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CeO2/TiO2 nanostructures enhance adsorption and photocatalytic degradation of organic compounds in aqueous suspension
摘要： Mixed oxide interfaces are critical in the delivery of active components in photocatalytic processes. Cerium doped TiO2 photocatalysts were prepared using a hydrothermal route to manipulate the morphology of the photocatalyst and improve the interaction between CeO2 and TiO2 nanoparticles. These changes were compared with the photocatalytic activity and adsorption capacity of the solids. The photocatalysts were used to degrade polyvinylpyrrolidone (PVP) and methylene blue (MB) as test compounds. A low photodegradation rate of PVP (0.0001 min?1 and 0.0005 min?1 under visible and UV light, respectively) was observed using Ce-doped photocatalysts, with no adsorption. The high adsorption capacity of MB (34.46 mg g?1) proved that the local morphology of the nanostructured CeO2/TiO2 photocatalysts is more important than the amount of CeO2 in the sample, and the main role of the CeO2 on mixed photocatalysts is to improve thermal stability during the synthesis. XRD, XPS, BET surface area, UV–vis and TEM techniques confirmed this conclusion. The rate of degradation of MB by the Ce-doped photocatalyst decreased dramatically when using the singlet oxygen scavenger L-Histidine (0.0214 min?1 to 0.0001 min?1), indicating a photocatalysis sensitized by the dye, under visible and UV light.
关键词： Cerium,Photosensitization,Reactive oxygen species,Adsorption,Morphology
更新于2025-09-23 15:23:52
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Photosensitized TiO2 films on polymers – Titania-polymer interactions and visible light induced photoactivity
摘要： Photocatalytic coatings at polymers, showing a visible light induced photoactivity, can be synthesized using a low temperature oxygen plasma treatment of the polymer (PP) followed by deposition of TiO2 nanoparticles and their sensitization with organic ligands. The whole process consists of three major steps: surface activation involving its partial oxidation, immobilization of TiO2 nanoparticles and photosensitization of titania film by impregnation with the solution of organic ligands forming surface Ti(IV) charge transfer complexes. XPS and IR analysis revealed the formation of oxygen-containing groups at the polymer surface upon plasma treatment. These groups participate in the formation of Ti-O-C bonds which ensure a very good adhesion of titania films to polymeric surface. The dip-coating process using an aqueous colloidal solution of TiO2 nanoparticles allows to synthesize a compact coating with a thickness of 100-300 nm. Coordination of catechol-like ligands to surface Ti(IV) centers results in formation of colored charge transfer complexes responsible for absorption of visible light and an effective photoinduced charge separation. Photogenerated electrons and holes can take part in surface redox reactions responsible for degradation of pollutants. Tests with various organic ligands (catechol, 2,3-naphthalenediol, pyrogallol and rutin) revealed, that the titanium dioxide coating modified with catechol was the most photoactive one when visible light irradiation was applied. Presented photocatalytic coatings can be effectively used as self-sterilizing surfaces activated by visible light.
关键词： photocatalysis,XPS analysis,TiO2 coatings,photosensitization,plasma treatment
更新于2025-09-23 15:23:52
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Structural and Functional Consequences of the Weak Binding of Chlorin e6 to Bovine Rhodopsin
摘要： The chlorophyll-derivative chlorin e6 (Ce6) identified in the retinas of deep-sea ocean fish is proposed to play a functional role in red bioluminescence detection. Fluorescence and 1H NMR spectroscopy studies with the bovine dim-light photoreceptor, rhodopsin, indicate that Ce6 weakly binds to it with μM affinity. Absorbance spectra prove that red light sensitivity enhancement is not brought about by a shift in the absorbance maximum of rhodopsin. 19F NMR experiments with samples where 19F labels are either placed at the cytoplasmic binding site or incorporated as fluorinated retinal, indicate that the cytoplasmic domain is highly perturbed by binding, while little to no changes are detected near the retinal. Binding of Ce6 also inhibits G protein activation. Chemical shift changes in 1H,15N NMR spectroscopy of 15N-Trp labeled bovine rhodopsin reveal that Ce6 binding perturbs the entire structure. These results provide experimental evidence that Ce6 is an allosteric modulator of rhodopsin.
