Investigation of cross-resistance to a range of photosensitizers, hyperthermia and UV light in two radiation-induced fibrosarcoma cell strains resistant to photodynamic therapy in vitro

Two distinct photodynamic therapy-resistant variants of the murine radiation-induced fibrosarcoma (RIF) cell line have been isolated. One strain displayed relative resistance over the parental RIF-1 strain to treatment with the porphyrin-based compound, polyhaematoporphyrin (PHP), whereas the other strain displayed relative resistance over the RIF-1 strain to treatment using the cationic zinc (II) pyridinium-substituted phthalocyanine (PPC). The PHP-resistant strain did not display cross-resistance to PPC-mediated treatment, and vice versa. In both PDT-resistant strains, the increased resistance could not be attributed to altered cellular growth rate, antioxidant capacity or intracellular sensitizer localization. The PHP-resistant strain displayed resistance to treatment with both short (1 h) and extended (16 h) sensitizer incubation periods, which may indicate that in this strain, the resistance has arisen through an alteration in a membrane component. Conversely, the PPC-resistant strain only displayed increased resistance over the parental cells to treatment involving the short drug incubation, which is likely to reflect the existence of a threshold effect caused by the alteration of an individual cellular target. Each resistant strain has been compared to the parental strain in terms of cellular sensitivity to treatment with a range of other photosensitizers, hyperthermia, UV light and the anticancer agent cis-diamminedichloroplatinum. The PHP-resistant strain exhibited crossresistance to photosensitization treatment using exogenously added protoporphyrin IX, and also to treatment with the anionic phthalocyanine sensitizers, zinc (II) tetrasulfonated phthalocyanine and zinc (II) tetraglycine-substituted phthalocyanine. The PPC-resistant strain did not display cross-resistance to any of the treatment strategies employed in this investigation. The results of this investigation indicate that there are at least two distinct mechanisms of PDT resistance in RIF cells, and that the mechanism of PHP resistance may, to some extent depend, upon the physical nature of the sensitizer molecule.     

Chemical Analysis of the Luminous Slime Secreted by the Marine Worm Chaetopterus (Annelida,Polychaeta)

The marine annelid Chaetopterus variopedatus produces bioluminescence by an unknown and potentially novel mechanism. We have advanced the study of this fascinating phenomenon, which has not been investigated for nearly 60 years after initial studies were first reported for this species. Here, we show that the luminous slime produced by the worm exhibits blue fluorescence that matches the bioluminescence emission. This result suggests that the oxyluciferin emitter is present. However, while the blue fluorescence decays over time green fluorescence is increasingly revealed that is likely associated with products of the luminescence reaction. LC/MS and fluorescence analysis of harvested luminescent material revealed riboflavin as the major green fluorescent component. Riboflavin is usually associated with the mechanism of light production in bacteria, yet luminous bacteria were not found in the worm mucus, and accordingly were not reported to be directly responsible for the light emission, which is under nervous control in the worm. We therefore propose a hypothesis in which riboflavin or a structurally related derivative serves as the emitter in the worm's light producing reaction.     

Adrenocorticotropic Hormone and Cyclic Adenosine Monophosphate are Involved in the Control of Shark Bioluminescence

Among Etmopteridae and Dalatiidae, luminous species use hormonal control to regulate bioluminescence. Melatonin (MT) triggers light emission and, conversely, alpha melanocyte-stimulating hormone (α-MSH) actively reduces ongoing luminescence. Prolactin (PRL) acts differentially, triggering light emission in Etmopteridae and inhibiting it in Dalatiidae. Interestingly, these hormones are also known as regulators of skin pigment movements in vertebrates. One other hormone, the adrenocorticotropic hormone (ACTH), also members of the skin pigmentation regulators, is here pharmacologically tested on the light emission. Results show that ACTH inhibits luminescence in both families. Moreover, as MT and α-MSH/ACTH receptors are members of the G-protein coupled receptor (GPCR) family, we investigated the effect of hormonal treatments on the cAMP level of photophores through specific cAMP assays. Our results highlight the involvement of ACTH and cAMP in the control of light emission in sharks and suggest a functional similarity between skin pigment migration and luminescence control, this latter being mediated by pigment movements in the light organ-associated iris-like structure cells.     

