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Suppression of Light-Induced Oxidative Stress in the Retina by Mitochondria-Targeted Antioxidant
摘要： Light-induced oxidation of lipids and proteins provokes retinal injuries and results in progression of degenerative retinal diseases, such as, for instance, iatrogenic photic maculopathies. Having accumulated over years retinal injuries contribute to development of age-related macular degeneration (AMD). Antioxidant treatment is regarded as a promising approach to protecting the retina from light damage and AMD. Here, we examine oxidative processes induced in rabbit retina by excessive light illumination with or without premedication using mitochondria-targeted antioxidant SkQ1 (10-(6’-plastoquinonyl)decyltriphenyl-phosphonium). The retinal extracts obtained from animals euthanized within 1–7 days post exposure were analyzed for H2O2, malondialdehyde (MDA), total antioxidant activity (AOA), and activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) using colorimetric and luminescence assays. Oxidation of visual arrestin was monitored by immunoblotting. The light exposure induced lipid peroxidation and H2O2 accumulation in the retinal cells. Unexpectedly, it prominently upregulated AOA in retinal extracts although SOD and GPx activities were compromised. These alterations were accompanied by accumulation of disulfide dimers of arrestin revealing oxidative stress in the photoreceptors. Premedication of the eyes with SkQ1 accelerated normalization of H2O2 levels and redox-status of lipids and proteins, contemporarily enhancing AOA and, likely, sustaining normal activity of GPx. Thus, SkQ1 protects the retina from light-induced oxidative stress and could be employed to suppress oxidative damage of proteins and lipids contributing to AMD.
关键词： SkQ1,superoxide dismutase,glutathione peroxidase,disulfide dimerization of proteins,visual arrestin,age-related macular degeneration,mitochondria-targeted antioxidant,antioxidant activity,light-induced retinal damage,oxidative stress
更新于2025-09-23 15:23:52
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Contrast of optical activity and rogue wave propagation in chiral materials
摘要： We report the contrast of optical activity and properties of nonparaxial optical rogue waves for the higher-order nonparaxial chiral nonlinear Schr?dinger (NLS) equation. The latter describes the propagation of ultrashort optical pulses in chiral optical fibers. Both first- and second-order rogue wave solutions are investigated analytically by the modified Darboux transformation (MDT) and numerically by one pseudo-spectral method. The interplay of chiral materials on rogue wave propagation is elucidated, and the results can be applied on optical communication and in others physical systems.
关键词： Chirality and optical activity,Chiral optical fibers,Rogue wave propagation,Chiral materials
更新于2025-09-23 15:23:52
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Graphene oxide-based zirconium oxide nanocomposite for enhanced visible light-driven photocatalytic activity
摘要： In the present investigation, an efficient visible light-active, graphene oxide-based zirconium oxide nanocomposite (GO–ZrO2) has been synthesized by co-precipitation method. The synthesized photocatalyst was characterized by XRD, FTIR, FE-SEM, EDS, TEM, TGA, PL, UV-DRS and BET surface area analysis. The characterization results illustrate the homogeneous dispersion of ZrO2 nanoparticles in the GO–ZrO2 nanocomposite with excellent harmony between GO and ZrO2 nanoparticles. The photocatalytic efficiency of the synthesized GO–ZrO2 nanocomposite was evaluated by photodegradation of hazardous, water-soluble rhodamine B and methylene blue dyes under visible light irradiation. The 90% photocatalytic degradation of rhodamine B dye (with initial conc. 30 mg/L) was observed in 105 min of visible light irradiation, while 99.23% of methylene blue (with initial conc. 100 mg/L) dyes degradation was observed in just 60 min using 25 mg/100 ml dose of GO–ZrO2 nanocomposite as a photocatalyst. The mechanistic investigation using scavengers suggest that the superoxide (O2·?) is the most reactive species involved in the photodegradation of organic dyes. The synthesized photocatalyst GO–ZrO2 nanocomposite also exhibits excellent thermal stability and reusability.
