A list of puns related to "Singlet oxygen"
Catalytic microenvironment-tailored nanoreactors (CMTNs) with a built-in ratiometric NIR-II fluorescent 1O2 sensor were fabricated for monitored chemodynamic therapy (CDT). Benefiting from the impermeability of liposomal lipid membrane to ions and glutathione (GSH), the liposome-based CMTNs afford favorable pH for MoO42−-catalyzed generation of 1O2 from H2O2 and protect MoO42− from GSH chelation-triggered inactivation.
Singlet oxygen (1O2) has a potent anticancer effect, but photosensitized generation of 1O2 is inhibited by tumor hypoxia and limited light penetration depth. Despite the potential of chemodynamic therapy (CDT) to circumvent these issues by exploration of 1O2-producing catalysts, engineering efficient CDT agents is still a formidable challenge since most catalysts require specific pH to function and become inactivated upon chelation by glutathione (GSH). Herein, we present a catalytic microenvironment-tailored nanoreactor (CMTN), constructed by encapsulating MoO42− catalyst and alkaline sodium carbonate within liposomes, which offers a favorable pH condition for MoO42−-catalyzed generation of 1O2 from H2O2 and protects MoO42− from GSH chelation owing to the impermeability of liposomal lipid membrane to ions and GSH. H2O2 and 1O2 can freely cross the liposomal membrane, allowing CMTN with a built-in NIR-II ratiometric fluorescent 1O2 sensor to achieve monitored tumor CDT.
https://ift.tt/32pG4xa
Journal of the American Chemical SocietyDOI: 10.1021/jacs.1c01626
Keita Nakane, Shinichi Sato, Tatsuya Niwa, Michihiko Tsushima, Shusuke Tomoshige, Hideki Taguchi, Minoru Ishikawa, and Hiroyuki Nakamura
https://ift.tt/3dWCT6y
Nature Chemistry, Published online: 15 March 2021; doi:10.1038/s41557-021-00643-z
Redox mediators are important for improving the rechargeability of metal–air batteries, however, how they affect singlet oxygen formation and hence parasitic chemistry is unclear, hindering strategies for their improvement. Now, the mechanism of mediated peroxide and superoxide oxidation is elucidated, explaining how redox mediators either enhance or suppress singlet oxygen formation.
https://ift.tt/3lk8H7z
New photocascades have been developed which transform simple and readily accessible substrates into three‐dimensionally complex alkaloids in one pot. Both energy transfer and electron transfer are used within the reaction sequences. The strategy is underpinned by the development of a chemical switch that is used to “switch off” one photocatalyst allowing a second photocatalyst to take over control of the multi‐photocatalyst process.
The development of photocascades that rapidly transform simple and readily accessible furan substrates into polycyclic alkaloid frameworks or erythrina natural products is described. Each of the sequences developed makes use of photocatalyzed energy transfer processes, which generate singlet oxygen, to set up the substrates for the second photocatalyzed reaction, wherein electron transfer generates carbon‐centered radicals for the cyclizations that give the final complex frameworks. A chemical switch has been developed that can “switch off” one photocatalyst; thus, allowing a second photocatalyst to take over control of the sequence. As a corollary, this strategy represents the first time it has been possible to use multiple photocatalysts in photocascades, and, as such, it expands significantly the reactions that can be included in such cascades and the order in which they can be initiated.
https://ift.tt/37RHrZB
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c13203
Luis A. Ortiz-Rodríguez, Sean J. Hoehn, Axel Loredo, Lushun Wang, Han Xiao, and Carlos E. Crespo-Hernández
https://ift.tt/3dgsVx3
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c12851
Hong-Bo Cheng, Bin Qiao, Hao Li, Jin Cao, Yuanli Luo, Kunemadihalli Mathada Kotraiah Swamy, Jing Zhao, Zhigang Wang, Jin Yong Lee, Xing-Jie Liang, and Juyoung Yoon
https://ift.tt/39t2v9c
In PMS activation 1O2 becomes the predominant reactive oxygen species mediated by single‐atom CoN2+2 sites. The weakly positive Co atoms and CoN2+2 coordination direct PMS oxidation by a non‐radical pathway with simultaneous 1O2 generation. This work is beneficial for rational regulation of 1O2 generation at the atomic level.
