THE PHOTO-OXIDATION OF N, N-DIETHYLHYDROXYLAMINE BY ROSE BENGAL IN ACETONITRILE AND WATER

The Rose Bengal photosensitized oxidation of N,N-diethylhydroxylamine has been investigated in water and acetonitrile using the techniques of oxygen uptake, singlet oxygen phosphorescence and electron spin resonance. In both solvents H₂O₂ is the major oxidation product and diethylnitroxide is an intermediate. In water, superoxide dismutase decreases oxygen uptake suggesting involvement of superoxide anions in the oxidation process. Results indicate that in water the photo-oxidation proceeds mainly by a Type I(electron transfer) mechanism, while in acetonitrile a Type II(energy transfer) mechanism has been confirmed (Encinas et al., 1987, J. Chem. Soc. Perkin Trans. II,1125–1127).     

HETEROEXCIMER SYSTEMS IN AQUEOUS MICELLAR SOLUTIONS

Fluorescence quenching due to charge transfer interactions in the excited state has been studied in aqueous micellar solutions. Fluorescers used were pyrene, various pyrene derivatives and several other conjugated π-electronic systems, and quenchers were N, N-dimethylaniline, N. N-dimethylaniline sulfonate, dicyanobenzenes and cyanopyridine. Strong quenching of the aromatic hydrocarbon fluorescence with dimethylanilines as well as dicyanobenzenes was observed, while no heteroexcimer emission was detected. The dependences of relative fluorescence yield and fluorescence decay curve upon the quencher concentration have been explained with equations derived on the basis of a simple model. Based on the obtained results, some discussions were given on the nature of micelle 'interior' and micelle 'surface'.     

COMPETITION BETWEEN THE SINGLET OXYGEN AND ELECTRON TRANSFER MECHANISMS IN THE PORPHYRIN-SENSITIZED PHOTOOXIDATION OF l-TRYPTOPHAN AND TRYPTAMINE IN AQUEOUS MICELLAR DISPERSIONS

Abstract— Kinetic studies of the hematoporphyrin–sensitized photooxidation of l -tryptophan and tryptamine at pH 10 in either homogeneous aqueous solutions or in aqueous dispersions of Triton X–100 and cetyltrimethylammonium bromide micelles indicate that the indole substrates are attacked via a mixed type I (electron transfer from triplet dye)/type II (¹O₂-involving) mechanism. Both reactive intermediates, generated by micelle-solubilized hematoporphyrin, can diffuse to attack substrate molecules located in either the bulk aqueous phase or a different micelle. In particular, incorporation of the substrate into a micelle has only minor effects on its reactivity toward¹O₂, although the ¹O₂—indole interaction appears to be more efficient in cationic micelles owing to a favourable orientation of the target with respect to the attacking species. On the other hand, the electron transfer from triplet porphyrin to a micellized substrate is virtually non-operative when the latter is located in an anionic micelle, whereas in neutral or cationic micelles, the efficiency of the process is again controlled by the substrate orientation. Studies of tryptamine photooxidation sensitized by meso-tetra-(4-sulfonato-phenyl) porphine in the presence of sodium dodecylsulphate micelles lend further support to the abovementioned conclusions.     

COMPARISON OF PHOTODYNAMIC ACTION BY ROSE BENGAL IN GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA

Abstract— The photodynamic inactivation by illuminated Rose Bengal of a number of bacterial species was compared. The gram-positive species, Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis and Streptococcus salivarius, were inactivated about 200x more quickly (99% inactivation) than a Salmonella typhimurium wildtype strain. The Salmonella inactivation curve exhibited an initial lag time during which bacteria were not significantly inactivated. The lag time for inactivation of a derivative of the wildtype Salmonella strain that is deficient in a large portion of its cell wall lipopolysaccharide coat was approximately half of the lag time for the wildtype strain but the subsequent rate of inactivation was approximately the same for the two strains. Dark preincubation of both Salmonella strains with Rose Bengal before illumination shortened the lag time, but did not increase the final rate of inactivation. Dark preincubation prior to illumination did not measurably change the inactivation curve of the gram-positive species. The lag time observed in the inactivation curves for Salmonella bacteria may reflect the time required for penetration of the Rose Bengal anion through the outer portion of the gram-negative cell wall to a critical location within the cell for effective photosensitization.     

