chlorophyll-a and titanium-dioxide

The applications of nanoparticles continue to expand into areas as diverse as medicine, bioremediation, cosmetics, pharmacology and various industries, including agri-food production. The widespread use of nanoparticles has generated concerns given the impact these nanoparticles - mostly metal-based such as CuO, Ag, Au, CeO

Topics: Chlorophyll; Chloroplasts; Electron Transport; Metal Nanoparticles; Oxidative Stress; Photosynthesis; Photosystem II Protein Complex; Plant Transpiration; Titanium

Nano-titanium dioxide (nTiO

Topics: Chlorophyll; Dehydration; Hydrogen Peroxide; Lipid Peroxidation; Nanoparticles; Nitric Oxide; Stress, Physiological; Superoxides; Titanium; Vicia faba

Chlorophyll

Topics: Chlorophyll; Porosity; Solar Energy; Titanium

Chlorophyll content in leaves is a convenient indicator of the physiological state of the plant following exposure to a stressor. In the present study, a pot experiment was carried out using two medicinal plant species - peppermint (Mentha X piperita L.) and common sage (Salvia officinalis L.) to determine the link between the chlorophyll content in the plant leaves and the exposure of the plants to nano-TiO

Topics: Antioxidants; Chlorophyll; Mentha piperita; Plant Extracts; Plant Leaves; Plant Roots; Plants, Medicinal; Salvia officinalis; Sodium; Titanium

Bean yellow mosaic virus (BYMV) is the main cause of the mosaic and malformation of many plants, worldwide. Thus, the triggering of plant systemic resistance against BYMV is of great interest. In this endeavor, we aimed to explore the capacity of new carboxymethyl chitosan-titania nanobiocomposites (NBCs, NBC1,2) to trigger faba bean plants resistance against BYMV. Effects of NBCs on faba bean (Vicia faba L.) disease severity (DS), growth parameters, and antioxidant defense system activity were investigated under BYMV stress. Noticeably that the DS in NBCs-treated faba bean was significantly reduced compared to untreated plants. Moreover, treatment with NBCs was remarkably increased growth indices, photosynthetic pigments, membrane stability index, and relative water content compared to challenge control. Additionally, enzymatic and non-enzymatic antioxidants and total soluble protein were significantly increased. Contrary, electrolyte leakage, hydrogen peroxide, and lipid peroxidation were reduced. Interestingly that NBC1 has higher efficacy than NBC2 in triggering plant immune-system against BYMV as indicated from DS percentage (DS = 10.66% and 19.33% in case of plants treated with NBC1 and NBC2, respectively). This could be attributed to the higher content of TNPs in NBC1 (21.58%) as compared to NBC2 (14.32%). Overall, NBCs offer safe and economic antiviral agents against BYMV.

Topics: Antioxidants; Carotenoids; Chitosan; Chlorophyll; Magnetic Resonance Spectroscopy; Molecular Weight; Nanocomposites; Particle Size; Plant Diseases; Potyvirus; Reactive Oxygen Species; Spectroscopy, Fourier Transform Infrared; Titanium; Vicia faba; X-Ray Diffraction

The effects of TiO

Topics: Alanine; Bacteria; Biodegradation, Environmental; Biotransformation; Chlorophyll; Fungicides, Industrial; Lolium; Nanoparticles; Soil; Soil Microbiology; Stereoisomerism; Titanium; Zinc Oxide

In this study, we investigated the physiological and photochemical influences of nanoTiO

Topics: Carotenoids; Chlorophyll; Environmental Pollutants; Fruit; Hydroponics; Light; Metal Nanoparticles; Plant Roots; Solanum lycopersicum; Titanium

Increasing evidence indicates the presence of engineered nanoparticles (ENPs) in sewage sludge derived from wastewater treatment. Land application of sewage sludge is, therefore, considered as an important pathway for ENP transfer to the environment. The aim of this work was to understand the effects of sewage sludge containing nano-TiO

Topics: Agriculture; Biomarkers; Biomass; Chlorophyll; Life Cycle Stages; Metal Nanoparticles; Plant Leaves; Sewage; Soil; Soil Pollutants; Solanum lycopersicum; Spectrophotometry; Spectroscopy, Fourier Transform Infrared; Synchrotrons; Tannins; Titanium; Wastewater; Water Pollutants, Chemical; Water Purification

TiO

Topics: Amino Acids; Antioxidants; Chlorophyll; Droughts; Drug Tolerance; Glomeromycota; Malondialdehyde; Nanoparticles; Osmosis; Plant Development; Plant Leaves; Plant Proteins; Plant Roots; Poaceae; Proline; Reactive Oxygen Species; Seedlings; Soil Microbiology; Stress, Physiological; Titanium; Water; Wetlands

Topics: Chlorophyll; Chlorophyta; Lipid Peroxidation; Nanoparticles; Titanium

TiO

Topics: Chlorophyll; Haptophyta; Microalgae; Nanoparticles; Osmolar Concentration; Titanium; Water Pollutants, Chemical

The present work is emphasised with the herbicidal tolerance of Azolla pinnata R.Br. and its modulation with TiO

Topics: 2,4-Dichlorophenoxyacetic Acid; Biodegradation, Environmental; Chlorophyll; Ferns; Metal Nanoparticles; Nanoparticles; Nitrogen; Oxidation-Reduction; Oxidative Stress; Photosynthesis; Potassium; Titanium; Water Pollutants, Chemical

It is very important to have a good understanding of the biological effects of nanoparticles (NPs) on marine diatoms. In this study, the physiological and biochemical responses of a marine diatom Phaeodactylum tricornutum to titanium dioxide NPs (nano-TiO

Topics: Cerium; Chlorophyll; Chlorophyll A; Diatoms; Nanoparticles; Photosynthesis; Titanium

The use of nanoparticles (NPs) is of increasing significance due to their large potential for various applications. Great attention should be paid on the possible impacts of nanoparticles on the environment as large amounts of them may reach the environment by accident or voluntarily. Marine algae are potential organisms for usage in nanopollution bioremediation in aquatic system, because of their ability to adapt to long exposure to NPs. Thus, it is of prime importance to study the possible interactions of different NPs with microalgae in assessing their potential environmental risks. Most studies on potential environmental effects of ZnO and TiO2 NPs have been performed independently and following the widely accepted, standardized test systems, which had been developed for the characterization of chemicals. In this study, we have examined the cumulative effect of ZnO and TiO2 NPs on Picochlorum sp. in addition to the individual effects of these NPs over 32 days. Our results indicate that the toxicity and availability of NPs to marine algae are reduced by their aggregation and sedimentation. NPs are found to have a negative effect on algal growth and chlorophyll a concentration during the early growth stages. In contrast, the case is reversed during the late growth stages. There is no significant difference between the effect of the NPs when they are used separately and when both ZnO and TiO2 are used together in the test (P > 0.05).