关键词： G protein coupled receptor,chlorophyll-derivative,porphyrin,night vision,light activation,photosensitization,bovine rhodopsin,Allosteric modulator
更新于2025-09-23 15:22:29
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Photonics of boron(III) and zinc(II) dipyrromethenates as active media for modern optical devices
摘要： Photonics of complexes of p- and d-elements with dipyrromethenates is investigated. The role of substituents (their type and localization in the ligand) and of the medium in which dipyrromethenates are placed (solvents, gas mixtures, or solid matrices) is discussed as well as the effect of complexing agents on photonics of the examined complexes. The possibilities for dipyrromethenates application as liquid and solid state laser active media, sensor media for determining the oxygen concentration in a gas mixture, and photosensitizers for singlet oxygen generation in optical devices are presented.
关键词： Photochemistry,Dipyrromethenates,Sensorics,Photophysics,Lasing,Photosensitization
更新于2025-09-23 15:22:29
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Photooxidation of unilamellar vesicles by a lipophilic pterin: Deciphering biomembrane photodamage
摘要： Pterins are natural products that can photosensitize the oxidation of DNA, proteins and phospholipids. Recently, a new series of decyl-chain (i.e., lipophilic) pterins were synthesized and their photophysical properties investigated. These decyl-pterins led to efficient intercalation in large unilamellar vesicles and produce, under UVA irradiation, singlet molecular oxygen, a highly oxidative species that react with polyunsaturated fatty acids (PUFAs) to form hydroperoxides. Here, we demonstrate that the association of 4-(decyloxy)pteridin-2-amine (O-decyl-Ptr) to lipid membranes is key to its ability to trigger phospholipid oxidation in unilamellar vesicles of phosphatidylcholine rich in PUFAs used as model biomembranes. Our results show that O-decyl-Ptr is at least one order of magnitude more efficient photosensitizer of lipids than pterin (Ptr), the unsubstituted derivative of the pterin family, which is more hydrophilic and freely passes across lipid membranes. Lipid peroxidation photosensitized by O-decyl-Ptr was detected by the formation of conjugated dienes and oxidized lipids, such as hydroxy and hydroperoxides derivatives. These primary products undergo a rapid conversion into short-chain secondary products by cleavage of the fatty acid chains some of which are due to subsequent photosensitized reactions. As a consequence, a fast increase in membrane permeability is observed. Therefore, lipid oxidation induced by O-decyl-Ptr could promote cell photodamage due to the biomembrane integrity loss which, in turn, may trigger cell death.
关键词： alkyl-pterins,membrane permeability,lipid peroxidation,photosensitization
更新于2025-09-23 15:21:21
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Visible light active titanates photosensitized by Ti(IV) surface complexes
摘要： For the first time, photosensitization of selected alkaline titanates with surface charge transfer complexes has been proven. Activation of BaTiO3, SrTiO3 and CaTiO3 to visible as well as ultraviolet light has been achieved by impregnation with catechol, salicylic acid and 2,3-naphthalenediol. Simple modification of titanates with organic compounds forming inner-sphere CT complexes with Ti atoms located at the surface of semiconductors resulted in coloration of the materials. Even though acceptor electronic states of titanates are characterized by a higher energy compared with titania (even up to 0.75 eV higher for CaTiO3), complexes formed at titanates’ surface absorb in similar or even broader optical range of visible light. Beside changes in the absorption properties, used modifications also strongly influenced their photoelectrochemical and photocatalytic properties. In contrast to similarly modified titanium dioxide, modified titanates show significantly improved photocatalytic activity not only under visible light but also within ultraviolet range of radiation. Remarkably increased efficiency of photocurrent generation within the UV range of radiation may suggest that apart from observed electron transfer from HOMO of the complex to conduction band (CB) of the semiconductor also indirect photosensitization mechanism through the electron transfer from the excited complexes to the CB of titanates may take place.