ZINC TETRAPHENYLPORPHYRIN-SENSITIZED PHOTOREDUCTION OF ANTHRAQUINONESULFONATE IN AQUEOUS MICELLAR SOLUTIONS*

Abstract— Zn-tetraphenylporphyrin (ZnTPP), solubilized in non-ionic surfactant micelles, was found to sensitize photoreductions of some sodium anthraquinonesulfonatesz in the presence of ascorbic acid under anaerobic conditions. The reaction rate was increased by the addition of an anionic surfactant, while retardation was observed with a cationic surfactant. The pH-reaction rate profiles showed maxima located in the order corresponding to pK_a-values for the semiquinone of each anthraquinone-sulfonate. A reaction scheme involving the formation of ZnTPP⁺ at the primary step, followed by back-reduction with ascorbic acid, is proposed. The reaction scheme is in good agreement with the results of flash photolysis. The surfactant micelles are suggested to aid the charge-separation between the ionic species just after the redox reaction involving the photoexcited ZnTPP and anthraquinonesulfonates.     

PHOTOINACTIVATION OF INFLUENZA VIRUS FUSION AND INFECTIVITY BY ROSE BENGAL

Rose bengal inactivated influenza virus upon exposure to light. Infectivity and fusion were inactivated with the same dose dependence, supporting the suggestion that the virucidal activity of photodynamic agents against enveloped viruses may be generally due to inactivation of their fusion protein(s). Concentrations required for inac-ti vation were found to depend upon the ratio of rose bengal to virus, rather than on the nominal aqueous concentration. Fusion-competent virosomes were inactivated similarly to intact virus particles. The HA_Z portion of the influenza fusion protein HA underwent two different, apparently mutually exclusive modifications upon illumination with rose bengal: cross-linking, and conversion to a form that moved slightly more slowly on sodium dodecyl sulfate poly-acrylamide gel electrophoresis. Inactivation of viral fusion was inhibited by oxygen removal or addition of azide or β-carotene, and was enhanced by D₂O, consistent with partial involvement of singlet oxygen. The possibility of a second mechanism of viral photoinactivation, by direct interaction between the viral fusion protein and the pho-toactivated dye, is also discussed.     

DEACTIVATION OF PYRENE BY INDOLE IN MICELLAR SOLUTIONS

Abstract— The deactivation rate of excited pyrene by indole strongly depends on the polarity of the media. In micellar systems (Triton X-100, cetyltrimcthylammonium chloride (CTAC) and sodium dodecylsulfate (SDS) the deactivation efficiency is enhanced due to the high local concentration of indole in the micellar pseudophase. Quantitative interpretation of the data in CTAC and SDS micelles requires to take into account indole exchange between the micelles and the aqueous phase. In SDS micelles, where due to their smaller size the exchange process is more relevant, the exit and entrance rates are (3.0 ± 0.6) x 10⁶ and (1.2 ± 0.3) x 10¹⁰ M ⁻¹s⁻¹ respectively. Intramicellar bimolecular quenching constants are (1.1 ± 0.2) x 10⁸ M⁻¹ s⁻¹ (1.4 ± 0.2) x 10⁸ M ⁻¹ s⁻¹ and (1.5 ± 0.2) x 10⁸ M ⁻¹ s⁻¹ in Triton X-100, SDS and CTAC respectively. These rates are similar to those measured in ethanol rich ethanol-water homogeneous solutions. This is in agreement with the average polarity sensed by both pyrene and indole in the micellar pseudophases.     

PHOTOSENSITIZATION OF SINGLE-STRAND BREAKS IN pBR322 DNA BY ROSE BENGAL

Rose bengal photosensitized the formation of frank single-strand breaks (SSBs) in double-stranded, supercoiled pBR322 DNA as measured by neutral agarose electrophoresis. The yield of SSBs followed first order kinetics with respect to light fluence and dye concentration. The efficiency of cleavage was more than 20 times greater in an argon atmosphere than in an oxygen atmosphere. The quantum yield in an air atmosphere was 1.7 (+/- 0.3) X 10(-8). Sodium azide quenched the cleavage more efficiently in an oxygen atmosphere than when the oxygen concentration was reduced. Isopropanol and mannitol were poor quenchers; ribose-5-phosphate and guanosine-5'-monophosphate did not quench the cleavage. Substituting D2O for H2O increased the yield of SSBs in both oxygen and oxygen-depleted atmospheres. The results are consistent with initiation of cleavage by reaction of the triplet state of rose bengal (or a radical derived from it) with DNA. In the presence of oxygen, an additional mechanism is introduced.     

