卤代对苝醌类光敏剂光敏活性影响的量子化学研究

以一种新型的醌类光敏剂—菌生素 (HMB)为模型化合物 ,利用量子化学从头算HF/ 6 31G和含时密度泛函TD B3LYP/ 6 31G方法计算研究了卤代作用对醌类光敏剂分子性质和光敏活性的影响 .结果发现 ,卤代作用降低了HMB母体的HOMO和LUMO能级 (EHOMO和ELUMO)及其差值△E ,随卤族元素从上到下 ,EHOMO和ELUMO呈增大趋势 ,而△E呈减小趋势 ,使得分子激发光谱有不同程度的红移 ,在增加PQP三重态量子产率的同时降低了分子最低三重激发态的能量 ,两种作用相互抵消 ,使得卤代物的 1O2 量子产率与母体相似 ;增加了分子的绝热电子亲合势 ,使分子产生O2 -的能力下降 ;卤原子的引入 ,降低了HMB母体分子内氢键的强度 ,同时使顺式构型的分子内质子传递势垒增大 ,而使反式构型势垒减小 .     

硫化物/Ru(II)络合物复合敏化TiO2纳米多孔膜

用光电化学方法研究了ＣｄＳ,ＰｄＳ和Ｒ１１Ｌ２（ＮＣＳ）２,（Ｌ＝２,２′－ｂｉｐｙｄｉｎｅ－４,４′－ｄｉｃａｒｂｏｘｙｌｉｃａｃｉｄ）复合敏化ＴｉＯ２纳米晶电极的光电化学行为,结果表明,采用复合敏化比用Ｒ１１（ＩＩ）络合物单独敏化ＴｉＯ２纳米晶电极效果好,大大提高了光电转换效率,主要原因是采用复合敏化,可防止ＴｉＯ２导带上由光注入产生的电子的反向转移,避免了电子的损失。     

Ionic liquid soluble photosensitizers

The preparation and investigation of triplet photosensitizers designed to be preferentially soluble in room-temperature ionic liquids are reported. Photosensitizers prepared by covalent attachment of 1-methylimidazole to aryl ketones are soluble in ionic liquids and remain in the ionic liquid layer when the solution is extracted with an organic solvent. The photosensitized isomerization of trans-β-ionol to cis-β-ionol was efficiently carried out in ionic liquid solution with the product ionol being extracted and the sensitizer/ionic liquid mixture being re-used in additional photosensitization reactions. The scope and utility of the sensitizers in sensitizing other reactions are discussed.     

The photosensitizing effect of the photoproduct of protoporphyrin IX

The photodynamic effect of a photoproduct of protoporphyrin IX (PpIX) induced by 5-aminolevulinic acid (ALA) was investigated in WiDr cells, a human adenocarcinoma cell line. The fluorescence excitation and emission spectra of PpIX and the photoproduct were measured. After 1, 3 or 5 min exposure of the ALA-incubated cells to 140 mW/cm² light at 635 nm, the photoproduct — the chlorin photoprotoporphyrin (Ppp), had an emission band around 670 nm. The Ppp excitation peak at 670 nm is well separated from the PpIX peak at 635 nm. The outcome of photodynamic therapy (PDT) was determined by measuring intracellular fluorescence intensity of propidium iodide (PI) 2 h following PDT and methylene blue (MB) staining 24 h following PDT. A significant increase in the fluorescence intensity of PI was noted when the ALA-loaded cells were exposed to 670 nm light after exposure to 635 nm, indicating enhanced cell membrane inactivation induced by the photodynamic action of the photoproduct. However, the fraction of the cells that survived following the same treatment as measured by MB staining was not significantly affected based on an analysis of variance. The fluorescence of PpIX decayed significantly during 635 nm light exposure. Exposure to light at 670 nm does not lead to any photodegradation of PpIX. The fluorescence of Ppp was bleached during 670 nm light exposure. Exposure of Ppp at 670 nm gives no PpIX back. Thus, the phototransformation of PpIX to Ppp is probably not a reversible process.     

Bioactive Polymers. XXVI. Immobilization of Pepsin on Biozan R

Pepsin was immobilized on BIOZAN R (Hercules) with dicyclohexylcarbodiimide as activator. The reaction product obtained has a protein content of 35–110 mg/g of polymer and a proteolytic activity between 20.85–28.75 μmol tyrosine/L·min·g of polymer). The coupling reaction rate is maximum under the following conditions: pepsin/BIOZAN R ratio = 0.52 g/g, DCCI/BIOZAN R ratio = 0.2 g/g, pH = 3.4, reaction time = 4 h.     

