Publications by authors named "Avinash Chettri"
Article Synopsis
- Light-responsive polymers can be engineered for precise cargo release by utilizing light to alter their properties, leading to targeted applications.
- The study focuses on photoacid polymers, where light-induced proton transfer changes their amphiphilic behavior, influenced by their local environment and molecular design.
- By examining oxazoline-based amphiphilic polymers with pyrenol photoacid side chains, findings suggest that statistical arrangements enhance proton transfer more than block arrangements, highlighting the role of polymer structure in photophysical behavior.
Article Synopsis
- A new luminescent Ir(III) complex has been developed with a bidentate halogen bond donor site that effectively binds anions like chloride, bromide, and acetate.
- This complex shows a higher emission quantum yield of 8.4%, outperforming previous Ir(III)-based sensors which had yields around 2.5%.
- The study introduces a novel method for calculating association constants based on emission shift, supported by quantum chemical simulations, revealing strong binding capabilities with constants up to 1.6×10 M.
Article Synopsis
- * The setup demonstrates impressive efficiency, achieving turnover numbers greater than 7300 and turnover frequencies over 450 hours, which are usually seen in systems using noble metals.
- * The presence of a long-lived triplet state in the photosensitizer is confirmed, indicating potential for future optimization of both the photosensitizer and catalyst components for enhanced hydrogen evolution.
Using Biological Photophysics to Map the Excited-State Topology of Molecular Photosensitizers for Photodynamic Therapy.
Angew Chem Int Ed Engl
April 2023
Article Synopsis
- This study uses TLD1433, a Ru-based photodynamic therapy agent being tested in human trials, to create protocols for understanding how photosensitizers (PSs) behave in living cancer cells.
- It addresses the lack of knowledge about the excited-state dynamics of PSs in real biological settings and aims to analyze the light-triggered processes crucial for effective phototherapy.
- The research also applies the findings to a similar compound, TLD1633, which helps standardize methods for studying the behavior of phototoxic substances in complex biological environments.
Article Synopsis
- * While their behavior in solution is well-researched, their functionality in live cells is not as thoroughly understood.
- * This study examines the excited-state dynamics of a specific BODIPY-perylene dyad, focusing on how it senses local viscosity in living cells using advanced time-resolved techniques.
Two four-coordinate organoboron N,C-chelate complexes with different functional terminals on the PEG chains are studied with respect to their photophysical properties within human MCF-7 cells. Their excited-state properties are characterized by time-resolved pump-probe spectroscopy and fluorescence lifetime microscopy. The excited-state relaxation dynamics of the two complexes are similar when studied in DMSO.
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- * A study was conducted on TLD1433 and its derivative TLD1633 to understand their excited-state properties using biologically relevant solvents, focusing on interactions with biological macromolecules like DNA.
- * Findings indicate that binding to DNA increases the lifetime of the lowest-energy excited state, which is crucial for generating reactive oxygen species and causing cancer cell damage, highlighting the importance of studying these compounds' dynamics in biological contexts.
Article Synopsis
- Researchers have developed new block copolymer membranes that are designed for photocatalysis, incorporating light-absorbing components known as photosensitizers.
- They investigated how these photosensitizers behave within the membranes using advanced techniques to measure their movements and orientations at a very short timescale (femtoseconds).
- The results showed that the photosensitizers are strongly attached to the membrane and exhibit varied orientations based on their location, likely due to differences in chemical interactions and protonation states within the membrane.
Article Synopsis
- A study was conducted on three Ru(II) polypyridine complexes to explore their ability to selectively oxidize NAD(P)H to NAD(P) in water using photocatalysis.
- The research showed that the design of the ligands in the complexes can influence the mechanism of the oxidation process; specifically, one complex, Rudppz, was found to initiate electron transfer more effectively due to its ability to bind with the substrate.
- Rudppz not only facilitates efficient turnover by releasing the oxidized product but also enables repetitive cycles of oxidation by recognizing the redox state of the cofactor, producing H₂O as a byproduct, which could be useful for photobiocatalytic applications.
We explore the photophysical properties of a family of Ru(II) complexes, , designed as photosensitizers (PSs) for photodynamic therapy (PDT). The complexes incorporate a 1-imidazo[4,5-][1,10]-phenanthroline (ip) ligand appended to one or more thiophene rings. One of the complexes studied herein, (known as TLD1433), is currently in phase II human clinical trials for treating bladder cancer by PDT.
View Article and Find Full Text PDFUnlabelled: TLD1433 is the first Ru(II) complex to be tested as a photodynamic therapy agent in a clinical trial. In this contribution we study TLD1433 in the context of structurally-related Ru(II)-imidozo[4,5-f][1,10]phenanthroline (ip) complexes appended with thiophene rings to decipher the unique photophysical properties which are associated with increasing oligothiophene chain length. Substitution of the ip ligand with ter- or quaterthiophene changes the nature of the long-lived triplet state from metal-to-ligand charge-transfer to ππ* character.
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- Small molecules, like dyes and labels, help visualize and study processes inside cells, but their behavior under light hasn't been well researched.
- This study focuses on the excited-state dynamics of astaxanthin, a well-known molecular marker, within live human cells.
- An experimental method is introduced to analyze how this marker reacts when exposed to light on a picosecond (ps) timescale.
This contribution describes the excited-state properties of an Osmium-complex when taken up into human cells. The complex 1 [Os(bpy) (IP-4T)](PF ) with bpy=2,2'-bipyridine and IP-4T=2-{5'-[3',4'-diethyl-(2,2'-bithien-5-yl)]-3,4-diethyl-2,2'-bithiophene}imidazo[4,5-f][1,10]phenanthroline) can be discussed as a candidate for photodynamic therapy in the biological red/NIR window. The complex is taken up by MCF7 cells and localizes rather homogeneously within in the cytoplasm.
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