Luminescence Study of Singlet Oxygen Production by Meso-Tetraphenylporphine

The research in the field of the photodynamic therapy of cancer (PDT) is focused on a development of photosensitizers exhibiting high quantum yield of singlet oxygen production. Direct time-resolved spectroscopic observation of singlet oxygen phosphorescence can provide time constants of its population and depopulation as well as photosensitizer phosphorescence lifetime and relative quantum yields. In our contribution, a study of time and spectral resolved phosphorescence of singlet oxygen photosensitized by meso-tetraphenylporphine in acetone together with the photosensitizer phosphorescence is presented. Time constants of singlet oxygen population and depopulation were determined at wide range of photosensitizer concentrations. The time constant of singlet oxygen generation (0.28 ± 0.01) s is slightly shorter then the lifetime of photosensitizer's triplet state (0.32 ± 0.01) s. It is caused by lower ability of TPP aggregates to transfer excitation energy to oxygen. The lifetime of singlet oxygen (50 s) decreases with increasing photosensitizer concentration. Therefore, the photosensitizer acts also as a quencher of oxygen singlet state, similarly to the effects observed in [A. A. Krasnovsky, P. Cheng, R. E. Blankenship, T. A. Moore, and D. Gust (1993). Photochem. Photobiol. 57, 324–330; H. Küpper, R. Ddic, A. Svoboda, J. Hála, and P. M. H. Kroneck (2002). Biochim. Biophys. Acta Gen. Subj. 1572, 107–113]. Moreover, the increasing concentraion of the photosensitizer causes a slight hypsochromic shift of the singlet oxygen luminescence maximum.     

The Efficiency of the Formation of Singlet Oxygen by a Sensitizer Based on Zinc Phthalocyanine

Using zinc octa(diethoxyphosphenylmethyl)phthalocyanine as an example, we determined experimentally the quantum yield of generation of singlet oxygen () which makes it possible to evaluate quantitatively the efficiency of photogeneration of ¹O₂ and the influence of biomolecules on this parameter. It is shown that the efficiency of generation of singlet oxygen by the sensitizers used in photodynamic therapy depends on their state in a solution and increases with disaggregation of the dye and its interaction with biomolecules. It is established that phthalocyanine in an aqueous buffer solution sensitizes the formation of ¹O₂ with the quantum yield = 0.16 ± 0.02. On introduction of the detergent Triton X100 into the buffer solution of phthalocyanine, increases up to 0.48 ± 0.07. In a microheterogeneous medium (buffer + albumin) = 0.42.     

关于PDT光敏剂敏化效应光谱及其量子产率的研究

从实验的角度研究了HA光敏剂激发态的敏化特性,建立了单态氧量子产率在近红外区的荧光光谱测量系统,测定了HA光敏剂的单态氧量子产率为0．78。结果表明,该类光敏剂具有较强的敏化效应,是一类有前途的光动力治疗(PDT)候选光敏剂。     

Localized Surface Plasmon Resonance Enhanced Singlet Oxygen Generation and Light Absorption Based on Black Phosphorus@AuNPs Nanosheet for Tumor Photodynamic/Thermal Therapy

Although photodynamic therapy is an efficient therapeutic strategy for cancer treatment, it always suffers from the low singlet oxygen (¹O₂) yields owing to the weak absorption in optical transparent window of biological tissues. Herein, the black phosphorus (BP) nanosheet is integrated with gold nanoparticles (AuNPs) to simultaneously enhance the singlet oxygen generation and hyperthermia by localized surface plasmon resonance (LSPR) in cancer therapy. In the design, BP nanosheet employed as two‐dimension (2D) inorganic photosensitizer is hybridized with AuNPs through polyetherimide (PEI) as bridge to form BP‐PEI/AuNPs hybrid nanosheet. Such hybridation not only significantly increases the ¹O₂ production of BP nanosheet through maximizing the local field enhancement of AuNPs, but also significantly enhances the light absorption of BP nanosheet to promote photothermal effect by LSPR. Accordingly, about 3.9‐fold enhancement of ¹O₂ production and 1.7‐fold increasement of photothermal conversion efficiency are achieved compared with BP‐PEI alone upon single 670 nm laser irradiation. As a proof‐of‐concept model, BP‐PEI/AuNPs hybrid nanosheet with simultaneous dual‐modal phototherapy functions result in effective suppression of tumor growth with minimized side effects both in vitro and in vivo, indicating the great potential of the BP‐PEI/AuNPs hybrid nanosheet as an effective strategy to enhance the cancer therapy efficiency.     

