Rod-shaped erbium-doped rare earth-based in-vivo fluorescent probe as well as preparation method and application thereof

Abstract

The invention discloses a rod-like erbium-doped rare earth-based in-vivo fluorescent probe as well as a preparation method and application thereof, and belongs to the technical field of synthesis of nano materials. The rod-like erbium-doped rare earth-based in-vivo fluorescent probe is NaYF4: Yb, Er (at) NaYF4: Yb of a rod-like core-shell structure, in the NaYF4: Yb and Er-coated NaYF4: Yb, NaYF4 is selected as a matrix, Yb < 3 + > is selected as a sensitizing agent, and Er < 3 + > is selected as an activating agent. The invention is applied to fluorescence imaging, and has the characteristics of excellent optical performance and capability of realizing high-resolution imaging of deep tissues.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material synthesis, and in particular relates to a rod-shaped erbium-doped rare earth-based living fluorescent probe, a preparation method and application thereof. Background Art

[0002] In vivo imaging plays an important role in the study of disease mechanisms, disease diagnosis and treatment, drug discovery, and clinical evaluation. Computed tomography, ultrasound scanning, magnetic resonance imaging, etc. have made significant progress in the field of whole-body imaging, which is particularly helpful for understanding and examining diseases such as femoral head necrosis. However, these imaging modes lack the ability to directly and quantitatively distinguish disease markers and drugs, and are unable to quantitatively distinguish disease markers or drug accumulation and drug target involvement in pathological sites, as well as unable to achieve real-time in vivo monitoring. Compared with the above imaging methods, near-infrared (NIR) imaging is lower in cost and faster in speed, filling the gap between high-cost whole-body scanning and low-cost surface scanning. This technology has the advantages of strong visualization, low cost, high sensitivity, high resolution, and real-time detection, so it has received widespread attention.

[0003] At present, NIR-Ⅰ imaging technology has been widely used in preclinical in vivo imaging studies. However, light with a wavelength less than 1000nm has strong scattering, which is also the main limitation of fluorescence imaging technology in vivo. Extending NIR imaging to the 1000-1700nm window can effectively improve the resolution of anatomical and dynamic imaging, increase tissue penetration depth, and has great potential for clinical transformation, and is widely used in biomedical research and disease diagnosis. To date, a variety of fluorescent agents emitting in the NIR-II region have been widely used for effective biosensing and real-time in vitro and in vivo imaging. They include single-walled carbon nanotubes, organic dyes, conjugated polymers, quantum dots, and rare earth-doped nanoparticles. However, most of them have shortcomings such as emission bandwidth, short accumulation time of organic dyes, high toxicity, low quantum yield, and low solubility of quantum dots, which hinder their further application in NIR-II imaging. Rare earth-doped nanoparticles have gradually become good candidate materials for NIR-II optical imaging because they show longer fluorescence lifetime, tunable emission wavelength, and lower biological toxicity. In particular, with the rapid development of rare earth nanoparticles, Er-doped nanoparticles have become a promising candidate for NIR-II optical imaging. 3+ The rare earth-based nanofluorescent probe has excellent optical properties such as narrow emission band, large anti-Stokes shift, and small background fluorescence interference. Under low-power laser excitation, it is expected to become a biological fluorescent probe with great application prospects. Summary of the invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a rod-shaped erbium-doped rare earth-based living fluorescent probe with excellent optical properties and capable of achieving high-resolution imaging of deep tissues, and a preparation method and application thereof.

[0005] In order to solve the technical problem, the technical solution adopted by the present invention is:

[0006] On the one hand, the present invention provides a rod-shaped erbium-doped rare earth-based living fluorescent probe, wherein the rod-shaped erbium-doped rare earth-based living fluorescent probe is a rod-shaped core-shell structure of NaYF 4 :Yb,Er@NaYF 4 :Yb; the NaYF 4 :Yb,Er@NaYF 4 :Yb, select NaYF 4 As a matrix, Yb 3+ As a sensitizer, Er 3+ As an activator.

