染料共敏化MoS2光催化产氢性能研究

染料敏化是提升二硫化钼(MoS₂)光催化制氢性能的一种有效手段。相较于单一敏化剂,共敏化可进一步拓展光吸收范围,提高催化剂的光催化效率,但目前尚无共敏化下MoS₂光催化制氢的报道。本文在利用液相法制得MoS₂的基础上,以藻红B钠盐(EB)和罗丹明B(RhB)为共敏化剂,测定了二者共敏化下MoS₂的光催化制氢性能,重点研究了EB和RhB的加入比例和加入顺序对产氢性能的影响。结果发现当少量RhB与EB共存时,产氢性能得到一定程度的提升;EB、RhB分步加入时的性能优于一同加入且RhB先加入时的性能最佳。此外,结合紫外-可见吸收光谱、荧光光谱结果和两种染料分子的结构对染料共敏化提升MoS₂光催化产氢性能的原因进行了初步分析。     

Enhancing the photoresponse by CdSe-Dye-TiO2-based multijunction systems for efficient dye-sensitized solar cells: A theoretical outlook

This work presents theoretical modeling of some systems, using density functional theory (DFT), for enhancing the photoresponse of a dye-sensitized solar cell. The optimization of the dye (NKX 2587) as well as the dye derivatives was carried out using B3LYP and 6-311g (d,p) level of theory, using DFT as incorporated in Gaussian 03 level of programming. The HOMO–LUMO energy gaps are lower for (CdSe)₁₃-Dye-(TiO₂)₆ multijunction systems in comparison with both the isolated dyes as well as dye-TiO₂ systems. The absorption peaks were found to be mostly red-shifted for (CdSe)₁₃-Dye-(TiO₂)₆ multijunction systems with respect to the Dye-TiO₂ systems, indicating the enhancement of the absorption behavior of the dye sensitizer by its interaction with the CdSe framework. The results thus indicate some sort of co-sensitization of the TiO₂ by the dye sensitizer as well as the CdSe quantum dot and are hence expected to increase the efficiency of the solar device. © 2019 Wiley Periodicals, Inc.     

可见光/H2O2体系中的协同敏化

分析了可见光/H₂O₂体系中产生协同敏化效应的原因. 通过分析苯酚红、 甲基橙、 天青Ⅰ及三者混合物的紫外-可见光谱发现, 三者混合后拓宽了在可见光区的响应范围, 提高了对可见光的利用率. 采用邻菲罗啉法、 二苯基卡巴肼法和磷钼酸铵分光光度法分别测试了上述有色物在可见光/H₂O₂体系中产生光生电子e、 单线态氧和超氧阴离子自由基的量, 结果表明, 三者混合物在可见光下超氧阴离子自由基的产量明显比单独有色物的高, 光生电子和单线态氧的产量相差不大, 说明超氧阴离子自由基产量的提高是产生协同敏化的主要原因. 测试结果还证实光生电子不能催化过氧化氢产生羟自由基.     

金属配合物Cd（phen）2（NO3）（NO2）对ZnO光阳极的敏化特性

采用具有紫外光区吸收的金属配合物Cd(phen)2(NO3)(NO2)和N719对ZnO光阳极进行共敏化.结果表明,配合物能够对ZnO光阳极进行共敏化,同时被电解液还原再生,共敏化增加电池对光的吸收,电池光电流密度增加63%,共敏化降低了电池各个界面电阻,有利于电子在界面的传输,电池的光电转换效率提高了37%.     

Highly efficient photoelectrochemical hydrogen generation using a ZnO nanowire array and a CdSe/CdS co-sensitizer

Highly efficient photoelectrochemical (PEC) hydrogen generation was achieved by fabricating CdSe deposited ZnO/CdS core/shell nanowire (NW) array photoanodes by a facile three-step solution-based method. Well-defined electrical pathways in 1-dimensional (1D) NW structures allowed efficient charge carrier collection, and CdSe/CdS co-sensitization enabled utilization of the visible region in the solar spectrum. PEC devices using CdSe/CdS/ZnO NW arrays showed improved absorption spectra, and they demonstrated a remarkable enhancement in PEC performance. Our proposed structure is a promising candidate photoanode for solar energy-to-hydrogen conversion devices.     