Topics: Chlorophyll; Chlorophyll A; Chlorophyta; Nanoparticles; Titanium; Zinc Oxide

In the present study we analyze the effect of seed treatment by a range of nano-TiO2 concentrations on the growth of Arabidopsis thaliana plants, on the vitamin E content and the expression of its biosynthetic genes, as well as activity of antioxidant enzymes and lipid peroxidation. To conduct the mechanistic analysis of nano-TiO2 on plants growth and antioxidant status we applied nanoparticles concentrations that are much higher than those reported in the environment. We find that as the concentration of nano-TiO2 increases, the biomass, and chlorophyll content in 5-week-old Arabidopsis thaliana plants decrease in a concentration dependent manner. In opposite, higher nano-TiO2 concentration enhanced root growth. Our results indicate that a high concentration of nano-TiO2 induces symptoms of toxicity and elevates the antioxidant level. We also find that the expression levels of tocopherol biosynthetic genes were either down- or upregulated in response to nano-TiO2. Thermoluminescence analysis shows that higher nano-TiO2 concentrations cause lipid peroxidation. To the best of our knowledge, this is the first report concerning the effect of nano-TiO2 on vitamin E status in plants. We conclude that nano-TiO2 affects the antioxidant response in Arabidopsis thaliana plants. This could be an effect of a changes in vitamin E gene expression that is diminished under lower tested nano-TiO2 concentrations and elevated under 1000 μg/ml.

Topics: Antioxidants; Arabidopsis; Biomass; Chlorophyll; Dose-Response Relationship, Drug; Environmental Pollutants; Genes, Plant; Lipid Peroxidation; Nanoparticles; Plant Roots; Seeds; Titanium; Vitamin E

Nine solvents, namely, n-hexane, ethanol, acetonitrile, chloroform, ethyl-ether, ethyl-acetate, petroleum ether, n-butyl alcohol, and methanol were used to extract natural dyes from Cordyline fruticosa, Pandannus amaryllifolius and Hylocereus polyrhizus. To improve the adsorption of dyes onto the TiO2 particles, betalain and chlorophyll dyes were mixed with methanol or ethanol and water at various ratios. The adsorption of the dyes mixed with titanium dioxide (TiO2) was also observed. The highest adsorption of the C.fruticosa dye mixed with TiO2 was achieved at ratio 3:1 of methanol: water. The highest adsorption of P.amaryllifolius dye mixed with TiO2 was observed at 2:1 of ethanol: water. H.polyrhizus dye extracted by water and mixed with TiO2 demonstrated the highest adsorption among the solvents. All extracted dye was adsorbed onto the surface of TiO2 based on Fourier Transform Infrared Spectroscopy (FTIR) analysis. The inhibition of crystallinity of TiO2 was likewise investigated by X-ray analysis. The morphological properties and composition of dyes were analyzed via SEM and EDX.

Topics: Adsorption; Betacyanins; Cactaceae; Chlorophyll; Cordyline; Electric Power Supplies; Pandanaceae; Picolinic Acids; Pigments, Biological; Solar Energy; Solvents; Titanium

In view of the increasing usage of anatase and rutile crystalline phases of titania NPs in the consumer products, their entry into the aquatic environment may pose a serious risk to the ecosystem. In the present study, the possible toxic impact of anatase and rutile nanoparticles (individually and in binary mixture) was investigated using freshwater microalgae, Chlorella sp. at low exposure concentrations (0.25, 0.5 and 1mg/L) in freshwater medium under UV irradiation. Reduction of cell viability as well as a reduction in chlorophyll content were observed due to the presence of NPs. An antagonistic effect was noted at certain concentrations of binary mixture such as (0.25, 0.25), (0.25, 0.5), and (0.5, 0.5) mg/L, and an additive effect for the other combinations, (0.25, 1), (0.5, 0.25), (0.5, 1), (1, 0.25), (1, 0.5), and (1, 1) mg/L. The hydrodynamic size analyses in the test medium revealed that rutile NPs were more stable in lake water than the anatase and binary mixtures [at 6h, the sizes of anatase (1mg/L), rutile NPs (1mg/L), and binary mixture (1, 1mg/L) were 948.83±35.01nm, 555.74±19.93nm, and 1620.24±237.87nm, respectively]. The generation of oxidative stress was found to be strongly dependent on the crystallinity of the nanoparticles. The transmission electron microscopic images revealed damages in the nucleus and cell membrane of algal cells due to the interaction of anatase NPs, whereas rutile NPs were found to cause chloroplast and internal organelle damages. Mis-shaped chloroplasts, lack of nucleus, and starch-pyrenoid complex were noted in binary-treated cells. The findings from the current study may facilitate the environmental risk assessment of titania NPs in an aquatic ecosystem.

Topics: Cell Survival; Chlorella; Chlorophyll; Fresh Water; Metal Nanoparticles; Microscopy, Electron, Transmission; Particle Size; Titanium; Ultraviolet Rays; Water Pollutants, Chemical

Recently nano-materials are widely used but they have shown contrasting effects on human and plant life. Keeping in view the contrasting results, the present study has evaluated plant growth response, antioxidant system activity and photosynthetic apparatus physiological and ultrastructural changes in Brassica napus L. plants grown under a wide range (0, 500, 2500, 4000 mg/l) of nano-TiO2 in a pot experiment. Nano-TiO2 has significantly improved the morphological and physiological indices of oilseed rape plants under our experimental conditions. All the parameters i-e morphological (root length, plant height, fresh biomass), physiological (photosynthetic gas exchange, chlorophyll content, nitrate reductase activity) and antioxidant system (Superoxide dismutase, SOD; Guaiacol peroxidase, POD; Catalase, CAT) recorded have shown improvement in their performance by following nano-TiO2 dose-dependent manner. No significant chloroplast ultra-structural changes were observed. Transmission electron microscopic images have shown that intact & typical grana and stroma thylakoid membranes were in the chloroplast, which suggest that nano-TiO2 has not induced the stressful environment within chloroplast. Finally, it is suggested that, nano-TiO2 have growth promoting effect on oilseed rape plants.

