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Jeffrey R Kanofsky - One of the best experts on this subject based on the ideXlab platform.
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Singlet Oxygen generation from liposomes a comparison of time resolved 1270 nm emission with Singlet Oxygen kinetics calculated from a one dimensional model of Singlet Oxygen diffusion and quenching
Photochemistry and Photobiology, 1995Co-Authors: Jeffrey R KanofskyAbstract:Abstract— Time-resolved measurements of 1270 nm Singlet-Oxygen emission following pulsed-laser excitation were made from unilamellar dimyristoyl 1-α-phosphatidylcholine liposomes labeled with zinc phthalocyanine. The effect of the hydrophobic quenchers, β-carotene and ethyl β-apo-8′trans carotenoate, and the hydrophilic quenchers, histidine and methionine, upon the kinetics of the 1270 nm Singlet-Oxygen emission was studied. Hydrophobic quenchers principally lowered the intensity of the 1270 nm emission and caused only modest changes in the lifetime of the 1270 nm emission. The decrease in 1270 nm emission caused by hydrophobic quenchers was related to the size of the liposomes. The larger the radius of the liposome, the greater the decrease in 1270 nm emission caused by a given concentration of hydrophobic quencher. In contrast, hydrophilic quenchers principally decreased the lifetime of the 1270 nm emission. The effect of hydrophilic quenchers was independent of the size of the liposomes. There was good agreement between the experimental results and the kinetics of the Singlet-Oxygen emission calculated using a one dimensional model of Singlet-Oxygen quenching and diffusion. The kinetics of Singlet-Oxygen emission from liposomes without added hydrophobic quenchers closely approximated the theoretical kinetics of Singlet Oxygen in a homogeneous aqueous solution.
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time resolved studies of Singlet Oxygen emission from l1210 leukemia cells labeled with 5 n hexadecanoyl amino eosin a comparison with a one dimensional model of Singlet Oxygen diffusion and quenching
Photochemistry and Photobiology, 1993Co-Authors: Ayse Baker, Jeffrey R KanofskyAbstract:Time-resolved measurements were made of near-infrared emission from 5-(N-hexadecanoyl)amino-eosin-labeled L1210 leukemia cells following pulsed-laser excitation. The cells were suspended in phosphate-buffered saline made with deuterium oxide solvent. A significant fraction of the emission occurring 10-80 microseconds after the laser pulse was due to Singlet Oxygen. This Singlet-Oxygen emission is believed to result from Singlet Oxygen generated near the cell-membrane surface, where 5-(N-hexadecanoyl)amino eosin is known to concentrate, and then diffusing out into the buffer. The intensity and the kinetics of the experimentally observed Singlet-Oxygen emission were in excellent agreement with the predictions of a theoretical one-dimensional model of Singlet-Oxygen diffusion and quenching. During the 10-80 microseconds time period studied, most of the Singlet Oxygen was located in the buffer. Thus, the use of water-soluble Singlet-Oxygen quenchers, such as histidine, provide one means of separating the Singlet-Oxygen emission from other sources of light during this time interval.
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quenching of Singlet Oxygen by biomolecules from l1210 leukemia cells
Photochemistry and Photobiology, 1992Co-Authors: Ayse Baker, Jeffrey R KanofskyAbstract:Singlet Oxygen lifetimes for detergent-dispersed L1210 leukemia cells in deuterium oxide buffer were measured by following the decay of 1270 nm phosphorescence. Four photosensitizers and two detergents were studied. Stern-Volmer plots were linear over the cell concentration range studied (0-10(7) cells/mL). The Singlet-Oxygen quenching constants obtained depended somewhat upon the specific combination of detergent and photosensitizer used. Extrapolation of the Singlet-Oxygen lifetime data to "100%" cell concentration (1.39 +/- 0.04 x 10(9) cells/mL) and correction for the contribution of the water solvent gave a Singlet-Oxygen lifetime between 0.17 and 0.32 microseconds for the L1210 leukemia cell. The theoretical contributions of various types of biological molecules within the L1210 cell to the total Singlet-Oxygen quenching were calculated from their concentrations and their quenching constants. These calculations suggest that proteins will quench most of the Singlet-Oxygen. Only about 7% of the Singlet-Oxygen is quenched by water.