Multichromophoric dye-sensitized solar cells based on supramolecular zinc-porphyrinperylene-imide dyads

Multichromophoric dye-sensitized solar cells (DSCs) based on self-assembled zinc-porphyrinperyleneimide dyads on TiO(2) films display more efficient light-to-electrical energy conversion than DSCs based on individual dyes. Higher efficiency of multichromophoric dyes can be attributed to co-sensitization as well as vectorial electron transfer that lead to better electron-hole separation in the device.     

Synthesis of new di-anchoring organic sensitizer based on quinoxaline acceptor for dye-sensitized solar cells

New quinoxaline-based organic sensitizer bearing di-anchoring group for dye-sensitized solar cells (DSSCs) was synthesized from diethyl 4,5-diaminophthaltate, in which was prepared under mild condition by using Takehito’s method. The synthesized sensitizer was compared with mono-anchoring sensitizer through absorption spectra, emission spectra, J-V curve, and IPCE spectra, indicating the di-anchoring group leads to a noticeable improvement of J_sc value owing to more efficient intramolecular charge transfer and channel number increment.     

两亲性D-π-A型有机染料在染料敏化太阳能电池中的应用

设计合成了6个带有烷基链的D-π-A型有机光敏染料应用于染料敏化太阳能电池. 发现长链烷基有利于电池开路光电压的提高. 利用脂肪酸共敏化可进一步提高染料分子的敏化效果, 且提高的程度与脂肪酸的链长有重要关系.     

Silver staining method for DNA in polyacrylamide gels using eriochrome black T as a silver-ion sensitizer

A sensitive silver staining method using eriochrome black T as a silver-ion sensitizer for DNA detection in polyacrylamide gels was developed. The sensitivity of this staining method was significantly improved by the new silver-ion sensitizer containing a diazo group, which has reducing power. The staining method lasted a total of approximately 15 min following a fixing step for 2 x 20 min. The detection limit of this staining method was 1-4 pg for PhiX174 DNA/HaeIII in both nondenaturing and denaturing polyacrylamide gels. This staining method was especially effective in low-base pair DNA, with a sensitivity that was approximately ten-fold higher than previously published silver staining methods.     

Photosensitizer drug delivery via an optical fiber

An optical fiber has been developed with a maneuverable mini-probe tip that sparges O(2) gas and photodetaches pheophorbide (sensitizer) molecules. Singlet oxygen is produced at the probe tip surface which reacts with an alkene spacer group releasing sensitizer upon fragmentation of a dioxetane intermediate. Optimal sensitizer photorelease occurred when the probe tip was loaded with 60 nmol sensitizer, where crowding of the pheophorbide molecules and self-quenching were kept to a minimum. The fiber optic tip delivered pheophorbide molecules and singlet oxygen to discrete locations. The 60 nmol sensitizer was delivered into petrolatum; however, sensitizer release was less efficient in toluene-d(8) (3.6 nmol) where most had remained adsorbed on the probe tip, even after the covalent alkene spacer bond had been broken. The results open the door to a new area of fiber optic-guided sensitizer delivery for the potential photodynamic therapy of hypoxic structures requiring cytotoxic control.     

PHOTOHEMOLYTIC LESIONS: STOICHIOMETRY OF CREATION BY PHLOXINE B

The uptake of the halogenated fluorescein sensitizers, Rose Bengal and phloxine B, by erythrocyte membranes was measured as a function of incubation time. Ghost membranes concentrate the sensitizers to levels greatly in excess of the sensitizer concentration in the suspension medium. Most of the uptake occurs in the first hour and is virtually complete by four hours. It is not significantly affected by stirring under the present conditions. The distribution of sensitizer cannot be explained as partitioning between immiscible solvents. Rather the data fits the Freundlich adsorption isotherm over a wide range of sensitizer concentrations and ghost protein values. Photohemolysis experiments were performed using sensitizer concentrations and incubation times similar to those used in the sensitizer uptake studies. The kinetics of lysis were found to vary with the 1.2 power of sensitizer concentration using PB. When combined with the uptake data for this sensitizer, these results imply that photohemolytic lesions in the red cell membrane are formed by the action of two sensitizer molecules.     