Single‐atom CoN4 active sites have demonstrated excellent efficiency in peroxymonosulfate activation. However, the identification of CoN4 active sites and the detailed singlet oxygen generation mechanism in peroxymonosulfate activation remains ambiguous. We demonstrate a strategy to regulate the generation of reactive oxygen species by atomically dispersed cobalt anchored on nitrogen‐doped carbon. As indicated by experiment and DFT calculations, CoN2+2 was the active site and singlet oxygen was the predominant reactive oxygen species with a proportion of 98.89 %. Spontaneous dissociation of adsorbed peroxymonosulfate on the CoN2+2 active sites was energetically unfavorable because of the weakly positive Co atoms and CoN2+2 coordination, which directed PMS oxidation by a non‐radical pathway and with simultaneous singlet oxygen generation. The generated singlet oxygen degraded several organic pollutants with high efficiency across a broad pH range.
https://ift.tt/36ZYDdi
Journal of the American Chemical SocietyDOI: 10.1021/jacs.0c10557
Ching-Wei Lin, Sergei M. Bachilo, and R. Bruce Weisman
https://ift.tt/2VCIxkx
Dr Matthew Johnathon Leonard 22-Apr-2020
Jianye Education group, Science/Geography teacher
Zhengzhou, China www.mjlphd.net
A coating with “sleeves” : The compact host–guest complexation of calixarene and oleic acid molecules prevents the oxidation of the complex monolayers at the air–water interface by the action of hydroxyl radicals and singlet oxygen.
The oxidation of antioxidants by oxidizers imposes great challenges to both living organisms and the food industry. Here we show that the host–guest complexation of the carefully designed, positively charged, amphiphilic guanidinocalix[5]arene pentadodecyl ether (GC5A‐12C) and negatively charged oleic acid (OA), a well‐known cell membrane antioxidant, prevents the oxidation of the complex monolayers at the air–water interface from two potent oxidizers hydroxyl radicals (OH) and singlet delta oxygen (SDO). OH is generated from the gas phase and attacks from the top of the monolayer, while SDO is generated inside the monolayer and attacks amphiphiles from a lateral direction. Field‐induced droplet ionization mass spectrometry results have demonstrated that the host–guest complexation achieves steric shielding and prevents both types of oxidation as a result of the tight and “sleeved in” physical arrangement, rather than the chemical reactivity, of the complexes.
https://ift.tt/34ngt8j
A fair COP: A covalent organic polymer is prepared by crosslinking the photosensitizer 4,4′,4′′,4′′′‐(porphyrin‐5,10,15,20‐tetrayl)tetraaniline (TAPP) and with 4,4′‐(anthracene‐9,10‐diyl)dibenzoic acid (ADDA). Simultaneous generation of singlet oxygen by two mechanisms is achieved, which is promising in treating hypoxic tumors.
A covalent organic polymer (COP) is prepared by crosslinking the photosensitizer 4,4′,4′′,4′′′‐(porphyrin‐5,10,15,20‐tetrayl)tetraaniline (TAPP) with 4,4′‐(anthracene‐9,10‐diyl)dibenzoic acid (ADDA) via 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide/4‐dimethylaminopyridine coupling. The COP is further modified with a hydrophilic polymer, poly(poly(ethylene glycol) methyl ether methacrylate) by grafting‐from reversible‐addition‐fragmentation chain transfer (RAFT) polymerization to enhance its solubility in various solvents. The modified COP can bind singlet oxygen through the formation of endoperoxide by ADDA upon the exposure to red light irradiation. Singlet oxygen can be then released via the photodynamic mechanism or the cycloreversion by endoperoxide when heated at 110 °C. These results open new possibilities for simultaneous generation of singlet oxygen by the photodynamic route and singlet oxygen carriers, demonstrating promise for treating hypoxic tumors.
https://ift.tt/2QCTMr8
Continuous photodynamic therapy: A 2‐pyridone‐based diblock polymer (PEG‐Py) was used to encapsulate the semiconducting, heavy‐atom‐free, photosensitizer pyrrolopyrrolidone‐tetraphenylethylene (DPPTPE). PEG‐Py can trap the 1O2 generated from DPPTPE under laser irradiation and then release 1O2 in the dark, hypoxic tumor microenvironment. As this nanoparticle can also be used for fluorescence‐guided imaging, it could be a used as a phototheranostic agent.