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direct observation of Singlet Oxygen phosphorescence at 1270 nm from l1210 leukemia cells exposed to polyporphyrin and light
Archives of Biochemistry and Biophysics, 1991Co-Authors: Ayse Baker, Jeffrey R KanofskyAbstract:Near-infrared emission (1170-1475 nm) was studied from L1210 leukemia cells incubated with polyporphyrin (fractionated hematoporphyrin derivative), suspended in deuterium oxide buffer, and then exposed to light. Following pulsed laser excitation, the near-infrared emission decayed in two phases. The first phase of the emission (0-2 microseconds) was principally due to polyporphyrin fluorescence. The second phase of the emission (20-90 microseconds) was due mainly to Singlet Oxygen. Evidence supporting the assignment of the second phase emission to Singlet Oxygen included a spectral analysis showing a peak near 1270 nm and reductions in the second phase emission caused by the Singlet Oxygen quenchers, histidine, carnosine, and water. The second phase emission decayed in a biexponential manner with lifetimes of 4.5 +/- 0.5 and 49 +/- 4 microseconds. Most of the Singlet Oxygen in the second phase emission was likely due to Singlet Oxygen that was generated near the surface of the L1210 leukemia cells and then diffused into the deuterium oxide buffer. Direct measurements of Singlet Oxygen phosphorescence at 1270 nm may prove to be a useful analytical technique for studying photochemical generation of Singlet Oxygen in cultured cells.
Peter R Ogilby - One of the best experts on this subject based on the ideXlab platform.
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aarhus sensor green a fluorescent probe for Singlet Oxygen
Journal of Organic Chemistry, 2014Co-Authors: Stephan K Pedersen, Jeppe Holmehave, Frances H Blaikie, Anita Gollmer, Thomas Breitenbach, Henrik H Jensen, Peter R OgilbyAbstract:A tetrafluoro-substituted fluorescein derivative covalently linked to a 9,10-diphenyl anthracene moiety has been synthesized, and its photophysical properties have been characterized. This compound, denoted Aarhus Sensor Green (ASG), has distinct advantages for use as a fluorescent probe for Singlet molecular Oxygen, O2(a1Δg). In the least, ASG overcomes several limitations inherent to the use of the related commercially available product called Singlet Oxygen Sensor Green (SOSG). The functional behavior of both ASG and SOSG derives from the fact that these weakly fluorescent compounds rapidly react with Singlet Oxygen via a π2 + π4 cycloaddition to irreversibly yield a highly fluorescent endoperoxide. The principal advantage of ASG over SOSG is that, at physiological pH values, both ASG and the ASG endoperoxide (ASG-EP) do not themselves photosensitize the production of Singlet Oxygen. As such, ASG better fits the requirement of being a benign probe. Although ASG readily enters a mammalian cell (i.e., He...
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Singlet Oxygen sensor green photochemical behavior in solution and in a mammalian cell
Photochemistry and Photobiology, 2011Co-Authors: Anita Gollmer, Frances H Blaikie, Thomas Breitenbach, Jacob Arnbjerg, Brian W Pedersen, Kim Daasbjerg, Marianne Glasius, Peter R OgilbyAbstract:Abstract The development of efficient and selective luminescent probes for reactive Oxygen species, particularly for Singlet molecular Oxygen, is currently of great importance. In this study, the photochemical behavior of Singlet Oxygen Sensor Green(®) (SOSG), a commercially available fluorescent probe for Singlet Oxygen, was examined. Despite published claims to the contrary, the data presented herein indicate that SOSG can, in fact, be incorporated into a living mammalian cell. However, for a number of reasons, caution must be exercised when using SOSG. First, it is shown that the immediate product of the reaction between SOSG and Singlet Oxygen is, itself, an efficient Singlet Oxygen photosensitizer. Second, SOSG appears to efficiently bind to proteins which, in turn, can influence uptake by a cell as well as behavior in the cell. As such, incorrect use of SOSG can yield misleading data on yields of photosensitized Singlet Oxygen production, and can also lead to photoOxygenation-dependent adverse effects in the system being investigated.