表面活性剂增敏催化光度法测定痕量亚硝酸根

基于稀磷酸介质中,溴化十六烷基吡啶对亚硝酸根催化溴酸钾氧化吡罗红B褪色反应的增敏作用,建立了测定亚硝酸根的表面活性剂增敏催化动力学光度法。加入溴化十六烷基吡啶,灵敏度增大2.2倍。测量亚硝酸根的线性范围为0.005-0.15 mg/L,检出限为0.004/L。用于水及蔬菜中痕量亚硝酸根的测定,结果满意。     

INTRAVENOUS vs INTRAPERITONEAL SENSITIZER: IMPLICATIONS FOR INTRAPERITONEAL PHOTODYNAMIC THERAPY

Photodynamic therapy (PDT) is a potential treatment for peritoneal carcinomatosis. However, little data is available regarding the relative distribution of sensitizer to tumor and intra-abdominal organs, optimal route of sensitizer administration, and maximal tolerated light dose. Tumor and normal tissue sensitizer levels were measured by tissue extraction 3, 24, 48 and 72 h after 10 mg/kg of Photofrin II was given intraperitoneally (IP) or intravenously (IV) in a mouse peritoneal tumor model, and the maximal tolerated PDT light dose determined. Equivalent tumor sensitizer levels were obtained regardless of the route of sensitizer administration. Route of administration, however, did affect the kinetics of tumor sensitizer elimination, with the half-time for elimination (T1/2) 113.6 h for IP drug and 60.6 h for IV drug. Route of administration also affected sensitizer levels in several intra-abdominal organs, resulting in somewhat higher tumor to liver and kidney levels at 24 and 72 h after IP sensitizer administration. Despite these tissue distribution differences, route of sensitizer administration did not significantly affect PDT toxicity or mortality when mice were treated with 630 nm light. The maximum tolerated light dose was 1.04 J/cm2. These parameters will prove helpful in designing large scale animal trials assessing the efficacy and safety of intra-abdominal PDT.     

Efficient co-sensitization of nanocrystalline TiO(2) films by organic sensitizers

Dye-sensitized solar cells based on co-sensitization of organic dyes having complementary spectral absorption in the visible region resulted in a panchromatic response, which exhibited 86% incident monochromatic photon-to-current conversion efficiency in the visible region; the optimized cell gave a short circuit current density of 15.5 mA cm(-2), an open circuit voltage of 685 mV and a fill factor of 0.70 corresponding to an overall conversion efficiency of 7.43% under solar simulated light irradiation of 100 mW cm(-2).     

Dual Upconverted and Downconverted Circularly Polarized Luminescence in Donor–Acceptor Assemblies

Through mimicking both the chiral and energy transfer in an artificial self‐assembled system, not only was chiral transfer realized but also a dual upconverted and downconverted energy transfer system was created that emit circularly polarized luminescence. The individual chiral π‐gelator can self‐assemble into a nanofiber exhibiting supramolecular chirality and circularly polarized luminescence (CPL). In the presence of an achiral sensitizer Pd^II octaethylporphyrin derivative, both chirality transfer from chiral gelator to achiral sensitizer and triplet‐triplet energy transfer from excited sensitizer to chiral gelator could be realized. Upconverted CPL could be observed through a triplet–triplet annihilation photon upconversion (TTA‐UC), while downconverted CPL could be obtained from chirality‐transfer‐induced emission of the achiral sensitizer. The interplay between chiral energy acceptor and achiral sensitizer promoted the communication of chiral and excited energy information.     

纯有机染料共敏化纳米晶太阳能电池的性能研究

采用曙红与香豆素混合的方法,配制成敏化剂修饰纳米晶薄膜.实验结果证明,这种共敏化的方法可以在可见光范围内有效提高电池的吸光度,使得电池的性能比单独使用曙红敏化有了大幅度提高.在模拟太阳光下,曙红与香豆素共敏化的电池的开路电压达到了532 mV,短路电流达到了0.1125 mA/cm2.     