关键词： photosensitization,visible light activity,surface complexes,titanates,charge transfer
更新于2025-09-23 15:21:21
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Probing the Advantageous Photosensitization Effect of Metal Nanoclusters over Plasmonic Metal Nanocrystals in Photoelectrochemical Water Splitting
摘要： Atomically precise metal nanoclusters (NCs)-based photocatalytic systems have garnered enormous attention owing to the fascinating merits including unique physicochemical properties, quantum confinement effect and photosensitization effect, which are distinct from conventional metal nanocrystals (NYs). Nevertheless, systematic comparison between electrons photoexcited from metal NCs and hot electrons from surface plasmonic resonance (SPR) effect of metal NYs in boosting photoelectrochemical water splitting reaction remains blank. Here, we report the strict and comprehensive comparison on the capability of electrons photoexcited from glutathione-capped gold nanoclusters (Aux@GSH) and hot electrons from plasmonic excitation of gold nanoparticles (Au NYs) self-transformed from Aux@GSH to trigger the PEC water splitting reaction under visible light irradiation. The results indicate photoelectrons of Aux NCs trigger more efficient charge transport rate than hot electrons of plasmonic Au NYs in terms of light harvesting and conversion efficiency under the identical conditions. Moreover, charge transfer characteristics in Aux NCs and Au NYs-based PEC systems were established. This work would reinforce our deep understanding on these two pivotal sectors of metal nanomaterials for solar energy conversion.
关键词： photosensitization effect,plasmonic metal nanocrystals,charge transfer,photoelectrochemical water splitting,metal nanoclusters
更新于2025-09-23 15:19:57
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DNA-modulated photosensitization: current status and future aspects in biosensing and environmental monitoring
摘要： Recently, photosensitized oxidation has been explored in many fields of research and applications, such as photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT). Although the photosensitized generation of ROS features emerging applications, controllable management of the photosensitization process is still sometimes problematic. DNA has long been considered the carrier for genetic information. With the in-depth study of the chemical properties of DNA, the molecular function of DNA is gradually witnessed by the scientific community. Undoubtedly, the selective recognition nature of DNA endows them excellent candidate modulators for photosensitized oxidation. According to current research, reports on DNA regulation of photosensitized oxidation can be roughly divided into two categories in principle: P-Q quenching pair-switched photosensitization and host-guest interaction-switched photosensitization. In this review, the development status of these two analytical methods will be summarized, and the future development direction of DNA-modulated photosensitization in biosensing and environmental monitoring will also be prospected.
关键词： DNA,ROS,Singlet oxygen,Photosensitization
更新于2025-09-19 17:15:36
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A UV‐LEDs based photomicroreactor for mechanistic insights and kinetic studies in the norbornadiene photoisomerization
摘要： In this work, we report a simple and inexpensive UV-LEDs based photomicroreactor assembly constructed by commercially available components. The photoisomerization of norbornadiene to quadricyclane was selected to validate this novel photomicroreactor design. Mass transport limitation was eliminated and indicated by dimensionless numbers Fo and DaII, and photons loss was evaluated considering the absorption and reflection of the microreactor walls. The solvents, photosensitizers and light sources selections were optimized for achieving better photochemical performance and mechanistic insights. The detailed comparison between the high-pressure mercury arc lamp and the UV-LEDs strip revealed great potential of UV-LEDs as appealing light source for photochemical transformations. Moreover, the reaction mechanism was thoroughly discussed and illustrated by the Jablonski diagram indicating electronic states transitions. According to possible intermediate steps, a kinetic model was proposed with the reaction rate constant being correlated with the photon flux, which is valuable for process optimization and further understanding reaction mechanisms.
关键词： photosensitization,reaction kinetics,microreactor,mass transport,UV-LED
更新于2025-09-19 17:13:59
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Photoactive Nanocarriers for Controlled Delivery
摘要： Photoactive nanocarriers have emerged as robust and minimally invasive systems for the on-demand delivery of active payloads. The easy manipulation offered by light irradiation as an external stimulus allows precise spatiotemporal control of payload release based on the time, intensity, location, and wavelength of light exposure. Compared to conventional passive delivery systems, photoactive nanocarriers offer the possibility of tailoring the release kinetics of the encapsulated active molecules, which is of considerable clinical relevance for targeted delivery to desired sites of interest. In this progress report, the recent advances in the design and fabrication of photoactive nanoplatforms based on three main modes of mechanisms: photochemical reactions, the photothermal effect, and photosensitization mechanism mediated by reactive oxygen species are highlighted. The combination of these mechanisms provides additional flexibility for the effective delivery of therapeutics and improved synergistic therapeutic effects. Finally, challenges in future perspectives on the development of photoactive nanomaterials and their medical translation are discussed.
关键词： photothermal effects,photosensitization,photochemical reaction,nanocarriers,controlled delivery
更新于2025-09-11 14:15:04