[0007] Preferably, the NaYF 4 :Yb,Er@NaYF 4 :Yb, fixed Y 3+ , Yb 3+ , Er 3+ The total amount of the three ions is 1mmol, and Y 3+ :Yb 3+ The amount of substance ratio is 4:1.

[0008] Preferably, the NaYF 4 :Yb,Er@NaYF 4 :Yb including core nanoparticles NaYF 4 :Yb, Er and NaYF coated on the core nanoparticles 4 :Yb, Er outer shell NaYF 4 :Yb.

[0009] Another aspect of the present invention provides a method for preparing a rod-shaped erbium-doped rare earth-based living fluorescent probe as described in any of the above technical solutions, comprising a core nanoparticle NaYF 4 :Yb,Er preparation steps, shell NaYF 4 :Yb preparation step, the NaYF 4 :Yb,Er@NaYF 4 : Preparation steps of Yb.

[0010] Preferably, the core nanoparticle NaYF 4 :Yb,Er preparation steps include: ErCl 3 6H 2 O, YbCl3 6H 2 O, YCl 3 After mixing, deionized water, 1-octadecene and oleic acid were added in sequence, and the mixture was reacted at 90-156°C. After the reaction, the mixture was cooled to room temperature, and dissolved NH 4 F and NaOH methanol solution, heated to 110℃ and evacuated, nitrogen was introduced, and the temperature was gradually increased to 310℃, and finally anhydrous ethanol was added for centrifugation, and the precipitate was washed with cyclohexane to obtain spherical core nanoparticles NaYF 4 :Yb,Er.

[0011] Preferably, the shell NaYF 4 :Yb preparation steps include: YCl 3 YbCl 3 6H 2 O was added to ionized water, 1-octadecene, and oleic acid, and reacted at 90-156°C to obtain the shell NaYF 4 :Yb.

[0012] Preferably, the NaYF 4 :Yb,Er@NaYF 4 The preparation steps of Yb include: 4 :Yb,Er added to the shell NaYF 4 :Yb, react at 30-70℃, introduce NaYF 4 The matrix, methanol was evaporated, sealed and vacuumed, the temperature was gradually increased to 310°C, washed and centrifuged to obtain NaYF 4 :Yb,Er@NaYF 4 :Yb.

[0013] Preferably, the NaYF 4 :Yb,Er@NaYF 4 :Yb water modification step: polyvinyl pyrrolidone was added to deionized water and ultrasonicated until it was completely dissolved. Then, the NaYF 4 :Yb,Er@NaYF 4 :Yb was added to the above solution, stirred at room temperature for reaction, and the water-modified NaYF 4 :Yb,Er@NaYF 4 :Yb was washed by centrifugation.

[0014] The present invention also provides the use of the rod-shaped erbium-doped rare earth-based living fluorescent probe described in any of the above technical solutions in fluorescent imaging.

[0015] Preferably, the excitation wavelength used in fluorescence imaging is 980 nm.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides a rod-shaped erbium-doped rare earth-based living fluorescent probe by 4 :Yb,Er coated with an inert shell NaYF 4 :Yb, effectively preventing the nuclear layer NaYF 4 :Yb,Er in Er 3+ The phenomenon of intrinsic NIR-Ⅱ fluorescence quenching under the doping concentration makes the fluorescence intensity of the sample in the near-infrared II region enhanced by up to 85 times; compared with the conventional near-infrared I region fluorescent probe, it has a higher emission wavelength, thus showing stronger tissue penetration in imaging tests, and realizing high-resolution in vivo fluorescence imaging of deep tissues; it was injected in situ into the right leg of 4T1 breast cancer tumor-bearing mice, and presented high-resolution fluorescence images under 980nm excitation light. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The schematic diagram of the structure of the prepared rod-shaped erbium-doped rare earth-based living fluorescent probe;

[0019] Figure 2 The NaYF provided in Example 1 of the present invention 4 :Yb,xmol%Er@NaYF 4 : Transmission electron microscopy images of Yb (x = 20%, 40%, 60%, 80% and 100%) a, b, c, d, e, f samples;

[0020] Figure 3 The NaYF provided in Example 1 of the present invention 4 :Yb,xmol%Er@NaYF 4 : XRD spectra of Yb (x = 20%, 40%, 60%, 80% and 100%);

