RU2817555C1 - Method of producing nanopowder of red photoluminophor with prolonged afterglow - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to chemical engineering and can be used in medicine for photodynamic therapy (PDT) of internal organs. Initial components Al(NO₃)₃, Ga(NO₃)₃, La(NO₃), Mn(NO₃)₂, sodium tungstate Na₂WO₄, as well as Na₃C₆H₅O₇ are dissolved in water. Mixed solution is placed for 1 hour in an ultrasonic bath with power of 100 W with frequency of 44 kHz at temperature of 60 °C. Formed precipitate is separated, washed and dried in air at 90 °C for 12 hours. Then high-temperature annealing of the dried precipitate is carried out at temperature of 700 °C for one hour under argon pressure of 1.5⋅10⁷ Pa to improve crystallinity and prevent particle growth. Nanopowder of red photoluminophor with prolonged afterglow is obtained, having chemical formula La_1-x-y-zAl_xGa_yWO₆:Mn_z, where concentration of ions of aluminium Al⁺³ and gallium Ga⁺³ is 10 at.% and 6 at.% respectively, and concentration of ion-activator – Mn⁺⁴ is 2 at.%. Peak of the luminescence wavelength of the luminophor is in the red region of the spectrum and is equal to 668 nm.

EFFECT: particle size of the obtained powder is not more than 50 nm, which enables to obtain a colloidal solution suitable for introduction into a patient's body.

1 cl, 4 dwg

Description

Technical field

The invention relates to chemical technology, in particular to the production of ultraviolet (UV) photoluminophore nanopowders, and can be used in medicine for photodynamic therapy (PDT) of internal organs.

State of the art

Photodynamic therapy is a modern method of treating pretumor diseases and malignant neoplasms, based on the introduction into the body of a photosensitizer - a substance that can selectively accumulate in tumor tissue and produce active oxygen under the influence of light, which destroys tumor cells. Currently, the PDT method is widely used in the treatment of tumors with superficial localization. However, the use of the PDT method for treating internal organs is ineffective due to the difficulty of bringing light radiation inside, since visible light is actively absorbed in the tissues of the body. At the moment, the problem is solved by adding phosphor nanopowders to the photosensitizer solution, which emit visible light in the far red region of the spectrum (which is necessary for the effective operation of photosensitizers), followed by its activation with X-ray radiation. However, this requires the use of expensive X-ray equipment and fairly large doses of radiation (comparable to radionuclide therapy) to activate nanoluminophores, which is harmful to the human body.

To carry out photodynamic therapy (PDT) of internal organs, without irradiating the patient's body, you need a biocompatible photoluminophore with a long afterglow, excited by UV radiation, emitted visible light in the far red region of the spectrum with a wavelength of 665-670 nm, with a particle size of no more than 50 nm (to obtain a colloidal solution suitable for administration into the patient’s body).

UV photoluminophors with long afterglow based on the SrAl2O4:Eu, Dy compound are known from the prior art (US 5424006 A dated 07/13/1995, RU 2634024 dated 10/10/2016). Also known from the prior art is the work (K. Bedyal et al. Effect of swift heavy ion irradiation on structural, optical and luminescence properties of SrAl2O4:Eu, Dy nanophosphorA //Radiation Physics and Chemistry 122(2016)48-5452), where this the material is presented in the form of nanoparticles with a size of 23-33 nm. However, in these works, these materials are intended for use in luminous paints and ultraviolet tags. There is no data on their biocompatibility with the human body. In addition, the emission peak of these materials is in the blue-green region of the spectrum (wavelength 520 nm) and is unsuitable for excitation of photosensitizers.

Patent RU 2604619 dated July 30, 2015 describes a biocompatible photoluminophore based on Zn ₃ (PO ₄ ) ₂ : Mn, obtained in the form of nanoparticles with an average particle size of 55 nm and a red glow, with a peak at a wavelength of 632 nm. However, this material is activated by “hard” X-ray radiation with wavelengths in the range of 0.12...0.31 Å, does not have a long afterglow and does not correspond to the absorption peak of photosensitizers (for example, E6-Chlorin has an absorption peak of 665 nm).

The closest to this invention is a biocompatible UV photoluminophore and the method of its synthesis described in the work (K. Naveen Kumar, L. Vijayalakshmi, J. Lim et al. Non-cytotoxic Dy3+ activated La10W22O81 nanophosphors for UV cool based white LEDs and anticancer applications / / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 278 (2022) 121309). The disadvantage of this technical solution is the absence of a long afterglow of the described UV photoluminophore, luminescence in the yellow-orange region of the spectrum with a peak of 571 nm and a large particle size of 200-300 nm.

Disclosure of the invention

The objective of the invention is to increase the effectiveness of photodynamic therapy.

The technical result of the invention is to produce an ultraviolet photoluminescent phosphor with a long afterglow.

An additional technical result consists in the creation of technological operations for producing nanoparticles with a size of no more than 50 nm for the production of ultraviolet photoluminescent powder.

An additional technical result consists in obtaining a powder with a red luminescence spectrum with a peak wavelength of 668 nm.

