Bi-TEMPO free radical platinum complex photosensitizer as well as preparation method and application thereof

Abstract

The invention provides a bi-TEMPO free radical platinum complex photosensitizer and a preparation method and application thereof, and belongs to the technical field of medical chemistry, the bi-TEMPO free radical platinum complex photosensitizer is obtained by a substitution terpyridine derivative and potassium chloroplatinate through a simple metal coordination method; the photosensitizer solves the problems that an existing PDT photosensitizer is low in light utilization efficiency and insufficient in antibacterial performance and has toxic and side effects, has the advantages of being high in light utilization efficiency, high in antibacterial performance, good in targeting performance and small in toxic and side effects, can be used for photodynamic therapy antibiosis and has a better sterilization effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical chemistry, and particularly relates to a linked TEMPO free radical platinum complex photosensitizer, a preparation method thereof, and an application thereof. Background Art

[0002] The pathogenicity of pathogenic microorganisms has become a global security issue, which is not only related to the health of all mankind, but also concerns the development of the entire national economy. Due to the overuse and abuse of antibiotics, the problem of antibacterial drug resistance has become a major challenge in the field of global public health. There are a wide variety of existing antibacterial drugs, the development pace of new antibiotics is slow, and the development speed of microbial resistance to new drugs far exceeds the drug research and development speed, which makes it extremely urgent to find new antibacterial strategies. Photodynamic therapy (PDT) antibacterial is a non-traditional antibacterial method. Since the concept of PDT was proposed by Paul Ehrlich in the early 20th century, PDT has been widely used in many medical fields such as dermatology, ophthalmology, oncology, etc. PDT has a broad-spectrum killing effect on microorganisms such as bacteria, fungi, and viruses by generating reactive oxygen species, and it is not easy to produce drug resistance, and it has been proven to be effective against a variety of drug-resistant strains.

[0003] The drug resistance of common antibacterial drugs is a very common and urgent problem, and antibacterial photodynamic therapy (PDT) provides an effective way to solve this thorny problem. For photodynamic therapy (PDT) antibacterial, the core key technology lies in the structural design of PDT photosensitizers and the development of photodynamic efficacy.

[0004] So far, many photosensitizers have been reported and widely used in antibacterial phototherapy, such as organic photosensitizers, aggregation-induced emission photosensitizers, etc. However, the current photosensitizers have many problems: on the one hand, in terms of synthesis, the synthesis of photosensitizers is usually difficult, which limits their large-scale production and application; on the other hand, in terms of performance, some photosensitizers have a short maximum absorption wavelength and a low molar absorption coefficient, which makes their light utilization efficiency not high, and there is also a problem of low singlet oxygen yield, thus affecting the antibacterial effect. In addition, some photosensitizers have certain toxic side effects, which not only may pose potential risks to human health, but also limit their application scope in clinical treatment.

[0005] In summary, a good PDT photosensitizer should have the following characteristics: a simple synthesis process for easy large-scale production; a longer maximum absorption wavelength (red light or near-infrared) and a larger molar extinction coefficient to improve the light utilization efficiency; a high singlet oxygen yield to enhance the antibacterial effect; good targeting to bacteria to reduce damage to normal cells; and low toxic side effects on normal human cells to ensure the safety of use. Summary of the Invention

[0006] To solve the problems of low light utilization efficiency, insufficient antibacterial performance, and toxic side effects existing in existing PDT photosensitizers, the present invention provides a conjugated TEMPO radical platinum complex photosensitizer, which has the advantages of high light utilization efficiency, strong antibacterial performance, good targeting, and low toxic side effects, can be used for antibacterial photodynamic therapy, and has a stronger bactericidal effect.

[0007] The present invention also provides a preparation method and application of the conjugated TEMPO radical platinum complex photosensitizer.

[0008] The present invention is achieved through the following technical solutions: The present invention provides a conjugated TEMPO radical platinum complex photosensitizer, and the structural formula of the conjugated TEMPO radical platinum complex photosensitizer is as follows: 。

[0009] Based on the same inventive concept, the present invention provides a preparation method of the conjugated TEMPO radical platinum complex photosensitizer, and the preparation method includes: Adding glacial acetic acid and 1,5-cyclooctadiene to a potassium tetrachloroplatinate solution, and then heating to 90 ± 5 °C and holding for 30 - 60 min to obtain a mixture; Performing reduced pressure evaporation treatment on the mixture, and then performing solid-liquid separation, washing, and drying to obtain dichloro-1,5-cyclooctadiene platinum complex, that is, Pt(COD)Cl2; Dispersing KOH in an organic solvent, and successively adding 4-Cl-2,2,6,6-tetramethylpiperidine-1-oxyl radical and 4'-OH-2,2':6',2''-terpyridine to the obtained suspension, and then heating to 50 ± 5 °C and stirring and reacting for 10 - 22 h to obtain a reaction solution; Adding an equal volume of water to the reaction solution to perform a quenching reaction, and then performing solid-liquid separation, drying, and recrystallization to obtain ligand L, that is, terpy-TEMPO; Dispersing Pt(COD)Cl2 in an organic solvent, and then adding methanol in which ligand L is dispersed, and placing it at 50 ± 5 °C and stirring and reacting for 2 - 4 h to obtain a clear mixed solution; Adding an equal volume of ether to the cooled clear mixed solution, and then performing solid-liquid separation, washing, and drying to obtain a conjugated TEMPO terpyridine platinum complex, denoted as complex 1, that is, [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH; [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and cuprous iodide (CuI) were co-dispersed in N,N-dimethylformamide (DMF), then triphenylphosphine (PPh3) and triethylamine were added, and the reaction was carried out in the dark. After the reaction, diethyl ether was added for quenching reaction, and then solid-liquid separation, washing and drying were carried out to obtain the linked TEMPO radical platinum complex, denoted as Complex 2, namely [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH.