[0021] Figure 4 The infrared spectrum of the fluorescent probe provided in Example 1 of the present invention;

[0022] Figure 5 The NaYF provided in Example 1 of the present invention 4 :Emission spectra of Yb and Er;

[0023] Figure 6 The actual luminescence image of the fluorescent probe provided in Example 1 of the present invention;

[0024] Figure 7 The CIE coordinate diagram provided by Example 1 of the present invention;

[0025] Figure 8 The NaYF provided in Example 1 of the present invention4 :Yb,Er@NaYF 4 :Yb emission spectrum;

[0026] Fig. 9 This is an in vivo fluorescence image of a 4T1 breast cancer tumor-bearing mouse under 980nm excitation light after injection of the nanoprobe provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The technical scheme in the specific embodiment of the present invention is described in detail and completely below. Obviously, the described embodiment is only a part of the specific implementation of the overall technical scheme of the present invention, rather than all implementations. Based on the overall concept of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention.

[0028] On the one hand, the present invention provides a rod-shaped erbium-doped rare earth-based living fluorescent probe, such as Figure 1 As shown, the rod-shaped erbium-doped rare earth-based living fluorescent probe is a rod-shaped core-shell structure of NaYF 4 :Yb,Er@NaYF 4 :Yb; the NaYF 4 :Yb,Er@NaYF 4 :Yb, select NaYF 4 As a matrix, Yb 3+ As a sensitizer, Er 3+ As an activator. 4 :Yb,Er@NaYF 4 :Yb including core nanoparticles NaYF 4 :Yb, Er and NaYF coated on the core nanoparticles 4 :Yb, Er outer shell NaYF 4 :Yb. Through the core nanoparticles NaYF 4 :Yb,Er coated with an inert shell NaYF 4 :Yb, effectively preventing the nuclear layer NaYF 4 :Yb,Er in Er 3+ The phenomenon of intrinsic NIR-Ⅱ fluorescence quenching under the doping concentration makes the fluorescence intensity of the sample in the near-infrared II region enhanced by up to 84 times; compared with the conventional near-infrared I region fluorescent probe, it has a higher emission wavelength, thus showing stronger tissue penetration in imaging tests, and realizing high-resolution in vivo fluorescence imaging of deep tissues; it was injected in situ into the right leg of 4T1 breast cancer tumor-bearing mice, and presented high-resolution fluorescence images under 980nm excitation light.

[0029] The present invention adopts rare earth nanoparticles NaYF 4:Yb, Er as near-infrared second-zone fluorescence imaging probes, and coated with an inert shell NaYF 4 :Yb,Er, after coating with inert shell, the core sample was successfully prevented from 3+高 The optical properties of the core-shell samples are enhanced, especially for Er 3+ For samples with a doping concentration of 100 mol%, the fluorescence intensity in the near-infrared second zone was enhanced by 85 times, which effectively improved the imaging performance of the core sample, provided higher resolution for deep tissue fluorescence imaging, and achieved in vivo imaging in 4T1 breast cancer-bearing mice.

[0030] In a preferred embodiment, the NaYF 4 :Yb,Er@NaYF 4 :Yb, fixed Y 3+ , Yb 3+ , Er 3+ The total amount of the three ions is 1mmol, and Y 3+ :Yb 3+ The amount ratio of NaYF is 4:1. 4 :Yb,Er@NaYF 4 The proportion and proportion relationship of each component in NaYF is that the sample has a good morphology at this ratio, showing an elliptical or capsule shape, and the nanoparticle size is uniform. 4 :Yb inert shell significantly improves NaYF 4 :Yb, Er core layer luminescence efficiency, improve Yb 3+ and Er 3+ The energy transfer luminescence process in the doping system makes NaYF 4 :Yb,Er@NaYF 4 :The luminescence performance of Yb in NIR-Ⅰ and NIR-Ⅱ regions is enhanced.

