Inverse Filtering and Linear Prediction as New Analytical Approaches to Analyze the Change of Absorbance Spectra in Visible Spectroscopy: in vivo Study of Protochlorophyll(ide) Phototransformation

Abstract— The common approach of analyzing spectra by derivation is known to be inadequate for kinetic studies in visible spectroscopy (R. I. Sharger, Photochem. Photobiol. 38, 615-617, 1983) because the side-lobes height introduces artifacts and reduces readability in three-dimensional graphic representation. In this study we present for the first time a parametric method that enables the use of inverse filtering and linear prediction for kinetic investigation in visible spectroscopy in cell biology studies. The protochlorophyll(ide) phototransformation at room temperature (295 K) was used to demonstrate the performance of this analytical approach. The change of absorption spectra in etiolated barley leaves was analyzed after being illuminated by a 50 ms flash.     

探针5-硝基水杨酸同步荧光法测定生物样品中蛋白质

在模拟体液离子强度下,基于5-硝基水杨酸(5-NSA)与人血清白蛋白(HSA)相互作用生成复合物,导致血清白蛋白的内源荧光产生特异性变化,而建立了以5-NSA为分子探针,用固定波长同步荧光光谱分析测定蛋白质的新方法. 体系同步荧光光谱特征及强度受Δλ、反应介质、反应温度等因素的影响. 结果表明,在最佳实验条件下,体系的同步荧光强度(ISF)与人血清白蛋白在3.2×10-8～6.4×10-8 mol/L的质量浓度范围内呈良好的线性关系,检测限为1.7×10-8 mol/L(n=11). 对血清、尿样和唾液样品进行了测定,回收率在99.96%～100.04%之间.     

Evolution of a Short Route to Strychnine by Using the Samarium‐Diiodide‐Induced Cascade Cyclization as a Key Step

This comprehensive report accounts the development of a highly diastereoselective samarium diiodide‐induced cascade reaction of substituted indolyl ketones. The complexity‐generating transformation with SmI₂ allows the diastereoselective generation of three stereogenic centers including one quaternary center in one step. The obtained tetra‐ or pentacyclic dihydroindole derivatives are structural motifs of many monoterpene indole alkaloids, and their subsequent transformations gave way to one of the shortest approaches towards strychnine (14 % overall yield in ten steps, or 10 % overall yield in eight steps). During the course of this report we discuss the influence of substituents on the cyclization step, plausible mechanistic scenarios for the SmI₂‐induced cascade reaction, diastereoselective reductive amination, and regioselective dehydratization protocols towards the pentacyclic core structure of strychnos alkaloids.     

罗丹明6G与核酸作用的共振光散射光谱及其分析应用

研究了罗丹明6G（Rh6G）与核酸（ctDNA和yRNA)作用的共振光散光谱（RLS）特征，基于RLS的增强，建立了一种测定核酸的新方法，考察了各种影响因素，在优化条件下确定了RLS强度与ctDNA和yRNA浓度之间的关系，相应的线性范围分别为0.05-37.0μg.mL^-1、0．1－10．0μg.mL^-1，检出限分别为3．0ng.mL^-1和9．5ng.mL^-1。四种合成样品五次平行测定结果的相对标准偏差（RSD）范围为2．0％－3．0％。     

可见光驱动的光催化产氢同时诱导低能核反应嬗变钾为钙

报道了曙红、氯铂酸钾、氧化石墨烯和三乙醇胺混合物悬浮体系在可见光照射条件下将钾嬗变为钙的现象.在大于440 nm光照的条件下,反应体系可以产生大量的氢气,同时体系中的部分钾原子转变为钙元子.在反应过程中,悬浮混合物中的钙元素浓度持续增加,同时伴随发生质子的还原为氢和部分质子反应为氦3和氦4的反应.分析表明,在自然界的某种环境和条件下,钙有可能通过在温和条件下的低能核反应(LENR)经历钾的嬗变生成,这个过程可能与光催化产氢过程中生成的负氢有关.     