The technical result is achieved using the proposed method, which consists in the fact that the synthesis of nanopowder red ultraviolet phosphor composition La _1-xyz Al _x Ga _y WO ₆ : Mn _z with a long afterglow is characterized by successive stages of precipitation from aqueous solutions of Al(NO ₃ ) ₃ nitrates , Ga(NO ₃ ) ₃ , La(NO ₃ ) ₃ , Mn(NO ₃ ) ₃ , sodium tungstate Na ₂ WO ₄ , sodium citrate Na ₃ C ₆ H ₅ O ₇ , under the influence of ultrasound, and high-temperature annealing of the deposit under pressure argon. At the first stage, spherical nanoparticles of ultraviolet photoluminophore with a size of 20 - 50 nm are formed, with low luminescence intensity, which is due to their low degree of crystallinity. (Figure 1.) It has been experimentally proven that for their formation, keeping an aqueous solution of the starting substances for 1 hour in an ultrasonic bath with a power of 100 W with a frequency of 44 kHz at a temperature of 60°C is sufficient. At the second stage, ultraviolet photoluminophore nanoparticles crystallize with the formation of nanorods measuring 20 nm by 50 nm (Figure 2.) It has been experimentally proven that an increase in the crystallinity of ultraviolet photoluminophore nanoparticles, without increasing their size, occurs during high-temperature annealing at a temperature of 700°C for 1 hours under argon pressure of 1.5⋅10 ⁷ Pa.

To obtain a far-red luminescence spectrum with a peak at a wavelength of 668 nm, the required concentration of manganese activator ions Mn ⁺⁴ in the ultraviolet photoluminophore is 2 at.%. (Fig. 3.)

The presence of gallium ions Ga ⁺³ and aluminum ions Al ⁺³ in the base of the ultraviolet photoluminophore in a concentration of 10 at.% and 6 at.% allows one to obtain the effect of a long afterglow (200 minutes) of the ultraviolet photoluminophor (Fig. 4).

The red emission spectrum of the ultraviolet photoluminophore with a peak at a wavelength of 668 nm allows one to effectively transmit the luminous energy flux to most photosensitizers used in medicine, and the long afterglow after irradiation with an ultraviolet lamp with a wavelength of 270 nm allows one to avoid irradiation of the body during photodynamic therapy. The 50 nm particle size of the resulting photoluminophore makes it possible to prepare a colloidal solution for their delivery to tumor formations in the body.

Description of drawings

In fig. Figure 1 shows an image of red ultraviolet photoluminescent phosphor nanospheres on a JEOL JEM-F200 transmission electron microscope.

In fig. Figure 2 shows an image of red ultraviolet photoluminescent phosphor nanorods on a JEOL JEM-F200 transmission electron microscope.

In fig. Figure 3 shows an image of the emission spectrum of a red ultraviolet photoluminophore.

In fig. Figure 4 shows an image of the visible afterglow of a red ultraviolet photoluminophore La _0.82 Al _0.1 Ga _0.06 WO ₆ : Mn _0.02 after removing the ultraviolet excitation source with a wavelength of 270 nm: a) 1 minute, b) 200 minutes.

Carrying out the invention

To obtain ultraviolet photoluminophore composition La_0.82 Al_0.1Ga_0.06WO₆: Mn_0.02, At the first stage of the synthesis, 35.46 g of La(NO₃)₃6H₂O, 2.85 g Al(NO₃)₃·4H₂O, 2.29 g Ga(NO₃)₃·7H₂O, 0.49 g Mn(NO₃)₂6H₂O, 32.9 g Na₂WO₄2H₂O and 2.48 g Na₃C₆H₅O₇2H₂O and dissolved in 500 ml of distilled water with vigorous stirring. Aluminum ion concentration Al⁺³ 10 at.% and gallium ions Ga⁺³ 6 at.%, and the concentration of the activator ion is Mn⁺⁴ is 2 at.%. Next, the solution is placed for 1 hour in an ultrasonic bath with a power of 100 W with a frequency of 44 kHz, at a temperature of 60°C. The resulting precipitate is centrifuged, washed with distilled water and dried in air at a temperature of 90°C for 12 hours. At the second stage of synthesis, the resulting powder is loaded into a corundum crucible with a capacity of 500 ml. The crucible is placed in a high-temperature, high-pressure furnace. The furnace is evacuated to 0.1 Pa, heated to a temperature of 700°C for one hour, and filled with argon to a pressure of 1.5⋅10⁷ Pa. After holding for one hour at a temperature of 700°C, the furnace is cooled to room temperature, the pressure is released and the resulting UV photoluminophor is unloaded.

Claims (1)

A method for producing photoluminophore nanopowder, including dissolving the starting components in water, separating, washing and drying the precipitate in air at 90°C for 12 hours, as well as its subsequent high-temperature annealing, characterized in that to obtain red photoluminophore nanopowder with a long afterglow La _{1 -xyz} Al _x Ga _y WO ₆ :Mn _z , in which the concentration of aluminum ions Al ⁺³ and gallium ions Ga ⁺³ is 10 at.% and 6 at.%, and the concentration of the activator ion – Mn ⁺⁴ is 2 at. %, Al( _NO3 ) ₃ , Ga( _NO3 ) ₃ , La( _{NO3 )} , _{Mn(NO3)2, sodium tungstate Na2WO4, and Na3C6H5O are used as starting components 7} , while the mixed solution is placed for 1 hour in an ultrasonic bath with a power of 100 W with an oscillation frequency of 44 kHz at a temperature of 60°C, after which the resulting precipitate is separated, washed and dried, and high-temperature annealing is carried out at a temperature of 700°C for one hour under argon pressure 1.5⋅10 ⁷ Pa.