[0031] Another aspect of the present invention provides a method for preparing a rod-shaped erbium-doped rare earth-based living fluorescent probe as described in any of the above technical solutions, comprising a core nanoparticle NaYF 4 :Yb,Er preparation steps, shell NaYF 4 :Yb preparation step, the NaYF 4 :Yb,Er@NaYF 4 : Preparation steps of Yb.

[0032] In a preferred embodiment, the core nanoparticle NaYF 4 :Yb,Er preparation steps include: ErCl 3 6H 2 O, YbCl 3 6H2 O, YCl 3 After mixing, deionized water, 1-octadecene and oleic acid were added in sequence, and the mixture was reacted at 90-156°C. After the reaction, the mixture was cooled to room temperature, and dissolved NH 4 F and NaOH methanol solution, heated to 110℃ and evacuated, nitrogen was introduced, and the temperature was gradually increased to 310℃, and finally anhydrous ethanol was added for centrifugation, and the precipitate was washed with cyclohexane to obtain spherical core nanoparticles NaYF 4 :Yb,Er.

[0033] Specifically include: Preparation of NaYF with core-shell by thermal decomposition 4 :Yb, Er, weigh ErCl according to the mass calculated by the doping ratio 3 6H 2 O, YbCl 3 6H 2 O, YCl 3 Add deionized water, 1-octadecene and oleic acid to a three-necked flask, and react at 90-156°C; sonicate to remove NH 4 F and NaOH were dispersed and completely dissolved in methanol to obtain a methanol solution, and the methanol solution was added into a three-necked flask, heated to 110°C and evacuated, nitrogen was introduced, and the temperature was gradually increased to 310°C. Finally, anhydrous ethanol was added and centrifuged (9000rpm, 5min), and the precipitate was taken and ultrasonically washed and dissolved with cyclohexane to obtain spherical core structure core nanoparticles.

[0034] In a preferred embodiment, the shell NaYF 4 :Yb preparation steps include: YCl 3 YbCl 3 6H 2 O was added to ionized water, 1-octadecene, and oleic acid, and reacted at 90-156°C to obtain the shell NaYF 4 :Yb.

[0035] In a preferred embodiment, the NaYF 4 :Yb,Er@NaYF 4 The preparation steps of Yb include: 4 :Yb,Er added to the shell NaYF 4 :Yb, react at 30-70℃, introduce NaYF 4 The matrix, methanol was evaporated, sealed and vacuumed, the temperature was gradually increased to 310°C, washed and centrifuged to obtain NaYF 4 :Yb,Er@NaYF 4 :Yb. Among them, NaYF 4 The introduction method of the matrix is ​​the same as that of the core nanoparticles NaYF 4NaYF:Yb,Er preparation steps 4 Matrix introduction method.

[0036] Finally, the target product NaYF 4 :Yb,xmol%Er@NaYF 4 :Yb (x=20%, 40%, 60%, 80% and 100%) was dissolved in 10 mL of cyclohexane to prepare a rod-shaped erbium-doped rare earth-based living fluorescent probe.

[0037] In a preferred embodiment, the NaYF 4 :Yb,Er@NaYF 4 :Yb water modification step: polyvinyl pyrrolidone was added to deionized water and ultrasonicated until it was completely dissolved. Then, the NaYF 4 :Yb,Er@NaYF 4 :Yb was added to the above solution, stirred at room temperature for reaction, and the water-modified NaYF 4 :Yb,Er@NaYF 4 :Yb was washed by centrifugation.

[0038] The present invention also provides the use of the rod-shaped erbium-doped rare earth-based living fluorescent probe described in any of the above technical solutions in fluorescent imaging.

[0039] Preferably, the excitation wavelength used in fluorescence imaging is 980 nm.

[0040] The above technical solution of the present invention provides a preparation method and application of a new rod-shaped erbium-doped rare earth-based living fluorescent probe with excellent optical properties and capable of achieving high-resolution imaging of deep tissues. During the research process, 20%, 40%, 60%, 80%, 100% Er were designed. 3+ Rod-shaped rare earth-based in vivo fluorescent probe with a doping concentration gradient.

