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Spatial Heterogeneity of Cadmium Effects on Salvia sclarea Leaves Revealed by Chlorophyll Fluorescence Imaging Analysis and Laser Ablation Inductively Coupled Plasma Mass Spectrometry
摘要： In this study, for a first time (according to our knowledge), we couple the methodologies of chlorophyll fluorescence imaging analysis (CF-IA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), in order to investigate the effects of cadmium (Cd) accumulation on photosystem II (PSII) photochemistry. We used as plant material Salvia sclarea that grew hydroponically with or without (control) 100 μM Cd for five days. The spatial heterogeneity of a decreased effective quantum yield of electron transport (ΦPSII) that was observed after exposure to Cd was linked to the spatial pattern of high Cd accumulation. However, the high increase of non-photochemical quenching (NPQ), at the leaf part with the high Cd accumulation, resulted in the decrease of the quantum yield of non-regulated energy loss (ΦNO) even more than that of control leaves. Thus, S. sclarea leaves exposed to 100 μM Cd exhibited lower reactive oxygen species (ROS) production as singlet oxygen (1O2). In addition, the increased photoprotective heat dissipation (NPQ) in the whole leaf under Cd exposure was sufficient enough to retain the same fraction of open reaction centers (qp) with control leaves. Our results demonstrated that CF-IA and LA-ICP-MS could be successfully combined to monitor heavy metal effects and plant tolerance mechanisms.
关键词： effective quantum yield (ΦPSII),non-photochemical quenching (NPQ),photoprotective mechanism,photochemical quenching (qp),photosynthetic heterogeneity,phytoremediation,reactive oxygen species (ROS),bioimaging,singlet oxygen (1O2),clary sage
更新于2025-09-11 14:15:04
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Short-Term Ultraviolet (UV)-A Light-Emitting Diode (LED) Radiation Improves Biomass and Bioactive Compounds of Kale
摘要： The aim of this study was to determine the influence of two types of UV-A LEDs on the growth and accumulation of phytochemicals in kale (Brassica oleracea var. acephala). Fourteen-day-old kale seedlings were transferred to a growth chamber and cultivated for 3 weeks. The kale plants were subsequently subjected to two types of UV-A LEDs (370 and 385 nm) of 30 W/m2 for 5 days. Growth characteristics were all significantly increased in plants exposed to UV-A LEDs, especially at the 385 nm level, for which dry weight of shoots and roots were significantly increased by 2.22 and 2.5 times, respectively, at 5 days of treatment. Maximum quantum efficiency of photosystem II photochemistry (Fv/Fm ratio) began to decrease after 3 h of treatment compared to the control. The total phenolic content of plants exposed to the two types of UV-A LEDs increased by 25% at 370 nm and 42% at 385 nm at 5 days of treatment, and antioxidant capacity also increased. The two types of UV-A LEDs also induced increasing contents of caffeic acid, ferulic acid, and kaempferol. The reactive oxygen species (ROS) temporarily increased in plants exposed to the two types of UV-A LEDs after 3 h of treatment. Moreover, transcript levels of phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), and flavanone 3-hydroxylase (F3H) genes and PAL enzyme activity were higher in plants treated with UV-A LEDs. Our results suggested that short-term UV-A LEDs were effective in increasing growth and improving antioxidant phenolic compounds in kale, thereby representing a potentially effective strategy for enhancing the production of phytochemicals.
关键词： transcript level,reactive oxygen species,phenolic compound,UV-A LEDs,kale,antioxidant capacity
更新于2025-09-11 14:15:04
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Smart Plasmonic Nanozyme Enhances Combined Chemo-Photothermal Cancer Therapy and Reveals Tryptophan Metabolic Apoptotic Pathway
摘要： The tumor microenvironment regulation is considered as an intelligent strategy for cancer therapeutics, but the related metabolic pathways of cell apoptosis still remains a great challenge. Herein, by applying multifunctional carbon dot-decorated Ag/Au bimetallic nanoshells (CDs-Ag/Au NSs, CAANSs) nanoprobes as smart plasmonic nanozymes for combined chemo-photothermal cancer therapy, we achieved a high efficiency in cancer cell therapy and revealed a tryptophan metabolic apoptotic pathway. In addition to high photothermal conversion efficiency, the CAANSs can act as a smart nanozyme to catalyze intracellular H2O2 to the cytotoxic reactive oxygen species (ROS) of superoxide anion (·O2-) in response to mild acidic cancerous cell microenvironment to damage cellular DNA. More importantly, the tryptophan metabolic pathway during the combined chemo-photothermal therapy has been revealed that the tryptophan participates in oxidative stress process, which can be decomposed to produce H2O2 and further formed into superoxide anion to kill cells under the catalytic nanomedicine process. The current work provides an effective platform for cancer therapeutics and is promising for cancer-related molecular biology studies.