粘度法研究胶团的球-棒转变

本文基于粘度测量求得了溴化十四烷基吡啶胶团水溶液的特性粘度随盐量(0.5—2.0 mol L~(-1)NaBr), 温度(20°—40 ℃)和活性剂浓度(3-25 g L~(-1))的变化。利用Missel等提出的热力学模型,由此求算了支配球-棒转变的平衡常数K和多分散胶团的重均聚集数, 当盐浓度为0.5和1.0 mol L~(-1)时, 由粘度法在不同温度下得到的K值以及在30 ℃下随活性剂浓度的变化, 与光散射的相应结果相当一致。此外, 在不同温度下求得的参数K在一定的胶团浓度范围内保持为常量。这符合模型的要求。盐量增至2 mol L~(-1)时, K明显地具有浓度依赖性,并且两法给出的K和值都相差较大。上述模型不再适用。对于符合球-棒转变的胶团体系, 从特性粘度具有浓度依赖性出发的粘度方法是研究胶团长大的简单而可靠的方法, 能够提供很多重要的信息。     

CONTINUOUS ABSORPTION OF TOLUENE VAPOR BY MICELLAR SOLUTIONS AND THE RESULTING MICROEMULSIONS

ABSTRACT

Microemulsions consisting of AOT-H₂O-toluene-hexyl carbitol (HC) or butyl carbitol (BC) were investigated in relation to the relative vapor pressure of toluene (P/P_o). The microemulsions generally revealed high (P/P_o). The relatively lower (P/P_o) was only obtained from those containing 10% and 15% AOT at higher levels of HC and BC respectively. From the linear plot of (P/P_o) against the volume fraction of toluene, the transition from micellar solution to microemulsion was evident. This transition phenomenon was also observed in the continuous absorption of toluene vapor. It was concluded chat the microemulsions studied were not efficient in scrubbing toluene vapor, but they were much more effective than their respective micellar solutions.     

QUENCHING OF PYRENE FLUORESCENCE BY TRYPTOPHAN IN MICELLAR SOLUTIONS

Deactivation of excited pyrene incorporated to cationic (cetyltrimethylammonium chloride), anionic (sodium dodecyl sulfate) and neutral (Triton X-100) micelles by tryptophan has been investigated over a wide pH range. Data obtained allow an estimation of the tryptophan association to the micelles, of the tryptophan apparent p K in the micellar solutions, and of the dynamics of tryptophan incorporation to the micellar pseudophase. In particular, the data obtained at pH 7 allow an estimation of the effect of the micellar charge upon the binding capacity of the tryptophan zwitterion.     

RATE PARAMETERS FOR THE QUENCHING OF SINGLET OXYGEN BY WATER-SOLUBLE AND LIPID-SOLUBLE SUBSTRATES IN AQUEOUS AND MICELLAR SYSTEMS

Abstract— The laser flash photolysis method has been used to determine the bimolecular rate constants for the reaction between O₂(¹Δ₉) and several lipid-soluble and water-soluble substrates. Values for lipid-soluble substrates have been obtained using aqueous dispersions of surfactants above the critical micelle concentration with 1,3 diphenylisobenzofuran as monitor of singlet oxygen. Under these conditions the hydrophobic substances are solubilized by the micellar phase. For substrates which are water-soluble, 9,10-anthracene dipropionic acid disodium salt was used as singlet oxygen monitor. For several substances, the values obtained are comparable to the values found in homogeneous nonaqueous solutions. In cases where significant differences have been found these have been rationalized according to the individual case. The only major unexpected result concerned β-carotene which, in micellar dispersion, failed to react at all with O₂(¹Δ₉) This may be due to multi-molecular aggregations occurring in the polar medium. The work described herein shows clearly that, under appropriate conditions, singlet oxygen kinetics can be effectively followed in aqueous solutions by time resolved methods. The indiscriminate use of β-carotene as a quencher of O₂(¹Δ₉)in mainly aqueous media is questioned.     

PHOTOSENSITIZED FORMATION OF SINGLET OXYGEN BY CHLOROPHYLL a IN NEUTRAL AQUEOUS MICELLAR SOLUTIONS WITH TRITON X-100

Abstract— Singlet oxygen (^lO₂) formed in the photolysis of neutral aqueous micellar (with Triton X-100) solution of chlorophyll a (dissolved inside the micelle) is detected in the aqueous phase by a test using imidazole in the presence of p -nitrosodimethylaniline. The quantum yield of ^lO₂ diffusing out of the micelle into the aqueous phase is also determined [θ(^lO₂) ⋍ 0.70–0.85].     

ELICITATION OF SPREADING DEPRESSION BY ROSE BENGAL PHOTODYNAMIC ACTION

Spreading depression refers to a slowly propagating depression of the ordinary electrical activity of the nervous tissue. It can be elicited by different types of physical or chemical non-specific stimuli. Various evidences suggest that transient alterations of cell membranes are involved. For this reason, and considering the action of free radicals on cell membranes, the elicitation of the reaction by dye photoactivation has been investigated. Isolated chick retina superfused in the dark with Ringer solution was able to regularly exhibit spreading depression when submitted to 1 microM rose bengal pulse of 5 min in duration, followed by 2.1 x 10(4) to 4.2 x 10(4) Jm-2 light pulse. The phenomenon was monitored either by visual inspection of the light-scattering milky wave that accompanies the reaction or by recording its characteristic slow voltage variation. The reaction was not triggered if the retina, superfused with the dye, was (a) maintained in the dark; (b) illuminated with red light (3.75 x 10(2) to 2.25 x 10(4) Jm-2), or (c) stimulated by white light but superfused with nitrogen-saturated solutions. It is concluded that, under the present conditions, the elicitation of spreading depression is contingent on the photoactivation of rose bengal in the presence of oxygen.     