[0010] Further, glacial acetic acid and 1,5-cyclooctadiene were added to the potassium tetrachloroplatinate solution, and then the temperature was raised to 90 ± 5 °C and kept warm for 30 - 60 min to obtain a mixture, specifically including: Glacial acetic acid and 1,5-cyclooctadiene were added to the potassium tetrachloroplatinate solution, and the obtained mixed solution was heated to 90 ± 5 °C and kept warm for 30 - 60 min to obtain a mixture; Among them, the molar ratio of potassium tetrachloroplatinate, glacial acetic acid and 1,5-cyclooctadiene in the mixed solution was (1 - 3):(5.3 - 13):(4 - 8); The concentration of potassium tetrachloroplatinate in the mixed solution was 1% - 12%.

[0011] Further, the mixture was subjected to reduced-pressure evaporation treatment, and then solid-liquid separation, washing and drying were carried out to obtain the dichloro-1,5-cyclooctadiene platinum complex, namely Pt(COD)Cl2, specifically including: The mixture was subjected to reduced-pressure evaporation treatment, and then solid-liquid separation was carried out. The obtained solid was washed successively with deionized water, methanol and diethyl ether, and dried to obtain the dichloro-1,5-cyclooctadiene platinum complex, namely Pt(COD)Cl2.

[0012] Further, KOH was dispersed in an organic solvent, and 4-Cl-2,2,6,6-tetramethylpiperidine-1-oxyl radical and 4’-OH-2,2’:6’,2’’-terpyridine were successively added to the obtained suspension, and then the temperature was raised to 50 ± 5 °C and stirred for reaction for 10 - 22 h to obtain a reaction solution, specifically including: KOH was dispersed in DMSO, and 4-Cl-2,2,6,6-tetramethylpiperidine-1-oxyl radical and 4’-OH-2,2’:6’,2’’-terpyridine were successively added to the obtained suspension, and then the temperature was raised to 50 ± 5 °C and stirred for reaction for 10 - 22 h to obtain a reaction solution; Among them, the molar ratio of KOH, 4-Cl-2,2,6,6-tetramethylpiperidine-1-oxyl radical and 4’-OH-2,2’:6’,2’’-terpyridine was (6 - 8):(1 - 2.5):(1 - 2); The concentration of KOH in the suspension was 6% - 26%.

[0013] Further, an equal volume of water is added to the reaction solution for quenching reaction, followed by solid-liquid separation, drying, and recrystallization to obtain ligand L, namely terpy-TEMPO, which specifically includes: An equal volume of water is added to the reaction solution for quenching reaction, followed by solid-liquid separation. The obtained solid is dried under reduced pressure at 50 ± 5 °C, and the obtained crude product is dissolved in a cyclohexane solution for recrystallization to obtain ligand L, namely terpy-TEMPO.

[0014] Further, Pt(COD)Cl2 is dispersed in an organic solvent, and then methanol dispersed with ligand L is added. The mixture is stirred at 50 ± 5 °C for 2 - 4 h to obtain a clear mixture, which specifically includes: Pt(COD)Cl2 is dispersed in an organic solvent, and then methanol dispersed with ligand L is added. The obtained reaction mixture is stirred at 50 ± 5 °C for 2 - 4 h to obtain a clear mixture; Among them, the molar ratio of Pt(COD)Cl2 to ligand L in the reaction mixture is (1.5 - 4):(1 - 3); The concentration of Pt(COD)Cl2 in the reaction mixture is 1.5% - 12%.

[0015] Further, an equal volume of ether is added to the cooled clear mixture, followed by solid-liquid separation, washing, and drying to obtain a terpyridine platinum complex linked with TEMPO, denoted as complex 1, namely [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH, which specifically includes: An equal volume of ether is added to the cooled clear mixture, followed by solid-liquid separation. The obtained precipitate is washed several times with methanol and ether, and dried under vacuum to obtain a terpyridine platinum complex linked with TEMPO, denoted as complex 1, namely [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH.

[0016] Further, [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and cuprous iodide are jointly dispersed in N,N-dimethylformamide, and then triphenylphosphine and triethylamine are added. The reaction is carried out in the dark. After the reaction is completed, ether is added for quenching reaction, followed by solid-liquid separation, washing, and drying to obtain a TEMPO-free radical platinum complex, denoted as complex 2, namely [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH, which specifically includes: [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and cuprous iodide were co-dispersed in N,N-dimethylformamide, then triphenylphosphine was added, and the mixture was stirred and heated under N2 protection. Then triethylamine was added, and the reaction was carried out in the dark. After the reaction was completed, diethyl ether was added for quenching reaction. Then, solid-liquid separation, washing and drying were carried out to obtain the linked TEMPO radical platinum complex, denoted as Complex 2, namely [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH; Among them, the molar ratio of [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH, cuprous iodide, triphenylphosphine and triethylamine in the reaction system is (3-7):(0.5-2.5):(6-15):(10-18); The concentration of triphenylphosphine in the reaction system is 0.7%-5%.

[0017] Based on the same inventive concept, the present invention provides an application of a linked TEMPO radical platinum complex photosensitizer in the preparation of a bactericide or an antibacterial photodynamic therapy drug.

[0018] Based on the same inventive concept, the present invention also provides an antibacterial photodynamic therapy drug, and the active ingredient of the drug includes the above-mentioned linked TEMPO radical platinum complex photosensitizer.

[0019] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages: 1. In the preparation method of the linked TEMPO radical platinum complex photosensitizer of the present invention, a substituted terpyridine (4'-substituted-2,2':6',2''-terpyridine) derivative and potassium chloroplatinate are used to synthesize a class of terpyridine platinum complex photosensitizers linked with TEMPO (2,2,6,6-tetramethylpiperidine oxide) radicals through a simple metal coordination method. This transition metal complex has excellent dual photodynamic sterilization effects induced by radicals and platinum metal complexes. It can well solve the problem of bacterial drug resistance when used in bacterial photodynamic therapy. At the same time, the synthesis process is simple, the product yield is high, the absorption wavelength of the obtained photosensitizer product is in the white light band (about 400-480 nm), the molar extinction coefficient is large, the singlet oxygen yield is high, the targeting property is high, and the toxicity to normal cells is small. It is expected to become an excellent antibacterial photodynamic therapy drug, bringing a new antibacterial strategy to the antibacterial medical cause in China and providing a new idea for ensuring people's health.