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Singlet Oxygen: there is indeed something new under the sun
Chemical Society reviews, 2010Co-Authors: Peter R OgilbyAbstract:Singlet Oxygen, O2(a1Δg), the lowest excited electronic state of molecular Oxygen, has been known to the scientific community for ∼80 years. It has a characteristic chemistry that sets it apart from the triplet ground state of molecular Oxygen, O2(X3Σ−g), and is important in fields that range from atmospheric chemistry and materials science to biology and medicine. For such a “mature citizen”, Singlet Oxygen nevertheless remains at the cutting-edge of modern science. In this critical review, recent work on Singlet Oxygen is summarized, focusing primarily on systems that involve light. It is clear that there is indeed still something new under the sun (243 references).
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Singlet Oxygen in a cell spatially dependent lifetimes and quenching rate constants
Journal of the American Chemical Society, 2009Co-Authors: Marina K Kuimova, Gokhan Yahioglu, Peter R OgilbyAbstract:Singlet molecular Oxygen, O(2)(a(1)Delta(g)), can be created in a single cell from ground-state Oxygen, O(2)(X(3)Sigma(g)(-)), upon focused laser irradiation of an intracellular sensitizer. This cytotoxic species can subsequently be detected by its 1270 nm phosphorescence (a(1)Delta(g) --> X(3)Sigma(g)(-)) with subcellular spatial resolution. The Singlet Oxygen lifetime determines its diffusion distance and hence the intracellular volume element in which Singlet-Oxygen-initiated perturbation of the cell occurs. In this study, the time-resolved phosphorescence of Singlet Oxygen produced by the sensitizers chlorin (Chl) and 5,10,15,20-tetrakis(N-methyl-4-pyridyl)-21H,23H-porphine (TMPyP) was monitored. These molecules localize in different domains of a living cell. The data indicate that (i) the Singlet Oxygen lifetime and (ii) the rate constant for Singlet Oxygen quenching by added NaN(3) depend on whether Chl or TMPyP was the photosensitizer. These observations likely reflect differences in the chemical and physical constituency of a given subcellular domain (e.g., spatially dependent Oxygen and NaN(3) diffusion coefficients), thereby providing evidence that Singlet Oxygen responds to the inherent heterogeneity of a cell. Thus, despite a relatively long intracellular lifetime, Singlet Oxygen does not diffuse a great distance from its site of production. This is a consequence of an apparent intracellular viscosity that is comparatively large.
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Singlet Oxygen in a cell spatially dependent lifetimes and quenching rate constants
Journal of the American Chemical Society, 2009Co-Authors: Marina K Kuimova, Gokhan Yahioglu, Peter R OgilbyAbstract:Singlet molecular Oxygen, O2(a1Δg), can be created in a single cell from ground-state Oxygen, O2(X3Σg−), upon focused laser irradiation of an intracellular sensitizer. This cytotoxic species can subsequently be detected by its 1270 nm phosphorescence (a1Δg → X3Σg−) with subcellular spatial resolution. The Singlet Oxygen lifetime determines its diffusion distance and hence the intracellular volume element in which Singlet-Oxygen-initiated perturbation of the cell occurs. In this study, the time-resolved phosphorescence of Singlet Oxygen produced by the sensitizers chlorin (Chl) and 5,10,15,20-tetrakis(N-methyl-4-pyridyl)-21H,23H-porphine (TMPyP) was monitored. These molecules localize in different domains of a living cell. The data indicate that (i) the Singlet Oxygen lifetime and (ii) the rate constant for Singlet Oxygen quenching by added NaN3 depend on whether Chl or TMPyP was the photosensitizer. These observations likely reflect differences in the chemical and physical constituency of a given subcellu...
Santi Nonell - One of the best experts on this subject based on the ideXlab platform.
