- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Spectroscopy Used as a Tool to Evaluate Hair Damage and Protection
摘要： OBJECTIVE: Methods that can be used to analyze hair damage and to support a claim of hair protection are important for the cosmetic industry. There are many approaches available, but they are usually laborious and expensive. The researchers propose a simple fluorescence method that is based upon the emissive properties of damaged hair. METHODS: Hair fluorescence was observed when using both fluorimetry and microscopic procedures. The method was developed by comparing native hair with hair that was damaged by UVA and visible light. RESULTS: Spectroscopic properties (absorption and emission) of hair in the visible range are presented. The changes in the emissive properties of hair during irradiation were characterized and they were correlated with photobleaching, which is due to the generation of singlet oxygen. Emissions were also obtained in the hair shafts that had been previously treated with chamomile extract and this treatment was able to avoid hair bleaching. CONCLUSION: The emissive properties of hair in the visible range can be used as a tool for the evaluation of hair damage and protection. This method can be useful as a tool in order to claim
关键词： Hair treatment,singlet oxygen,spectroscopy,claim substantiation,fluorescence,visible
更新于2025-11-21 11:24:58
-
Light Controlled In Vitro Gene Delivery Using Polymer-Tethered Spiropyran as a Photoswitchable Photosensitizer
摘要： A gene delivery system using spiropyran as a photoswitchable photosensitizer for controlled photochemical internalization effect was developed by engineering the outer coating of polyethylenimine/DNA complex with a small amount of spiropyran-containing cationic copolymers. The successful binding of cationic polymers by the polyethylenimine coating was detected by the distance-sensitive fluorescence resonance energy transfer technique that evidenced occurrence of energy transfer between fluorescein-labeled cationic copolymers and polyethylenimine-condensed rhodamine-labeled DNA. The ternary polyplexes feature reversible controllability of singlet oxygen generation based on the dual effect of spiropyrans in photochromism and aggregation-induced enhanced photosensitization, allowing significant light-induced amplification of bPEI-mediated in vitro transgene efficiency (from original 15% to final 91%) at a low DNA dose, with the integrity of supercoiled DNA structure unaffected. The use of spiropyran without the need of other photosensitizers circumvents the issue of uncontrolled long-lasting photocytotoxicity in gene delivery.
关键词： gene delivery,spiropyran,photoswitching,singlet oxygen,fluorescence resonance energy transfer
更新于2025-11-21 11:08:12
-
Dual-action Platinum(II) Schiff Base Complexes: Photocytotoxicity and Cellular Imaging
摘要： Nine photo-stable Pt(II) Schiff base complexes [Pt(O^N^N^O)] (Pt1-Pt9) containing tetradentate salicylaldimine chelating ligands have been synthesized and characterized as potential photosensitisers for photodynamic therapy (PDT). The effects of electron-withdrawing versus electron-donating substituents on their electronic spectral properties are investigated. Pt1-Pt9 show broad absorption bands between 400-600 nm, which makes them useful for green-light photodynamic therapy. The complexes showed intense phosphorescence with emission maxima at ca. 625 nm. This emission was used to track their cellular localization in cancer cells. Confocal cellular imaging showed that the complexes localized mostly in the cytoplasm. In the dark, the complexes were non-toxic to A549 human lung cancer cells, but exhibited high photo-toxicity upon low-dose green light (520 nm, 7.02 J/cm2) irradiation via photo-induced singlet oxygen generation. Thus, these photoactive Pt(II) complexes have the potential to overcome the problem of drug resistance and side effects of current clinical Pt(II) drugs, and to act as both theranostic as well as therapeutic agents.
关键词： Schiff Base,Platinum(II),Photocytotoxicity,Cellular Imaging,Singlet oxygen
更新于2025-11-21 11:08:12
-
Long-lived triplet excited state in a platinum( <scp>ii</scp> ) perylene monoimide complex
摘要： We report the synthesis and solution based photophysical properties of a new Pt(II)-terpyridine complex coupled to a perylene monoimide (PMI) chromophoric unit through an acetylene linkage. This structural arrangement resulted in quantitative quenching of the highly fluorescent PMI chromophore by introducing metal character into the lowest energy singlet state, thereby leading to the formation of a long-lived PMI-ligand localized triplet excited state (τ = 8.4 μs). Even though the phosphorescence from this triplet state was not observed, highly efficient quenching of this excited state by dissolved oxygen and the observation of singlet oxygen photoluminescence in the near-IR at 1270 nm initially pointed towards triplet excited state character. Additionally, the coincidence of the excited state absorbance difference spectra from the sensitized PMI ligand using a triplet donor and the Pt-PMI complex provided strong evidence for this triplet state assignment, which was further supported by TD-DFT calculations.