[0020] 2. A TEMPO - radical - linked platinum complex photosensitizer of the present invention. This photosensitizer is almost non - toxic to normal cells, has high safety, and has a high singlet oxygen yield. Moreover, the structure of this photosensitizer is stable and its properties are stable under light irradiation conditions. The terpyridine platinum complex prepared in the present invention is a radical - enhanced photosensitizer, which has a stronger bactericidal effect and can be applied to the preparation of antibacterial agents or antibacterial photodynamic therapy drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is the synthetic process route diagram of [Pt(terpy - TEMPO)(PPh3)]·Cl·H2O·CH3OH of the present invention.

[0023] Figure 2 It is the fluorescence emission spectra of complex 1 reacting with DHR123 at 0 min, 10 min, 20 min, and 30 min.

[0024] Figure 3 It is the fluorescence emission spectra of complex 2 reacting with DHR123 at 0 min, 10 min, 20 min, and 30 min.

[0025] Figure 4 It is the ultraviolet spectra of complex 1 reacting with ABDA at 0 min, 10 min, 20 min, 30 min and reacting under light - shielding conditions for 30 min.

[0026] Figure 5 It is the ultraviolet spectra of complex 2 reacting with ABDA at 0 min, 10 min, 20 min, 30 min and reacting under light - shielding conditions for 30 min.

[0027] Figure 6 It is the cytotoxicity test results of complex 1 and complex 2. DETAILED DESCRIPTION OF THE INVENTION

[0028] The following will specifically describe the present invention in combination with specific embodiments and examples, and the advantages and various effects of the present invention will be presented more clearly therefrom. Those skilled in the art should understand that these specific embodiments and examples are used to illustrate the present invention, rather than to limit the present invention.

[0029] Throughout the specification, unless otherwise specifically stated, the terms used herein shall be construed as having the meanings as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention pertains. In case of any contradiction, the present specification shall prevail.

[0030] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0031] Next, a kind of linked TEMPO radical platinum complex photosensitizer, its preparation method and application of the present application will be described in detail with reference to examples and experimental data.

[0032] Example 1: As Figure 1 shown, the present example provides a preparation method of a linked TEMPO radical platinum complex photosensitizer, which is specifically as follows: 1. Synthesis of Complex 1: (1) In a 1000 ml reaction flask, 12.5 g of potassium tetrachloroplatinate (K2PtC14) is dissolved in 200 ml of deionized water, stirred evenly until a clear orange - red solution is obtained, and then filtered (the purpose is to remove impurities insoluble in water. If potassium tetrachloroplatinate is completely and thoroughly dissolved in water, this filtration step can be omitted). Add 12.5 ml of glacial acetic acid and 12.5 ml of analytical - grade 1,5 - cyclooctadiene to the above - mentioned clear solution. Rapidly stir the mixture and heat it in a water bath to 90 ± 5 °C. After heating for about 30 - 60 min, the clear orange - red solution gradually turns light yellow, and fine crystal precipitates come out. Stop heating, immediately evaporate the mixture under reduced pressure to 150 ml of solution. During this process, a large amount of solid will precipitate. Filter the solution and collect the pale - yellow solid. Wash the solid continuously with 250 ml of deionized water, methanol, and ether to remove the raw materials, dry it, and obtain Pt(COD)Cl2 solid. Weigh it and get 11.1 g, with a yield of 99%.

[0033] Elemental analysis of [Pt(COD)Cl2], theoretical values: C, 25.67; H, 3.21; experimental values: C, 25.56; H, 3.19. The synthesized [Pt(COD)Cl2] is used directly when synthesizing other complexes next time without recrystallization again.

[0034] (2) In a 1000 ml reaction flask, add 175 ml of DMSO solution and then add 13.2 g of dry KOH powder, and stir evenly. Add 10.00 g of 4-Cl-2,2,6,6-tetramethylpiperidine-N-oxyl radical to the above suspension, then add 13 g of 4'-OH-2,2':6',2''-terpyridine. Raise the temperature to 50 ± 5 °C and stir and heat in an oil bath for 10 - 22 h. After the reaction is completed, add deionized water with the same volume as the reaction solution to the reaction flask to quench the reaction, and light pink flocculent solids immediately appear in the round-bottom flask. Filter to obtain solids, and dry under reduced pressure at 50 ± 5 °C to remove water. The obtained crude product is redissolved in a hot cyclohexane solution. If there are solid impurities in the solution, filter while it is hot to remove the impurities. Cool at room temperature and recrystallize. After recrystallization is completed, feathery pink needle-shaped crystals are obtained, which is the ligand L: terpy-TEMPO.

[0035] Yield of terpy-TEMPO: 19.5 g; Yield rate: 81%; Melting point: 128 - 130 °C. Mass spectrometry detection ESI-MS: [M+H] + 404.01, 426.13. Elemental analysis C 12 H 27 N4O2, Theoretical value: C, 71.44; H, 6.74; N, 13.90. Experimental value (%): C, 71.09; H, 6.72; N, 13.87.

