A chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticle and a preparation method thereof

Abstract

The application relates to a chromium-manganese co-doped gallium germanate zinc long-afterglow nanoparticle and a preparation method thereof. Based on low saturated vapor pressure under high-vacuum heat treatment conditions, a chromium-doped gallium germanate zinc nanoparticle mixture with manganese dioxide powder is heat treated at a lower temperature, near-infrared afterglow emission performance of the nanoparticle is improved, and nanoparticle aggregation is avoided. Meanwhile, Mn 4+ in the manganese dioxide is reduced into Mn 2+ in the nanoparticle interior in a weak reduction vacuum environment and a cation diffusion process, chromium-manganese co-doped gallium germanate zinc long-afterglow nanoparticles are obtained, the nanoparticles have near-infrared afterglow emission originating from Cr 3+ and green long-afterglow emission originating from Mn 2+ . After ultraviolet light excitation, based on energy transfer from Mn 2+ ions to Cr 3+ ions, utilization efficiency of anti-site traps far from Cr 3+ ions in the afterglow light emission process is improved, and near-infrared afterglow emission is further enhanced. The nanoparticles have an average particle size of less than 60 nm and can be used for in-vivo biological application research.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation process of long-afterglow nanoparticles and a method for improving afterglow performance, in particular to chromium and manganese co-doped zinc gallium germanate long-afterglow nanoparticles and a preparation method thereof. BACKGROUND

[0002] After the excitation of an external light source stops, the emission process of the afterglow material can continue for a long time. Therefore, its application in warning signs, life medicine, luminescent lighting and other fields has been widely studied. Compared with other afterglow materials, chromium ion (Cr 3+ ) doped zinc gallium germanate nanoparticles (ZnGaGeO:Cr) have a luminescence wavelength in the first near-infrared transmission window of biological optics (650-1000 nm), and there is a cation "anti-lattice site" inside, which leads to a large number of "anti-lattice site" defect states (Zn Ga ′-Ga Zn · ) are generated and exist as traps in the afterglow luminescence process. Therefore, the near-infrared afterglow emission of Cr 3+ doped zinc gallium germanate nanoparticles can last for several hours or more, and has a broad application prospect in the field of non-invasive image-guided disease diagnosis and treatment. However, due to the single afterglow emission wavelength of the current Cr 3+ doped zinc gallium germanate afterglow nanoparticles, it is difficult to meet the needs of imaging and other functional application research, such as loading photosensitizers on the surface of the nanoparticles, which will significantly reduce the quality and duration of near-infrared afterglow imaging, and low loading rate will affect the quality of photodynamic therapy. Therefore, it is necessary to prepare zinc gallium germanate nanoparticles containing Cr 3+ and having near-infrared and other wavelength afterglow emission.

[0003] At present, the afterglow emission intensity of Cr 3+ doped zinc gallium germanate afterglow nanoparticles still needs to be further strengthened to achieve the application purpose of long-term in-vivo tracking imaging and long-acting in-vivo treatment. High-temperature heat treatment is a common and efficient method to improve the luminescence performance of afterglow materials and increase the number of traps in the material. The current Cr 3+The doped gallium germanate zinc afterglow nanoparticles also often need to add an air atmosphere high temperature heat treatment technology link during the synthesis process or after the synthesis by sol-gel, coprecipitation, solvothermal and other methods to enhance the near-infrared afterglow emission intensity. However, this technical link will cause a large number of nanoparticles to agglomerate, the particle size will grow, the particle morphology will become uneven, the particle size distribution will widen, and it will seriously hinder its application in the field of biological medicine. On the other hand, the general strategy for enhancing the near-infrared afterglow performance is to introduce impurities into the gallium germanate zinc nanoparticle matrix to construct new trap defects. Although this strategy introduces new traps in the afterglow emission process, it will also destroy a large number of "anti-substitution" traps in the matrix lattice of gallium germanate zinc nanoparticles when the doping concentration is high. Therefore, it is difficult to obtain Cr 3+ The afterglow performance of the doped gallium germanate zinc afterglow nanoparticles is greatly improved.