Topics: Antioxidants; Biodegradation, Environmental; Brassica napus; Brassica rapa; Cadmium; Catalase; Chlorophyll; Chloroplasts; Hydroponics; Malondialdehyde; Nanostructures; Peroxidase; Photosynthesis; Plant Leaves; Plant Roots; Soil Pollutants; Stress, Physiological; Superoxide Dismutase; Titanium

Cyanobacteria were inactivated under sunlight using mixed phase silver (Ag) and deposited titanium dioxide (TiO₂) coated on the surface of diatomite (DM) as a hybrid photocatalyst (Ag-TiO₂/DM). The endpoints of dose-response experiments were chlorophyll a, photosynthetic efficiency, and flow cytometry measurements. In vitro experiments revealed that axenic cultures of planktonic cyanobacteria lost their photosynthetic activity following photocatalyzed exposure to sunlight for more than 24 h. Nearly 92% of Microcystis aeruginosa cells lost their photosynthetic activity, and their cell morphology was severely damaged within 24 h of the reaction. Preliminary carbon-14 ((14)CO₃(-2)) results suggest that the complete inactivation of cyanobacteria arises from damage to cell wall components (peroxidation). A small concomitant increase in cell wall disorder and a consequent decrease in cell wall functional groups increase the cell wall fluidity prior to cell lysis. A high dosage of Ag-TiO₂/DM during photocatalysis increased the concentration of extracellular polymeric substances (EPSs) in the Microcystis aeruginosa suspension by up to approximately 260%. However, photocatalytic treatment had a small effect on the disinfection by-product (DBP) precursor, as revealed by only a slight increase in the formation of trihalomethanes (THMs) and haloacetic acids (HAAs).

Topics: Cell Proliferation; Chlorophyll; Chlorophyll A; Cyanobacteria; Diatomaceous Earth; Disinfection; Microcystis; Photosynthesis; Silver; Sunlight; Titanium

Chlorophylls based-dyes obtained from seaweeds represent attractive alternatives to the expensive and polluting pyridil based Ru complexes because of their abundance in nature. Another important characteristic is that the algae do not subtract either cropland or agricultural water, therefore do not conflict with agro-food sector. This pigment shows a typical intense absorption in the UV/blue (Soret band) and a less intense band in the red/near IR (Q band) spectral regions and for these reasons appear very promising as sensitizer dyes for DSSC. In the present study, we utilized chlorophylls from samples of the brown alga Undaria pinnatifida as sensitizer in DSSCs. The dye, extracted by frozen seaweeds and used without any chemical purification, showed a very good fill factor (0.69). Even the photelectrochemical parameters if compared with the existent literature are very interesting.

Topics: Absorption; Chlorophyll; Coloring Agents; Electrochemistry; Photochemistry; Seaweed; Solar Energy; Spectrophotometry, Ultraviolet; Titanium; Ultraviolet Rays

Sunscreens have been shown to give the most effective protection for human skin from ultraviolet (UV) radiation. Chemicals from sunscreens (i.e., UV filters) accumulate in the sea and have toxic effects on marine organisms. In this report, we demonstrate that photoexcitation of inorganic UV filters (i.e., TiO2 and ZnO nanoparticles) under solar radiation produces significant amounts of hydrogen peroxide (H2O2), a strong oxidizing agent that generates high levels of stress on marine phytoplankton. Our results indicate that the inorganic oxide nanoparticle content in 1 g of commercial sunscreen produces rates of H2O2 in seawater of up to 463 nM/h, directly affecting the growth of phytoplankton. Conservative estimates for a Mediterranean beach reveal that tourism activities during a summer day may release on the order of 4 kg of TiO2 nanoparticles to the water and produce an increment in the concentration of H2O2 of 270 nM/day. Our results, together with the data provided by tourism records in the Mediterranean, point to TiO2 nanoparticles as the major oxidizing agent entering coastal waters, with direct ecological consequences on the ecosystem.

Topics: Chlorophyll; Chlorophyll A; Diatoms; Hydrogen Peroxide; Nanoparticles; Phytoplankton; Seawater; Sunlight; Sunscreening Agents; Titanium; Water Pollutants, Chemical; Zinc Oxide

Titanium dioxide nanoparticles (nano-TiO2) are manufactured and used worldwide in large quantities. However, phytotoxicity research on nano-TiO2 has yielded confusing results, ranging from strong toxicity to positive effects. Therefore, in this research, the effects of nano-TiO2 on the germination and root elongation of seed and seedlings were studied. Additionally, the uptake and physiological responses of mature plants were investigated. Physical chemistry data were analyzed to assess the availability of nano-TiO2. Finally, a hydroponic system designed to overcome nano-TiO2 precipitation was used to reproduce the environmental conditions of actual fields. Nano-TiO2 did not have any effect on seed germination or on most of the plant species tested. Nano-TiO2 had positive effects on root elongation in some species. No physiological differences in enzyme activities or chlorophyll content were detected, even though the plants absorbed nano-TiO2. Physical chemistry data showed that nano-TiO2 agglomerated rapidly and formed particles with much bigger hydrodynamic diameters, even in distilled water and especially in a hydroponic system. Furthermore, agglomerated nano-TiO2 formed precipitates; this would be more severe in an actual field. Consequently, nano-TiO2 would not be also readily available to plants and would not cause any significant effects on plants. Our results and other reports suggest that titanium itself is not phytotoxic, even though plants absorb titanium. In conclusion, nano-TiO2 is not toxic to the three plant species, in vitro or in situ.