[0036] (3) Slowly add 100 ml of a methanol solution containing 8.05 g of ligand L (i.e., terpy-TEMPO in Figure 1 ) to a mixed solution formed by 11.3 g of [Pt(COD)Cl2] and 500 ml of methanol solution in a 1000 ml reaction flask, and stir and heat in an oil bath at 50 ± 5 °C for reaction. After about 10 - 60 minutes, the light yellow suspension slowly turns into a clear deep yellow solution, and continue to heat and stir for 2 - 3 hours until the raw materials react completely. After the clear mixed solution is cooled to room temperature, add an equal volume of ether solution, and flocculent precipitates immediately appear in the solution. Filter, collect the precipitate, and wash it three times with 250 ml of methanol and three times with 250 ml of ether. Finally, dry the solid in a vacuum drying oven under reduced pressure overnight to obtain 13.4 g of the product [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH (i.e., complex 1), and the yield rate is 95%. ESI-MS: [M-Cl] + 634.5. Elemental analysis C 25 H 33Cl2N4O5Pt, theoretical values: C, 41.72; H, 4.62; N, 7.79. Experimental values: C, 41.63; H, 4.64; N, 7.70.

[0037] 2. Complex 2: Synthesis of [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH: ; Mix 0.7 g of [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and 0.06 g of CuI in 100 ml of DMF solution in a 200 ml three-necked flask. Add 0.52 g of triphenylphosphine (PPh3). Under N2 protection, stir and heat in an oil bath at 55 ± 3 °C. Subsequently, inject 0.3 ml of triethylamine with a syringe. React in the dark for about 48 h. After the reaction mixture turns into a dark brown solution, add 500 ml of ether in three portions to quench the reaction and precipitate the ocher solid. Filter the ocher solid with a sintered glass funnel and wash the solid with 10 ml of ether. Place the solid in the sintered glass funnel in a vacuum drying oven and dry overnight to obtain the solid of [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH, which is Complex 2, weighing 0.67 g with a yield of 96%.

[0038] Example 2: This example provides a preparation method of a linked TEMPO radical platinum complex photosensitizer. Step 1 is the same as that in Example 1, and Step 2 is as follows: Mix 10 g of [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and 1 g of CuI in 100 ml of DMF solution in a 200 ml three-necked flask. Add 1.5 g of triphenylphosphine (PPh3). Under N2 protection, stir and heat in an oil bath at 65 ± 3 °C. Subsequently, inject 2 ml of triethylamine with a syringe. React in the dark for about 48 h. After the reaction mixture turns into a dark brown solution, add 500 ml of ether in three portions to quench the reaction and precipitate the ocher solid. Filter the ocher solid with a sintered glass funnel and wash the solid with 50 ml of ether. Place the solid in the sintered glass funnel in a vacuum drying oven and dry overnight to obtain the solid of [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH, which is Complex 2, weighing 0.82 g with a yield of 76%.

[0039] Example 3: This example provides a preparation method of a linked TEMPO radical platinum complex photosensitizer. Step 1 is the same as that in Example 1, and Step 2 is as follows: In a 200 ml three-necked flask, 0.9 g of [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and 0.1 g of CuI were mixed in 100 ml of DMF solution. 1 g of triphenylphosphine (PPh3) was added. Under N2 protection, the mixture was stirred and heated in an oil bath at 75 ± 3 °C. Subsequently, 0.6 ml of triethylamine was injected with a syringe. The reaction was carried out in the dark for about 24 h. After the reaction mixture turned into a dark brown solution, 500 ml of ether was added in three portions to quench the reaction and precipitate the ochre solid. The ochre solid was filtered through a sintered glass funnel and then washed with 20 ml of ether. The solid in the sintered glass funnel was placed in a vacuum drying oven and dried overnight to obtain the solid of [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH, which was Complex 2, weighing 0.97 g with a yield of 85%.

[0040] Example 4: This example provides a method for preparing a binuclear TEMPO radical platinum complex photosensitizer. Step 1 is the same as that in Example 1, and Step 2 is as follows: In a 200 ml three-necked flask, 12 g of [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and 0.06 g of CuI were mixed in 100 ml of DMF solution. 1.3 g of triphenylphosphine (PPh3) was added. Under N2 protection, the mixture was stirred and heated in an oil bath at 85 ± 3 °C. Subsequently, 1 ml of triethylamine was injected with a syringe. The reaction was carried out in the dark for about 12 h. After the reaction mixture turned into a dark brown solution, 500 ml of ether was added in three portions to quench the reaction and precipitate the ochre solid. The ochre solid was filtered through a sintered glass funnel and then washed with 20 ml of ether. The solid in the sintered glass funnel was placed in a vacuum drying oven and dried overnight to obtain the solid of [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH, which was Complex 2, weighing 0.75 g with a yield of 74%. The theoretical calculated values of the elemental analysis of Complex 1 (C 42 H 42 N4O2PtP2F6) are: C, 50.15; H, 4.21; N, 5.57, and the experimental results are C, 52.2; H, 3.99; N, 5.74.

[0041] Example 5: This example examines the oxygen production types and capabilities of Complexes 1 and 2.

[0042] The reagents involved in the process described in this example include: Dihydrorhodamine 123 (DHR123), methanol, ABDA (9,10-anthracenediyl-bis(methylene)dicarboxylic acid), dimethyl sulfoxide solution (DMSO), phosphate buffer solution (PBS), and deionized water.

[0043] Instruments: LED light strip, fluorescence spectrophotometer, ultraviolet spectrophotometer.

[0044] Under the condition of phosphate buffer solution, upon quantitative light excitation, two typical dyes, namely Dihydrorhodamine 123 (DHR123) and 9,10-anthracenediyl-bis(methylene)dicarboxylic acid (ABDA), were used to react with Complex 1 and Complex 2 respectively, and the changes in the ultraviolet absorption spectra of the two dyes were detected to determine whether the singlet oxygen generated by Complex 1 and Complex 2 is type I singlet oxygen or type II singlet oxygen. The ability to generate singlet oxygen was judged according to the change rate of the ultraviolet spectrum diagram.

[0045] Reaction reagents and dosages: 1 ml of 5 mM Dihydrorhodamine 123 (DHR123) stock solution; 1 ml of 5 mM 9,10-anthracenediyl-bis(methylene)dicarboxylic acid (ABDA) stock solution; 10 ml of phosphate buffer solution (PBS); 10 ml of dimethyl sulfoxide solution (DMSO); appropriate amount of deionized water; appropriate amount of methanol solution.