[0004] The problem to be solved by the present application is how to improve the morphology, size, near-infrared afterglow emission enhancement and other waveband afterglow emission of the chromium-containing gallium germanate zinc nanoparticles by combining heat treatment technology and impurity doping strategy adjustment. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a preparation method of chromium and manganese co-doped gallium germanate zinc long afterglow nanoparticles, comprising the following steps:

[0006] (1) A certain amount of zinc acetate, gallium nitrate, chromium nitrate, germanium chloride and deionized water are configured into a mixed solution;

[0007] (2) A certain amount of the mixed solution of step (1) is added dropwise into deionized water, and stirred thoroughly to obtain a pre-reaction solution. The volume ratio of the mixed solution to deionized water is 1:15-40. Then, NaOH solution is added dropwise into the pre-reaction solution to adjust the pH value of the reaction solution to 7.2-8.5, and the stirring is continued until the reaction solution becomes a uniform white suspension;

[0008] (3) The white suspension is placed in a high-pressure reaction kettle with a Teflon lining, and then heated to 175-190℃, and the temperature is maintained for 4-24 hours. After sufficient reaction, the reaction kettle is naturally cooled to room temperature, and the reaction product is taken out and washed with water for 2-3 times, and then dried at 50-90℃ for 3-12 hours. The dried sample is ground for 5-15 minutes to obtain initial chromium-doped gallium germanate zinc long afterglow nanoparticles;

[0009] (4) A certain amount of initial chromium-doped gallium germanate zinc long afterglow nanoparticles and manganese dioxide powder are mixed; the mixed powder material is placed in a mortar and ground to make the initial chromium-doped gallium germanate zinc long afterglow nanoparticles and manganese dioxide powder uniformly mixed;

[0010] (5) Put the mixed powder sample after grinding into a high-vacuum tube furnace; when the vacuum degree reaches 8*10 -3 Pa to 1*10 -4 Pa, the tube furnace starts to heat the mixed powder sample for heat treatment; the heat treatment temperature is 650-810 DEG C, the heat treatment time is 1-1.5 hours, and the vacuum degree is maintained at 8*10 -3 Pa to 1*10 -4 Pa during the heat treatment process;

[0011] (6) After the heat treatment of the mixed powder sample, the furnace is cooled to room temperature, and the vacuum degree in the furnace is maintained below 5*10 -3 Pa during the cooling process;

[0012] (7) The cooled mixed powder sample is ground for 5-10 minutes to obtain chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles (ZnGaGeO:Cr, Mn).

[0013] Further, in the step (1), the volume molar concentrations of zinc, gallium, germanium and chromium ions in the mixed solution are 1M, 1.49M, 0.375M and 0.002-0.01M respectively.

[0014] Further, in the step (2), the volume of the mixed solution is 0.5-1ml, and the volume of the deionized water is 15-20ml; after the mixed solution is dropped into the deionized water, the stirring time is not less than half an hour to obtain a pre-reaction solution.

[0015] Further, in the step (4), the mass ratio of the initial chromium-doped zinc gallium germanate long afterglow nanoparticles to manganese dioxide is 400:0.2-1; and the mixed powder is ground in a mortar for 10-30 minutes.

[0016] The chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared according to the above method have a small nanoparticle size, and can emit green and near-infrared dual-color long afterglow after irradiation under ultraviolet light.

[0017] The working principle of the present application is as follows:

[0018] The present application is based on the low saturated vapor pressure of high-vacuum heat treatment conditions, and the chromium-doped zinc gallium germanate nanoparticles and manganese dioxide powder mixture are heat treated at a lower temperature, which can cause a large amount of zinc and germanium elements to volatilize, thereby improving the near-infrared afterglow emission performance and avoiding the aggregation and growth of the nanoparticles. The weak reduction vacuum environment is relied on to reduce the tetravalent manganese ions in the manganese dioxide into divalent manganese ions (Mn 2+), and through a cation diffusion process, into the chromium-doped zinc gallium germanate long afterglow nanoparticles, so that the final chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles not only have the near-infrared afterglow emission originating from Cr 3+ ions, but also have the green long afterglow emission originating from Mn 2+ ions.