Topics: Antioxidants; Brassica napus; Chlorophyll; Dose-Response Relationship, Drug; Germination; Hydroponics; Lactuca; Nanoparticles; Phaseolus; Plant Proteins; Plant Roots; Seeds; Species Specificity; Superoxide Dismutase; Time Factors; Titanium

The transfer of nanoparticles (NPs) into the food chain through edible plants is of great concern. Cucumis sativus L. is a freshly consumed garden vegetable that could be in contact with NPs through biosolids and direct agrichemical application. In this research, cucumber plants were cultivated for 150 days in sandy loam soil treated with 0 to 750 mg TiO2 NPs kg(-1). Fruits were analyzed using synchrotron μ-XRF and μ-XANES, ICP-OES, and biochemical assays. Results showed that catalase in leaves increased (U mg(-1) protein) from 58.8 in control to 78.8 in 750 mg kg(-1) treatment; while ascorbate peroxidase decreased from 21.9 to 14.1 in 500 mg kg(-1) treatment. Moreover, total chlorophyll content in leaves increased in the 750 mg kg(-1) treatment. Compared to control, FTIR spectra of fruit from TiO2 NP treated plants showed significant differences (p ≤ 0.05) in band areas of amide, lignin, and carbohydrates, suggesting macromolecule modification of cucumber fruit. In addition, compared with control, plants treated with 500 mg kg(-1) had 35% more potassium and 34% more phosphorus. For the first time, μ-XRF and μ-XANES showed root-to-fruit translocation of TiO2 in cucumber without biotransformation. This suggests TiO2 could be introduced into the food chain with unknown consequences.

Topics: Ascorbate Peroxidases; Catalase; Chlorophyll; Cucumis sativus; Elements; Environmental Monitoring; Food Chain; Fruit; Nanoparticles; Plant Leaves; Reproducibility of Results; Soil; Spectrometry, X-Ray Emission; Spectroscopy, Fourier Transform Infrared; Synchrotrons; Titanium; X-Ray Absorption Spectroscopy

Titanium dioxide nanoparticles (TiO(2) NPs) have raised concern of environmental risks due to their widespread applications, but little is known about the potential toxicity of TiO(2) NPs to aquatic plants. The aim of this work was to study the effects of TiO(2) NPs on Lemna minor and to study the behavior of TiO(2) NPs under modified ISO 20079 test conditions. TiO(2) NPs had a tendency to aggregate in ISO (Steinberg) growth medium, but modification of the standard growth medium enabled the exposure of L. minor to TiO(2) NPs. By dilution of the growth medium (1:10), and exposure under semi-static conditions with medium renewal every second or third day, the size of TiO(2) particles remained rather stable throughout the test period. TiO(2) NPs showed no adverse effect on the growth rate or chlorophyll a content of L. minor, even at a high exposure concentration of 5 mg L(-1) and extended exposure time of 14 days. TiO(2) NPs attached onto L. minor cell walls, but no cellular uptake was observed. Although TiO(2) NPs were not toxic to L. minor, the potential transfer of TiO(2) NPs in aquatic food chains, e.g. attached to the plant leaves and other biological surfaces may be of importance, causing exposure of other organisms and contributing to the environmental fate of nanoparticles.

Topics: Araceae; Chlorophyll; Nanoparticles; Time Factors; Titanium; Water Pollutants, Chemical

To achieve artificial photosynthesis it is necessary to couple the single-electron event of photoinduced charge separation with the multi-electron reactions of fuel formation and water splitting. Therefore, several rounds of light-induced charge separation are required to accumulate enough redox equivalents at the catalytic sites for the target chemistry to occur, without any sacrificial donors or acceptors other than the catalytic substrates. Herein, we discuss the challenges of such accumulative electron transfer in molecular systems. We present a series of closely related systems base on a Ru(II)-polypyridine photosensitizer with appended triaryl-amine or oligo-triaryl-amine donors, linked to nanoporous TiO2 as the acceptor. One of the systems, based on dye 4, shows efficient accumulative electron transfer in high overall yield resulting in the formation of a two-electron charge-separated state upon successive excitation by two photons. In contrast, the other systems do not show accumulative electron transfer because of different competing reactions. This illustrates the difficulties in designing successful systems for this still largely unexplored type of reaction scheme.

Topics: Chlorophyll; Coordination Complexes; Electron Transport; Electrons; Kinetics; Light; Oxidation-Reduction; Oxygen; Photochemistry; Photons; Photosensitizing Agents; Photosynthesis; Ruthenium; Static Electricity; Titanium; Water

Manufactured metal oxide nanoparticles (NPs) are being used on a large scale, and these particles will inevitably reach a body of water through wastewater and urban runoff. The ecotoxicological study of these NPs on hydrophyte is limited at present. Lemna minor was exposed to media with different concentrations of titanium dioxide (TiO(2)) NPs or bulk TiO(2) for 7 d. The changes in plant growth, chlorophyll, antioxidant defense enzymes (peroxidase [POD], catalase [CAT], and superoxide dismutase [SOD] activities), and malondialdehyde (MDA) content were measured in the present study. The particle size of TiO(2) NPs and the zeta potential of TiO(2) NPs and of bulk TiO(2) in the culture media were also analyzed to complementally study the toxicity of these materials on duckweed. The results showed that the effect of TiO(2) NPs on plant growth was more obvious than bulk TiO(2.) Titanium dioxide NPs stimulated plant growth in low concentrations, but inhibited plant growth at high concentrations. The POD, SOD, and CAT activity of Lemna minor increased when TiO(2) NP concentration was lower than 200 mg/L to eliminate accumulated reactive oxygen species in plant cells. The SOD activity decreased when the TiO(2) NP concentration was higher than 200 mg/L, and the plant cell membrane encountered serious damage from 500 mg/L TiO(2) NP concentration in the culture media.

Topics: Antioxidants; Araceae; Catalase; Chlorophyll; Malondialdehyde; Nanoparticles; Oxidoreductases; Particle Size; Peroxidase; Reactive Oxygen Species; Superoxide Dismutase; Titanium; Water Pollutants

The toxicological effects of nanometer titanium dioxide (nano-TiO2) on a unicellular green alga Chlamydomonas reinhardtii were assessed by investigating the changes of the physiology and cyto-ultrastructure of this species under treatment. We found that nano-TiO2 inhibited photosynthetic efficiency and cell growth, but the content of chlorophyll a content in algae did not change, while carotenoid and chlorophyll b contents increased. Malondialdehyde (MDA) content reached maximum values after 8h exposure and then decreased to a moderately low level at 72 h. Electron microscopy images indicated that as concentrations of nano-TiO2 increased, a large number of C. reinhardtii cells were noted to be damaged: the number of chloroplasts declined, various other organelles were degraded, plasmolysis occurred, and TiO2 nanoparticles were found to be located inside cell wall and membrane. It was also noted that cell surface was surrounded by TiO2 particles, which could present an obstacle to the exchange of substances between the cell and its surrounding environment. To sum up, the effect of nano-TiO2 on C. reinhardtii included cell surface aggregation, photosynthesis inhibition, lipid peroxidation and new protein synthesis, while the response of C. reinhardtii to nano-TiO2 was a rapid process which occurs during 24 h after exposing and may relate to physiological stress system to mitigate damage.