[0046] Reaction conditions: Room temperature condition (25 °C).

[0047] Detection of type I singlet oxygen (O2 •− ) Detection of type I singlet oxygen (O2 •− ) was carried out using Dihydrorhodamine 123 (DHR123) as an indicator to measure the generation of O2 •− . The experimental operation method is as follows: Take 5 μL of DHR123 stock solution (5 mM, dissolved in DMSO) and add it to 5 mL of phosphate buffer solution (PBS) containing Complex 1 or Complex 2 (10 μM). Irradiate with a white LED light strip (15 mW cm⁻²) at room temperature, and monitor the fluorescence signal of DHR123 at 0 minute, 10 minutes, 20 minutes, and 30 minutes respectively, with an excitation wavelength of 495 nm. Record the fluorescence intensity at 525 nm to indicate the generation of O2 •− .

[0048]

[0049] Analysis of the detection results of type I singlet oxygen: Since the dihydrorhodamine 123 (DHR123) indicator detects type I singlet oxygen, the stronger the fluorescence intensity detected in the experiment, the stronger the ability to generate type I singlet oxygen. The detection results show that both complex 1 and complex 2 can generate a certain amount of type I singlet oxygen. After 30 minutes of photocatalysis, complex 2 induces stronger fluorescence of DHR123, proving that the ability of complex 2 to generate type I singlet oxygen is stronger than that of complex 1.

[0050] Detection of type II singlet oxygen (O2 •− ): The detection of type II singlet oxygen ( 1 O2 ) is carried out using 9,10-anthracenediyl-bis(methylene)-dimalonic acid (ABDA) as an indicator for the determination of 1 O2 generation. The operation method is as follows: Add 5 μL of ABDA stock solution (5 mM, dissolved in DMSO) to 5 mL of phosphate buffer (PBS) containing complex 1 or complex 2 (10 μM). Irradiate with a white LED light strip (15 mW cm⁻²) at room temperature, and monitor the absorption spectrum of ABDA in the range of 330 - 450 nm at 0 minutes, 10 minutes, 20 minutes, and 30 minutes respectively. Record the absorption spectrum in the range of 330 - 450 nm to indicate 1 the generation of

[0051]

[0052] Analysis of the detection results of type II singlet oxygen: Since the 9,10-anthracenediyl-bis(methylene)-dimalonic acid (ABDA) indicator detects type II singlet oxygen ( 1 O2 ), the stronger its absorption intensity, the stronger the ability to induce the generation of type II singlet oxygen. The detection results show that there is no obvious increase in the ultraviolet absorption spectrum after the reaction of complex 1 with ABDA, indicating that the ability of complex 1 to generate type II singlet oxygen is weak. After the reaction of complex 2 with ABDA, its ultraviolet absorption spectrum increases with the increase of the photoinduced time and stabilizes after 30 minutes, indicating that the ability of complex 2 to generate type II singlet oxygen is strong.

[0053] Figure 2In it, the mixed solution of complex 1 and DHR123 was irradiated with white light at room temperature for 0 min, 10 min, 20 min, and 30 min, and the fluorescence intensity at the excitation wavelength of 495 nm and the emission wavelength of 525 nm was measured. It was found that the fluorescence intensity at the initial 0 min was the lowest, gradually increased over time, and reached a stable peak at 30 min. Since the Dihydrorhodamine 123 (DHR123) indicator detects singlet oxygen of type I, the stronger the fluorescence intensity detected in the experiment, the stronger the ability to generate singlet oxygen of type I. The detection results showed that complex 1 induced DHR123 to produce fluorescence. After 30 min of photocatalysis, the fluorescence intensity reached a stable value, indicating that the concentration of singlet oxygen of type I also reached a stable value.

[0054] Figure 3 In it, the mixed solution of complex 2 and DHR123 was irradiated with white light at room temperature for 0 min, 10 min, 20 min, and 30 min, and the fluorescence intensity at the excitation wavelength of 495 nm and the emission wavelength of 525 nm was measured. It was found that the fluorescence intensity at 0 min was the lowest, gradually increased over time, and reached a stable peak at 30 min. Since the DHR123 indicator detects singlet oxygen of type I, the stronger the fluorescence intensity detected in the experiment, the stronger the ability to generate singlet oxygen of type I. The detection results showed that complex 2 induced DHR123 to produce fluorescence. After 30 min of photocatalysis, the fluorescence intensity reached a stable value, indicating that the concentration of singlet oxygen of type I also reached a stable value.

[0055] Figure 4 In it, the mixed solution of complex 1 and ABDA was irradiated with white light at room temperature, and the absorption spectra of the mixed solution in the range of 330 - 450 nm were monitored at 0 min, 10 min, 20 min, and 30 min respectively. The absorption spectra in the range of 330 - 450 nm were recorded to indicate 1 the generation of O2. It was found that there was no obvious change in the ultraviolet absorption intensity from 0 min to 30 min. The ultraviolet absorption intensity measured for the control group of the mixed solution of complex 1 and ABDA without light radiation at room temperature changed slightly but not significantly. The detection results showed that the ultraviolet absorption spectrum after the reaction of complex 1 and ABDA did not show a significant increase in absorption, indicating that the ability of complex 1 to generate singlet oxygen of type II was weak.

[0056] Figure 5 In it, the mixed solution of complex 2 and ABDA was irradiated with white light at room temperature, and the absorption spectra of the mixed solution in the range of 330 - 450 nm were monitored at 0 min, 10 min, 20 min, and 30 min respectively. The absorption spectra in the range of 330 - 450 nm were recorded to indicate 1Generation of O2. The ultraviolet absorption intensity measured from 0 to 30 minutes increased over time. After 30 minutes of photocatalysis, the ultraviolet absorption intensity reached a stable value. The ultraviolet absorption intensity of the control group, the mixed solution of complex 2 and ABDA, measured without light radiation at room temperature was higher than that measured with 30 minutes of light radiation. This detection result shows that after the reaction of complex 2 and ABDA, its ultraviolet absorption spectrum increased with the increase of photoinduced time and reached stable absorption after 30 minutes, indicating that complex 2 has a strong ability to generate type II singlet oxygen.