Fluorescence lifetime of terbium(III) as a probe for the ion-binding properties of tactic poly(methacrylic acids)

The binding properties of trivalent metal ions to polyelectrolytes were investigated through the use of terbium [Tb(III)] in fluorescence studies. The fluorescence intensity and lifetimes of the lanthanide ions are directly dependent upon the number of water molecules bound to their inner coordination sphere. The more efficiently a ligand coordinates to a lanthanide ion, the more water molecules are expelled and consequently, the greater the fluorescence intensity and lifetime. This effect was used to probe for differences in the complexation behavior of tactic polymers. Aqueous solutions of isotactic and syndiotactic poly(methacrylic acid) (PMA) were neutralized and complexed with Tb(III) ions. The fluorescence intensity of the 286 nm hypersensitive excitation band was monitored and the lifetimes were measured using several excitation wavelengths. It was found that the isotactic PMA/Tb(III) complex exhibited a six times greater fluorescence intensity than the syndiotactic PMA complex. Lifetime measurements gave the number of water molecules coordinated by Tb(III) in the isotactic complex to be 2.4 while 3.4 waters remained bound to the Tb(III) ion in the syndiotactic PMA complex. These results indicate that isotactic PMA has the greater binding affinity towards Tb(III) ions. © 1997 John Wiley & Sons, Inc.     

Efficient Improvement of Fluorescence Quantum Yield of Fluoreneethynylene‐Based Polymers by Introducing a Perfluoroalkylbenzene Unit to the Polymers

In comparison with poly(9,9‐dialkylfluorene)s widely used in organic optoelectronic devices, poly(9,9‐dialkylfluoreneethynylene)s ( PFEs ) have attracted less attention partly because of their poor fluorescence quantum yield (FQY) in the solid state. In order to improve the FQY, a 1,4‐bis(perfluorohexyl)benzene (BFB) unit was introduced to PFEs , and the results showed that the absolute FQY in the solid state was dependent on the mol‐% of the BFB unit in the copolymers. When mol‐% was 40 and 50%, respectively, the absolute FQY had greatly increased from 4.9% of PFE to 7.8 and 17.4% of the copolymers, respectively. For comparison, a 1,4‐dihexylbenzene (DHB) unit was also introduced to PFE , whereas the obtained copolymer showed the absolute FQY of 3.8%, suggesting that the DHB unit was not suitable for improvement of the FQY of PFEs . Electrochemically, the PFE containing BFB units showed lower reduction potential than that of PFE . All the fluorine‐containing polymers have good thermal stability.

     

Investigation of the Formation of Squalene Oligomers Exposed to Ultraviolet Light and Changes in the Exposed Squalene as a Potential Skin Model

UV-induced oligomerisation of squalene was undertaken to indicate the potential for squalene-containing biological systems to exhibit rheology changes. DOSY NMR enabled the determination of the molecular weight (MW) range using Stokes–Einstein Gierer–Wirtz Estimation (SEGWE Calculator, University of Manchester). This approach was validated by Atmospheric Solids Analysis Probe Time of Flight Mass Spectrometry (ASAP TOF MS). To demonstrate the principle, both benzoyl peroxide and AIBN were used, separately, to initiate rapid, radical oligomerisation. Subsequent experiments in the absence of initiators compared the influence of UV wavelength and time on the resulting oligomer formation. To further model a relevant biological implication of this potentially chaotic UV oligomerisation, both saturated and unsaturated free fatty acids were added to squalene and exposed to UV at 285 nm and 300 nm to determine if cross oligomerisation could be observed. This representation of sebum evidenced the formation of a distribution of higher MW oligomers. Internal viscosity was normalised using the DMSO solvent, but to confirm that changes in rheology did not affect diffusion, a final experiment where fresh squalene was added to our oligomer mixture, representative of sebum, showed that unchanged squalene possessed the anticipated monomeric diffusion coefficient and hence MW. This work suggests, at least qualitatively, that UV-induced squalene oligomerisation can occur over time and that this may have a role in the behaviour of squalene on the skin.     

From Dark to Light to Fluorescence Resonance Energy Transfer (FRET): Polarity‐Sensitive Aggregation‐Induced Emission (AIE)‐Active Tetraphenylethene‐Fused BODIPY Dyes with a Very Large Pseudo‐Stokes Shift

The work presented herein is devoted to the fabrication of large Stokes shift dyes in both organic and aqueous media by combining dark resonance energy transfer (DRET) and fluorescence resonance energy transfer (FRET) in one donor–acceptor system. In this respect, a series of donor–acceptor architectures of 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) dyes substituted by one, two, or three tetraphenylethene (TPE) luminogens were designed and synthesised. The photophysical properties of these three chromophore systems were studied to provide insight into the nature of donor–acceptor interactions in both THF and aqueous media. Because the generation of emissive TPE donor(s) is strongly polarity dependent, due to its aggregation‐induced emission (AIE) feature, one might expect the formation of appreciable fluorescence emission intensity with a very large pseudo‐Stokes shift in aqueous media when considering FRET process. Interestingly, similar results were also recorded in THF for the chromophore systems, although the TPE fragment(s) of the dyes are non‐emissive. The explanation for this photophysical behaviour lies in the DRET. This is the first report on combining two energy‐transfer processes, namely, FRET and DRET, in one polarity‐sensitive donor–acceptor pair system. The accuracy of the dark‐emissive donor property of the TPE luminogen is also presented for the first time as a new feature for AIE phenomena.     