Topics: Chlamydomonas reinhardtii; Chlorophyll; Chlorophyll A; Chloroplasts; Lipid Peroxidation; Malondialdehyde; Microscopy, Electron; Nanoparticles; Photosynthesis; Titanium

In view of their increasing commercial applications metal oxide NPs like titania have elevated chances of entry to the environment. The ecotoxicity analyses are required to assess their environmental risks. The present work aims to demonstrate the effect of titania NPs on microalgae isolated from freshwater environment (Scenedesmus sp. and Chlorella sp.). The growth inhibitory effect of titania NPs was observed for both the species (72 h EC₅₀ value, 16.12 mg/L for Chlorella sp.; 21.2 mg/L for Scenedesmus sp.). Bulk micron-sized titania also showed toxicity though to a lesser extent (72 h EC₅₀ value, 35.50mg/L for Chlorella sp.; 44.40 mg/L for Scenedesmus sp.). A concentration dependent decrease in chlorophyll content was observed in the treated cells compared to the untreated ones, more effect being notable in case of NPs. Preliminary results based on FT-IR studies and microscopic images suggest interaction of the NPs with the cell surface.

Topics: Chlorella; Chlorophyll; Fresh Water; Metal Nanoparticles; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Particle Size; Scenedesmus; Titanium; Water Pollutants, Chemical; X-Ray Diffraction

The UV/Ag-TiO2/O3 process was investigated for ballast water treatment using Dunaliella salina as an indicator. Inactivation curves were obtained, and the toxicity of effluent was determined. Compared with individual unit processes using ozone or UV/Ag-TiO2, the inactivation efficiency of D. salina by the combined UV/Ag-TiO2/O3 process was enhanced. The presence of ozone caused an immediate decrease in chlorophyll a (chl-a) concentration. Inactivation efficiency and ch1-a removal efficiency were positively correlated with ozone dose and ultraviolet intensity. The initial total residual oxidant (TRO) concentration of effluent increased with increasing ozone dose, and persistence of TRO resulted in an extended period of toxicity. The results suggest that UV/Ag-TiO2/O3 has potential for ballast water treatment.

Topics: Chlorophyll; Chlorophyll A; Chlorophyta; Introduced Species; Oxidants; Oxidation-Reduction; Ozone; Photochemistry; Ships; Silver Compounds; Titanium; Ultraviolet Rays; Water Purification

Ballast water poses a biological threat to the world's waterways by transferring aquatic species from one body of water to another. This study investigates the use of combined ultraviolet (UV)/Ag-TiO(2)+ozone (O(3)) processes for treating ballast water using Amphidinium sp. as an indicator microorganism. Sufficient Amphidinium sp. cells in ballast waters can be inactivated using O(3) alone, UV irradiation alone (with or without an Ag-TiO(2) coating), and combined treatments. For the low inactivation ratio (<40%) regime, the effects of ozonation and photocatalysis were observed to be cumulative. The combined UV/Ag-TiO(2)+O(3) treatment produced excess hydroxyl radicals and total residual oxidants (TROs), and readily damaged cell membranes to release intracellular substances. The comparison tests revealed that the combined treatments synergistically inactivate Escherichia coli in ballast waters. However, the combined process did not synergistically inactivate Amphidinium sp. cells. Inactivating different aqua species in ballast waters needs distinct treatment methods and dosages.

Topics: Chlorobenzoates; Chlorophyll; Chlorophyll A; Dinoflagellida; Malondialdehyde; Oxidants; Oxidation-Reduction; Ozone; Ships; Silver; Time Factors; Titanium; Ultraviolet Rays; Waste Disposal, Fluid; Water

Five chlorophyll-a derivatives, chlorins-1-5 possessing C3(2)-carboxy and O17(4)-esterified hydrocarbon groups including methyl, hexyl, dodecyl, 2-butyloctyl, and cholesteryl were synthesized. Their performance as sensitizers in dye-sensitized solar cells (DSSCs) was compared. These sensitizers have similar surface coverage on the unit surface of TiO(2) film and their absorption spectra on transparent TiO(2) films were identical. On the basis of DFT and TD-DFT calculations of these sensitizers in ethanol, a major difference between them was the geometry of the hydrocarbon ester group, to affect their electron injection and charge recombination with the TiO(2) electrode rather than the energy level of their molecular orbitals. DSSC based on chlorin-3 with a dodecyl ester group gave a solar energy-to-electricity conversion efficiency of 8%, which was the highest among all the chlorophyllous sensitizers. The large photocurrent in the chlorin-3 sensitized solar cell can be explained by the least impedance in the electrolyte-dye-TiO(2) interface in electrical impedance spectroscopy measurements. Subpicosecond time-resolved absorption spectroscopic studies have also been carried out to evaluate the electron injection and charge recombination dynamics in the dye-TiO(2) interface. For the electron injection and charge recombination processes, a charge separated state of the dye-TiO(2) complex has been found to be free from the type and concentration of dye sensitizer, reflecting the same type of electron transfer process for all the five chlorin sensitizers. A new quenching pathway of the dye excitation, which is probably from the exciton annihilation, in addition of the charge recombination has been observed for chlorin-1 and chlorin-5, but not for chlorin-3. The higher open-circuit photocurrent observed in the present dyes with larger ester groups can be attributed to the reduced leaking of charges in the TiO(2)-electrolyte interface, which was supported by the longer electron lifetimes.

