Chapter 17. Remote Singlet Oxygen Delivery Strategies

Walalawela, Niluksha; Greer, Alexander

doi:10.1039/9781782622208-00335

Cited by 3 publications

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“…[ 34 ] Unlike alkyl alcohols, phenolic compounds have high antioxidant potencies and thus are often used in tenths or single digit millimolar concentrations, such as in 5‐amino salicylic acid [ 35 ] and butylated hydroxytoluene (BHT). [ 36 ] In terms of our system for alkoxy radical photogeneration at the air/solid interface, it bears some resemblance to surface‐bound photochemical [ 37–39 ] and sensitization reactions, [ 40,41 ] and selective photooxidation chemistry, [ 42–48 ] although usually in porous media unlike our current study on nonporous nanoparticles.…”

Section: Mechanismmentioning

confidence: 99%

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

Ghosh

Greer

2020

J of Physical Organic Chem

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With interests in alkoxy radical formation on natural and artificial surfaces, a physical‐organic study was carried out with a Hammett series of triaryl phosphites (p‐MeO, H, p‐F, and p‐Cl) to trap adsorbed alkoxy radicals on silica nanoparticles. A mechanism which involves PhC (Me)2O• and EtO• trapping in a cumylethyl peroxide sensitized homolysis reaction is consistent with the results. The p‐F phosphite was able to indirectly monitor the alkoxy radical formation, and 31P NMR readily enabled this exploration, but other phosphites of the series such as the p‐MeO phosphite were limited by hydrolysis reactions catalyzed by surface silanol groups. Fluorinated silica nanoparticles helped to suppress the hydrolysis reaction although adventitious water also plays a role in hindering efficient capture of the alkoxy radicals by the phosphite traps.

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Section: Mechanismmentioning

confidence: 99%

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

Ghosh

Greer

2020

J of Physical Organic Chem

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“…Several studies have focused on the generation of airborne singlet oxygen ( 1 O ), including formation of O at air/solid surfaces. [1][2][3][4][5][6] However, the literature is lacking with respect to airborne 1 O 2 delivery without the actual contact of the 1 O 2 -generating surface with a second (distal) surface receiving 1 O 2 .…”

Section: Introductionmentioning

confidence: 99%

“…Since some sensitizer particles could be located within microns of the water droplet in this configuration, we wondered whether sensSH surfaces would be suited to deliver airborne 1 O 2 over greater distances. However, no evidence yet exists for a "contact-free" delivery of 1 O 2 between a sensSH surface and a water sample.…”

Section: Introductionmentioning

confidence: 99%

“…Reports exist on 1 O 2 gas bubbles 8 and a SH surface with tips coated with silicone in contact with water 7,9 providing for minimal contact and sensitizer-free production of 1 O 2 . However, the literature is 5 devoid of measurements for the steady-state concentration and number of airborne 1 O 2 molecules that diffuse outward from a SH surface over µm or mm distances.…”

Section: Introductionmentioning

confidence: 99%

“…The objective of the SH sandwich system developed here (Figure 2) is to determine how efficiently airborne 1 O 2 migrates as a function of distance to a distal water droplet. Our hypothesis is that airborne 1 O 2 will be detected tenths of millimeters beyond the generating surface.…”

Section: Introductionmentioning

confidence: 99%

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Superhydrophobic Surfaces as a Source of Airborne Singlet Oxygen through Free Space for Photodynamic Therapy

Aebisher

Bartusik‐Aebisher

Belh

et al. 2020

ACS Appl. Bio Mater.

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A superhydrophobic (SH) sandwich system has been developed to enable "contact-free" airborne singet oxygen ( O ) delivery to a water droplet. The contact-free feature means that the sensitizer is physically separated from the droplet, which presents opportunities for photodynamic therapy (PDT). Trapping of airborne 1 O 2 in a H 2 O droplet residing on a lower SH surface was monitored with 9,10-anthracene dipropionate dianion by varying distances to an upper 1 O 2generating surface. Short distances of 20 µm efficiently delivered airborne 1 O 2 to the droplet in single-digit picomolar steady-state concentrations. Delivery decreases linearly with distance, but 50% of the 1 O 2 steady-state concentration is trapped at a distance of 300 µm from the generating surface. The 1270 nm luminescence intensity was measured within the SH sandwich system confirming the presence of airborne 1 O 2 . Physical quenching of 1 O 2 to ground-state 3 O 2 by the water droplet itself; and both physical and chemical quenching of 1 O 2 by the water droplet containing the trap 9,10-anthracene dipropionate dianion is observed. Unlike a majority of work in the field of PDT with dissolved sensitizers, where 1 O 2 diffuses short (hundreds of nanometer) distances, we show the delivery of airborne 1 O 2 via a superhydrophobic surface is effective through-air in tenths of millimeter distances to oxidize an organic compound in water. Our results provide not only potential relevance to PDT, but also surface bacterial inactivation processes.

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Practical Aspects in the Study of Biological Photosensitization Including Reaction Mechanisms and Product Analyses: A Do's and Don'ts Guide^†

Baptista

Cadet

Greer

et al. 2023

Photochem & Photobiology

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The interaction of light with natural matter leads to a plethora of photosensitized reactions. These reactions cause the degradation of biomolecules, such as DNA, lipids, proteins, being therefore detrimental to the living organisms, or they can also be beneficial by allowing the treatment of several diseases by photomedicine. Based on the molecular mechanistic understanding of the photosensitization reactions, we propose to classify them in four processes: oxygendependent (type I and type II processes) and oxygen-independent [triplet-triplet energy transfer (TTET) and photoadduct formation]. In here, these processes are discussed by considering a wide variety of approaches including time-resolved and steady-state techniques, together with solvent, quencher, and scavenger effects. The main aim of this survey is to provide a description of general techniques and approaches that can be used to investigate photosensitization reactions of biomolecules together with basic recommendations on good practices. Illustration of the suitability of these approaches is provided by the measurement of key biomarkers of singlet oxygen and one-electron oxidation reactions in both isolated and cellular DNA. Our work is an educational review that is mostly addressed to students and beginners.

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Chapter 17. Remote Singlet Oxygen Delivery Strategies

Cited by 3 publications

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A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

Superhydrophobic Surfaces as a Source of Airborne Singlet Oxygen through Free Space for Photodynamic Therapy

Practical Aspects in the Study of Biological Photosensitization Including Reaction Mechanisms and Product Analyses: A Do's and Don'ts Guide^†

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Chapter 17. Remote Singlet Oxygen Delivery Strategies

Cited by 3 publications

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A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

A fluorinated phosphite traps alkoxy radicals photogenerated at the air/solid interface of a nanoparticle

Superhydrophobic Surfaces as a Source of Airborne Singlet Oxygen through Free Space for Photodynamic Therapy

Practical Aspects in the Study of Biological Photosensitization Including Reaction Mechanisms and Product Analyses: A Do's and Don'ts Guide†

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Practical Aspects in the Study of Biological Photosensitization Including Reaction Mechanisms and Product Analyses: A Do's and Don'ts Guide^†