[0041] Yf 4 :Yb,20%Er@NaYF 4 :Yb, doped with Er 3+ , Yb 3+ , Y 3+ The molar percentages of ErCl are 20%, 16%, and 64%, respectively. 3 6H 2 O, YbCl 3 6H 2 O, YCl 3 The amounts of reactants used were 0.07634 g, 0.0633 g, and 0.1240 g, respectively, denoted as a;

[0042] Yf 4:Yb,40%Er@NaYF 4 :Yb, doped with Er 3+ , Yb 3+ , Y 3+ The molar percentages of ErCl are 40%, 12%, and 48%, respectively. 3 6H 2 O, YbCl 3 6H 2 O, YCl 3 The amounts of reactants used were 0.1526 g, 0.0474 g, and 0.0930 g, respectively, denoted as b;

[0043] Yf 4 :Yb,60%Er@NaYF 4 :Yb, doped with Er 3+ , Yb 3+ , Y 3+ The molar percentages of ErCl are 60%, 8%, and 32%, respectively. 3 6H 2 O, YbCl 3 6H 2 O, YCl 3 The amounts of reactants used were 0.22902 g, 0.0316 g, and 0.0620 g, respectively, denoted as c;

[0044] Yf 4 :Yb,80%Er@NaYF 4 :Yb, doped with Er 3+ , Yb 3+ , Y 3+ The molar percentages of ErCl are 80%, 4%, and 16%, respectively. 3 6H 2 O, YbCl 3 6H 2 O, YCl 3 The amounts of reactants used were 0.30536 g, 0.0158 g, and 0.0310 g, respectively, denoted as d;

[0045] Yf 4 :Yb,100%Er@NaYF 4 :Yb, doped with Er 3+ , Yb 3+ , Y 3+ The molar percentages are 100%, 0%, and 0%, respectively. 3 6H 2 O, YbCl 3 6H 2 O, YCl 3The amounts of reactants used are 0.3817 g, 0.0000 g, and 0.0000 g, respectively, recorded as e.

[0046] The excitation wavelength used by the above erbium-doped rare earth-based in vivo fluorescent probes is 980 nm. The fluorescence intensity of the erbium-doped rare earth-based in vivo fluorescent probe at 1530 nm increases with the increase of erbium doping concentration, especially in the case of Er 3+ When the doping amount is 100%, the fluorescence intensity in the NIR-II region reaches the highest. 4 :Yb,Er@NaYF 4 :Yb fluorescence intensity in NIR-Ⅱ region and core-type NaYF 4 : Compared with Yb and Er, the strength is enhanced up to 85 times.

[0047] In order to more clearly and in detail introduce the rod-shaped erbium-doped rare earth-based living fluorescent probe provided by the embodiments of the present invention, its preparation method and application, the following will be described in conjunction with specific embodiments.

[0048] Example 1

[0049] The preparation process of the rod-shaped erbium-doped rare earth-based in vivo fluorescent probe includes:

[0050] Step 1: Weigh ErCl 3 6H 2 O, YbCl 3 6H 2 O, YCl 3 Add to a three-necked flask, and then add 1 mL of deionized water to the three-necked flask. Then add 15 mL of 1-octadecene and 6 mL of oleic acid, heat the mixed solution to 90 ° C until no bubbles emerge, and then heat to 105 ° C until no bubbles are generated, ensuring that the water in the flask is completely removed. After no bubbles emerge, increase the reaction temperature to 156 ° C, react for 1 hour, until there is no black drug residue, set the reaction temperature to 20 ° C, and let the system cool to room temperature.

[0051] Step 2: Weigh 4 mmol of NH 4 F, 2.5mmol NaOH, dissolved in 10mL methanol, ultrasonically washed to make NH 4 F and NaOH are dispersed and completely dissolved in methanol. After the reaction system cools to room temperature, add the prepared methanol solution to the three-necked flask. Heat to 60°C and keep for about 30 minutes. After no bubbles are generated in the system, seal it, heat the solution to 110°C and evacuate, and keep it for 30 minutes. Then, nitrogen is introduced into the three-necked flask, and the temperature is gradually increased to 310°C, and the reaction is carried out for 1 hour. After the reaction is completed, cool the system to room temperature.