Two‐Color Laser Photodynamic Therapy of Tumors

A method of photodynamic therapy of tumors (neoplasms) based on simultaneous action of radiation from two lasers with different generation wavelengths is proposed and implemented in an experiment on animals. The antineoplastic effect was evaluated by the dimensions of the necrosis region determined using the method of vital staining of tissues. The effect of photodynamic therapy in the case of simultaneous use of the two lasers (₁ = 627.8 nm and ₂ = 671 nm) turned out to be higher than in the case of their separate application. The hypothetical reason for the phenomenon is oxyhemoglobin photodissociation that leads to the enrichment of blood with free oxygen.     

青蒿素光化学合成中二氢青蒿酸与单线态氧反应的动力学研究

青蒿素是一种优异的抗疟药,广泛用于临床医学. 但由于青蒿素天然来源的限制,青蒿素的化学合成一直受到高度关注. 二氢青蒿酸是合成青蒿素的关键前体. 二氢青蒿酸与单线态氧反应形成过氧化物是青蒿素光化学制备中的关键步骤,制约着青蒿素化学合成的产率. 然而关于二氢青蒿酸与单线态氧反应的重要动力学信息并未有报道. 本文通过光敏化法产生单线态氧,研究二氢青蒿酸与单线态氧之间的反应速率常数. 通过直接检测单线态氧在1270 nm处的发光衰减动力学,得出单线态氧与二氢青蒿酸在不同溶剂中的反应速率常数分别为：在CCl₄中为1.81×10⁵ (mol/L)^-1·s^-1,在CH₃CN中为5.69×10⁵ (mol/L)^-1·s^-1,DMSO中为3.27×10⁶ (mol/L)^-1·s^-1. 发现在三种溶剂中二氢青蒿酸与单线态氧的反应速率常数随着溶剂极性的增加而增加. 这些结果为优化青蒿素光化学合成的实验条件提供了基础知识,有助于提高青蒿素的合成效率.     

Spectral and photosensitizing properties of bacteriochlorin a and its monomethyl and dimethyl esters

We have carried out a comparative study of the photosensitizing activity of bacteriochlorin a (BCA) and its methylated derivatives: monomethyl and dimethyl esters of BCA (BCA MME and BCA DME). We have shown that BCA and its derivatives are bound to the erythrocyte membranes in monomolecular form, and upon photoexcitation in the region of their long-wavelength Q_y absorption band, they sensitize oxidation of the major membrane components: proteins and lipids. We have established that despite greater binding of the methylated BCA derivatives to the membranes, their specific activity in photosensitization of peroxide oxidation of membrane lipids and membrane protein tryptophanyls is lower than for BCA. At the same time, BCA MME and BCA DME sensitize oxidation of a larger number of SH groups in membrane proteins, which suggests methylated BCA is predominantly localized in the erythrocyte membrane close to the protein sulfhydryl groups. We also show that the rate of erythrocyte photohemolysis sensitized by BCA MME and BCA DME is significantly faster than for sensitization by BCA. This correlates with the lipophilicity of BCA, BCA MME, and BCA DME, which is responsible for the ability of bacteriochlorins to bind to cell membranes and cells. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 98–105, January–February, 2006.     