关键词： Methylene blue,Rhodamine B,Photocatalytic activity,Zirconium oxide,Graphene oxide,Visible light,Co-precipitation method
更新于2025-09-23 15:23:52
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Synthesis of Ag nanoparticles decorated on TiO2 nanotubes for surface adsorption and photo-decomposition of methylene blue under dark and visible light irradiation
摘要： TiO2 nanotubes and Ag/TiO2 nanotubes (TNT) have been synthesized by simple hydrothermal and solvothermal method and were characterized by XRD, UV, ICP, TEM, SEM, BET and XPS. In this study the photocatlytic activity of Ag/TNT (contain 3.33% Ag) was investigated through decolorization of MB (standard methylene blue tablets for milk testing) in aqueous solution. Because of the surface plasmon resonance (SPR) effect of Ag nanoparticles, under visible light, Ag/TNT showed superior photocatalytic activity, and due to high surface area of TNT, it showed high surface absorption in dark conditions. In this study, the photocatalytic effect of Ag/TNT for the destruction and absorption of MB in aqueous solution indicated good application.
关键词： Absorption,Destruction,Ag/TiO2 nanotubes,Photocatlytic activity,MB
更新于2025-09-23 15:23:52
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The study of Fe-doped CdS nanoparticle-assisted photocatalytic degradation of organic dye in wastewater
摘要： Size-tunable nanoparticles (NPs) for pristine cadmium sulfide (CdS) and iron (Fe)-doped (5, 10 and 15%) CdS were synthesized using facile chemical co-precipitation. Size-controlled NPs were prepared with thioglycolic acid (TGA) as the capping agent and their structural, optical, morphological and physiochemical evaluations were performed using X-ray diffraction (XRD), UV–visible spectroscopy, Raman spectroscopy, field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FTIR). XRD revealed single cubic phase of CdS and later broader peaks upon mixing of Fe, and intensive absorption was recorded in the visible regime upon doping with redshift. FESEM confirmed spherical nanoparticles of Fe–CdS, and Cd–S linkage along with other functional groups was recognized by FTIR. Cd1?xFexS (x = 0, 0.05, 0.10 and 0.15) powder was used as the photocatalyst for methylene blue (MB) degradation in visible light and catalyst in NaBH4’s presence. The control CdS bleached MB faster than doped but doped CdS showed higher catalytic degradation. The Fe-doped CdS NPs showed superior catalytic potential compared to undoped CdS which suggests their use in dye industries, especially leather and tanneries. Additionally, NPs not only show superior catalytic characteristics but also help in cost reduction and complete removal of dyes for wastewater management.
关键词： Metal oxide,Photocatalytic activity,XRD,Graphene,Sol–gel
更新于2025-09-23 15:23:52
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Two-step synthesis of reduced graphene oxide with columnar-shaped ZnO composites and their photocatalytic performance with natural dye
摘要： Composites of ZnO with reduced graphene oxide were prepared in two-step synthesis process with constant temperature in variation with pH values. The synthesized composites were characterized and the results suggest that ZnO structure in the composites has a columnar morphology with an average diameter ranging 0.8–1.57 μm. The obtained properties of the composites with the present method confirmed that the material morphology influences the absorption and photocatalytic activity of natural dye under sunlight irradiation. The result shows that the maximum degradation efficiency is 64.40% achieved in 120 min.
关键词： Zinc oxide,Columnar morphology,Photocatalytic activity,Reduced graphene oxide,Natural dye
更新于2025-09-23 15:23:52
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Photocatalytic degradation of phenol by LaFeO3 nanocrystalline synthesized by gel combustion method via citric acid route
摘要： Focusing on the photocatalytic degradation of phenol under visible light, the synthesized lanthanum orthoferrites (LaFeO3) by gel combustion method using citric acid as sacrificial agent were investigated. With the highest reaction temperature of 200 °C, the physicochemical properties of synthesized samples were characterized by X-Ray diffraction (XRD) analysis, Brunauer–Emmet–Teller (BET), and Energy Dispersive X-Ray spectroscopy (EDS). On the other hand, UV–Vis spectroscopy analysis was carried out to determine the phenol photodegradation activities and mechanism. The results suggested the well-defined LaFeO3 nanocrystals with specific area of 28 m2 g?1 were successfully synthesized. Besides that, variations in operating parameters such as pH, catalyst dosage and initial concentration of phenol in synthetic wastewater were also examined. In conclusion, LaFeO3 nanocrystalline exhibited an exceptional photocatalytic activity for phenol degradation, thus providing a perfect alternative for pharmaceutical wastewater treatment.
