A Mn 2+ Method for activating naLuF4 nanoscintillator and applications

Abstract

The application discloses a kind of Mn 2+ Preparation method and application of activated NaLuF4 nanometer scintillator belong to the field of X-ray imaging in optical imaging technology.Through co-doping Mn 2+ And Gd 3+ , realize the regulation of luminescent performance in NaLuF4 nanocrystal matrix.The prepared NaLuF4:Gd / Mn (42 / 18%) nanocrystal can be used to prepare high-density, high-resolution, reusable X-ray imaging plate, and the resolution of the imaging plate reaches 22 lp / mm, and also has the function of optical information memory storage, and the information storage time can reach 30 days.The preparation process is simple, the operability is strong, the performance is excellent, and the application prospect is broad.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of X-ray imaging in optical imaging, and particularly relates to a Mn 2+ Preparation method and application of activated NaLuF4 nanoscintillator. BACKGROUND

[0002] Persistent luminescence scintillators are characterized by a unique delayed emission after the stop of excitation. It has been widely proven that persistent luminescence can last for minutes, hours or even weeks. Its basic principle is usually attributed to the capture of photo-generated charge carriers by lattice defects, which are then slowly released under external stimuli (such as thermal fluctuations and light irradiation). Given their ability to store excitation energy and produce persistent emission, these phosphors show great prospects in a wide range of applications that do not require real-time excitation, including multi-level anti-counterfeiting, optical information encryption and storage, and background-free imaging, guiding medical diagnosis and treatment.

[0003] Recently, lanthanide-doped fluorides have become a new type of nanoscintillator that exhibits persistent luminescence upon X-ray activation. By combining the deep penetration ability of X-rays, these small-sized fluoride nanoscintillators, prepared by solution method, can be conveniently processed into radiographic plates to realize high-resolution three-dimensional X-ray imaging of various complex devices. In the field of biological imaging, combined with the characteristics of near-infrared two-zone luminescence of rare earth elements, deep tissue imaging of blood vessels, tumors and ureters in vivo can be realized. Although nanoscintillators with a single lanthanide-doped element have good persistent radioluminescence performance, the unadjustability of emission wavelength and decay kinetics of afterglow makes them unsuitable for applications such as fast erasing imaging or multi-coding.

[0004] Compared with the highly localized 4f orbitals of lanthanide ions, the d orbitals of transition metal ions are more dispersed, and thus are sensitive to the coordination environment, making it possible to realize the regulation of emission wavelength and afterglow performance by changing the microstructure environment of nanocrystals. In particular, Mn 2+ Inorganic compounds of activators have long been considered as environmentally friendly and inexpensive phosphors, and can be prepared under mild conditions, Mn 2+ is considered as a potential dopant. Therefore, by co-doping Mn 2+ and Gd 3 + , the regulation of luminescence performance in NaLuF4 nanocrystal matrix can be realized, and used to construct persistent luminescence imaging analysis with high penetration and high resolution. In summary, the development of such Mn 2+ activated NaLuF4 nanoscintillator and X-ray imaging applications reveals the correlation between long afterglow fluorescence kinetics and microenvironment changes, providing a reference for the development of long afterglow long fluorescent materials. SUMMARY

[0005] The purpose of this invention is to provide a Mn 2+ Preparation method and application of activated NaLuF4 nanoscintillators. This invention incorporates the transition metal ion Mn 2+ The dispersion of d orbitals and lanthanide ions Gd 3+ Co-doping leads to the phase transition of rare earth fluorides from cubic to hexagonal phases, and can be tuned for Mn. 2+ The invention revealed the coordination microstructure of the emitter and fabricated a high-density, high-resolution, reusable X-ray imaging plate with a resolution of 22 lp / mm, which also possesses optical information memory storage capabilities. This invention provides new insights into the correlation between long-afterglow fluorescence dynamics and microenvironmental changes, thereby facilitating the expansion of high-energy nanophotonics applications, such as multiplex radiometric imaging and multimode information encryption.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A type of Mn 2+ Activating NaLuF4 nanoscintillators with single-doped Mn 2+ The NaLuF4:Mn(18%) nanocrystals are cubic phase with an average diameter of approximately 25 nm. They were obtained by doping with Gd at a concentration of 42 mol%. 3+ NaLuF4:Mn / Gd (18% / 42%) nanocrystals transformed into a hexagonal phase with an average diameter of approximately 50 nm. Using Gd... 3+ Completely replace the main body Lu 3+ At this time, NaGdF4:Mn(18%) nanocrystals maintained a hexagonal phase and were free of impurity phases, with an average diameter of approximately 25 nm. By gradually increasing the amount of Gd... 3+ When the doping level increases to about 50%, the nanoparticles transform from a cubic phase to a hexagonal phase.