Probing the Proton-Coupled Electron-Transfer (PCET) Reactivity of a Cross-Conjugated Cruciform Chromophore by Redox-State-Dependent Fluorescence

Proton-coupled electron transfer (PCET) reactions are of great importance in synthetic chemistry and in biology, but the acquisition of kinetic information for these reactions is often difficult. Herein, we report the synthesis of a new PCET reagent, showing redox-state dependent fluorescence, by merging the concept of cross-conjugated cruciform chromophores with the strategy of imposing redox activity and Brønsted basicity to aromatic compounds by substitution with guanidino groups. The compound is isolated and characterized in all stable states—reduced, twofold and fourfold protonated and twofold oxidized—and then applied in PCET reactions by using its redox-state dependent fluorescence signal for kinetic measurements.     

以meso-四(4-磺基苯)卟啉作为探针毛细管电泳法分析蛋白质的研究

建立了利用水溶性的meso-四(4-磺基苯)卟啉(TPPS4)作为光谱探针，采用毛细管区带电泳定量蛋白质的方法。考察了pH值和TPPS4浓度对定量动态范围的影响，优化了电泳分离条件，并探讨了溶液酸度和加入p环糊精对蛋白与卟啉复合物稳定性的影响。该方法对蛋白质的检测范围为l～20μg／mL，线性相关系数大于0．993，适用于实验室和临床上微量蛋白质总量的分析。     

DNA分子结构的多态性研究(Ⅲ)——生物大分子探针吖啶橙诱导λ-DNA由线型向环型的转变

病毒和细胞体内的DNA是以高度紧密的凝聚态存在的.自从在体外发现亚精胺、精胺可诱导无规卷曲的DNA形成有序、独特的凝聚结构形态以来,许多学者深入研究了多价阳离子的诱导特性,以期阐明DNA在病毒内的组装和染色体中凝聚作用的机制[1,2].     

共振光散射探针铁的混配物的合成及其在脱氧核糖核酸测定中的应用

1　引　　言共振光散射技术在测定核酸方面有较广阔的应用前景。而在核酸探针的探索中 ,人们发现邻菲咯啉、联吡啶等大环配体有共轭π键和刚性平面 ,可进行手性异构体的识别。本实验合成了铁 与邻菲咯啉、联吡啶的混配物 ,并通过紫外、荧光和共振光散射等技术研究了混配物与DNA作用状况 ,证明此混配物可作为脱氧核糖核酸的共振光散射探针 ,且定量测定DNA时灵敏度高。2　实验部分2 .1　仪器与试剂　GSP 77 0 3磁力搅拌器 (江苏秦县医疗器械厂 ) ;RF 5 40荧光分光光度计 (日本岛津公司 ) ;λ 17型紫外 可见分光光度计 (美国P E公司 ) …     

Studies on Micellization of a Polystyrene-b-poly(acrylic acid) Copolymer in Aqueous Media by Pyrene Fluorescence

The aggregation of amphiphilic block copolymers is a crucial phenomenon that controls various applications, and has been extensively treated in the literature1-3. Pyrene is a widely used fluorescence probe for the relative intensities of the vibrational fine structure (five bands) of its fluorescence spectra have been found to be sensitive to the polarity of its environment, the so-called Ham effect4. We report the studies of the aggregation properties of a PS-b-PAA copolymer using pyrene …     

Simultaneous Determination of Phenanthrene and Benzo(a)pyrene in Water Samples by Synchronous Fluorescence Spectroscopy

Abstract

A simple and sensitive method was developed to simultaneously determine phenanthrene and benzo(a)pyrene in water samples using synchronous fluorescence spectroscopy with a 56-nm Δλ. The method was used to simultaneously determine both compounds in samples of spiked surface water. Analytical recoveries were 96.9–101.1% for phenanthrene and 95.8–103.5% for benzo(a)pyrene. Analytical results were checked for precision with 15 measurements for each compound. Relative standard deviations were 1.9% for phenanthrene and 2.9% for benzo(a)pyrene, which shows that the proposed method is quite precise.     

Fluorescence response of 3-trifluoroacetylaminophthalimide to a Li(+)-I(-) ion pair induced by 254 nm photolysis in acetonitrile

A 3-trifluoroacetylaminophthalimide selectively distinguished LiI from other alkaline-metal iodides and lithium halides by a marked fluorescence colour change, from orange-yellow to sky-blue, subsequent to 254 nm photolysis.