[0019] After the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the present application are excited by ultraviolet light, the energy transfer from Mn 2+ ions to Cr 3+ ions improves the utilization efficiency of the anti-site traps far from Cr 3+ ions in the afterglow luminescence process, and further enhances the near-infrared afterglow emission of Cr 3+ ions.

[0020] The present application has the following beneficial effects:

[0021] The chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the present application have a pure phase spinel structure after X-ray diffraction spectrum detection. Compared with ordinary chromium single-doped zinc gallium germanate long afterglow nanoparticles, the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the present application can produce green and near-infrared dual-color long afterglow emission after ultraviolet irradiation, so that the nanoparticles can be applied not only to near-infrared afterglow imaging research, but also to medical application research such as photodynamic therapy based on the green long afterglow emission. Therefore, the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the present application can become a good multifunctional drug carrier and a research basis for diagnosis and treatment technology. In addition, the method of high-vacuum low-temperature heat treatment of nanoparticles used in the preparation of chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles in the present application effectively controls the nanoparticle agglomeration phenomenon under the premise of improving the afterglow performance of the nanoparticles, so that the nanoparticle size remains almost unchanged before and after heat treatment, and the average nanoparticle size is less than 60 nm, which can be used for in vivo biological application research. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 X-ray diffraction spectrum of the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the present application;

[0023] Figure 2 Transmission electron micrograph of the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the present application;

[0024] Figure 3 Emission spectrum of the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the present application under 254 nm ultraviolet excitation;

[0025] Figure 4The green and near-infrared dual-wavelength afterglow decay curve diagram of the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the application after being excited by 254 nm ultraviolet light for 5 minutes;

[0026] Figure 5 The near-infrared afterglow decay curve of the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the application before and after high vacuum heat treatment;

[0027] Figure 6 The near-infrared afterglow decay curve diagram of the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles and the chromium single-doped zinc gallium germanate long afterglow nanoparticles after being excited by 254 nm ultraviolet light for 5 minutes. DETAILED DESCRIPTION

[0028] Example 1,

[0029] The preparation method of the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles provided in the embodiment comprises the following steps:

[0030] (1) A certain amount of zinc acetate, gallium nitrate, chromium nitrate and germanium chloride are taken to prepare a mixed solution with deionized water, and the volume molar concentrations of zinc ions, gallium ions, germanium ions and chromium ions in the mixed solution are 1M, 1.49M, 0.375M and 0.006M respectively;

[0031] (2) 0.5 milliliters of the mixed solution is dropped into 15 milliliters of deionized water, and stirred and shaken uniformly for half an hour to obtain a pre-reaction solution; then, NaOH solution is dropped into the pre-reaction solution to adjust the pH value of the reaction solution to 7.5, and the stirring is continued until the reaction solution becomes a uniform white suspension;

[0032] (3) The white suspension is placed in a high-pressure reaction kettle with a Teflon lining, and then heated to 185°C, and the temperature is maintained for 12 hours; after sufficient reaction, the reaction kettle is naturally cooled to room temperature, and the reaction product is taken out, washed with water repeatedly for three times, and dried at 75 degrees Celsius for 7 hours. Then the dried sample is ground for 6 minutes to obtain initial chromium-doped zinc gallium germanate long afterglow nanoparticles;

[0033] (4) A certain amount of the initial chromium-doped zinc gallium germanate long afterglow nanoparticles and manganese dioxide powder are mixed, and the mass ratio of the mixed materials is 400:0.6; the mixed powder materials are placed in a mortar and ground for 20 minutes to make the initial chromium-doped zinc gallium germanate long afterglow nanoparticles and the manganese dioxide powder uniformly mixed;

[0034] (5) The ground mixed powder sample is placed in a high vacuum tube furnace; when the vacuum degree reaches 5×10 -4 Pa, the tube furnace starts to heat and heat treats the mixed powder sample; the heat treatment temperature is 700°C, and the heat treatment time is 1 hour, and the vacuum degree is maintained at 5×10 -3below;

[0035] (6) After the mixed powder sample is heat treated, it is cooled to room temperature in the furnace, and the vacuum degree in the furnace is maintained at 3.5*10 -3 below;

[0036] (7) The cooled mixed powder sample is ground for 5 minutes to obtain chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles (ZnGaGeO:Cr, Mn).