发光二极管应用于光动力学疗法的可行性分析

讨论了发光二极管(Light-emitting-diode,LED)在航天医学中作为激光器的替代光源用于光动力学疗法(Photodynamic therapy,PDT)的可行性。分析了发光二极管用于光动力学疗法的优势,介绍了LED用于不同类型光敏剂进行PDT治疗的实验研究,概括了LED-PDT治疗系统在国内外的研制现状。说明了LED替代激光器作为PDT的激发光源是可行的。LED作为我国航天医学领域中的一种重要光源,为维护航天员的健康将会发挥重要作用。     

钯酞菁配合物的荧光光谱与单线态氧的生成速率

分别测定了四-α-(2,2,4-三甲基-3-戊氧基)酞菁钯(锌)和四-α-(2,4-二叔丁基苯氧基)酞菁钯(锌)配合物的紫外-可见电子吸收光谱,荧光发射光谱和单线态氧生成速率,结果表明虽然酞菁钯的中心金属离子为开壳层电子结构,但其生成单线态氧(1O₂)的能力与中心金属为闭壳层结构的相应取代酞菁锌相近,这可能是与其荧光发射很弱,系间串跃很强相关。     

Pentacene Nanorods as Effective Photosensitizer for Photodynamic Therapy of Tumor via Singlet Fission

Singlet fission (SF), whereby a singlet exciton is converted into a pair of triplet excitons, can improve the efficiency of solar cells. Pentacene has been extensively studied as the most promising SF compound, owing to its 200% yield of triplet states. However, the easy degradation of pentacene in the presence of light and air owing to photooxidation cannot be explained by the classical ¹O₂ generation mechanism. To address this issue, in the present study, pentacene nanorods (Pc NRs) are prepared as a novel photosensitizer (PS); self-carried Pc NRs exhibited higher ¹O₂ generation capacity. Thus, a novel ¹O₂ generation mechanism is proposed based on the SF effect. The initial photon absorption occurs to access single-exciton states, S1–S3. Excited-state Pc pairs accelerate the SF effect in pentacene NRs, leading to a non-adiabatic transition to the dark D state. Dark D state is a singlet state by two triplets coupled overall, and it can transfer its energy to ³O₂ for generating ¹O₂. Using Pc NRs as PSs, photodynamic therapy (PDT) inhibits tumor growth in 4T1 tumor-bearing mice upon 405-nm-wavelength and 650-nm-wavelength laser irradiations. This study paves the way to discover novel PSs that are not considered with classical ¹O₂ generation mechanisms.     

新型光敏剂叶绿酸f对人膀胱癌T24细胞的光动力杀伤作用

将自主研发的新型光敏剂叶绿酸f与T24细胞共同孵育后,以650nm激光照射,通过MTT法检测光动力处理后T24细胞的生长抑制率,流式细胞术检测凋亡情况,同时利用激光共聚焦显微镜488nm和405nm双波长激发,应用线粒体探针,进行叶绿酸f的亚细胞定位。结果显示叶绿酸f为浓度2.5,5,10μg/mL对T24细胞生长抑制率在光能量密度4J/cm2下为17.68%,49.35%和84.42%,在1J/cm2时为4.34%,37.42%和78.38%;流式细胞术显示T24细胞光动力处理后,凋亡率为(45.23±1.2)%,显著高于对照组;激光共聚焦显微镜显示504nm激发叶绿酸f发出的红光与488nm激发线粒体探针产生的绿光分布基本一致。实验证明叶绿酸f对T24细胞杀伤效果明显,主要是通过作用于线粒体,诱导细胞凋亡来完成的。     