[0052] Step 3: Weigh 0.446mmol of YCl3 and 0.05mmol YbCl 3 6H 2 O, add 1mL deionized water, 15mL 1-octadecene, 6mL oleic acid and add to a three-necked flask, add a high-temperature rotor, place the three-necked flask on a heating jacket and insert a thermocouple thermometer below the liquid surface. Turn on the ventilation device and stirring device, first heat to 90℃ until no bubbles are generated, and then heat to 105℃ until no bubbles are generated. Then increase the reaction temperature to 156℃, and cool to room temperature after reacting for 1h.

[0053] Step 4: Pour the previously washed core layer sample into the above-mentioned NaYF shell layer cooled to room temperature. 4 :Yb in a three-necked flask, heated to 70°C for 30 min and then cooled to 30°C. 4 Matrix, evaporate methanol, seal and evacuate, gradually increase the temperature to 310℃, wash and centrifuge.

[0054] Figure 2 Transmission electron microscopy image of the prepared rod-shaped erbium-doped rare earth-based living fluorescent probe. Figure 2 It can be found that most of the nanoparticles have uniform particle size, and NaYF 4 :Yb,Er@NaYF 4 :Yb is oval or capsule-shaped. The bright white part on the outer layer of the particle in the figure is oleic acid introduced on the surface of the particle.

[0055] Figure 3 The XRD pattern of the prepared rod-shaped erbium-doped rare earth-based living fluorescent probe is Figure 3 It can be found that there is no other reflection surface in the entire XRD test range. 3+ and Er 3+ The ions are completely dispersed in NaYF 4 This indicates that the hexagonal stacking of NaYF 4 :Formation of Yb, Er nanocrystals.

[0056] Figure 4 The infrared spectrum of the prepared rod-shaped erbium-doped rare earth-based living fluorescent probe is Figure 4 It can be found that the wave number is 2930cm -1 The characteristic peaks appearing around 2850cm are caused by the antisymmetric stretching vibration of the methylene group on oleic acid, while the peaks at 2850cm -1 The characteristic peaks appearing on the left and right are caused by the symmetric stretching vibration of methylene. - The characteristic peak around 1 is caused by the stretching vibration of the carbon-carbon double bond of oleic acid, at 1460 cm -1 The methylene CH bond is in-plane swinging vibration, and the last one is at 1360cm -1The absorption peaks at these two locations are characteristic absorption peaks of methyl groups. However, the carboxyl group at one end of the oleic acid carbon chain accounts for too small a proportion of the entire oleic acid, so no characteristic peaks related to the carboxyl group appear in the infrared spectrum. Sample NaYF 4 :Yb,Er and NaYF 4 :Yb,Er@NaYF 4 The functional groups and groups corresponding to the absorption peaks in the infrared spectrum of Yb are consistent with those of oleic acid, proving that NaYF was successfully synthesized. 4 :Yb,Er@NaYF 4 :Yb nanoparticles.

[0057] Figure 5 It shows that the Er doping ratio increases from 20mol% to 100mol% in NaYF 4 :Yb,Er core layer fluorescence intensity in the visible light region to NIR-Ⅰ region wavelength range and fluorescence intensity in the NIR-Ⅱ region wavelength range. Figure 5 It can be found that in the wavelength range from the visible light region to the NIR-Ⅰ region, with the increase of the Er element doping concentration, NaYF 4 : The green peak intensity of the Yb, Er core layer at wavelengths of 540nm and 650nm gradually decreases. 3+ As the doping concentration of NaYF increases, 4 : The luminescence peak of the Yb, Er core layer red-shifts from the visible region to the NIR-Ⅰ region. On the other hand, in the NIR-Ⅱ wavelength range, the Er 3+ The down-conversion peak at 1520nm weakens with the increase of Er doping concentration.

[0058] Figure 6 NaYF 4 :Yb,Er and NaYF 4 :Yb,Er@NaYF 4 : Actual luminescence of Yb sample under 980nm laser light. Figure 6 It can be found that for NaYF 4 :Yb, xmol% Er core, when x=20%, the sample actually emits green fluorescence, and as x increases, the green gradually fades until x=80% and x=100%, almost no light is emitted. 4 :Yb,xmol%Er@NaYF 4 :Yb sample, its actual luminescence changes from green to red with the increase of x value, and red shift occurs. 4 :After Yb, Er 3+ The core with doping concentration of 80% and 100% changes from being completely non-luminescent to emitting red light.