Fabrication of PbS nanocrystal-sensitized ultrafine TiO2 nanotubes for efficient and unusual broadband-light-driven hydrogen production

It is highly desired to maximize the use of solar light by developing broadband-light-responsive H₂ production system in the field of photocatalysis. Herein, a novel PbS/(Pt–TiO₂) nanocomposite with efficient and unusual broadband-light-driven H₂ production feature is constructed by using infrared-bandgap PbS nanocrystals as sensitizer of Pt-loaded ultrafine anatase TiO₂ nanotubes (Pt–TiO₂). After optimizing the component ratio, the resultant PbS/(Pt–TiO₂) nanocomposite delivers a H₂ production activity of 813 and 186 μmol h^?1 under ultraviolet (UV)-visible (Vis)-near-infrared (NIR) and Vis-NIR light irradiation, respectively. Moreover, an apparent quantum yield of 38.6%, 26.2%, 2.43%, 3.21%, 2.17%, 0.36%, 0.11% and 0.01% can be attained from the PbS/(Pt–TiO₂) nanocomposite illuminated at 350, 420, 550, 700, 760, 850, 950 and 1064 nm monochromatic light, respectively. The intimate interfacial contacts in the PbS nanocrystals decorated ultrafine TiO₂ nanotubes, which serve as the support and electron acceptor of PbS nanocrystals, can effectively promote the photoexcited hot electrons transferring from PbS nanocrystals to TiO₂ nanotubes before the thermalization losses, and thus causing the efficient Vis-NIR-light-responsive H₂ production activity of the PbS/(Pt–TiO₂) nanocomposite. These results provide an intriguing application of infrared-bandgap materials to exploit the low-energy photons of the solar light for constructing efficient and unusual broadband-responsive H₂ production system.     

硫化物/Ru(Ⅱ)结合物复合敏化TiO_2纳米多孔膜

用光电化学方法研究了Cds、Pbs和RuL2（NCS）2（L＝2.2′-bipydine-4.4′-dicarboxylicacid）复合敏化TiO2。纳米晶电极的光电化学行为．结果表明，采用复合敏化比用rul（Ⅱ）络合物单独敏化TiO2。纳米晶电极效果好，大大提高了光电转换效率．主要原因是采用复合敏化，可防止TiO2导带上由光注入产生的电子的反向转移，避免了电子的损失．     

Selective determination of doxorubicin and doxorubicinol in rat plasma by HPLC with photosensitization reaction followed by chemiluminescence detection

A highly sensitive and selective high-performance liquid chromatography (HPLC) method was developed for the determination of doxorubicin (DXR) and its metabolite doxorubicinol (DXR-ol) in rat plasma. The method was based on photosensitization reaction followed by peroxyoxalate chemiluminescence detection (PO-CL). DXR and DXR-ol that were fluorescent quinones, served as a photosensitizer in the presence of a hydrogen atom donor such as ethanol under aerobic conditions to produce hydrogen peroxide. Then the generated hydrogen peroxide and DXR or DXR-ol were monitored through PO-CL reaction by mixing with aryloxalate as a single post-column reagent that enabled highly selective and sensitive determination of DXR and DXR-ol. The separation of DXR and DXR-ol by HPLC was accomplished isocratically on an ODS column within 15 min. The method involves a simple one step protein precipitation by methanol and a sample size of 50-μL was sufficient. Besides, it can detect accurately the low plasma concentrations. The detection limits (signal-to-noise ratio = 3) were 4.5 and 3.8 fmol for DXR and DXR-ol, respectively. The percentage recovery was found to be 90.7-102.4% and the inter- and intra-assay RSD values in rat plasma were 2.5-8.9%. The method has been successfully used to study pharmacokinetic profiles of DXR and DXR-ol in rats after a single-dose of DXR.     

Effect of temperature on the photobehavior of Rose Bengal associated with dipalmitoylphosphatidyl choline liposomes

The association and photobehavior of Rose Bengal (RB) in the presence of dipalmitoylphosphatidyl choline (DPPC) small unilamellar liposomes is determined by the temperature. At temperatures above the main phase transition of the bilayer, the incorporation of the dye is ca. 2.5 times more efficient than that taking place when the bilayer is in the gel state. In both temperature ranges, adsorption isotherms show a noticeable anti-cooperativity that can be related to electrostatic repulsion between bound molecules. The photophysics and the photochemistry of the bound dye molecules also depend on the bilayer status. In particular, in the liquid crystalline state the surrounding of the dye is more polar and production of singlet oxygen is less efficient (Φ∼0.1). This reduced singlet oxygen production is partially due to a low triplet yield (Φ_T=0.35) and triplet self-quenching due to a high local RB concentration. In spite of these, tryptophan is efficiently photobleached when RB is associated to liposomes in the liquid crystalline state, probably due to a Type I mechanism favored by its high local concentration in the sensitized surroundings.     

Modification and photosensitization of size-quantized particulate CdS film photoelectrodes with bacteriorhodopsin (BR)

Bacteriorhodopsin (BR) was used to modify the surface of a novel size-quantized particulate CdS photoelectrode fabricated by electro-deposition. The photovoltaic features and interfacial electron transfer of the electrodes were studied by surface photovoltaic spectroscopy and a photoelectrochemical method. The results show that BR-modified CdS film photoelectrodes achieve a higher photocurrent yield due to the incorporation of the proton pump BR. On the basis of the observations, the mechanisms of photosensitization and interfacial electron transfer are proposed.