Topics: Absorption; Chlorophyll; Chlorophyll A; Coloring Agents; Electron Transport; Esters; Hydrocarbons; Light; Quantum Theory; Solar Energy; Time Factors; Titanium

Chlorophyll has been extracted from cyanobacteria. The adsorption of chlorophyll on the surface of colloidal TiO(2) through electrostatic interaction was observed. The apparent association constant (K(app)) of chlorophyll-TiO(2) obtained from absorption spectra is 3.78x10(4)M(-1). The K(app) value of chlorophyll-TiO(2) as determined from fluorescence spectra is 1.81x10(4)M(-1), which matches well with that determined from the absorption spectra changes. These data indicate that there is an interaction between chlorophyll and colloidal TiO(2) nanoparticle surface. The dynamics of photoinduced electron transfer from chlorophyll to the conduction band of colloidal TiO(2) nanoparticle has been observed and the mechanism of electron transfer has been confirmed by the calculation of free energy change (DeltaG(et)) by applying Rehm-Weller equation as well as energy level diagram. Lifetime measurements gave the rate constant (k(et)) for electron injection from the excited state chlorophyll into the conduction band of TiO(2) is 4.2x10(8)s(-1).

Topics: Absorption; Catalysis; Chlorophyll; Colloids; Cyanobacteria; Energy Transfer; Models, Biological; Photochemistry; Photosensitizing Agents; Spectrometry, Fluorescence; Titanium

A bioinspired hybrid system, composed of colloidal TiO2 nanoparticles surface modified with a photochemically active mimic of the PSII chlorophyll-Tyr-His complex, undergoes photoinduced stepwise electron transfer coupled to proton motion at the phenolic site. Low temperature electron paramagnetic resonance studies reveal that injected electrons are localized on TiO2 nanoparticles following photoexcitation. At 80 K, 95% of the resulting holes are localized on the phenol moiety and 5% are localized on the porphyrin. At 4.2 K, 52% of the holes remain trapped on the porphyrin. The anisotropic coupling tensors of the phenoxyl radical are resolved in the photoinduced D-band EPR spectra and are in good agreement with previously reported g-tensors of tyrosine radicals in photosystem II. The observed temperature dependence of the charge shift is attributed to restricted nuclear motion at low temperature and is reminiscent of the observation of a trapped high-energy state in the natural system. Electrochemical studies show that the phenoxyl/phenol couple of the model system is chemically reversible and thermodynamically capable of water oxidation.

Topics: Chlorophyll; Electron Spin Resonance Spectroscopy; Electron Transport; Histidine; Nanoparticles; Oxidation-Reduction; Photochemistry; Photosystem II Protein Complex; Protons; Temperature; Titanium; Tyrosine; Water

With the rapid development of nanotechnology, there is an increasing risk of human and environmental exposure to nanotechnology-based materials and products. As water resources are particularly vulnerable to direct and indirect contamination of nonomaterials (NMs), the potential toxicity and environmental implication of NMs to aquatic organisms must be evaluated. In this study, we assessed potential toxicity of two commercially used NMs, titanium dioxide (TiO(2)) and quantum dots (QDs), using the unicellular green alga Chlamydomonas reinhartii as a model system. The response of the organism to NMs was assessed at physiological, biochemical, and molecular genetic levels. Growth kinetics showed that growth inhibition occurred during the first two to three days of cultivation in the presence of TiO(2) or QDs. Measurements of lipid peroxidation measurement indicated that oxidative stress of the cells occurred as early as 6 h after exposure to TiO(2) or QDs. The transcriptional expression profiling of four stress response genes (sod1, gpx, cat, and ptox2) revealed that transient up-regulation of these genes occurred in cultures containing as low as 1.0 mg L(-1) of TiO(2) or 0.1 mg L(-1) of QDs, and the maximum transcripts of cat, sod1, gpx, and ptox2 occurred at 1.5, 3, 3, and 6 h, respectively, and were proportional to the initial concentration of the NMs. As the cultures continued, recovery in growth was observed and the extent of recovery, as indicated by the final cell concentration, was dosage-dependent. QDs were found to be more toxic to Chlamydomonas cells than TiO(2) under our experimental conditions.

Topics: Animals; Biocompatible Materials; Chlamydomonas reinhardtii; Chlorophyll; Dose-Response Relationship, Drug; Lipid Peroxidation; Nanoparticles; Oxidative Stress; Polymerase Chain Reaction; Quantum Dots; Time Factors; Titanium; Water Pollutants, Chemical

Photovoltaic conversion using zinc chlorin-e6 (ZnChl-e6), which is zinc chlorophyll-a derivative, and fatty acid (myristic acid or cholic acid) co-adsorbed nanocrystalline TiO2 layer onto ITO glass (OTE) electrode is developed. The maximum peaks of photocurrent action spectrum of the ZnChl-e6 adsorbed TiO2 layer onto OTE (ZnChl-e6/TiO2) are 400, 660 and 800 nm, respectively. Especially the IPCE value at 800 nm (7.5%) is larger than that of 660 nm (6.9%). This result indicates that ZnChl-e6 molecules is aggregated or formed dimer on a nanocrystalline TiO2 layer onto OTE and the absorption band is shifted to near IR region. The photocurrent action spectrum of ZnChl-e6 and cholic acid adsorbed TiO2 layer onto OTE (ZnChl-e6-Cho/TiO2 is similar to that of the UV-vis absorption spectrum in methanol solution, and IPCE values at 400 and 660 nm (8.1%) increase and the IPCE value at 800 nm (4.1%) decreases, indicating that the aggregation of ZnChl-e6 molecules on the TiO2 is suppressed by cholic acid. By using ZnChl-e6-Cho/TiO2, the short-circuit photocurrent density and open-circuit photovoltage also increase compared with that of ZnChl-e6 adsorbed nanocrystalline TiO2 electrode.