Continuous irradiation during photodynamic therapy (PDT) inevitably induces tumor hypoxia, thereby weakening the PDT effect. In PDT‐induced hypoxia, providing singlet oxygen from stored chemical energy may enhance the cell‐killing effect and boost the therapeutic effect. Herein, we present a phototheranostic (DPPTPE@PEG‐Py NPs) prepared by using a 2‐pyridone‐based diblock polymer (PEG‐Py) to encapsulate a semiconducting, heavy‐atom‐free pyrrolopyrrolidone‐tetraphenylethylene (DPPTPE) with high singlet‐oxygen‐generation ability both in dichloromethane and water. The PEG‐Py can trap the 1O2 generated from DPPTPE under laser irradiation and form a stable intermediate of endoperoxide, which can then release 1O2 in the dark, hypoxic tumor microenvironment. Furthermore, fluorescence‐imaging‐guided phototherapy demonstrates that this phototheranostic could completely inhibit tumor growth with the help of laser irradiation.
https://ift.tt/2NnIXaR
Could someone explain, or suggest sources, as to why singlet oxygen is not in violation of Hund's rule?
Hello everyone,
my question ist: why is it not possible for radiation alone to create singlet oxygen out of the triplet molecular oxygen? Why is there a need for a photosensitizer?
Thank you
I'm trying to detect 1O2 production in a Ru complex upon irradiation but have been having some issues. I don't have access to time resolved near IR, so I cannot do direct detection with that method. I have easy access to UV-Vis and EPR. There is a fluorometer in a different lab but the machine is unreliable. UV-vis is preferable since it's in my lab and not department equipment (like the EPR)
Here are the methods I've tried so far, both have been inconclusive
Any help/advice would be greatly appreciated!
The spin states on the hydrogen of water can either be the same as one another or opposite to one another. Also, the spin states of Oxygen in O2 are the same way
My question is, how does this effect biochemistry? If I somehow obtained a supply of pure Para- or Ortho- Water, or filled a pure Oxygen breathing environment with Singlet Oxygen instead of Triplet Oxygen, could I safely drink said water and breath said Oxygen? What if I used air with Singlet Oxygen instead of pure Singlet Oxygen?
Also, how stable are these spin states? Would my water remain in that spin state long enough to interact with it? Would my Singlet O2 remain Singlet long enough to breath? Would it interact with my body in a way that causes injury or toxicity? Would it ignite on contact with flammable things like me?
What would happen if I tried to drink pure Ortho or pure Para water? What about breathing Pure Singlet Oxygen? Why?
Does anyone know qualitatively or quantitatively where singlet oxygen (the more stable one) falls compared to other oxidants?
http://www.h2o2.com/products-and-services/us-peroxide-technologies.aspx?pid=112&name=Hydrogen-Peroxide
Where does it fall as compared to ozone, peroxide or chlorine dioxide? I know it is obviously larger than oxygen because it can react with many more organic compounds. I assume the potential is less than ozone because there is less energy per molecule.
Can anyone explain to me, why a molecule might be kinetically slow during a redox reaction? Is it due to solvent or molecule reorganization or is it due to something else? Also, can you point to literature that highlights this phenomenon? Thanks a bunch, this a helpful subreddit!
I thought you guys might enjoy reading about this substance. It seems like it could possibly be a miracle drug/antioxidant
https://en.wikipedia.org/wiki/SkQ
> SkQ is a class of mitochondria-targeted antioxidants, developed by Professor Vladimir Skulachev and his team. In a broad sense, SkQ is a lipophilic cation, linked via saturated hydrocarbon chain to an antioxidant. Due to its lipophilic properties, SkQ can effectively penetrate through various cell membranes. The positive charge provides directed transport of the whole molecule including antioxidant moiety into the negatively charged mitochondrial matrix. Substances of this type, various drugs that are based on them, as well as methods of their use are patented in Russia and other countries such as USA, EU, China, Japan, etc.[1][2][3][4] Sometimes the term SkQ is used in a narrow sense for the denomination of a cationic derivative of the plant antioxidant plastoquinone.