关键词： singlet oxygen,perylene monoimide,photophysics,platinum(II) complex,triplet excited state
更新于2025-11-19 16:56:42
-
Complementary Chromophore Decoration in NU-1000 via Solvent-Assisted Ligands Incorporation: Efficient Energy Transfer within the Metal-Organic Frameworks
摘要： BODIPY-incorporated solvent-assisted ligand incorporation metal-organic frameworks (SALI-MOFs) were designed and synthesized using NU-1000 and carboxylic acid functionalized BODIPY moieties by the solvent-assisted ligand incorporation (SALI) approach. SALI-MOFs were characterized by various technique including powder X-ray diffraction, scanning electron microscope, N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The SALI-MOFs were found to have cooperative light-harvesting properties and shown to possess efficient singlet oxygen (1O2) generation ability.
关键词： Light-harvesting properties,Singlet oxygen,Metal-organic frameworks,Solvent-assisted ligands incorporation,Energy transfer,BODIPY
更新于2025-11-14 15:14:40
-
Kinetics of singlet oxygen sensing using 9-substituted anthracene derivatives$$^{\#}$$#
摘要： Singlet oxygen (1O2), the lowest excited-state of molecular oxygen receives great attention in basic research and clinical and industrial settings. Despite several spectroscopic methods available for 1O2 sensing, fluorescence sensing receives great attention, for which many fluorogenic sensors based on substituted anthracene are reported. Nonetheless, the roles of substituents on the sensing efficiency, in terms of detection time, remain largely unknown. In this work, we examine the 1O2 sensing efficiency of a fluorescence sensor based on a coumarin–anthracene conjugate, which is an electron donor-acceptor dyad, and compare the efficiency with that of 9-methylanthracene. Here, 1O2 is generated using the standard photosensitizer Rose Bengal, which is followed by estimation of the rate of reaction of 1O2 to the sensor and 9-methylanthracene. The second order reaction rate of the sensor is an order of magnitude less than that of 9-methylanthracene. The lower reactivity of the sensor to 1O2 suggests that the roles of substituents, such as electronic interactions, steric interactions and the reactivity of precursor complexes, on sensing efficiency should be carefully considered during construction of fluorogenic molecular sensors.
关键词： photochemistry,reaction kinetics,anthracene,fluorescence sensing,Singlet oxygen
更新于2025-09-23 15:23:52
-
Improvement of the ON/OFF Switching Performance of a pH-Activatable Porphyrin Derivative by the Introduction of Phosphorus(V)
摘要： An activatable photosensitizer for singlet oxygen is of significance due to its potential applications for high tumor-specific photodynamic therapy and diagnosis. In this study, a pH-activatable system that enables the specific photosensitization of singlet oxygen at a low pH was developed based on the complexation of a porphyrin–aniline conjugate with phosphorus(V). As a result of complexation with phosphorus, the water solubility of the porphyrin–aniline conjugate was improved by 100 times. Furthermore, this complexation strongly suppressed the singlet-oxygen-generating activity of the porphyrin photosensitizer under basic conditions, and the quantum yield of the singlet oxygen photosensitization markedly increased under acidic conditions. Based on these improvements, an extremely high ON/OFF switching ratio of the quantum yield was obtained (>400 times).