[0059] Figure 7 is the CIE chromaticity coordinate diagram, Figure 7 NaYF 4 :Yb,Er@NaYF 4 :CIE coordinate diagram of Yb sample and Figure 6 The description is consistent. Under 980nm excitation, with Er 3+ As the doping concentration increases, the sample color coordinates move from green to red.

[0060] Figure 8 NaYF 4 :Yb,Er@NaYF 4 :Yb emission spectrum. Figure 8 It can be found that the nuclear layer NaYF 4 Compared with Yb and Er, NaYF 4 :Yb,Er@NaYF 4 The upconversion fluorescence intensity of Yb samples at 540nm, 650nm and 800nm ​​is enhanced, which is comparable to NaYF 4 :Yb,Er strength is increased by more than 3 times, and after being coated with an inert shell, it is comparable to NaYF 4 :Yb, xmol%Er core has different results, NaYF 4 :Yb,xmol%Er@NaYF 4 The fluorescence intensity of Yb (x = 20%, 40%, 60%, 80% and 100%) at 1530 nm increases with the increase of x and reaches the highest when x = 100%. 4 :Yb,Er@NaYF 4 The fluorescence intensity of Yb samples in NIR-Ⅱ region is similar to that of NaYF 4 :Yb, Er compared to the maximum enhancement of 85 times, indicating that the kernel NaYF 4 :Yb,Er wrapped in an inert shell NaYF 4 :Yb effectively 3+ The emitted photons bounce back and are then transferred to Er 3+ , improved Yb 3+ and Er 3+ The energy transfer luminescence process in the doping system makes NaYF 4 :Yb,Er@NaYF 4 :The luminescence performance of Yb in NIR-Ⅰ and NIR-Ⅱ regions is enhanced.

[0061] Application Example 1: Using NaYF 4 :Yb,xmol%Er@NaYF 4:Yb (x = 20%, 40%, 60%, 80% and 100%) probes were used to perform near-infrared second-zone fluorescence imaging tests on 4T1 breast cancer cells and tumor-bearing mice in vivo and in vitro. The specific steps are as follows:

[0062] In vitro cell experiments: 4T1 cells were cultured in DMEM medium (high glucose, 10% fetal bovine serum, 100 IU / mL penicillin and 100 μg / mL streptomycin) in a 5% CO 2 The cells were transferred to a 96-well plate (10,000 cells per well) and different concentrations of Er were added to the plate. 3+ Doped (increasing from left to right) NaYF 4 :Yb,Er@NaYF 4 :Yb probe, incubated for 2.5h. After the cells and materials were incubated for a period of time, the well plate was placed under a near-infrared zone II in vivo imaging device for observation; In vivo mouse experiment: Take the NaYF obtained in Example 1 4 :Yb,100%Er@NaYF 4 :300 μL of Yb probe fluorescent probe was injected into 4T1 breast cancer tumor-bearing mice in situ. The mice were then placed under a near-infrared zone II in vivo imager for imaging, with an excitation light of 980 nm and a laser power density of 300 mW / cm 2 , the distribution of fluorescent probes in mice can be monitored by imaging under a 1600nm long-pass filter. Fig. 9 As shown in the figure, the in vitro NIR-Ⅱ fluorescence imaging test results (a-e) and (f-j) show that NaYF 4 :Yb and Er have weak fluorescence intensity in the NIR-Ⅱ region, and the imaging effect in the cell well plate is not obvious, while NaYF coated with an inert shell 4 :Yb,Er@NaYF 4 :Yb has good biocompatibility, the phagocytic effect gradually increases, and the fluorescence intensity (a-e) is significantly higher than that of NaYF without inert shell. 4 :Yb,Er(f~j). The in vivo fluorescence imaging test of mice showed that under the irradiation of 980nm excitation light, a fluorescence image with high resolution and obvious light and dark difference was presented, indicating that the synthesized nanoparticles NaYF with core-shell structure 4 :Yb,Er@NaYF 4 :Yb is more suitable for in vivo NIR-II region fluorescence imaging.