[0037] Referring to FIG. 1, Figures 1-5 As shown in FIG. 1, the chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the present application have a pure phase spinel structure, and the average nanoparticle size is less than 60 nm. After being irradiated under ultraviolet light, the nanoparticles can emit green and near-infrared dual-color long afterglow. In particular, after vacuum heat treatment, the initial near-infrared afterglow emission intensity is increased by more than 10 times.

[0038] Example 2,

[0039] The present embodiment provides a preparation method of chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles, which comprises the following steps:

[0040] (1) A certain amount of zinc acetate, gallium nitrate, chromium nitrate, germanium chloride and deionized water are configured into a mixed solution, and the volume molar concentrations of zinc, gallium, germanium and chromium ions in the mixed solution are 1M, 1.49M, 0.375M and 0.01M, respectively;

[0041] (2) 0.5 milliliters of the mixed solution are dropped into 15 milliliters of deionized water, and stirred and shaken uniformly for half an hour to obtain a pre-reaction solution. Then, NaOH solution is dropped into the pre-reaction solution to adjust the pH value of the reaction solution to 7.5, and the stirring is continued until the reaction solution becomes a uniform white suspension;

[0042] (3) The white suspension is placed in a high-pressure reaction kettle with a Teflon lining, and then heated to 185°C, and the temperature is maintained for 12 hours. After sufficient reaction, the reaction kettle is naturally cooled to room temperature, and the reaction product is taken out, washed with water repeatedly for three times, and dried at 80°C for 5 hours. Then, the dried sample is ground for 10 minutes to obtain initial chromium-doped zinc gallium germanate long afterglow nanoparticles;

[0043] (4) A certain amount of initial chromium-doped zinc gallium germanate long afterglow nanoparticles and manganese dioxide powder are mixed, and the mass ratio of the mixed powder is 400:0.2. The mixed powder material is ground in a mortar for 20 minutes to uniformly mix the initial chromium-doped zinc gallium germanate long afterglow nanoparticles and the manganese dioxide powder;

[0044] (5) The ground mixed powder sample is placed in a high-vacuum tube furnace. When the vacuum degree reaches 5*10 -4After Pa, the tube furnace was heated to perform heat treatment on the mixed powder sample; the heat treatment temperature was 700℃, the heat treatment time was 1 hour, and the vacuum degree was maintained at 5×10⁻⁶ throughout the heat treatment process. -3 Below Pa;

[0045] (6) After heat treatment, the mixed powder sample was cooled to room temperature in the furnace, with the vacuum level maintained at 3.5 × 10⁻⁶ during the cooling process. -3 Below Pa;

[0046] (7) Grind the cooled mixed powder sample for 5 minutes to obtain chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles (ZnGaGeO:Cr,Mn).

[0047] This invention also provides a comparative example: a method for preparing chromium-doped zinc gallium germanate long afterglow nanoparticles, comprising the following steps:

[0048] (1) Take a certain amount of zinc acetate, gallium nitrate, chromium nitrate, germanium chloride and deionized water to prepare a mixed solution. The volume molar concentrations of zinc, gallium, germanium and chromium ions in the mixed solution are 1M, 1.49M, 0.375M and 0.01M, respectively.

[0049] (2) Take 0.5 ml of the mixed solution and add it to 15 ml of deionized water. Stir and shake for half an hour to obtain the pre-reaction solution. Then, add NaOH solution to the pre-reaction solution to adjust the pH value of the reaction solution to 7.5. Continue stirring until the reaction solution becomes a uniform white suspension.

[0050] (3) The white suspension was placed in a high-pressure reactor with a Teflon liner, and then heated to 185°C and maintained at that temperature for 12 hours. After the reaction was complete, the reactor was allowed to cool naturally to room temperature. The reaction product was then removed, washed with water three times, and dried at 80°C for 5 hours. The dried sample was then ground for 10 minutes to obtain the initial chromium-doped zinc gallium germanate long afterglow nanoparticles.