[0057] Example 6: In this example, the antibacterial photodynamic effects of complexes 1 and 2 were detected.

[0058] The reagents used included: phosphate buffer solution (PBS), MASA BAA-1768 bacteria, Rn4220 bacteria, LED light strip, Luria-Bertani medium (i.e., LB medium), and CFU counting agar plate.

[0059] Gram-positive and Gram-negative bacteria were cultured, diluted in phosphate buffer solution and added to a multi-well plate for culturing bacteria. Under the conditions of quantitative light irradiation time and intensity, they were incubated for another 14 hours, and the survival rate of the bacteria was observed to evaluate the photoinduced sterilization or antibacterial ability of complex 2.

[0060] Experimental materials Samples to be tested: Complex 1, Complex 2 (need to be dissolved in appropriate solvents such as DMSO, PBS, etc., and the concentration is determined according to preliminary experiments).

[0061] Bacterial strains: MASA BAA-1768 bacteria, Rn4220 bacteria, which need to be cultured in advance to the logarithmic growth phase.

[0062] Light source: LED lamp, the light intensity needs to be controlled at 10 - 20 mW cm⁻², and the time is 0 minutes - 30 minutes.

[0063] Control groups: Solvent control (without complex), light control (without complex + light), dark control (with complex + without light).

[0064] Other reagents: PBS buffer solution, LB medium, CFU counting agar plate.

[0065] Experimental procedures: 1. Bacterial culture and treatment The target bacterial strain was inoculated into LB liquid medium and cultured in a shaker at 37°C until the logarithmic growth phase (OD600 ≈ 0.6).

[0066] Collect the bacterial cells by centrifugation (3000 rpm, 5 min), wash them twice with PBS, and resuspend them in PBS to adjust the cell concentration to approximately 1×10 6 CFU / mL.

[0067] 2. Complex treatment Divide the bacterial suspension into multiple groups (at least 3 parallels in each group): Experimental group: Bacterial suspension + Complex 1 / Complex 2 (different concentration gradients).

[0068] Dark control group: Bacterial suspension + Complex 1 / Complex 2 (without light illumination).

[0069] Light illumination control group: Bacterial suspension + Solvent (without complex) + Light illumination.

[0070] Solvent control group: Bacterial suspension + Solvent (without complex, without light illumination).

[0071] Incubate in the dark: Incubate the mixture at 37°C in the dark for 30 - 60 min to allow the complex to fully bind to the bacteria.

[0072] 3. Light illumination treatment Use a white light wavelength LED lamp, adjust the light source intensity (10 - 20 mW / cm²) and irradiation time (0 - 30 min), and keep the temperature constant during the light illumination process (such as ice bath or constant temperature device) to avoid interference from thermal effects.

[0073] The dark control group is treated in the dark throughout the process.

[0074] 4. Detection of bacterial survival rate CFU counting method: Dilute the bacterial suspension after light illumination in gradients (10⁻¹ to 10⁻ 6 ), and take 50 μL to spread on the LB agar plate.

[0075] Culture at 37°C for 18 - 24 h, count the number of colonies, and calculate the survival rate: Survival rate (%) = (CFU in experimental group / CFU in control group) × 100.

[0076] Detection results and result analysis: Table 1 Comparison of photodynamic antibacterial activities between the experimental group and the control group

[0077] From the viable cell rates of the experimental group and the control group detected, it can be seen that both Complex 1 and Complex 2 have relatively excellent photodynamic antibacterial effects, among which the antibacterial activity of Complex 2 is significantly better than that of Complex 1; the antibacterial effects of Complex 1 and Complex 2 are not obvious without photoinduction conditions, manifested by a high bacterial survival rate; the bacterial survival rate in the light control group and the solvent control group is high, indicating that in the absence of photosensitizer, the solvent and light have weak effects on bacteria.

[0078] Example 7: 1. Detection of the optical properties of Complex 1 and Complex 2: Complex 1 and Complex 2 were dissolved in DMSO solution to prepare 1 mM stock solutions. 200 μL of each of Complex 1 and Complex 2 was taken and diluted to a concentration of 20 μM, and their absorption spectra were detected in a UV-visible spectrophotometer. The maximum absorption wavelength of Complex 1 was about 400 nm, and the molar extinction coefficient was in the range of 7.5 - 2.5×10 3 L·mol⁻¹·cm⁻¹; the maximum absorption wavelength of Complex 2 was about 450 nm, and the molar extinction coefficient was in the range of 10 - 2.5×10 3 L·mol⁻¹·cm⁻¹, as shown in Table 2.

[0079] 2. The targeting of Complex 1 and Complex 2 to bacteria can refer to the antibacterial activity detection experiment. Under the condition of medium concentration (20 μM), the viable cell rates of bacteria were 20% and 11% respectively. It shows that the complexes have targeting to bacteria under photoinduction conditions.

[0080] The antibacterial activity detection experiment is as follows: The reagents used include: phosphate buffer (PBS), MASA BAA-1768 bacteria, LED light strip, Luria-Bertani medium (i.e., LB medium), and CFU counting agar plate.

[0081] Cultivate bacteria, dilute them in phosphate buffer solution and add them to the multi-well plate for culturing bacteria. Under the conditions of quantitative light time and intensity, incubate for another 14 hours, and observe the survival rate of bacteria to evaluate the photoinduced sterilization or bacteriostatic ability of Complex 2.

[0082] Experimental materials Samples to be tested: Complex 1, Complex 2 (need to be dissolved in appropriate solvents such as DMSO, PBS, etc., and the concentration is determined according to preliminary experiments).