THE 1-CYANONAPHTHALENE EXCIMER IN HOMOGENEOUS AND MICELLAR SOLUTIONS

Abstract— An excimer of 1-cyanonaphthalene is produced in homogeneous organic solvents and in micelle containing detergent solutions. From solvent effects in homogeneous solution it is concluded that the excimer is relatively polar (dipole moment ∼ 4D). From a comparison with emission from that observed in homogeneous solvents, it is concluded that 1-cyanonaphthalene is solubilized mainly in the Stern Layer of sodium dodecyl sulfate (SDS) and hexadecyltrimethyl ammonium bromide (HDTBr) micelles. The influence of variation of detergent concentration on the excimer to monomer emission ratio and the influence of NaCl concentration on the excimer to monomer emission ratio have been determined. Excimer formation is shown to be a convenient method for determination of the Kraft point of SDS solutions.     

四氯四碘荧光素镧系络合物的制备与性质

荧光素类分子中含有羧基和羟基,可与多种金属离子形成络合物。荧光素及碘代荧光素的镧系络合物的性质已进行过研究。最近虽报道了其镧系络合物的制备,但未见有关组成和性质等方面的记载。我们制取了12种四氯四碘荧光素镧系络合物,通过元素分析确定了其化学组成,并探讨了它们的溶解性能、电导、热重、红外光谱和紫外-可见光谱等性质。     

EFFECTS OF INDOLE AND TRYPTOPHAN ON FURAN OXIDATION BY SINGLET OXYGEN IN MICELLAR SOLUTIONS

Abstract— The 1,3-diphenylisobenzofuran oxidation by singlet oxygen was investigated in aqueous dode-cyltrimethylammonium chloride micellar solutions using pyrene as photosensitizer. It was found that indole and tryptophan markedly enhanced the furan oxidation in micellar solutions. This enhancement effect strongly depended on the ethanol content in micellar solutions; enhancement effect below about 0.3 mol fraction of ethanol and inhibition effect above this mole fraction. In the former ethanol range, a quenching of pyrene fluorescence by indole or tryptophan and a difference spectrum of furan between micellar solutions in the presence and absence of indole or tryptophan appeared strongly, but they were weakened in the latter ethanol range. The interactions between indole or tryptophan and pyrene and/or furan might be responsible for the enhancement effect observed. Discussion was made in connection with the micelle structure.     

ON THE NATURE OF CHLOROPHYLL a IN AQUEOUS MICELLAR SYSTEMS

Abstract— Absorption and fluorescence spectra of chlorophyll a in aqueous micellar solutions were studied. Solutions in anionic micelles gave an absorption band at 740 nm, attributable to microcrystal- line chlorophyll a. Solutions in cationic and nonionic micelles do not show this band. The positions of the spectral bands in anionic micelles and the possible structure of microcrystalline form are discussed. A comparison is made of the behaviour of microcrystalline form in hydrocarbon solvents and in micellar solutions.     

MMA在胶束水溶液中的光敏聚合

应用动力学方法研究了二苯甲酮/三乙胺引发MMA在胶束水溶液中的光敏聚合反应,结果表明表面活性剂的胶束对聚合反应具有催化作用,以离子型胶束的效果显著,可使反应的量子收率提高4—5倍。聚合速度和产物分子量随胶速浓度而增加,用紫外光谱和~1H—NMR测定了BP/TEA/MMA在离子型胶束中增溶位置,结果表明反应发生在胶束-水界面层。由于增溶于离子胶束中的单体分子具有一定取向性,提高了PMMA的立构有序性。     

溴代十四烷基吡啶胶团长大的光子相关谱研究

本文用光子相关谱方法在15—85 ℃温度范围内, 研究了溴代十四烷基吡啶(TPB)胶团在高盐量介质(0.5—2.0M NaBr)中的长大规律。自光子相关实验测定了胶团的平均流体力学半径。增加盐量、降低温度和增大活性剂浓度均使胶团变大。TPB胶团长大时由球转变为棒。自实验测量结果求算了在0.5 M和1.0 M盐中支配球-棒转变的平衡常数及热力学函数值。本文检验了梯子模型对TPB体系的适用性, 并对2 M盐介质中TPB胶团的长大具有不同的特征作了讨论。