[0008] NaLuF4:Mn with different doping concentrations (0, 22, 42, 52, and 82%) 2+ / Gd 3+ Preparation of (18 / x%): ① Mix NaOH solution (0.2 g / mL, 0.5 mL) with 5 mL ethanol and 5 mL oleic acid. ② Add 0.36 mL LmnCl2 (0.2 M), x mL LdCl3·xH2O (0.2 M), (1.64-x) mL LuCl3·xH2O (0.2 M), and 2 mL NaF (0.8 M) to the resulting mixture sequentially. ③ Transfer the well-stirred solution to a 25 mL PTFE-lined autoclave and heat at 200 °C for 12 h. ④ After cooling to room temperature, collect the product by centrifugation at 8000 rpm, wash several times with ethanol, and finally disperse in cyclohexane.

[0009] Further, the luminescence performance modulation of NaLnF4:Mn / Gd (18 / x%) nanoparticles:

[0010] a) The nanoparticles were excited with X-ray, and the spectra showed that the emission peak shifted from 580 nm to 512 nm as the Gd 3+ doping level increased to about 50%, and further increasing the Gd 3+ concentration caused the emission peak to red shift to 550 nm. Among them, the NaLuF4:Mn / Gd (18 / x%) nanocrystals exhibited the strongest radiation luminescence at 512 nm under X-ray irradiation.

[0011] b) After the excitation stopped, the residual signal was recorded. The residual emission signal recorded at the strongest radiation luminescence at 512 nm could last up to 108 hours, and the information could be read by heating even after 30 days of storage. Compared with Lu-based and Gd-based nanocrystals with different Mn 2+ doping concentrations, NaLuF4:Gd / Mn (42 / 18%) nanocrystals exhibited the longest residual lifetime, and multicolor residual emission could be achieved by changing the Mn 2+ concentration.

[0012] Further, high penetration, high resolution, persistent luminescence imaging applications:

[0013] a) Preparation of high penetration, high resolution, persistent luminescence imaging plates: A certain mass of NaLuF4:Mn 2+ / Gd 3+ (18 / 42%) nanocrystal material was uniformly laid in a mold with a diameter of 11 cm, then pressed with a tablet press and kept under 8 tons of pressure for 60 seconds. The thickness of the imaging plate was proportional to the mass of the NaLuF4:Mn 2+ / Gd 3+ (18 / 42%) nanocrystal solid powder. After careful demolding, a flat and compact NaLuF4:Mn 2+ / Gd 3+ (18 / 42%) high-density X-ray imaging plate was obtained.

[0014] b) High penetration, high resolution persistent luminescence imaging application: By placing the object between the X-ray excitation source and the prepared imaging plate, under the irradiation of X-ray, the imaging plate begins to collect and store the internal structure information of the object. After stopping the excitation, the structure information can be extracted from the imaging plate by heating means, which only needs to use a simple digital camera to read and record. By thoroughly heating, the stored information can be completely erased, along with the writing, reading, erasing of information. The imaging plate can be repeatedly used. The resolution of the imaging plate can reach 22 lp / mm by calculating the modulation transfer function, and very high-definition mouse bone images can also be obtained by using the above imaging method.

[0015] The beneficial effects of the present application are:

[0016] (1) The present application utilizes the characteristics of the more dispersed d orbitals of transition metal ions and the sensitivity to coordination environment, and realizes the regulation of emission wavelength and afterglow performance through the design of nanocrystal microstructure environment.