THE CHEMISTRY AND BIOLOGY OF BACTERIAL LIGHT EMISSION

Abstract—Bioluminescent bacteria may be isolated from sea water, and grown on a medium containing fish (or meat or yeast) extract. Cells harvested at the peak of luminescence can be lysed osmotically, releasing into the medium the soluble enzyme bacterial luciferase, which catalyzes the bioluminescent oxidation of reduced riboflavin 5′-phosphate and long chain aldehyde by molecular oxygen. Luciferase is the simplest possible heterpolymeric protein, with an α (catalytic, 42,000 daltons)-β (regulatory, 37,000 daltons) dimeric structure. Luciferase is not constitutive; it is induced by a substance produced by the bacteria themselves and excreted into the medium. Control also involves repression (glucose) and cyclic nucleotides. Recent work has resulted in the characterization of an intermediate in the light emitting reaction postulated to be luciferase-bound 4a-peroxy-dihydro FMN. The final steps in the in vitro light-emitting reaction involve reaction of this peroxy intermediate with aldehyde in a mixed function oxidase-type reaction, yielding an excited luciferase-flavin and long chain acid. The excited state is postulated to be the luciferase-bound 4a-hydroxy-dihydro-FMN. Although the identity of the in vivo aldehyde, its localization and its metabolism is unknown, studies with mutants which fail to synthesize aldehyde suggest that the 14 carbon fatty acid is a precursor. Moreover, although bacterial luciferase is highly soluble (200 mg ml^-1 in aqueous solution) there is recent evidence from our laboratory and others that its function may involve the cytoplasmic membrane. The function of light emission is of particular interest since a considerable amount of energy is involved; assuming a quantum yield of 10%, the cell foregoes the production of about 60 ATP molecules per photon. A fully induced cell emits about 10⁴ quanta/s and about 20% (!) of the oxygen consumption of the cell has been estimated to go via the light emitting pathway. One function is in light organs of higher organisms, where they occur as symbionts. The inducible (and repressible) nature of the luminescent system may be appreciated in terms of ecological options; the bacteria may be biologically very versatile. Induction by an inducer produced by the bacteria themselves would occur only under conditions where it accumulates, as in a luminous organ of a host. In the open ocean such an accumulation does not occur; the luminous system would thus not be synthesized and energy loss via luminescence is averted, allowing the bacteria to compete in an alternate “life style”.     

3D electrogenerated chemiluminescence: from surface-confined reactions to bulk emission

Among luminescence techniques, electrogenerated chemiluminescence (ECL) provides a unique level of manipulation of the luminescent process by controlling the electrochemical trigger. Despite its attractiveness, ECL is by essence a 2D process where light emission is strictly confined to the electrode surface. To overcome this intrinsic limitation, we added a new spatial dimension to the ECL process by generating 3D ECL at the level of millions of micro-emitters dispersed in solution. Each single object is addressed remotely by bipolar electrochemistry and they generate collectively the luminescence in the bulk. Therefore, the entire volume of the solution produces light. To illustrate the generality of this concept, we extended it to a suspension of multi-walled carbon nanotubes where each one acts as an individual ECL nano-emitter. This approach enables a change of paradigm by switching from a surface-limited process to 3D electrogenerated light emission.     

Crosslink-Enhanced Emission Effect on Luminescence in Polymers: Advances and Perspectives

The crosslink-enhanced emission effect was first proposed to explore the strong luminescence of nonconjugated polymer dots possessing only either non-emissive or weakly emissive sub-luminophores. Interesting phenomena in recent research indicate such enhancement caused by extensive crosslinking appears in diverse luminescent polymers with sub-luminophores (electron-rich heteroatomic moieties) or luminophores (conjugated π domains). This enhancement can promote the emission from nonluminous to luminous, from weakly luminous to strongly luminous, and even convert the pathway of radiative transitions. The concept of the crosslink-enhanced emission effect should be updated and extended to an in-depth spatial effect, such as electron overlap and energy splitting in confined domains by effective crosslinking, more than initial immobilization. This Minireview outlines the development of the crosslink-enhanced emission effect from the perspective of the detailed classification, inherent mechanism and applicable systems. An outlook on the further exploration and application of this theory are also proposed.     