[0083] Bacterial strain: MASA BAA-1768 bacteria, which need to be cultured to the logarithmic growth phase in advance.

[0084] Light source: LED lamp, the light intensity needs to be controlled at 10 - 20 mW cm⁻² and the time is 20 minutes.

[0085] Experimental procedures: 1. Bacterial culture and treatment Inoculate the target strain into LB liquid medium and culture it in a shaker at 37 °C until the logarithmic growth phase (OD600 ≈ 0.6).

[0086] Centrifuge (3000 rpm, 5 min) to collect the bacteria, wash them twice with PBS, and resuspend them in PBS to adjust the bacterial concentration to approximately 1×10 6 CFU / mL.

[0087] 2. Complex treatment: Bacterial solution + solvent (without complex) + light irradiation.

[0088] 3. Light irradiation treatment Use a white light wavelength LED lamp, adjust the light source intensity (10 - 20 mW / cm²) and irradiation time (0 - 30 min), and keep the temperature constant during the light irradiation process (such as ice bath or constant temperature device) to avoid interference from thermal effects.

[0089] 4. Detection of bacterial survival rate CFU counting method: Dilute the bacterial solution after light irradiation in gradients (10⁻¹ to 10⁻ 6 ), and take 50 μL to coat on an LB agar plate.

[0090] Culture at 37 °C for 18 - 24 h, count the number of colonies, and calculate the survival rate: Survival rate (%) = (CFU in experimental group / CFU in control group) × 100.

[0091] Table 2 Optical properties and antibacterial specificity of the complex

[0092] 3. Investigation of the toxic and side effects on normal cells: Experimental materials Cell line: Human fibroblast HFF-1.

[0093] Test drugs: Complex 1, Complex 2 are dissolved in DMSO solvent to prepare a 1 mM stock solution.

[0094] Culture medium: DMEM (dulbecco's modified eagle medium) medium containing 10% fetal bovine serum (FBS).

[0095] Detection reagents: WST-8 reagent (2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium monosodium salt) Instruments: CO2 incubator, microplate reader, inverted microscope.

[0096] Experimental procedures 1. Cell culture and seeding After cell resuscitation, the cells were cultured in a medium containing 10% FBS until 80%-90% confluence.

[0097] The cells were digested with trypsin, centrifuged (1000 rpm, 5 min), resuspended, and the cell density was adjusted to 1×10 4 ~5×10 4 cells / mL.

[0098] The cell suspension was inoculated into a 96-well plate (100 μL per well) and incubated at 37°C and 5% CO2 in an incubator for 24 h to allow cell attachment.

[0099] 2. Drug treatment Concentration gradient design: Six to eight drug concentration gradients (e.g., 0.1 μM - 100 μM) were set to cover the expected toxicity range.

[0100] It was necessary to include a blank control group (only medium) and a solvent control group (containing an equal amount of solvent).

[0101] Drug addition method: The original medium was aspirated, and fresh medium containing different concentrations of the drug (100 μL) was added to each well.

[0102] Three to six replicate wells were set for each group to improve statistical power.

[0103] Incubation time: 24 - 72 h.

[0104] 3. Cell toxicity detection WST-8 method After the drug treatment was completed, 10 μL of WST reagent (5 mg / mL) was added to each well, and the incubation was continued for 1 - 4 h. After the incubation, the absorbance at 450 nm was directly measured using the instrument, and the survival rate was calculated according to the formula.

[0105] Survival rate (%) = [(ODexperimental group - ODblank) / (ODsolvent control - ODblank)] × 100.

[0106] IC 50 Calculation: The dose - effect curve was fitted using GraphPad Prism or SPSS to calculate the drug concentration that inhibited 50% of cell activity. The calculated IC 50 of complex 1 was 100.2 μM, and the IC 50 of complex 2 was 136.1 μM (see Figure 6 )). This IC50 The concentration has little toxic and side effects on normal cells.

[0107] Finally, it should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0108] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0109] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A conjugated TEMPO radical platinum complex photosensitizer, characterized in that, The structural formula of the linked TEMPO free radical platinum complex photosensitizer is as follows: 。 2. The preparation method of a conjugated TEMPO radical platinum complex photosensitizer according to claim 1, characterized in that, The preparation method includes: Adding glacial acetic acid and 1,5-cyclooctadiene to a potassium tetrachloroplatinate solution, and then heating to 90 ± 5 °C and holding for 30 - 60 min to obtain a mixture; Performing a reduced-pressure evaporation treatment on the mixture, followed by solid-liquid separation, washing, and drying to obtain dichloro-1,5-cyclooctadiene platinum complex, i.e., Pt(COD)Cl2; Dispersing KOH in an organic solvent, sequentially adding 4-Cl-2,2,6,6-tetramethylpiperidine-1-oxyl free radical and 4’-OH-2,2’:6’,2’’-terpyridine to the obtained suspension, and then heating to 50 ± 5 °C and stirring for reaction for 10 - 22 h to obtain a reaction solution; Adding an equal volume of water to the reaction solution for quenching reaction, followed by solid-liquid separation, drying, and recrystallization to obtain ligand L, i.e., terpy-TEMPO; Dispersing Pt(COD)Cl2 in an organic solvent, and then adding methanol in which ligand L is dispersed, and placing it at 50 ± 5 °C for stirring reaction for 2 - 4 h to obtain a clear mixed solution; Adding an equal volume of ether to the cooled clear mixed solution, followed by solid-liquid separation, washing, and drying to obtain the terpyridine platinum complex of linked TEMPO, denoted as complex 1, i.e., [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH; Co-dispersing [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and cuprous iodide in N,N-dimethylformamide, then adding triphenylphosphine and triethylamine, carrying out the reaction in the dark, adding ether for quenching reaction after the reaction ends, and then performing solid-liquid separation, washing, and drying to obtain the linked TEMPO free radical platinum complex, denoted as complex 2, i.e., [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH.