Topics: Chlorophyll; Electrochemistry; Electrodes; Hydrophobic and Hydrophilic Interactions; Light; Nanoparticles; Titanium; Zinc

Simulated solar UV/TiO(2) photocatalysis was efficient to detoxify a mixture of 100 mgphenoll(-1) and 50 mgp-nitrophenol (PNP) l(-1) and allow the subsequent biodegradation of the remaining pollutants and their photocatalytic products under photosynthetic aeration with Chlorella vulgaris. Photocatalytic degradation of phenol and PNP was well described by pseudo-first order kinetics (r(2)>0.98) with removal rate constants of 1.9x10(-4) and 2.8x10(-4)min(-1), respectively, when the pollutants were provided together and 5.7x10(-4) and 9.7x10(-4)min(-1), respectively, when they were provided individually. Photocatalytic pre-treatment of the mixture during 60 h removed 50+/-1% and 62+/-2% of the phenol and PNP initially present but only 11+/-3% of the initial COD. Hydroquinone, nitrate and catechol were identified as PNP photocatalytic products and catechol and hydroquinone as phenol photocatalytic products. Subsequent biological treatment of the pre-treated samples removed the remaining contaminants and their photocatalytic products as well as 81-83% of the initial COD, allowing complete detoxification of the mixture to C. vulgaris. Similar detoxification efficiencies were recorded after biological treatment of the irradiated mixture with activated sludge microflora or with an acclimated consortia composed of a phenol-degrading Alcaligenes sp. and a PNP-degrading Arthrobacter sp., although the acclimated strains biodegraded the remaining pollutants faster. Biological treatment of the non-irradiated mixture was inefficient due to C. vulgaris inhibition.

Topics: Alcaligenes; Arthrobacter; Catalysis; Chlorella vulgaris; Chlorophyll; Lepidium sativum; Nitrophenols; Phenol; Photosynthesis; Plant Stems; Titanium; Ultraviolet Rays; Waste Disposal, Fluid; Water Pollutants, Chemical

The improvement of spinach growth is proved to relate to N2 fixation by nano-anatase TiO2 in this study. The results show that all spinach leaves kept green by nano-anatase TiO2 treatment and all old leaves of control turned yellow white under culture with N-deficient solution. And the fresh weight, dry weight, and contents of total nitrogen, NH4(+), chlorophyll, and protein of spinach by nano-anatase TiO2 treatment presented obvious enhancement compared with control. Whereas the improvements of yield of spinach were not as good as nano-anatase TiO2 treatment under N-deficient condition, confirming that nano-anatase TiO2 on exposure to sunlight could chemisorb N2 directly or reduce N2 to NH3 in the spinach leaves, transforming into organic nitrogen and improving the growth of spinach. Bulk TiO2 effect, however, was not as significant as nano-anatase TiO2. A possible metabolism of the function of nano-anatase TiO2 reducing N2 to NH3 was discussed.

Topics: Chlorophyll; Nanocomposites; Nitrogen; Nitrogen Fixation; Oxidation-Reduction; Photochemistry; Plant Proteins; Quaternary Ammonium Compounds; Spinacia oleracea; Sunlight; Titanium

Being a proven photocatalyst, nano-anatase is capable of undergoing electron transfer reactions under light. In previous studies we had proven that nano-anatase improved photosynthesis and greatly promoted spinach growth. The mechanisms by which nano-anatase promotes energy transfer and the conversion efficiency of the process are still not clearly understood. In the present paper, we report the results obtained with the photosystem II (PSII) isolated from spinach and treated by nano-anatase TiO2 and studied the effect of nano-anatase TiO2 on energy transfer in PSII by spectroscopy and on oxygen evolution. The results showed that nano-anatase TiO2 treatment at a suitable concentration could significantly change PSII microenvironment and increase absorbance for visible light, improve energy transfer among amino acids within PSII protein complex, and accelerate energy transport from tyrosine residue to chlorophyll a. The photochemical activity of PSII (fluorescence quantum yield) and its oxygen-evolving rate were enhanced by nano-anatase TiO2. This is viewed as evidence that nano-anatase TiO2 can promote energy transfer and oxygen evolution in PSII of spinach.

Topics: Chlorophyll; Chlorophyll A; Energy Transfer; Oxygen; Photosystem II Protein Complex; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Spinacia oleracea; Titanium

In this work, spinach stroma membrane, instead of thylakoid, has been investigated for the presence of phosphorylated proteins. We identified seven previously unknown phosphorylation sites by taking advantage of TiO(2) phosphopeptides enrichment coupled to mass spectrometric analysis. Upon illumination at 100 micromol m(-2) s(-1), two novel phosphopeptides belonging to the N-terminal region of Lhcb1 light-harvesting protein were detected: NVSSGS(p)PWYGPDR and T(p)VQSSSPWYGPDR. Moreover, three new threonine residues in CP43 (Thr-6, Thr-8, and Thr-346) and, for the first time, two amino acid residues of the N-terminus of Rieske Fe-S protein of the cytochrome b(6)f complex (Thr-2 and Ser-3) were revealed to be phosphorylated. Since Lhcb1 and CP43 have been reported as mobile proteins, it may be suggested that illumination derived phosphorylation, and consequently the addition of negatively charged groups to the protein, is a necessary condition to induce a significant protein structural change.

Topics: Cell Fractionation; Cell Membrane; Chlorophyll; Chromatography, Liquid; Mass Spectrometry; Nanotechnology; Phosphorylation; Plant Leaves; Plant Proteins; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spinacia oleracea; Stromal Cells; Subcellular Fractions; Titanium

Previous research showed that nano-TiO2 could significantly promote photosynthesis and greatly improve growth of spinach, but we also speculated that an increase of spinach growth by nano-TiO2 treatment might be closely related to the change of nitrogen metabolism. The effects of nanoanatase TiO2 on the nitrogen metabolism of growing spinach were studied by treating them with nano-anatase TiO2. The results showed that nano-anatase TiO2 treatment could obviously increase the activities of nitrate reductase, glutamate dehydrogenase, glutamine synthase, and glutamic-pyruvic transaminase during the growing stage. Nano-anatase TiO2 treatment could also promote spinach to absorb nitrate, accelerate inorganic nitrogen (such as NO3--N and NH4+-N) to be translated into organic nitrogen (such as protein and chlorophyll), and enhance the fresh weight and dry weights.