脉冲激光法连续制备高蓝光荧光性的修饰纳米ZnO乙醇溶胶

采用聚焦脉冲激光束轰击浸于含有水杨酸的无水乙醇流动相中的ZnO固体靶, 连续制备得到了强度高达1.12×105的蓝色荧光(440 nm)的水杨酸修饰纳米ZnO乙醇溶胶. 考察了修饰剂的种类、浓度、添加顺序和流动相流速对其荧光性能的影响. 透射电镜结果表明, 所制备的纳米ZnO粒径分布在15—30 nm.     

喷雾热解法制备球形SrAl_2O_4:Eu,Dy长余辉发光材料

采用喷雾热解两段法制备了SrAl2O4:Eu,Dy长余辉发光材料,利用SEM、荧光长余辉亮度测试、F-4500荧光分光光度等方法分析了不同制备工艺条件下SrAl2O4:Eu,Dy发光材料的形貌、余辉性能以及光谱性能的变化。采用喷雾热解两段法可制备出余辉性能良好的球形SrAl2O4:Eu,Dy长余辉发光材料。前驱体溶液浓度、热解温度、添加剂对产物的形貌、粒度分布、发光性能有较大影响。较之高温固相法,喷雾热解法制备的SrAl2O4:Eu,Dy具有合成温度低、发光性能好、形貌好、粒度分布窄等优点。     

Crosslink‐Enhanced Emission Effect on Luminescence in Polymers: Advances and Perspectives

The crosslink‐enhanced emission effect was first proposed to explore the strong luminescence of nonconjugated polymer dots possessing only either non‐emissive or weakly emissive sub‐luminophores. Interesting phenomena in recent research indicate such enhancement caused by extensive crosslinking appears in diverse luminescent polymers with sub‐luminophores (electron‐rich heteroatomic moieties) or luminophores (conjugated π domains). This enhancement can promote the emission from nonluminous to luminous, from weakly luminous to strongly luminous, and even convert the pathway of radiative transitions. The concept of the crosslink‐enhanced emission effect should be updated and extended to an in‐depth spatial effect, such as electron overlap and energy splitting in confined domains by effective crosslinking, more than initial immobilization. This Minireview outlines the development of the crosslink‐enhanced emission effect from the perspective of the detailed classification, inherent mechanism and applicable systems. An outlook on the further exploration and application of this theory are also proposed.     

基于乙醇和铝离子聚集诱导的铜纳米团簇

金属纳米团簇(MNCs)作为一种新型的纳米材料,具有合成方法简单、光稳定性强、毒性低、生物相容性好以及发光效率高等优点。在本研究中,使用“一锅法”合成谷胱甘肽保护的铜纳米团簇。在激发波长为370 nm时,GS@CuNCs的荧光发射波长在610 nm左右。铜纳米团簇可以通过有溶剂诱导和阳离子诱导两种方法聚集诱导增强其荧光强度。通过测定在不同溶剂(乙醇、甲醇、N, N-二甲基甲酰胺)中铜纳米团簇的荧光强度,探究了溶剂极性对聚集的影响。研究结果表明：在水溶液中铜纳米团簇只发射弱的荧光,随着乙醇含量从0%到85%,其荧光强度逐渐增强。此外,我们开发了一种新的选择性好、灵敏性高的检测铝离子的荧光探针。线性范围为2–20 μmol·L^-1,且检测限(LOD)为33 nmol·L^-1。进一步探究可得,乙醇和铝离子能使GS@CuNCs荧光强度显著增加的机理为聚集诱导荧光增强。     

Non-Aufbau Principle to Achieve High Stability Organic Luminescence Radicals

To solve the problem of stability of organic luminescence radicals, Li et al. proposed a new kind of organic luminescence radicals with non-Aufbau electronic structure by using donor-acceptor molecular structure. The stability of this kind of radicals was greatly improved and the high luminous efficiency was maintained. Using a non-Aufbau radical as the emission layer of an OLED, the maximum external efficiency of 5.3% has been achieved, which is among the highest efficiencies for pure organic near-intrared electroluminescence. This work has been published online in the Nature Materials on July 22,2019.     