[0051] (4) Place the initial chromium-doped zinc gallium germanate long afterglow nanoparticles in a high-vacuum tube furnace; when the vacuum degree reaches 5×10 -4 After Pa, the tube furnace was heated to perform heat treatment on the mixed powder sample; the heat treatment temperature was 700℃, the heat treatment time was 1 hour, and the vacuum degree was maintained at 5×10⁻⁶ throughout the heat treatment process. -3 Below Pa;

[0052] (5) After initial chromium-doped zinc gallium germanate long afterglow nanoparticles were heat-treated, they were cooled to room temperature in the furnace, with the vacuum level inside the furnace maintained at 3.5 × 10⁻⁶ during the cooling process. -3 Below Pa;

[0053] (6) The cooled nanoparticle sample was ground for 5 minutes to obtain the chromium-doped zinc gallium germanate long-persistence nanoparticles (ZnGaGeO:Cr).

[0054] Referring to Figure 6 As shown in the figure, after the chromium and manganese co-doped zinc gallium germanate long-persistence nanoparticle sample was irradiated under ultraviolet light, the near-infrared afterglow emission intensity thereof was about twice that of the chromium-doped zinc gallium germanate long-persistence nanoparticle sample without manganese doping.

Claims

1. A method for preparing chromium- and manganese-co-doped zinc gallium germanate long afterglow nanoparticles, characterized in that: The method comprises the following steps: (1) a certain amount of zinc acetate, gallium nitrate, chromium nitrate, germanium chloride and deionized water are configured into a mixed solution, the volume molar concentration of zinc, gallium, germanium and chromium ions in the mixed solution is 1M, 1.49M, 0.375M and 0.002-0.01M respectively; (2) a certain amount of the mixed solution in step (1) is dropped into deionized water, and is fully stirred to obtain a pre-reaction solution, the volume ratio of the mixed solution to deionized water is 1:15-40; then, NaOH solution is dropped into the pre-reaction solution to adjust the pH value of the reaction solution to 7.2-8.5, and the stirring is continued until the reaction solution becomes a uniform white suspension; (3) the white suspension is placed in a high-pressure reaction kettle with a Teflon lining, and then heated to 175-190°C, and the temperature is kept for 4-24 hours; after sufficient reaction, the reaction kettle is naturally cooled to room temperature, the reaction product is taken out, washed with water, dried and ground to obtain initial chromium-doped zinc gallium germanate long afterglow nanoparticles; (4) a certain amount of initial chromium-doped zinc gallium germanate long afterglow nanoparticles and manganese dioxide powder are mixed, the mass ratio of the initial chromium-doped zinc gallium germanate long afterglow nanoparticles to manganese dioxide is 400:0.2-1; the mixed powder material is ground in a mortar to mix the initial chromium-doped zinc gallium germanate long afterglow nanoparticles and manganese dioxide powder uniformly; (5) Put the mixed powder sample into a high vacuum tube furnace, and start to heat the mixed powder sample when the vacuum degree reaches 8×10 -3 Pa to 1×10 - 4 Pa; the heat treatment temperature is 650-810℃, the heat treatment time is 1-1.5 hours, and the vacuum degree is maintained at 8×10 -3 Pa to 1×10 -4 Pa during the heat treatment. (6) After heat treatment, the mixed powder sample is cooled to room temperature in the furnace, and the vacuum degree in the furnace is maintained at 5 x 10 -3 Pa or less during the cooling process. (7) the cooled mixed powder sample is ground for 5-10 minutes to obtain chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles ZnGaGeO:Cr,Mn. 2.The method for preparing chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles according to claim 1, characterized in that: In step (4), the mixed powder is ground in a mortar for 10-30 minutes.

3. A chromium, manganese co-doped zinc gallium germanate long afterglow nanoparticle, characterized by: The chromium and manganese co-doped zinc gallium germanate long afterglow nanoparticles prepared by the method of any one of claims 1-2 have an average particle size of less than 60 nm, and can emit green and near-infrared dual-color long afterglow emission after being irradiated by ultraviolet light.

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