterization experiments of PEG-DA modified Fe2O3 nanoparticles:

[0049] Transmission electron microscopy analysis of PEG-DA modified Fe2O3 nanoparticles:

[0050] Take 15 mL of a 1 mg / mL Fe₂O₃ nanoparticle aqueous solution, add 10 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and 15 mg of N-hydroxysuccinimide (NHS), mix well, and place the mixture in a 37°C oven for 30 min. Then add 50 mg of PEG-DA (Mn = 2 kDa), stir magnetically for 24 h, and centrifuge and wash to remove large particles. After centrifugation and washing, dialyze the solution for 48 h to obtain Fe₂O₃@PEG-DA nanoparticles. Morphology and size were examined using a Tecnai G20 high-resolution transmission electron microscope (HRTEM) from FEI Corporation, USA, at an operating voltage of 200 kV.

[0051] PEG-DA modified Fe2O3 nanoparticles exhibited regular morphology, uniform distribution, and monodispersity, with a size distribution of 55±5.63 nm. Figure 7 As shown.

[0052] XPS analysis of PEG-DA modified Fe2O3 nanoparticles:

[0053] XPS analysis of Fe2O3@PEG-DA nanoparticles was performed using Shimadzu's X-ray photoelectron spectroscopy (XPS) system with Al Kα as the excitation source. The surface elemental composition and chemical state information of the corresponding atoms of the sample were obtained through the photoelectric effect.

[0054] Full-scan XPS spectroscopy revealed that PEG-DA modified Fe2O3 nanoparticles are mainly composed of iron, carbon, oxygen, and nitrogen, consistent with the elemental composition of nanoparticles. Figure 8 As shown. The full-scan XPS spectrum also exhibits typical binding energies, corresponding to the energy levels and positions of the chiral coupling Fe (Fe2p) and Fe (Fe3p) peaks, which are similar to those of Fe in Fe2O3. 3+ The consistency of these peaks confirms the successful construction of Fe₂O₃ nanoparticles. High-resolution spectroscopy revealed four peaks in Fe(Fe₂p) (710.42 eV, 717.42 eV, 723.22 eV, 740.62 eV), which are similar to the Fe(Fe₂p³ / ₂) peak, Fe(Fe₂p¹ / ₂) peak, and their satellite peaks in Fe₂O₃, further confirming the successful construction of Fe₂O₃ nanoparticles. Figure 9 As shown.

[0055] Relaxation rate analysis of PEG-DA modified Fe2O3 nanoparticles:

[0056] In vitro MRI imaging of Fe2O3@PEG-DA nanoparticle aqueous solution was performed using a 0.5 T MesoMR23-060-I nuclear magnetic resonance analyzer. First, the Fe2O3@PEG-DA nanoparticle aqueous solution was diluted with deionized water to prepare iron ion standard solutions with concentration gradients (5, 10, 20, 40, 80 μg / mL). These solutions were then arranged in ascending order of iron ion concentration for longitudinal and transverse relaxation characterization. The parameters used for T1-weighted in vitro MRI were: SF = 21 MHz, O1 = 232246 Hz, RFA90° = 2.6, RFA180° = 3.9, TR = 260 ms, TE = 18.9 ms, Slice width (mm) = 3, Slices = 1, Average = 4, Read Size = 256, Phase Size = 256. The parameters used for T2-weighted in vitro magnetic resonance imaging were: SF=21MHz, O1=232246Hz, RFA90°=2.6, RFA180°=3.9, TR=4000ms, TE=200ms, Slice width (mm)=3, Slices=1, Average=4, Read Size=256, Phase Size=256.

[0057] T1WI and T2WI of PEG-DA modified Fe2O3 nanoparticles at different iron ion concentrations are as follows: Figure 10 As shown. From Figure 10 It can be observed that as the iron ion concentration increases, the T1WI signal intensity gradually increases, while the T2WI signal intensity does not change significantly.

[0058] The values ​​of r1 and r2 for PEG-DA modified Fe2O3 nanoparticles were calculated using the linear relationship between iron ion concentration and relaxation rate. A very good linear relationship was observed between different iron ion concentrations and their corresponding relaxation rates, such as... Figure 11 As shown, the r1 value of PEG-DA modified Fe2O3 nanoparticles is 0.224 mM. -1 s -1 r2=0.24mM -1 s -1 The ratio r2 / r1 = 1.071 indicates that PEG-DA modified Fe2O3 nanoparticles have the potential to serve as MRI-T1 contrast agents.