[0017] (2) The present application successfully images the internal structure of biological and electronic objects with a high resolution of 22 lp / mm by using the X-ray imaging plate prepared by the optimal ratio NaLuF4:Mn / Gd (18 / 42%) nanocrystals. The correlation between long afterglow fluorescence kinetics and microenvironment changes is revealed, which provides a reference for the development of new long afterglow long fluorescent materials. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Transmission electron microscopy (TEM) of NaLuF4:Mn 2+ / Gd 3+ (18 / x=0-82%) nanocrystals;

[0019] Figure 2 X-ray powder diffraction pattern (XRD) of NaLuF4:Mn 2+ / Gd 3+ (18 / x=0-82%) nanocrystals;

[0020] Figure 3 X-ray radiation luminescence spectrum of NaLuF4:Mn 2+ / Gd 3+ (18 / x=0-82%) nanocrystals;

[0021] Figure 4 Afterglow decay curve of nanocrystals activated by different manganese concentrations (recorded at room temperature after X-ray excitation stops);

[0022] Figure 5A photograph of NaLuF4:Mn / Gd(18 / 42%) nanocrystals dispersed in cyclohexane at room temperature.

[0023] Figure 6 This is a schematic diagram of a high-resolution continuous emission X-ray imaging process;

[0024] Figure 7 High-resolution X-ray imaging of mice: (ad) After X-ray irradiation was stopped, mouse skeleton images stored for different time periods were read using a digital camera; (e) Medical imaging of mouse fractures was performed with the aid of computer digital processing. Detailed Implementation

[0025] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0026] Example 1

[0027] NaLuF4:Mn with different doping concentrations (0, 22, 42, 52, and 82%) 2+ / Gd 3+ Preparation of (18 / x%):

[0028] First, a NaOH solution (0.2 g / mL, 0.5 mL) was mixed with 5 mL of ethanol and 5 mL of oleic acid. Then, 0.36 mL of MnCl2 (0.2 M), x mL of GdCl3·xH2O (0.2 M), (1.64-x) mL of LuCl3·xH2O (0.2 M), and 2 mL of NaF (0.8 M) were added sequentially to the resulting mixture. The solution was transferred to a 25 mL PTFE-lined autoclave and heated at 200 °C for 12 h. After cooling to room temperature, the product was collected by centrifugation at 8000 rpm, washed several times with ethanol, and finally dispersed in cyclohexane.

[0029] Figure 1 NaLuF4:Mn 2+ / Gd 3+ Transmission electron microscopy (TEM) of (18 / x=0-82%) nanocrystals.

[0030] For single-doped Mn 2+ The NaLuF4:Mn(18%) nanocrystals are cubic in phase, and transmission electron microscopy (TEM) images show that these nanoparticles exhibit a typical cubic shape. This was achieved by doping Gd at a concentration of 42 mol%. 3+ The NaLuF4:Mn / Gd (18% / 42%) nanocrystals transform into a hexagonal phase. Notably, these nanocrystals exhibit a hexagonal plate shape. When Gd... 3+Fully substituted host Lu 3+ The phase of NaGdF4:Mn (18%) nanocrystals remains hexagonal and is free of impurity phases.

[0031] Example 2

[0032] Radioluminescence and afterglow tuning of NaLnF4:Mn / Gd (18 / x%) nanoparticles

[0033] Step 1: A series of Mn 2+ and Gd 3+ co-doped NaLuF4 nanocrystals were synthesized using a typical hydrothermal method. The radioluminescence spectra of NaLuF4:Mn / Gd (18 / x = 0-82%) nanocrystals were recorded under X-ray excitation (50 kV, 80 μΑ). The trend of the radioluminescence of NaLnF4:Mn / Gd (18 / x = 0-82%) nanoparticles was measured as a function of Gd 3+ doping concentration.

[0034] Step 2: After 30 days of storage, the afterglow intensity can be recovered by heating at 120 °C (bottom). The afterglow decay curves of various Mn-activated nanocrystals were recorded at room temperature after the stop of X-ray excitation. The afterglow emission lasts up to 108 hours and information can be read by heating even after 30 days of storage.