射流式单重态氧发生器研究

单重态氧O2 (a1Δg)是迄今唯一能用纯化学反应高效产生的具有长寿命的亚稳激发态分子 .为了考察提出的用两个O2 (1Δ)能量汇集反应生成氧第二单重激发态O2 (b1Σ+ g)以实现近可见短波长化学激光方案的现实性 ,设计和实验了一个氯流量为 3～ 10mmol/s的射流式单重态氧发生器 (JSOG) .考察了三种具有不同孔径和孔数目的喷头、氯气流量和脱水冷阱温度等对JSOG出口的O2 (1Δ)浓度、O2 (1Δ)分压、氯利用率及水蒸气含量的影响 .发现用聚氯乙烯管作冷阱时 ,最佳冷阱介质温度为 - 140～ - 15 0℃ ,对此提出了O2 (1Δ)表面脱活与脱水互相竞争的解释 .在最佳条件下 ,可将O2 (1Δ)气中水分压降低至 4Pa ,这一结果是首次报导     

硫代碱基与单态氧反应速率常数的时间分辨光谱测定

硫代碱基作为一类免疫抑制性药物被广泛关注,由于硫原子的取代,硫代碱基可以吸收UVA波段紫外光,并通过系间窜越至激发三重态敏化氧气生成广泛应用于光动力学治疗的活性氧物质单态氧(~1O_2).然而,硫代碱基容易与自身敏化产生的~1O_2氧化发生反应,导致光毒性.在已有关于硫代碱基与~1O_2反应机理的研究基础上,本文采用瞬态光谱方法直接测得~1O_2在1270 nm处磷光信号的衰减动力学,得到硫代碱基与单态氧反应的速率常数.通过比较6-硫代鸟嘌呤、4-硫代尿嘧啶、2,4-二硫代尿嘧啶分别在水、乙腈以及二者混合溶剂中与~1O_2的反应,发现硫代碱基与单态氧反应速率常数受溶剂的极性影响.随着溶剂极性增大,反应速率常数则减小.此外,通过对比研究,发现硫代嘧啶类碱基与~1O_2的反应速率小于硫代嘌呤类碱基,说明在光动力学治疗中以硫代嘧啶类药物作为光敏剂是较为合适的选择.     

亚磷酸三苯酯臭氧化合物分解产生单重态氧的研究

现在世界上功率最大的短波长化学激光、氧碘化学激光是以亚稳态的O2 (a1△)作为储能分子,通过近共振碰撞传能给碘原子,使碘原子激发而发射激光,因此,O2 (a1△)的发生是其主要关键技术.目前使用的方法是H2 O2 的碱溶(BHP)与Cl2 气反应[1] .它具有化学效率高的优点,但此方法产生的O2 (a1△)中含有水份,而水对碘原子具有强的猝灭作用;另外,BHP不能长期保存;氯气还有毒性.196 1年Thompson发现,在- 78℃时亚磷酸三苯酯(TPP)与O3加成为亚磷酸三苯酯臭氧化合物(TPPO3) [2 ] ,并在高于- 35℃分解产生O2 (a1△) .　(C6 H5O) 3P +O3-78℃(…     

Determination of photosensitizer concentration in biological tissues from diffuse reflectance and fluorescence

We present a fiber-optic device for noninvasive determination of the optical properties of biological tissues and photosensitizer concentration. The device developed can be used in two modes: the mode for detection of the spatial distribution of diffuse reflectance, and the fluorescence mode. We tested the device in vitro on specimens simulating tissue and on whole blood, and also in vivo on rats. We have shown that with additional modification and adaptation, the device can be used for in vivo monitoring of parameters important for photodynamic therapy.     