Claims

1. A rod-shaped erbium-doped rare earth-based living fluorescent probe, characterized in that: The rod-shaped erbium-doped rare earth-based living fluorescent probe is a rod-shaped core-shell structure of NaYF4:Yb, Er@NaYF4:Yb; in the NaYF4:Yb, Er@NaYF4:Yb, NaYF4 is selected as the matrix, Yb 3+ As a sensitizer, Er 3+ As an activator.

2. The rod-shaped erbium-doped rare earth-based living fluorescent probe according to claim 1, characterized in that: In the NaYF4:Yb,Er@NaYF4:Yb, Y is fixed 3+ , Yb 3+ , Er 3+ The total amount of the three ions is 1mmol, and Y 3+ :Yb 3+ The amount of substance ratio is 4:

1.

3. The rod-shaped erbium-doped rare earth-based living fluorescent probe according to claim 1, characterized in that: The NaYF4:Yb,Er@NaYF4:Yb comprises a core nanoparticle NaYF4:Yb,Er and a shell layer NaYF4:Yb coated outside the core nanoparticle NaYF4:Yb,Er.

4. The method for preparing a rod-shaped erbium-doped rare earth-based living fluorescent probe according to any one of claims 1 to 3, characterized in that: The invention comprises the steps of preparing the core nanoparticle NaYF4:Yb,Er, preparing the shell NaYF4:Yb and preparing the NaYF4:Yb,Er@NaYF4:Yb.

5. The method for preparing a rod-shaped erbium-doped rare earth-based living fluorescent probe according to claim 4, characterized in that: The preparation steps of the core nanoparticle NaYF4:Yb,Er include: mixing ErCl3·6H2O, YbCl3·6H2O and YCl3, adding deionized water, 1-octadecene and oleic acid in sequence, reacting at 90-156°C, cooling to room temperature after the reaction, adding a methanol solution in which NH4F and NaOH are dissolved, heating to 110°C and evacuating, introducing nitrogen, and gradually heating to 310°C, finally adding anhydrous ethanol and centrifuging, taking the precipitate and washing with cyclohexane to obtain spherical core nanoparticles NaYF4:Yb,Er.

6. The method for preparing a rod-shaped erbium-doped rare earth-based living fluorescent probe according to claim 5, characterized in that: The shell NaYF4:Yb preparation steps include: YCl3 and YbCl3·6H2O are added to ionized water, 1-octadecene and oleic acid, and reacted at 90-156°C to obtain the shell NaYF4:Yb.

7. The method for preparing a rod-shaped erbium-doped rare earth-based living fluorescent probe according to claim 6, characterized in that: The preparation steps of the NaYF4:Yb,Er@NaYF4:Yb include: adding the nanoparticles NaYF4:Yb,Er into the shell layer NaYF4:Yb, reacting at 30-70°C, introducing NaYF4 matrix, evaporating methanol, sealing and vacuuming, gradually heating to 310°C, washing and centrifuging to obtain NaYF4:Yb,Er@NaYF4:Yb.

8. The method for preparing a rod-shaped erbium-doped rare earth-based living fluorescent probe according to claim 7, characterized in that: The method also includes a step of performing water-transfer modification on the NaYF4:Yb, Er@NaYF4:Yb: adding polyvinyl pyrrolidone into deionized water, ultrasonicating until it is completely dissolved, then adding the NaYF4:Yb, Er@NaYF4:Yb into the above solution, stirring the reaction at room temperature, and then washing and centrifuging the water-transfer modified NaYF4:Yb, Er@NaYF4:Yb.

9. Use of the rod-shaped erbium-doped rare earth-based living fluorescent probe according to any one of claims 1 to 3 in fluorescent imaging.

10. The use of the rod-shaped erbium-doped rare earth-based living fluorescent probe in fluorescence imaging according to claim 9, characterized in that: The excitation wavelength used in fluorescence imaging was 980 nm.

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