关键词： Tryptophan Metabolic Apoptotic Pathway,Smart Plasmonic Nanozyme,Tumor Microenvironment,Chemo-Photothermal Cancer Therapy,Reactive Oxygen Species
更新于2025-09-11 14:15:04
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Mode-locked Tm-doped fiber laser with large modulation depth ReS <sub/>1.02</sub> Se <sub/>0.98</sub> nanosheet saturable absorber
摘要： Microcystis blooms and their associated microcystins pose a significant health risk to humans. Microcystis normally occurs as colonies in eutrophic water bodies, and its physiological tolerance to algaecides is dissimilar to that of unicellular forms. However, the differences of physiological response to algaecides between unicellular and colonial Microcystis have been poorly explored. The current study investigated the effects of hexane extract of Acorus calamus rhizome (HEACR) on the physiological and photosynthetic mechanisms of unicellular and colonial M. aeruginosa in the laboratory. We analyzed the cell density, reactive oxygen species (ROS) level, malonaldehyde (MDA) content, photosynthetic pigments, capsular polysaccharide (CPS), and photosystem (PS II) parameters of the two morphological forms of Microcystis. Our results show that HEACR suppresses the growth of both unicellular and colonial M. aeruginosa, increases the intracellular ROS level and cause lipid peroxidation, as well as exerting a detrimental effect on chlorophyll a (chl a) content and photosynthetic efficiency. Almost 100% inhibition was observed for unicellular and colonial M. aeruginosa after 3 d exposure to 50 and 100 mg L?1 HEACR, respectively. The ROS level increase, MDA accumulation, the chl a decrease and carotenoid increase in unicellular M. aeruginosa were all more obvious than that in colonial cells. The fall in photosynthetic efficiency of unicellular M. aeruginosa were also more significant than that of colonial cells. After 3d exposure, the maximum quantum yield of PS II photochemistry (Fv/Fm), effective quantum yield of PS II photochemistry (Fv’/Fm’) and effective quantum yield of photochemical energy conversion in PS II (YII) of unicellular M. aeruginosa was almost totally inhibited by 20 mg L?1 HEACR, while the Fv/Fm, Fv’/Fm’ and YII of colonial M. aeruginosa decreased by 43%, 26% and 66% for 100 mg L?1 of HEACR, respectively. Comparing the two morphological forms of Microcystis, colonies show a greater increase in CPS level to more effectively resist the stress of HEACR and to mitigate ROS generation thereby better defending against oxidative damage. Furthermore, colonial M. aeruginosa shows better photoprotection ability than the unicellular form when exposed to HEACR. The colonies also sustain their maximum electron transport rate, increase their tolerance to strong light, and maintain a higher ability to disperse excess energy. These results demonstrated that HEACR can significantly interfere with the growth and physiological processes of both unicellular and colonial M. aeruginosa, but that colonial M. aeruginosa has a greater ability to adjust physiological tolerance to resist the stresses of HEACR.