Influence of substitutions on asymmetric dihydroxychlorins with regard to intracellular uptake, subcellular localization and photosensitization of Jurkat cells

The search for new efficient sensitizers for photodynamic therapy (PDT) points to improve photophysical properties like absorption in the red region and singlet oxygen quantum yield as well as to control the localization of the sensitizer within the tumour cell. Depending on their physicochemical properties and their uptake mechanism, sensitizers can reach different intracellular concentrations and localize in different subcellular compartments. Moreover, the preferential localization of a sensitizer in target organelles, like mitochondria or lysosomes, could determine the cell death mechanism after PDT. This study aimed to investigate the influence of substitutions on dihydroxychlorins with regard to intracellular uptake, subcellular localization and cell death pathway. Moreover, the effect of a liposome-based delivery system was tested. The intracellular uptake was found to be strictly dependent on the sensitizer molecular structure and the means of its delivery. The most polar sensitizer in this study (compound 3) had, depending on incubation time, an intracellular concentration 2-8 times higher than the unsubstituted chlorin 1. All investigated photosensitizers localize predominantly in lysosomes but after longer incubation times weak fluorescence intensity was also detected in mitochondria and Golgi apparatus. The cell death pathway was found to be influenced by the sensitizer intracellular concentration and the applied light doses. In general, the increasing amphiphilicity of the sensitizer molecules is correlated with an increased sensitizer uptake and an increased rate of necrotic cells after irradiation.     

Photosensitization of bioinspired thymine-containing polymers

Here, we report a sensitization study on a family of water-soluble photopolymers based on thymine. The goal of this study was to determine whether the presence of sensitizer molecules would promote photocrosslinking/immobilization of the polymers using low-energy irradiation (520 nm) as compared to the UV irradiation (approximately 280 nm) necessary for the standard photoinduced process to take place. With the aid of Eosin Y Spirit Soluble (EY) as a sensitizer, water-soluble polystyrene copolymers of vinylbenzylthymine-vinylbenzyltriethylammonium chloride (VBT-VBA) were immobilized after exposure to visible irradiation. By exciting the sensitizer molecule in the presence of VBT copolymers at a wavelength where absorption by the latter does not occur, the triplet state of the sensitizer is generated in high yields, and consequently, polymer photocross-linking takes place. UV-vis spectroscopy has been used to study the effect of irradiation dose, copolymer composition, and sensitizer concentration on the photoreactivity of VBT polymers. These studies demonstrate the feasibility of using Eosin Y as a sensitizer to achieve the thymine photodimer formation, resulting in immobilization of VBT-VBA-EY films on PET substrate. This provides complementary information on photoinduced immobilization of VBT-VBA films that are crucial for developing new classes of environmentally benign materials and new energy-saving methods.     

“Pointsource” Delivery of a Photosensitizer Drug and Singlet Oxygen: Eradication of Glioma Cells In Vitro

We describe a pointsource sensitizer‐tipped microoptic device for the eradication of glioma U87 cells. The device has a mesoporous fluorinated silica tip which emits singlet oxygen molecules and small quantities of pheophorbide sensitizer for additional production of singlet oxygen in the immediate vicinity. The results show that the device surges in sensitizer release and photokilling with higher rates about midway through the reaction. This was attributed to a self‐amplified autocatalytic reaction where released sensitizer in the extracellular matrix provides positive feedback to assist in the release of additional sensitizer. The photokilling of the glioma cells was analyzed by global toxicity and live/dead assays, where a killing radius around the tip with ~0.3 mm precision was achieved. The implication of these results for a new PDT tool of hard‐to‐resect tumors, e.g. in the brain, is discussed.     

Paper electrophoresis with surface-enhanced fluorimetric detection

Amorphous fumed silica was used as a fluorescence sensitizer coated on a filter-paper substrate for use in paper electrophoresis. The usefulness of the separation method was illustrated for a mixture of two polynuclear aromatic compounds of biological interest: benzo[a]pyrene (BaP) and benzo[a]pyrene-r-7,t-8,9,10-tetrahydrotetrol, a hydrolysis product of BaP—DNA adduct. These two compounds were well separated and an enhancement of the fluorescence intensity was also observed when the sensitizer was applied to filter-paper prior to electrophoretic separation.