反构造原理策略实现高稳定有机发光自由基

To solve the problem of stability of organic luminescence radicals, Li et al. proposed a new kind of organic luminescence radicals with non-Aufbau electronic structure by using donor-acceptor molecular structure. The stability of this kind of radicals was greatly improved and the high luminous efficiency was maintained. Using a non-Aufbau radical as the emission layer of an OLED, the maximum external efficiency of 5.3% has been achieved, which is among the highest efficiencies for pure organic near-infrared electroluminescence. This work has been published online in the Nature Materials in July 22, 2019.     

Observation of oscillation in bacterial luminescence.

Oscillation in the bioluminescent intensity from a luminous bacteria suspension was observed. The time course of the luminescence intensity from a suspension containing luminous bacteria was measured. The oscillation mode changed with the liquid broth component. The optical density and dissolved oxygen (DO) concentration were measured simultaneously with the luminescence intensity, and a possibility was indicated that both diauxic growth and oxygen reaction-consumption resulted with oscillation.     

Yb3+/Tm3+掺杂的NaY(WO4)2纳米晶的制备及发光特性

以聚乙二醇为配位剂,用水热法制备出纳米级上转换发光粉Yb3+和Tm3+共掺杂的NaY(WO4)2。研究了不同cYb/cTm对上转换发光强度的影响,实验表明当cYb/cTm=5∶1时,上转换发光强度最强。用XRD,SEM确定了Yb3+和Tm3+共掺杂的NaY(WO4)2是四方晶系,其粒径在25~35 nm范围,且分散均匀。用980 nm半导体激光器(LD)对其进行激发,在室温下观察到了365 nm附近紫外发射峰、456 nm,476 nm附近的蓝光发射峰和648 nm附近的红光发射峰,分别对应于Tm3+离子的1D2→3H6,1D2→3F4,1G4→3H6和1G4→3F4的跃迁。根据泵浦功率与发光强度的关系得出紫外发射峰、蓝光和红光发射均为双光子过程。     

Inverse relaxation-model and relation to recovery internal friction

Inverse relaxation is studied for hard elastic polypropylene (HEPP), rubber and non-elastic polypropylene. The results show that contractive stress, stress, and internal friction are three essential factors related to the phenomenon. A three-element model in which each element has a definite meaning is proposed to describe this phenomenon. The results also show that, in the first cyclic deformation, relaxation time increases with the increase of recovery for all the materials, which indicates that recovery viscosity increases with the increase of recovery, but the stress rising amplitude (SRA) of inverse relaxation has a maximum in the recovery range. Analysis indicates that SRA equals recovery internal friction (RIF) for ideal material in which stress is solely a function of strain, independent of paths, and approximately equals RIF for non-ideal material at a given strain. From this principle it is found that the order of the work counteracted by RIF for the four materials is the same as that of their second hysteresis loop, and the RIF of HEPP has a sudden increase at the later recovery range.     

BIOLUMINESCENCE OF THE BRITTLE STAR OPHIOPSILA CALIFORNICA

The light-emitting principle of the brittle star Ophiopsila californica has been isolated and purified. It was found to be a green-fluorescent photoprotein (molecular weight 45000) which emits green light (λ_max 500 nm) when H₂O₂ is added, independently of the presence or absence of O₂. The green fluorescence (emission maximum 500 nm, excitation maximum 440 nm) spectrally coincided with the H₂O₂-triggered luminescence, indicating that the green fluorescent chromophore is the light-emitter of the photoprotein luminescence.     