>History
In 1969, triphenylphosphonium (TPP, charged triphenylphosphine) was proposed for use for the first time.[5] This compound with a low molecular weight consists of a positively charged phosphorus atom and surrounded by three hydrophobic phenyls that are accumulating in mitochondria. In 1970, the use of the TPP for targeting the delivery of compounds to the mitochondrial matrix was proposed. In 1974, the TPP, as well as its derivatives and ot
... keep reading on reddit ➡I'm currently extracting alkaloids from powdered leaf with 99% ISO, I'm curious if anyone has tips to increasing the 7-Hydroxymitragynine content while in the ISO solution before evaporating the solvent off. I've read UV light increases levels somewhat, should I attempt exposing the solution to high levels of UV light before evaporating off the solvent? Any other ideas?
The bioinspired, divergent total syntheses of trichodermone and trichoderone A were accomplished from a common biogenetic precursor, aspochalasin Z. Key steps include transannular alkene cyclizations, a singlet oxygen ene reaction, and hydrogen atom transfer (HAT) cascade reactions. This approach validates the proposed biosynthetic pathway from a chemical perspective and paves the way for the synthesis and characterization of other cytochalasans.
We accomplished the divergent total syntheses of ten pentacyclic cytochalasans (aspergillin PZ, trichodermone, trichoderones, flavipesines, and flavichalasines) from a common precursor aspochalasin D and revised the structures of trichoderone B, spicochalasin A, flavichalasine C, aspergilluchalasin based on structure network analysis of the cytochalasans biosynthetic pathways and DFT calculations. The key steps of the syntheses include transannular alkene/epoxyalkene and carbonyl-ene cyclizations to establish the C/D ring of pentacyclic aspochalasans. Our bioinspired approach to these pentacyclic cytochalasans validate the proposed biosynthetic speculation from a chemical view and provide a platform for the synthesis of more than 400 valuable cytochalasans bearing different macrocycles and amino-acid residues.
https://ift.tt/2QtjVeP
Phil
Gram-scale organic semiconductor C5N2 NPs were synthesized by a one-pot bottom-up method. The all-in-one semiconductor, with a low band gap of 1.63 eV and inherent nucleus targeting and strong photooxidation capacity, could accumulate at cell nucleus, split H2O to produce O2 and also generate cytotoxia 1O2 under high-tissue-penetrable NIR irradiation, successfully achieving effective and enhanced PDT in a hypoxic tumor.
Tumor hypoxia severely limits the therapeutic effects of photodynamic therapy (PDT). Although many methods for oxygen generation exist, substantial safety concerns, spatiotenporal uncontrollability, limited efficacy, and complicated procedures have compromised their practical application. Here, we demonstrate a biocompatiable all-in-one organic semiconductor to provide a photoxidation catalysis mechanism of action. A facile method is developed to produce gram-level C5N2 nanoparticles (NPs)-based organic semiconductor. Under 650 nm laser irradiation, the semiconductor split water to generate O2 and simultaneously produce singlet oxygen (1O2), showing that the photocatalyst for O2 evolution and the photosensitizer (PS) for 1O2 generation could be synchronously achieved in one organic semiconductor. The inherent nucleus targeting capacity endows it with direct and efficient DNA photocleavage. These findings pave the way for developing organic semiconductor-based cancer therapeutic agents.
https://ift.tt/3xcy5l7
Catalytic microenvironment-tailored nanoreactors (CMTNs) with a built-in ratiometric NIR-II fluorescent 1O2 sensor were fabricated for monitored chemodynamic therapy (CDT). Benefiting from the impermeability of liposomal lipid membrane to ions and glutathione (GSH), the liposome-based CMTNs afford favorable pH for MoO42−-catalyzed generation of 1O2 from H2O2 and protect MoO42− from GSH chelation-triggered inactivation.
Singlet oxygen (1O2) has a potent anticancer effect, but photosensitized generation of 1O2 is inhibited by tumor hypoxia and limited light penetration depth. Despite the potential of chemodynamic therapy (CDT) to circumvent these issues by exploration of 1O2-producing catalysts, engineering efficient CDT agents is still a formidable challenge since most catalysts require specific pH to function and become inactivated upon chelation by glutathione (GSH). Herein, we present a catalytic microenvironment-tailored nanoreactor (CMTN), constructed by encapsulating MoO42− catalyst and alkaline sodium carbonate within liposomes, which offers a favorable pH condition for MoO42−-catalyzed generation of 1O2 from H2O2 and protects MoO42− from GSH chelation owing to the impermeability of liposomal lipid membrane to ions and GSH. H2O2 and 1O2 can freely cross the liposomal membrane, allowing CMTN with a built-in NIR-II ratiometric fluorescent 1O2 sensor to achieve monitored tumor CDT.