关键词： Reactive oxygen species,Acorus calamusrhizome extract,Microcystis aeruginosa,Physiological tolerance,Capsular polysaccharide,Chlorophyll fluorescence parameters
更新于2025-09-11 14:15:04
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Polyacrylamide-Based Biocompatible Nanoplatform Enhances the Tumor Uptake, PET/fluorescence Imaging and Anticancer Activity of a Chlorophyll Analog
摘要： In this report we demonstrate the outstanding advantages of multifunctional nanoplatforms for cancer-imaging and therapy. The non-toxic polyacrylamide (PAA) nanoparticles (size:18-25 nm) formulation drastically changed the pharmacokinetic profile of the 124I- labeled chlorophyll-a derivative (formulated in 10% ethanol in PBS) with a remarkable enhancement in tumor uptake, and significantly reduced uptake in spleen and liver. Among the various nanoformulations investigated, the 124I- labeled photosensitizer (dose: 0.6142 MBq), and the cyanine dye-nanoparticles (CD-NP) conjugate (dose 0.3 μmol/kg) in combination showed great potential for tumor imaging (PET/NIR fluorescence) in BALB/c mice bearing Colon26 tumors. Compared to free non-labeled photosensitizer, the corresponding PAA nanoformulation under similar treatment parameters showed a remarkable enhancement in long-term tumor cure by PDT (photodynamic therapy) and provides an opportunity to develop a single nanoplatform for tumor-imaging (PET/fluorescence) and phototherapy, a practical “See and Treat” approach.
关键词： Positron Imaging Tomography,Nanoparticles,photodynamic therapy,Reactive Oxygen species
更新于2025-09-10 09:29:36
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Role of reactive oxygen species in the visible light photocatalytic mineralization of rhodamine B dye by P25–carbon dot photocatalyst
摘要： An undoped carbon dot (C-dot) with very high photoluminescence quantum yield (PLQY) (25%) and the P25/C-dot composite photocatalyst with improved visible light (VL) photocatalytic activity is reported. The composite exhibits superior VL photodegradation (PD) towards the dyes (RhB) and methyl orange compared to that of control P25. The effect of reactive oxygen species (ROS) is studied in the VL PD of the dye RhB using scavengers. Our study suggests that the ROS responsible for the mineralization of RhB is hydroxyl radical (?OH) and the combination of ?OH and singlet oxygen (1O2) has a synergistic effect on the mineralization of RhB. The ?OH formation is thought to be through the secondary reactions of ROS. Enhancement in the VL PD and the formation of ?OH are attributed to the presence of C-dot. The results suggest that C-dot assists the formation of ?OH through secondary reactions.
关键词： photocatalytic activity,mineralization,reactive oxygen species,visible light,rhodamine B,carbon dot
更新于2025-09-10 09:29:36
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Raman spectroscopic characterisation of photo-active keratin doped with Methylene Blue for wound dressings and tissue engineering
摘要： BACKGROUND: The design of wound dressings with extraordinary functionalities that fully address the problem of wound healing is an ambitious challenge in biomedical ?eld. Keratin is a protein most abundant in nature, being the major component of wool, feather, hair, etc., with promising applications in biomedical and regenerative medicine ?elds. A high level of antibacterial functionality is another desirable property for applications in biomedical ?eld in response to the increasing resistance of bacteria to antibiotics. One of the emerging methods of disinfection and sterilization is the antimicrobial photodynamic therapy (APDT), which uses light combined to a photosensitizer and oxygen to produce phototoxic species. OBJECTIVE: Biomatrices (photo-active keratin) made of wool keratin functionalized with methylene blue, a powerful photo-sensitizer, have been developed and tested as systems that combine the bioactive properties with the antimicrobial photodynamic functionality. METHODS: The biomatrix resistance to photo-degradation and the formation of reactive oxygen species were evaluated by spectroscopic methods, whereas the antibacterial properties were tested towards gram-positive bacteria. RESULTS: The Raman analysis revealed that speci?c damages occur at sensitive amino acid sites, selectively, rather than indiscriminately. However, keratin resulted to be a suitable biomaterial for APDT, since it has enough resistance to photo-degradation and the radical-induced oxidation is not able to induce strong structural changes in the protein. CONCLUSIONS: The results clearly indicate the potential use of these novel photo-active keratin biomatrices in wound dressing and tissue engineering.