关键词： pH activatable photosensitizer,ON/OFF switching,singlet oxygen,aniline,phosphorous porphyrin,protonation,fluorescence,acid
更新于2025-09-23 15:23:52
-
Suppression of riboflavin-sensitized singlet oxygen generation by l-ascorbic acid, 3-O-ethyl-l-ascorbic acid and Trolox
摘要： Riboflavin (RF), a water-soluble vitamin B2, is an endogenous singlet oxygen photosensitizer in human skin and eye. Time profiles of the near-infrared phosphorescence of singlet oxygen generated by RF have been measured in the absence and presence of L-ascorbic acid (AA, vitamin C), 3-O-ethyl-L-ascorbic acid (3-EtAA) and Trolox (TX, a water-soluble analogue of vitamin E) in phosphate buffer (pH 6.8). These substances suppress the RF-photosensitized singlet oxygen generation. For example, the quantum yield of singlet oxygen generation is decreased to a third by adding 0.4 mmol dm?3 AA or TX (the concentration of dissolved oxygen in air-saturated water is 0.27 mmol dm?3). AA and TX are more efficient suppressors of RF-photosensitized singlet oxygen generation than 3-EtAA. The bimolecular rate constants for quenching of the excited singlet and triplet states of RF by AA, 3-EtAA and TX have been determined through measurements of fluorescence and transient absorption. These measurements suggest that the observed suppression is due to the quenching of the excited singlet and triplet states of RF by AA, 3-EtAA and TX. The bimolecular rate constants for quenching of singlet oxygen by AA, 3-EtAA and TX were determined to be 1.8 × 108, 0.27 × 108, and 4.4 × 108 mol?1 dm3 s?1, respectively.
关键词： Trolox,Riboflavin,Singlet oxygen,3-O-ethyl-L-ascorbic acid,L-ascorbic acid
更新于2025-09-23 15:23:52
-
Theoretical study of photoreactions between oxidized pterins and molecular oxygen
摘要： Pterins are low molecular weight heterocyclic compounds that are widely distributed in living organisms, primarily in the form of reduced coenzyme forms. Oxidized pterins are present in the cells for the most part as oxidation products of tetrahydropterins and dihydropterins. Oxidized pterins are known to cause DNA photodamage under UV-irradiation. Photosensitization of oxidized pterins may cause oxidative stress in the human skin depigmentation disorder vitiligo. There have been made attempts to use oxidized pterins as sensitizers in photodynamic therapy (PDT) of cancer. The photoreactions between a set of six pterin compounds and molecular oxygen were explored using density functional theory, a time-dependent formalism for excited states (TD-DFT) and a continuum COSMO model to include the effects of H2O solvation. Both acid and base forms of pterins were taken into consideration. The computed singlet and triplet excitation energies are in agreement with the experimental data. We showed that compounds with the most electronegative lateral substituent (formyl, carboxyl) at C6 position have the highest value of both S0 and T1 state ionization potential. We conclude that pterin molecules do participate in photoreactions with molecular oxygen. Oxidized pterins are able to generate singlet oxygen and may also produce superoxide-anion radicals indirectly through autoionization reactions. Direct electron transfer reactions between pterins and oxygen were also studied.
关键词： TDDFT,DFT,Pterins,Singlet oxygen,Triplet states
更新于2025-09-23 15:23:52
-
Two phenothiazine dyes as photosensitizers for the production of singlet oxygen. Photophysics, photochemistry and effects of aggregation
摘要： The aim of this work was to investigate the aggregation effect of Azure B and monobrominated Azure B on their singlet oxygen generation. The monomeric and dimeric forms of these dyes were evaluated to select the species with better properties as photosensitizers. The results demonstrate that the monomeric forms are better producers of singlet oxygen than their aggregated species. However, the dimeric species of monobrominated Azure B is also a good producer of singlet oxygen. The bromination of this phenothiazine dye significantly increases the singlet oxygen quantum yields of the monomeric and dimeric species, enhancing its properties like photosensitizer and its application in Photodynamic Therapy. In addition, significant differences were observed in the singlet oxygen production of the monomeric forms of both photosensitizers determined by phosphorescence decay of singlet oxygen and photooxidation of 9,10-dimethylanthracene (DMA). The physicochemical interaction between the excited species of the phenothiazine monomers and the molecules of DMA could be responsible for the lower values of singlet oxygen production because the disaggregated forms did not present any activity as physical or chemical attenuators. The dimeric form of phenothiazine dyes did not show this interaction. In conclusion, there is a need for developing vehiculization systems that stabilize the monomers of phenothiazine dyes because they have better properties than their aggregates in terms of singlet oxygen production.
关键词： Azure B,Monobrominated azure B,Monomer- dimer- singlet oxygen
更新于2025-09-23 15:23:52