Large-area periodic lead halide perovskite nanostructures for lenticular printing laser displays

Lenticular printing technique provides a promising way to realize stereoscopic displays,especially,when microscopic optical structures are integrated into light-emitting materials/devices.Here,we fabricated large-area periodic structures with a spatial resolution at a wavelength scale from hybrid perovskite materials via a space-confined solution growth method.It takes advantages of both high refractive index contrast and high luminescence brightness,which allows the optical modulation on not only the reflection of illumination,but also the light emission from hybrid perovskites.The distributed feedback within these periodic structures significantly improves the degree of polarization and directionality of laser actions while their threshold is also reduced.These findings enable us to present a prototype of lenticular printing laser displays that vary emission colors at different view angles,which may find applications in creating high-resolution and high-contrast holographical images.     

White luminescence of Tm-Dy ions co-doped aluminoborosilicate glasses under UV light excitation

Tm³⁺ and Dy³⁺ ions co-doped aluminoborosilicate glasses were prepared in this study. The luminescence properties of the glasses were analyzed. A combination of blue, green, yellow, and red emission bands was shown for these glasses, and white light emission could be observed under UV light excitation. White light luminescence color could be changed by varying the excitation wavelength. Concentration quenching effect was investigated in this paper. Furthermore, the dependence of luminescence properties on glass compositions was studied. Results showed that the luminescence intensity changed with different network modifier oxides, while the white color luminescence was not affected significantly.     

在发光二极管背光源上极具应用前景的Beta-sialon (Si6-zAlzOzN8-z):Eu2+窄带绿色荧光粉

基于氮化镓的白光发光二极管(LED)是目前一项崭新的背光源技术,广泛应用于宽色域、高光效的液晶显示屏。 在此项技术中,作为关键材料的荧光粉决定着背光单元的色域范围、发光效率和可靠性,因而要求它应具合适的发射波长和窄带发射。 β-sialon:Eu²⁺(sialon:silicon aluminum oxynitride(赛龙))就是一款非常适合背光应用的绿色荧光粉,这得益于其位于525~545 nm发射峰和只有55 nm狭窄的峰宽。 此文回顾和综述了β-sialon:Eu²⁺的合成方法、光谱特性、电子结构、晶体结构、可靠性和它的具体应用。 计算模拟和实验测试结果表明,Eu²⁺位于沿c轴方向的大孔道之中,并与6个最紧邻的(O,N)原子等距离配位。 因而,Eu²⁺的狭窄发射峰源自于Eu²⁺局域结构的高度对称性。 β-sialon:Eu²⁺的发射波长和带宽都能通过组成裁剪,即z值,进行调控;低z值组成能够实现更短波长发射和更窄带宽。 与传统的基于钇铝石榴石(YAG)荧光粉的背光源相比,β-sialon:Eu²⁺再搭配红色荧光粉制备的背光源具有更宽的色域,色域范围可提高15%以上。 其优异的发光性能和高可靠性使得β-sialon:Eu²⁺成为应用于先进显示屏的极其重要的绿色发光材料。     

Enzyme-mediated biodegradation of heat treated commercial polyethylene by Staphylococcal species

Extruded low-density polyethylene (LDPE) films commonly available in the market as 20-micron thick carrier bags were autoclaved, overlaid on nutrient agar plates and inoculated with BP/SU1 strain of Staphylococcus epidermis. The nutrient agar plate showed growth of the organism within two to three days. The polymer film supporting the growth of the organism showed pore formation as recorded by SEM analysis. The growth of BP/SU1 is supported by the presence of shredded LDPE as its only carbon source in inorganic salt minimal nutrient medium. The organism survives even after three months of inoculation and this is accompanied by gradual breakdown of the size of the shredded plastic as seen by light scattering. The cell-free supernatant of the organism, grown with the help of shredded plastic shows the presence of the over expressed proteins with approximate molecular weight of about 55 kDa and 35 kDa, through SDS-PAGE analysis.