https://ift.tt/32pG4xa
Singlet oxygen ( 1 O 2 ) has a potent anticancer effect, but photosensitized generation of 1 O 2 is inhibited by tumor hypoxia and limited light penetration depth. Despite the potential of chemodynamic therapy (CDT) to circumvent these issues by exploration of 1 O 2 ‐producing catalysts, engineering efficient CDT agents is still a formidable challenge since most catalysts require specific pH to function and become inactivated upon chelation by glutathione (GSH). Herein, we present a catalytic microenvironment‐tailored nanoreactor (CMTN), constructed by encapsulating MoO 4 2‐ catalyst and alkaline sodium carbonate within liposomes, which offers a favorable pH condition for MoO 4 2‐ ‐catalyzed generation of 1 O 2 from H 2 O 2 and protects MoO 4 2‐ from GSH chelation due to the impermeability of liposomal lipid membrane to ions and GSH. Importantly, H 2 O 2 and 1 O 2 can freely cross liposomal membrane, allowing the CMTN with a built‐in NIR‐II ratiometric fluorescent 1 O 2 sensor to achieve monitored tumor CDT.
https://ift.tt/32pG4xa
New photocascades have been developed which transform simple and readily accessible substrates into three‐dimensionally complex alkaloids in one pot. Both energy transfer and electron transfer are used within the reaction sequences. The strategy is underpinned by the development of a chemical switch that is used to “switch off” one photocatalyst allowing a second photocatalyst to take over control of the multi‐photocatalyst process.
The development of photocascades that rapidly transform simple and readily accessible furan substrates into polycyclic alkaloid frameworks or erythrina natural products is described. Each of the sequences developed makes use of photocatalyzed energy transfer processes, which generate singlet oxygen, to set up the substrates for the second photocatalyzed reaction, wherein electron transfer generates carbon‐centered radicals for the cyclizations that give the final complex frameworks. A chemical switch has been developed that can “switch off” one photocatalyst; thus, allowing a second photocatalyst to take over control of the sequence. As a corollary, this strategy represents the first time it has been possible to use multiple photocatalysts in photocascades, and, as such, it expands significantly the reactions that can be included in such cascades and the order in which they can be initiated.
https://ift.tt/37RHrZB
Single‐atom CoN 4 active sites have demonstrated excellent efficiency in peroxymonosulfate activation. However, the identification of CoN 4 active sites and the detailed singlet oxygen generation mechanism in peroxymonosulfate activation still remain ambiguous. In this study, we demonstrated a strategy to regulate the generation of reactive oxygen species by atomically dispersed cobalt anchored on nitrogen‐doped carbon. As assisted by experimental and DFT calculations, CoN 2+2 was the definite active sites. Singlet oxygen was the absolutely predominant reactive oxygen species that the proportion was 98.89%. Different from the traditional CoN 4 configuration, the CoN 2+2 active sites transformed the pathway of peroxymonosulfate activation and facilitated the singlet oxygen generation. Spontaneous dissociation of adsorbed peroxymonosulfate on Co single atoms was prevented due to the energy barriers caused by weak positive Co atoms and CoN 2+2 coordination, determining PMS oxidation in non‐radical pathway and simultaneous singlet oxygen generation. The generated singlet oxygen showed efficient activity for degradation of several organic pollutants in a broad pH range.
https://ift.tt/36ZYDdi
The development of photocascades that rapidly transform simple and readily accessible furan substrates into polycyclic alkaloid frameworks or erythrina natural products is described. Each of the sequences developed makes use of photocatalyzed energy transfer processes, which generate singlet oxygen, to set up the substrates for the second photocatalyzed reaction, wherein electron transfer generates carbon‐centered radicals for the cyclizations that give the final complex frameworks. A chemical switch has been developed that can “switch off” one photocatalyst; thus, allowing a second photocatalyst to take over control of the sequence. As a corollary, this strategy represents the first time it has been possible to use multiple photocatalysts in photocascades, and, as such, it expands significantly the reactions that can be included in such cascades and the order in which they can be initiated.
https://ift.tt/37RHrZB
Singlet oxygen is written as O₂, but so is oxygen that is involved in respiration. What is the difference and why is Singlet oxygen toxic?
Please note that this site uses cookies to personalise content and adverts, to provide social media features, and to analyse web traffic. Click here for more information.