关键词： reactive oxygen species,Raman spectroscopy,antimicrobial photodynamic activity,Keratin
更新于2025-09-10 09:29:36
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Effective Removal of Emerging Dissolved Cyanotoxins from Water using Hybrid Photocatalytic Composites
摘要： Harmful algal blooms are occurring more frequently in fresh water throughout the world. Certain cyanobacteria can produce and release potent toxic compounds, known as cyanotoxins, such as microcystins, cylindrospermopsin, saxitoxin, and anatoxin-a, and as such they have become a human and environmental health concern. Hybrid photocatalytic composites (HPCs) comprising carbon nanotubes on the surface of TiO2 nanotubes were designed in this study. The HPCs have a selective adsorption capacity to cyanotoxins and provide photocatalytic activity to produce reactive oxygen species for the degradation of cyanotoxins. HPCs with 5.2 mg carbon nanotubes/cm2 showed an excellent removal efficiency of microcystins-LR (> 95%) at 55.6 L/m2/hr/bar. The HPCs more efficiently removed the relatively larger and more hydrophobic cyanotoxins (i.e., microcystin-LR) than the relatively smaller and more hydrophilic compounds (such as cylindrospermopsin, saxitoxin, and anatoxin-a). With a further increased in the carbon nanotube content to 8.6 mg/cm2, the adsorption capacity of the HPCs for cyanotoxins increased to 70.6% for MC-LR. However, there was significant decrease in the photocatalytic activity of the HPCs for production of reactive oxygen species, and consequently a decrease in the degradation of cyanotoxins. It is considered that this device could be used to provide complete rejection of particles and pathogens, and also to significantly reduce trace organic compounds and harmful algal toxins in emergency water supplies.
关键词： Adsorption,Harmful algal blooms,Cyanotoxins,Photocatalytic activity,Reactive oxygen species,Hybrid photocatalytic composites
更新于2025-09-10 09:29:36
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Photo-Induced Depletion of Binding Sites in DNA-PAINT Microscopy
摘要： The limited photon budget of fluorescent dyes is the main limitation for localization precision in localization-based super-resolution microscopy. Points accumulation for imaging in nanoscale topography (PAINT)-based techniques use the reversible binding of fluorophores and can sample a single binding site multiple times, thus elegantly circumventing the photon budget limitation. With DNA-based PAINT (DNA-PAINT), resolutions down to a few nanometers have been reached on DNA-origami nanostructures. However, for long acquisition times, we find a photo-induced depletion of binding sites in DNA-PAINT microscopy that ultimately limits the quality of the rendered images. Here we systematically investigate the loss of binding sites in DNA-PAINT imaging and support the observations with measurements of DNA hybridization kinetics via surface-integrated fluorescence correlation spectroscopy (SI-FCS). We do not only show that the depletion of binding sites is clearly photo-induced, but also provide evidence that it is mainly caused by dye-induced generation of reactive oxygen species (ROS). We evaluate two possible strategies to reduce the depletion of binding sites: By addition of oxygen scavenging reagents, and by the positioning of the fluorescent dye at a larger distance from the binding site.
关键词： photo-induced DNA damage,surface-integrated fluorescence correlation spectroscopy (SI-FCS),reactive oxygen species,super-resolution microscopy,DNA-PAINT
更新于2025-09-09 09:28:46
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New Sensitizers Developed on a Methylpheophorbide a Platform for Photodynamic Therapy: Synthesis, Singlet Oxygen Generation and Modeling of Passive Membrane Transport
摘要： This study focuses on the behavior of new potential sensitizers for photodynamic therapy of cancer developed on a chlorophyll a platform. Pheophorbide a 17-(3) methylester and its two glycol derivatives have been synthesized from chlorophyll and identified via visible, UV-, NMR- and MS-spectra. The behavior of photosensitizers in solutions has been studied with various experimental techniques. They are found to generate singlet oxygen with a sufficient quantum yield and reveal a tendency to effectively penetrate into cell membranes due to high lipophilicity. Thermodynamic analysis indicates that the sensitizer transfer from a water-like to a lipid-like medium is controlled by a large and negative enthalpic term excepting the case of the most polar solute, where for phosphate saline buffer the favorable entropic term dominates. Our study highlights the important feature dealing with the temperature dependence of partition coefficients between saline buffer and 1-octanol which is found to be surprisingly strong for hydrophobic solutes and temperature independent for the species containing both H-donor and H-acceptor groups.
关键词： Hydrophobicity,Photosensitizers,Photodynamic therapy,Thermodynamics of solvation,Partition coefficients,Reactive oxygen species
更新于2025-09-09 09:28:46