目标自辐射与干扰目标反射光谱的氧气吸收特性分析

为分析不同目标反射太阳光谱的特性,研究被动测距中抑制干扰目标的方法,利用高光谱成像光谱仪作为测量设备,200 W卤钨灯作为模拟探测目标,玻璃板、光滑铝板、塑料板作为干扰目标,对模拟目标发射光谱和干扰目标反射太阳光谱进行了实验采集与分析。实验采集了晴朗天气条件下干扰目标反射光谱及卤钨灯目标辐射光谱的信息,并对其氧气吸收率进行了计算,综合分析了镜面反射干扰目标、漫反射目标及背景反射光与卤钨灯发射光光谱的氧气吸收率差异,结果表明：在455 m处,镜面反射目标和漫反射目标反射光的氧气吸收率是卤钨灯的2~3倍。因此,在一定距离下可以利用氧气吸收率的差异设置阈值来对目标进行判别,提高探测概率。     

光敏化反应生成单线态氧的电子耦合计算及其分子轨道重叠描述

三重态融合反应又称三重态-三重态湮灭反应,近年来被广泛应用于光催化、太阳能电池和生物成像等前沿领域. 在光敏化生成单线态氧的反应中,三重态激发的光敏剂分子通过三重态融合反应将激发态能量传递给基态氧分子³O₂,生成单重态的激发氧分子即单线态氧. 本文以6-aza-2-thiothymine为光敏剂,通过量子化学计算得到该反应的非绝热耦合强度,然后通过分子间运动下的积分转换,得到反应的透热电子耦合强度. 最后使用光敏剂分子和O₂的前线分子轨道计算轨道重叠强度,对量子化学计算得到的电子耦合值进行拟合,验证三重态融合反应的分子轨道重叠描述. 结果表明,分子轨道重叠可以较好地描述不同间距下光敏剂-O₂三线态融合反应的电子耦合强度分布,为预测三重态融合反应电子耦合提供了一种简便而有效的新方法.     

Absorption and Emission Properties of a New Two-photon Absorption Dye

The emission properties of a newly synthesized organic two-photon absorption dye, trans-4-[p-(N-ethyl-N-ethylamino)-styryl]-N-methyl-pyridinium tetraphenylborate, have been investigated. When pumped by infrared pulses from a picosecond Nd∶YAG laser, the dye exhibits intense upconverted fluorescence and strong superradiance properties. For comparison, the one-photon induced fluorescence and superradiance are also measured. The one- and two-photon excited fluorescent lifetimes are 86 and 64 ps, respectively. The maximum efficiency of the dye is measured to be 1.97% and the upconversion efficiencies at different pump wavelengths have also been investigated by the optical parametric amplifier.     

Kinetics of the redistribution of porphyrins between the proteins of blood and membranes

A comparative investigation of the kinetics of the redistribution of porphyrins between the lipoproteins of plasma and biological membranes is made. Isolated proteins were colored by the derivatives of chlorin e₆ and Zn-phthalocyanine, and the dynamics of the redistribution of pigments from the protein-carrier onto biological membranes (unilamellar lipid vesicles) were recorded by fluorescent methods. It is found that the rate of redistribution depends on the polarity of the molecule of the pigment. The time needed to attain equilibrium distribution of porphyrin increases on decrease in the degree of polarity from several seconds for chlorin e₆ to tens of minutes for nonpolar pigments. Very slow redistribution (several hours) was observed on displacement of the trimethyl ester of chlorin e₆ and Zn-phthalocyanine from low-density lipoproteins. It is shown that this effect can be attributed to the specific features of the localization of the centers of binding extremely nonpolar porphyrins in the composition of low-density lipoproteins. Reported at the VIIIth International Conference on Spectroscopy of Porphyrins and Their Analogs, Minsk, September 22–26, 1998. Belarusian State University, 4, F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 4, pp. 541–545, July–August, 1999.     

Procedure for quantitative determination of effectiveness of photoinduced destruction of malignant tumors

We have developed a procedure for analysis of the functional status of blood vessels in tumor tissues using computer-assisted color scanning of tumor slices and also for a quantitative assessment of the effectiveness of photoinduced destruction of tumor tissues in animal experiments. Its major advantage is direct determination of the size of the tumor necrosis zone. The procedure has been tested in an experiment on three strains of malignant tumors with different morphologies. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 521–524, July–August, 2006.