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nanososg a nanostructured fluorescent probe for the detection of intracellular Singlet Oxygen
Angewandte Chemie, 2017Co-Authors: Ruben Ruizgonzalez, Santi Nonell, Roger Bresoliobach, Oscar Gulias, Montserrat Agut, Huguette Savoie, Ross W Boyle, Francesca GiuntiniAbstract:A biocompatible fluorescent nanoprobe for Singlet Oxygen (1O2) detection in biological systems was designed, synthesized, and characterized, that circumvents many of the limitations of the molecular probe Singlet Oxygen Sensor Green® (SOSG). This widely used commercial Singlet Oxygen probe was covalently linked to a polyacrylamide nanoparticle core using different architectures to optimize the response to 1O2. In contrast to its molecular counterpart, the optimum SOSG-based nanoprobe, which we call NanoSOSG, is readily internalized by E. coli cells and does not interact with bovine serum albumin. Furthermore, the spectral characteristics do not change inside cells, and the probe responds to intracellularly generated 1O2 with an increase in fluorescence.
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Singlet Oxygen photosensitisation by the fluorescent probe Singlet Oxygen sensor green
Chemical Communications, 2009Co-Authors: Xavier Ragas, Ana Jimenezbanzo, David Sanchezgarcia, Xavier Batllori, Santi NonellAbstract:The fluorescent probe Singlet Oxygen Sensor Green® is able to produce Singlet Oxygen under exposure to UV or visible radiation.
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kinetics of Singlet Oxygen photosensitization in human skin fibroblasts
Free Radical Biology and Medicine, 2008Co-Authors: Ana Jimenezbanzo, Luisa M Sagrista, Margarita Mora, Santi NonellAbstract:The roles played by Singlet Oxygen ((1)O(2)) in photodynamic therapy are not fully understood yet. In particular, the mobility of (1)O(2) within cells has been a subject of debate for the last two decades. In this work, we report on the kinetics of (1)O(2) formation, diffusion, and decay in human skin fibroblasts. (1)O(2) has been photosensitized by two water-soluble porphyrins targeting different subcellular organelles, namely the nucleus and lysosomes, respectively. By recording the time-resolved near-IR phosphorescence of (1)O(2) and that of its precursor the photosensitizer's triplet state, we find that the kinetics of Singlet Oxygen formation and decay are strongly dependent on the site of generation. (1)O(2) photosensitized in the nucleus is able to escape out of the cells while (1)O(2) photosensitized in the lysosomes is not. Despite showing a lifetime in the microsecond time domain, (1)O(2) decay is largely governed by interactions with the biomolecules within the organelle where it is produced. This observation may reconcile earlier views that Singlet Oxygen-induced photodamage is highly localized, while its lifetime is long enough to diffuse over long distances within the cells.
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Singlet Oxygen photosensitization by egfp and its chromophore hbdi
Biophysical Journal, 2008Co-Authors: Ana Jimenezbanzo, Santi Nonell, Johan Hofkens, Cristina FlorsAbstract:The photosensitization of reactive Oxygen species and, in particular, Singlet Oxygen by proteins from the green fluorescent protein (GFP) family influences important processes such as photobleaching and genetically targeted chromophore-assisted light inactivation. In this article, we report an investigation of Singlet Oxygen photoproduction by GFPs using time-resolved detection of the NIR phosphorescence of Singlet Oxygen at 1275 nm. We have detected Singlet Oxygen generated by enhanced (E)GFP, and measured a lifetime of 4 μs in deuterated solution. By comparison with the model compound of the EGFP fluorophore 4-hydroxybenzylidene-1,2-dimethylimidazoline (HBDI), our results confirm that the β-can of EGFP provides shielding of the fluorophore and reduces the production of this reactive Oxygen species. In addition, our results yield new information about the triplet state of these proteins. The quantum yield for Singlet Oxygen photosensitization by the model chromophore HBDI is 0.004.