[0059] In summary, the Fe₂O₃ nanoparticles prepared by this invention have regular morphology, uniform distribution, and an average size of 13.82 ± 1.73 nm. The r₁ value of the unmodified Fe₂O₃ nanoparticles is 0.4 mM. -1 s -1r2 = 4.048 mM -1 s -1 The r2 / r1 ratio is 10.12; while the r1 value of PEG-DA-modified Fe2O3 nanoparticles is 0.224 mM. -1 s -1 r2=0.24mM -1 s -1 The ratio r2 / r1 is 1.071, a decrease of approximately 9.45 times. It is generally believed that magnetic nanoparticles with an r2 / r1 ratio less than 5 exhibit superior T1 performance. This implies that PEG-DA modification of Fe2O3 nanoparticles enhances their T1 performance.

[0060] The technical solution of this invention enhances the potential for biological applications of Fe2O3 nanoparticles:

[0061] This invention synthesizes small-sized Fe2O3 nanoparticles using a thermal decomposition method, while selecting aqueous ferric chloride as the iron precursor to synthesize aqueous Fe2O3 nanoparticles. Compared to oil-phase Fe2O3 nanoparticles, aqueous Fe2O3 nanoparticles have better water solubility and are more suitable for future applications in the human body environment.

[0062] The technical solution of this invention enhances the potential of Fe2O3 nanoparticles as a T1 contrast agent:

[0063] This invention employs PEG-DA modification of Fe2O3 nanoparticles. PEG is commonly used to coat iron oxide nanoparticles to increase hydrophilicity and improve biocompatibility. Dopamide (DA) is selected as a specific ligand at the end of PEG. This ligand chelates PEG onto the surface of Fe2O3 nanoparticles without affecting the magnetic moment of the Fe2O3 nanoparticles. This modification method effectively improves T1 performance and the product exhibits good stability.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., 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 preparing PEG-DA modified magnetic iron oxide nanoparticles, characterized in that, Includes the following steps: S1. Synthesis of small-sized Fe2O3 nanoparticles: Fe2O3 nanoparticles were synthesized by thermal decomposition. S2. Polyethylene glycol-dopaamide (PEG-DA) modified Fe2O3 nanoparticles: Take 10-20 mL of 0.5-2 mg / mL Fe2O3 nanoparticle aqueous solution, add 5-20 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and 10-25 mg of N-hydroxysuccinimide (NHS), mix well, and place the mixture in an oven at 25-40℃ for 15-60 min; then add 30-100 mg of PEG-DA, stir magnetically at room temperature for 12-48 h, centrifuge and wash to remove large particles; after centrifugation and washing, dialyze the solution for 24-72 h to obtain Fe2O3@PEG-DA nanoparticles.

2. The method for preparing PEG-DA modified magnetic iron oxide nanoparticles according to claim 1, characterized in that, The synthesis method of the small-sized Fe2O3 nanoparticles in S1 is as follows: First, weigh 0.1 g of sodium citrate dihydrate and 0.045 g of FeCl3·6H2O and dissolve them in 100 mL of deionized water by ultrasonication. Place the mixture in a 250 mL three-necked flask and stir vigorously under N2 protection; add 0.1 mol L... −1 The pH of the sodium hydroxide solution was adjusted to 5.8; then 0.024 g of urea was added, and the mixture was heated to 100 °C and refluxed for 24 h; after the solution was naturally cooled to room temperature, the cooled solution was dialyzed for 24 h and then freeze-dried and weighed to obtain aqueous Fe2O3 nanoparticles, which were golden yellow in color and prepared to a concentration of 1 mg / mL.

3. The method for preparing PEG-DA modified magnetic iron oxide nanoparticles according to claim 1, characterized in that, The specific method for modifying Fe2O3 nanoparticles with PEG-DA in S2 is as follows: Take 15 mL of Fe2O3 nanoparticle aqueous solution with 1 mg / mL, add 10 mg of EDC and 15 mg of NHS, mix well, and place the mixture in an oven at 37°C for 30 min; then add 50 mg of PEG-DA, stir magnetically for 24 h, centrifuge and wash to remove large particles; after centrifugation and washing, dialyze the solution for 48 h to obtain Fe2O3@PEG-DA nanoparticles.

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