关键词： Citric acid,Photocatalytic activity,Lanthanum orthoferrite,Phenol,Gel combustion
更新于2025-09-23 15:23:52
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Interfacial engineering of Fe2O3@BOC heterojunction for efficient detoxification of toxic metal and dye under visible light illumination
摘要： Recent developments of small band gap semiconductor coupled bismuth carbonate (BOC) heterojunction are advantageous for photocatalysis application because of their improved solar harvesting ability and enhanced charge-carrier collection. In this work, we have developed iron (III) oxide decorated bismuth carbonate (Fe2O3@BOC) heterojunction via a simple two-step process. The developed heterojunction exhibits excellent photocatalytic activity towards reduction of carcinogenic and mutagenic Cr(VI) to nontoxic Cr(III) and degradation of toxic dye [methylene blue (MB)] under visible light illumination. Further investigation revealed that the loading of Fe2O3 nanoparticles had an impact on efficient charge carrier collection at the interface of Fe2O3@BOC heterojunctions. The unprecedented photocatalytic activity for Fe2O3@BOC1 heterojunction at room temperature could be attributed due to the enhancement in light absorption ability and suppression of electron–hole pair recombination at the heterojunction interface. In addition, reduction in efficacy of the heterojunction with increase in loading of Fe2O3 nanoparticles on BOC surface further confirms the role of interface on the modulation of photocatalytic activity. The role of photogenerated electrons and reactive oxygen species involved during photocatalytic reduction of Cr(VI) and degradation of MB was studied in detail. Moreover, recyclability experiment demonstrates that the developed photocatalyst can be reused without decay in performance. Finally, development of inexpensive prototype reactor is demonstrated towards reduction of Cr(VI) and degradation of MB under continuous flow operation. Thus, good efficacy of the developed reactor for cleaning of toxic pollutants in water makes the heterojunction (Fe2O3@BOC1) a promising photocatalyst for water purification in near future.
关键词： photocatalytic activity,charge separation,Heterojunction,toxic pollutants,visible light
更新于2025-09-23 15:23:52
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Photocatalytic Activity of ZnO Nanopowders: The role of production techniques in the formation of structural defects
摘要： The effect of the type of structural defect in zinc oxide on its photocatalytic properties was studied for phenol photodegradation under UV-irradiation. It was shown that the use of different types of precursors (zinc oxalate and zinc hydroxide) for the production of zinc oxide leads to the formation of a material with the same phase composition and equal energy of the forbidden band, but different photocatalytic activities. Simultaneously, the peculiarities of the luminescence and electron spin resonance spectra indicate the formation of different types of defects in the structure of the material, namely, oxygen vacancies (Vo) in the anionic and zinc vacancies (VZn) in the cationic sublattices of zinc oxide synthesised from the zinc oxalate and hydroxide, respectively. Also, the different characteristics of the luminescence decays reveal the different recombination paths for the free charge carriers in the systems synthesised from the different precursors. The different times of the luminescence decay also confirmed the different methods of recombination of free charge carriers in systems synthesised from different precursors. It was shown that the appearance of defects in the cationic sublattice leads to a decrease in the photocatalytic activity of the material relative to phenol degradation.
关键词： vacancies,luminescence.,Photocatalytic activity,structure defects,ZnO
更新于2025-09-23 15:23:52
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Optically active polyaniline film based on cellulose nanocrystals
摘要： Chiral transfer from cellulose nanocrystals (CNCs) chiral nematic liquid crystal to polyaniline (PANI) is successfully achieved through co-assembly method for the first time, affording the PANI film based on CNCs optical activity. Meanwhile, the CNCs/PANI composite film displays notable Cotton effect ascribed to the polaron band transitions of PANI in circular dichroism (CD) spectrum. Hydrogen bond and electrostatic attraction favor the combination of two molecular chains in the mixed aqueous suspension and will lead to the chiral assembly of the PANI in the host chiral nematic film. However, the CD signal disappears when cholesteric phase collapse by acid protonation, and which demonstrates the chiral nematic ordering of the CNCs is essential to the chiral transfer. With the assistance of CNCs, PANI chains form a helically stacked structure. Thus, the optical activity of PANI originates from its long range organization.
关键词： co-assembly,chiral transfer,polaron transition,optical activity,Cotton effect
更新于2025-09-23 15:23:52