3. The preparation method of a conjugated TEMPO free radical platinum complex photosensitizer according to claim 2, characterized in that, The step of adding glacial acetic acid and 1,5-cyclooctadiene to a potassium tetrachloroplatinate solution, and then heating to 90 ± 5 °C and holding for 30 - 60 min to obtain a mixture specifically includes: Adding glacial acetic acid and 1,5-cyclooctadiene to a potassium tetrachloroplatinate solution, heating the obtained mixed solution to 90 ± 5 °C and holding for 30 - 60 min to obtain a mixture; Among them, the molar ratio of potassium tetrachloroplatinate, glacial acetic acid, and 1,5-cyclooctadiene in the mixed solution is (1 - 3):(5.3 - 13):(4 - 8); The concentration of potassium tetrachloroplatinate in the mixed solution is 1% - 12%.

4. The preparation method of a conjugated TEMPO free radical platinum complex photosensitizer according to claim 2, wherein, The step of performing a reduced-pressure evaporation treatment on the mixture, followed by solid-liquid separation, washing, and drying to obtain dichloro-1,5-cyclooctadiene platinum complex, i.e., Pt(COD)Cl2, specifically includes: Performing a reduced-pressure evaporation treatment on the mixture, then performing solid-liquid separation, washing the obtained solid with deionized water, methanol, and ether in sequence, and drying to obtain dichloro-1,5-cyclooctadiene platinum complex, i.e., Pt(COD)Cl2.

5. The preparation method of a conjugated TEMPO radical platinum complex photosensitizer according to claim 2, characterized in that, Disperse KOH in an organic solvent, and successively add 4-Cl-2,2,6,6-tetramethylpiperidine-1-oxyl radical and 4’-OH-2,2’:6’,2’’-terpyridine to the obtained suspension, and then heat to 50 ± 5 °C and stir for reaction for 10 - 22 h to obtain a reaction solution, specifically including: Disperse KOH in DMSO, and successively add 4-Cl-2,2,6,6-tetramethylpiperidine-1-oxyl radical and 4’-OH-2,2’:6’,2’’-terpyridine to the obtained suspension, and then heat to 50 ± 5 °C and stir for reaction for 10 - 22 h to obtain a reaction solution; Among them, the molar ratio of KOH, 4-Cl-2,2,6,6-tetramethylpiperidine-1-oxyl radical and 4’-OH-2,2’:6’,2’’-terpyridine is (6 - 8):(1 - 2.5):(1 - 2); The concentration of KOH in the suspension is 6% - 26%.

6. The preparation method of a conjugated TEMPO free radical platinum complex photosensitizer according to claim 2, characterized in that, Add an equal volume of water to the reaction solution for quenching reaction, and then carry out solid-liquid separation, drying and recrystallization to obtain ligand L, that is, terpy-TEMPO, specifically including: Add an equal volume of water to the reaction solution for quenching reaction, and then carry out solid-liquid separation. The obtained solid is dried under reduced pressure at 50 ± 5 °C, and the obtained crude product is dissolved in a cyclohexane solution for recrystallization to obtain ligand L, that is, terpy-TEMPO.

7. The preparation method of a conjugated TEMPO radical platinum complex photosensitizer according to claim 2, characterized in that, Disperse Pt(COD)Cl2 in an organic solvent, and then add methanol in which ligand L is dispersed, and place it at 50 ± 5 °C and stir for reaction for 2 - 4 h to obtain a clear mixed solution, specifically including: Disperse Pt(COD)Cl2 in an organic solvent, and then add methanol in which ligand L is dispersed, and place the obtained reaction mixture at 50 ± 5 °C and stir for reaction for 2 - 4 h to obtain a clear mixed solution; Among them, the molar ratio of Pt(COD)Cl2 and ligand L in the reaction mixture is (1.5 - 4):(1 - 3); The concentration of Pt(COD)Cl2 in the reaction mixture is 1.5% - 12%.

8. The preparation method of a conjugated TEMPO radical platinum complex photosensitizer according to claim 2, characterized in that, Add an equal volume of ether to the cooled clear mixed solution, and then carry out solid-liquid separation, washing and drying to obtain the terpyridine platinum complex linked with TEMPO, denoted as complex 1, that is, [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH, specifically including: Add an equal volume of ether to the cooled clear mixed solution, and then carry out solid-liquid separation. The obtained precipitate is washed several times with methanol and ether successively, and dried under vacuum to obtain the terpyridine platinum complex linked with TEMPO, denoted as complex 1, that is, [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH.

9. The preparation method of a conjugated TEMPO free radical platinum complex photosensitizer according to claim 2, wherein, Disperse [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and cuprous iodide in N,N-dimethylformamide together, then add triphenylphosphine and triethylamine, and react in the dark. After the reaction is completed, add diethyl ether for quenching reaction, and then carry out solid-liquid separation, washing and drying to obtain the linked TEMPO radical platinum complex, denoted as Complex 2, that is, [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH, specifically including: Disperse [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH and cuprous iodide in N,N-dimethylformamide together, then add triphenylphosphine, stir and heat under N2 protection, then add triethylamine, and react in the dark. After the reaction is completed, add diethyl ether for quenching reaction, and then carry out solid-liquid separation, washing and drying to obtain the linked TEMPO radical platinum complex, denoted as Complex 2, that is, [Pt(terpy-TEMPO)(PPh3)]·Cl·H2O·CH3OH; Among them, the molar ratio of [Pt(terpy-TEMPO)Cl]·Cl·H2O·CH3OH, cuprous iodide, triphenylphosphine and triethylamine in the reaction system is (3 - 7):(0.5 - 2.5):(6 - 15):(10 - 18); The concentration of triphenylphosphine in the reaction system is 0.7% - 5%.

10. Use of a linked TEMPO radical platinum complex photosensitizer as described in claim 1 in the preparation of a bactericide or an antibacterial photodynamic therapy drug.

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