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imaging the production of Singlet Oxygen in vivo using a new fluorescent sensor Singlet Oxygen sensor green
Journal of Experimental Botany, 2006Co-Authors: Cristina Flors, Santi Nonell, Michael J Fryer, Jen Waring, Brandon J Reeder, Ulrike Bechtold, Philip M Mullineaux, Michael T Wilson, Neil R BakerAbstract:Singlet Oxygen is known to be produced by cells in response to photo-oxidative stresses and wounding. Due to Singlet Oxygen being highly reactive, it is thought to have a very short half-life in biological systems and, consequently, it is difficult to detect. A new commercially available reagent (Singlet Oxygen sensor green, SOSG), which is highly selective for Singlet Oxygen, was applied to a range of biological systems that are known to generate Singlet Oxygen. Induction of Singlet Oxygen production by the addition of myoglobin to liposome preparations demonstrated that the Singlet Oxygen-induced increases in SOSG fluorescence closely followed the increase in the concentration of conjugated dienes, which is stoichiometrically related to Singlet Oxygen production. Applications of photo-oxidative stresses to diatom species and leaves, which are known to result in the production of Singlet Oxygen, produced large increases in SOSG fluorescence, as did the addition of 3-(3',4'-dichlorophenyl)1,1-dimethylurea (DCMU) to these systems, which inhibits electron transport in photosystem II and stimulates Singlet Oxygen production. The conditional fluorescent (flu) mutant of Arabidopsis produces Singlet Oxygen when exposed to light after a dark period, and this coincided with a large increase in SOSG fluorescence. Wounding of leaves was followed by an increase in SOSG fluorescence, even in the dark. It is concluded that SOSG is a useful in vivo probe for the detection of Singlet Oxygen.
Ayse Baker - One of the best experts on this subject based on the ideXlab platform.
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time resolved studies of Singlet Oxygen emission from l1210 leukemia cells labeled with 5 n hexadecanoyl amino eosin a comparison with a one dimensional model of Singlet Oxygen diffusion and quenching
Photochemistry and Photobiology, 1993Co-Authors: Ayse Baker, Jeffrey R KanofskyAbstract:Time-resolved measurements were made of near-infrared emission from 5-(N-hexadecanoyl)amino-eosin-labeled L1210 leukemia cells following pulsed-laser excitation. The cells were suspended in phosphate-buffered saline made with deuterium oxide solvent. A significant fraction of the emission occurring 10-80 microseconds after the laser pulse was due to Singlet Oxygen. This Singlet-Oxygen emission is believed to result from Singlet Oxygen generated near the cell-membrane surface, where 5-(N-hexadecanoyl)amino eosin is known to concentrate, and then diffusing out into the buffer. The intensity and the kinetics of the experimentally observed Singlet-Oxygen emission were in excellent agreement with the predictions of a theoretical one-dimensional model of Singlet-Oxygen diffusion and quenching. During the 10-80 microseconds time period studied, most of the Singlet Oxygen was located in the buffer. Thus, the use of water-soluble Singlet-Oxygen quenchers, such as histidine, provide one means of separating the Singlet-Oxygen emission from other sources of light during this time interval.
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quenching of Singlet Oxygen by biomolecules from l1210 leukemia cells
Photochemistry and Photobiology, 1992Co-Authors: Ayse Baker, Jeffrey R KanofskyAbstract:Singlet Oxygen lifetimes for detergent-dispersed L1210 leukemia cells in deuterium oxide buffer were measured by following the decay of 1270 nm phosphorescence. Four photosensitizers and two detergents were studied. Stern-Volmer plots were linear over the cell concentration range studied (0-10(7) cells/mL). The Singlet-Oxygen quenching constants obtained depended somewhat upon the specific combination of detergent and photosensitizer used. Extrapolation of the Singlet-Oxygen lifetime data to "100%" cell concentration (1.39 +/- 0.04 x 10(9) cells/mL) and correction for the contribution of the water solvent gave a Singlet-Oxygen lifetime between 0.17 and 0.32 microseconds for the L1210 leukemia cell. The theoretical contributions of various types of biological molecules within the L1210 cell to the total Singlet-Oxygen quenching were calculated from their concentrations and their quenching constants. These calculations suggest that proteins will quench most of the Singlet-Oxygen. Only about 7% of the Singlet-Oxygen is quenched by water.