[0035] Figure 3 As shown, the recorded spectra show a broad-band emission of Mn 2+ characteristic of d-d optical transitions. With increasing Gd 3+ concentration, the emission color changes from yellow to green. By increasing the doping level of Gd 3+ to about 50%, the emission peak shifts from 580 nm to 512 nm, while further increasing the Gd 3+ concentration results in a red-shift of the emission peak to 550 nm. Under X-ray irradiation, NaLuF4:Mn / Gd (18 / x%) nanocrystals exhibit the strongest radioluminescence at 512 nm.

[0036] Figure 4 As shown, the radioluminescence remains for a long time after the stop of excitation. The afterglow emission lasts up to 108 hours and information can be read by heating even after 30 days of storage. Compared to Lu-based and Gd-based nanocrystals with different Mn 2+ doping concentrations, NaLuF4:Gd / Mn (42 / 18%) nanocrystals exhibit the longest afterglow lifetime.

[0037] Figure 5As shown, these co-doped nanocrystals emit visible light after X-ray (50 kV, 200 μΑ) is turned off. No significant change in luminescence intensity is observed after 20 cycles of X-ray charging, by changing the Mn 2+ The concentration can easily achieve multicolor afterglow emission.

[0038] Example 3

[0039] High penetration, high resolution, persistent luminescence imaging application: A mass of NaLuF4:Mn 2+ / Gd 3+ (18 / 42%) nanocrystal material is uniformly spread in a 11 cm diameter mold, then pressed with a tablet press and kept under 8 tons of pressure for 60 seconds. The thickness of the plate is proportional to the mass of the NaLuF4:Mn 2+ / Gd 3+ (18 / 42%) nanocrystal solid powder. After careful demolding, a flat and compact NaLuF4:Mn 2+ / Gd 3+ (18 / 42%) high density X-ray imaging plate is obtained.

[0040] By placing the target object between the X-ray excitation source and the prepared imaging plate, under the irradiation of X-rays, the imaging plate begins to collect and store the internal structure information of the target object. After stopping the excitation, the structure information can be extracted from the imaging plate by heating means, which only needs to use a simple digital camera to read and record. By thoroughly heating, the stored information can be completely erased, along with the information writing, reading. Erasing, the imaging plate can be repeatedly used. The resolution of this imaging plate can reach 22 lp / mm by calculating the modulation transfer function, and very high-definition mouse skeleton images can also be obtained using the above imaging method.

[0041] Figure 6 As shown, the target object is placed between the X-ray imaging plate and the X-ray source. After X-ray irradiation, the X-ray imaging plate begins to store X-ray energy and remember the internal structure of the object. The schematic diagram of the afterglow X-ray imaging reading system is composed of a digital camera and a carefully designed sample injector, which contains a heater panel and an imaging plate tray. After the excitation is stopped, the X-ray imaging plate is transferred to the customized readout device for thermal activation and imaging readout.

[0042] Figure 7 As shown, the mouse structure information can be stored in the nanocrystals for 30 days after the X-ray irradiation is stopped. And the mouse fracture is imaged medically with the aid of computer digital processing, and the fracture is visualized.

[0043] The above-described specific embodiments can further illustrate the purposes, technical solutions and beneficial effects of the present application, but it should be understood that the above-described are only specific embodiments of the present application and are not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the principles of the present application shall be included in the protection scope of the present application.

Claims

1. A Mn 2+ activating NaLuF4 nanoscintillator characterized by: Mn 2+ Gd 3+ NaLuF4:Mn with a doping concentration of 22-82 mol% 2+ / Gd 3+ nanocrystals.

2. A process for the preparation of Mn 2+ A method of activating NaLuF4 nanoscintillators, characterized by: Comprising the following steps: (1) mixing NaOH solution, ethanol and oleic acid; (2) adding MnCl2 solution, GdCl3 solution, LuCl3 solution and NaF solution to the mixture of step (1) in turn, and stirring uniformly; (3) reacting at 200℃ for 12h; (4) After cooling to room temperature, centrifugation, washing with ethanol, the Mn 2+ Activate NaLuF4 nanoscintillator.

3. A Mn as claimed in claim 1 2+ The activated NaLuF4 nanoscintillator or the Mn prepared by the method as claimed in claim 2 2+ The activated NaLuF4 nanoscintillator is used for preparing a long-lasting luminescence imaging material.

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