Topics: Chlorophyll; Nitrate Reductase; Nitrates; Nitrogen; Plant Proteins; Quaternary Ammonium Compounds; RNA-Binding Proteins; Spinacia oleracea; Titanium

A Zn chlorophyll-a derivative, Zn chlorin-e6 (ZnChl-e6), adsorbed onto a nanocrystalline TiO2 film (ZnChl-e6/TiO2) electrode was prepared, and the photovoltaic properties of the ZnChl-e6/TiO2 electrode were studied. The absorption peaks of ZnChl-e6/TiO2 observed at 420, 654, and 795 nm were attributed to the ZnChl-e6 molecules aggregating onto TiO2 film. The fluorescence attributed to the ZnChl-e6 monomer and aggregate was observed at 710 and 820 nm, respectively, and the fluorescence in both cases was quenched by TiO2 particles. The maximum of the incident photon-to-current conversion efficiency (IPCE) value in the photocurrent action spectrum was 800 nm, and the IPCE value was 7.0%. ZnChl-e6 molecules formed aggregates on a nanocrystalline TiO2 film electrode. From the photocurrent-photovoltage characteristics of the ZnChl-e6/TiO2 electrode irradiated with 100 mW cm(-2), the short-circuit photocurrent (I(SC)) was found to be 0.19 mA cm(-2) and the open-circuit photovoltage (V(OC)) was found to be 375 mV. The maximum power was estimated to be 28.7 microW cm(-2), and the fill factor (FF) was estimated to be 40.1%. A near-IR light induced photovoltaic conversion system using a ZnChl-e6 aggregate formed onto a nanocrystalline TiO2 film electrode was achieved.

Topics: Chlorophyll; Crystallization; Electrodes; Light; Molecular Structure; Nanostructures; Photochemistry; Spectrum Analysis; Titanium; Zinc

The effects of nano-TiO(2) (rutile) and non-nano-TiO(2) on the germination and growth of naturally aged spinach seeds were studied by measuring the germination rate and the germination and vigor indexes of aged spinach seeds. An increase of these factors was observed at 0.25-4% nano-TiO(2) treatment. During the growth stage, the plant dry weight was increased, as was the chlorophyll formation, the ribulosebisphosphate carboxylase/oxygenase activity, and the photosynthetic rate. The best results were found at 2.5% nano-TiO(2). The effects of non-nano-TiO(2) are not significant. It is shown that the physiological effects are related to the nanometer-size particles, but the mechanism by which nano-TiO(2) improves the growth of spinach seeds still needs further study.

Topics: Chlorophyll; Germination; Kinetics; Particle Size; Photosynthesis; Ribulose-Bisphosphate Carboxylase; Seeds; Spinacia oleracea; Titanium

Photocatalytic inactivation of algae, Anabaena, Microcystis, and Melosira, was carried out with TiO2-coated Pyrex hollow glass beads under the illumination of UV light (370 nm wavelength). After being irradiated with UV light in the presence of the TiO2-coated Pyrex glass beads, Anabaena and Microcystis, known as typical cyanobacteria, lost their photosynthetic activity, and the string of Anabaena cells and the colonies of Microcystis cells were completely separated into individual spherical ones. In the case of Melosira, which is a typical diatom, however, somewhat lower photocatalytic inactivation efficiency was obtained, which was believed to be due to the presence of the inorganic siliceous wall surrounding the cells of Melosira. The TiO2-coated hollow glass beads could successfully be employed for the practical application in a eutrophicated river under sunlight. More than 50% of the chlorophyll-a concentration could be reduced by the action of TiO2 photocatalysis.

Topics: Catalysis; Chlorophyll; Chlorophyll A; Coloring Agents; Eutrophication; Glass; Photochemistry; Rivers; Titanium; Water Purification

Excited-state interactions between chlorophyll a (Chla) and gold nanoparticles have been studied. The emission intensity of Chla is quenched by gold nanoparticles. The dominant process for this quenching has been attributed to the process of photoinduced electron transfer from excited Chla to gold nanoparticles, although because of a small overlap between fluorescence of Chla and absorption of gold nanoparticles, the energy-transfer process cannot be ruled out. Photoinduced electron-transfer mechanism is supported by the electrochemical modulation of fluorescence of Chla. In absence of an applied bias, Chla cast on gold film, as a result of electron transfer, exhibits a very weak fluorescence. However, upon negatively charging the gold nanocore by external bias, an increase in fluorescence intensity is observed. The negatively charged gold nanoparticles create a barrier and suppress the electron-transfer process from excited Chla to gold nanoparticles, resulting in an increase in radiative process. Nanosecond laser flash experiments of Chla in the presence of gold nanoparticles and fullerene (C60) have demonstrated that Au nanoparticles, besides accepting electrons, can also mediate or shuttle electrons to another acceptor. Taking advantage of these properties of gold nanoparticles, a photoelectrochemical cell based on Chla and gold nanoparticles is constructed. A superior performance of this cell compared to that without the gold film is due to the beneficial role of gold nanoparticles in accepting and shuttling the photogenerated electrons in Chla to the collecting electrode, leading to an enhancement in charge separation efficiency.

Topics: Chlorophyll; Chlorophyll A; Electrochemistry; Electrons; Fluorescence; Gold; Lasers; Metal Nanoparticles; Photochemistry; Surface Properties; Titanium

A bio-photovoltaic conversion device based on dye-sensitised solar cell (DSSC) using the visible light sensitisation of chlorine-e6 (Chl-e6) derived from chlorophyll from Spirulina adsorbed on a nanocrystalline TiO2 film was developed. Form fluorescence spectrum of Chl-e6 adsorbed on a nanocrystalline TiO2 film, the emission of Chl-e6 was effectively quenched by TiO2 nanocrystalline indicating that the effective electron injection from the excited singlet state of Chl-e6 into the conduction band of TiO2 particles occurred. The short-circuit photocurrent density (Isc). the open-circuit photovoltage (Voc). and the fill factor (FF) of solar cell using Chl-e6 adsorbed on a nanocrystalline TiO2 film electrode were estimated to be 0.305 +/- 0.012 mA cm(-2), 426 +/- 10 mV, and 45.0%, respectively. IPCE values were reached a maximum around the wavelength of absorption maximum (7.40% at 400 nm; 1.44% at 514 nm and 2.91% at 670 nm), indicating that the DSSC using visible light sensitisation of nanocrystalline TiO2 film by Chl-e6 was developed.

Topics: Bacterial Proteins; Chlorophyll; Chlorophyllides; Crystallization; Electric Power Supplies; Electrochemistry; Electrodes; Equipment Design; Equipment Failure Analysis; Light; Nanotechnology; Photochemistry; Porphyrins; Reproducibility of Results; Sensitivity and Specificity; Spirulina; Titanium; Transducers