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direct observation of Singlet Oxygen phosphorescence at 1270 nm from l1210 leukemia cells exposed to polyporphyrin and light
Archives of Biochemistry and Biophysics, 1991Co-Authors: Ayse Baker, Jeffrey R KanofskyAbstract:Near-infrared emission (1170-1475 nm) was studied from L1210 leukemia cells incubated with polyporphyrin (fractionated hematoporphyrin derivative), suspended in deuterium oxide buffer, and then exposed to light. Following pulsed laser excitation, the near-infrared emission decayed in two phases. The first phase of the emission (0-2 microseconds) was principally due to polyporphyrin fluorescence. The second phase of the emission (20-90 microseconds) was due mainly to Singlet Oxygen. Evidence supporting the assignment of the second phase emission to Singlet Oxygen included a spectral analysis showing a peak near 1270 nm and reductions in the second phase emission caused by the Singlet Oxygen quenchers, histidine, carnosine, and water. The second phase emission decayed in a biexponential manner with lifetimes of 4.5 +/- 0.5 and 49 +/- 4 microseconds. Most of the Singlet Oxygen in the second phase emission was likely due to Singlet Oxygen that was generated near the surface of the L1210 leukemia cells and then diffused into the deuterium oxide buffer. Direct measurements of Singlet Oxygen phosphorescence at 1270 nm may prove to be a useful analytical technique for studying photochemical generation of Singlet Oxygen in cultured cells.
Yi Xie - One of the best experts on this subject based on the ideXlab platform.
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ultrathin black phosphorus nanosheets for efficient Singlet Oxygen generation
Journal of the American Chemical Society, 2015Co-Authors: Hui Wang, Xianzhu Yang, Wei Shao, Shichuan Chen, Junfeng Xie, Xiaodong Zhang, Jun Wang, Yi XieAbstract:Benefiting from its strong oxidizing properties, the Singlet Oxygen has garnered serious attentions in physical, chemical, as well as biological studies. However, the photosensitizers for the generation of Singlet Oxygen bear in low quantum yields, lack of long wavelength absorption band, poor biocompatibility, undegradable in living tissues, and so on. Here we first demonstrate the exfoliated black phosphorus nanosheets to be effective photosensitizers for the generation of Singlet Oxygen with a high quantum yield of about 0.91, rendering their attractive applications in catalysis and photodynamic therapy. Through in vitro and in vivo studies, the water dispersible black phosphorus nanosheets show notable cancer therapy ability. In addition, the photodegradable character of black phosphorus from element to biocompatible phosphorus oxides further highlights its therapeutic potential against cancer. This study will not only expand the breadth of study in black phosphorus but also offer an efficient catalyst and photodynamic therapy agent.
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ultrathin black phosphorus nanosheets for efficient Singlet Oxygen generation
Journal of the American Chemical Society, 2015Co-Authors: Hui Wang, Xianzhu Yang, Wei Shao, Shichuan Chen, Junfeng Xie, Xiaodong Zhang, Jun Wang, Yi XieAbstract:Benefiting from its strong oxidizing properties, the Singlet Oxygen has garnered serious attentions in physical, chemical, as well as biological studies. However, the photosensitizers for the generation of Singlet Oxygen bear in low quantum yields, lack of long wavelength absorption band, poor biocompatibility, undegradable in living tissues, and so on. Here we first demonstrate the exfoliated black phosphorus nanosheets to be effective photosensitizers for the generation of Singlet Oxygen with a high quantum yield of about 0.91, rendering their attractive applications in catalysis and photodynamic therapy. Through in vitro and in vivo studies, the water dispersible black phosphorus nanosheets show notable cancer therapy ability. In addition, the photodegradable character of black phosphorus from element to biocompatible phosphorus oxides further highlights its therapeutic potential against cancer. This study will not only expand the breadth of study in black phosphorus but also offer an efficient catalys...
