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1. Hydropersulfides (RSSH) and Nitric Oxide (NO) Signaling: Possible Effects on S-Nitrosothiols (RS-NO)

   https://doi.org/10.3390/antiox11010169  

   Fukuto, Jon M.; Perez-Ternero, Cristina; Zarenkiewicz, Jessica; Lin, Joseph; Hobbs, Adrian J.; Toscano, John P. (January 2022, Antioxidants)

   S-Nitrosothiol (RS-NO) formation in proteins and peptides have been implicated as factors in the etiology of many diseases and as possible regulators of thiol protein function. They have also been proposed as possible storage forms of nitric oxide (NO). However, despite their proposed functions/roles, there appears to be little consensus regarding the physiological mechanisms of RS-NO formation and degradation. Hydropersulfides (RSSH) have recently been discovered as endogenously generated species with unique reactivity. One important reaction of RSSH is with RS-NO, which leads to the degradation of RS-NO as well as the release of NO. Thus, it can be speculated that RSSH can be a factor in the regulation of steady-state RS-NO levels, and therefore may be important in RS-NO (patho)physiology. Moreover, RSSH-mediated NO release from RS-NO may be a possible mechanism allowing RS-NO to serve as a storage form of NO. 

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2. Harnessing Plasma Technology in Cream Formulations for Medical Applications as a Nitric Oxide Donor: Proof-of-Concept

   https://doi.org/10.1615/PlasmaMed.2023049741  

   Hadaya, Maher; Blackbay, Alexander; He, Jinjie; Rabinovich, Alexander; Sales, Christopher; Fridman, Alexander A. (January 2023, Plasma Medicine)

   Plasma's role in healthcare has been steadily gaining recognition, particularly for its capacity to produce reactive species that foster wound healing, combat microbial infections, and augment drug delivery. Despite its promise, implementation of plasma technologies is often impeded by logistical constraints, accessibility issues, and challenges integrating with established medical treatments. In this paper, we describe an innovative solution to deliver the benefits of plasma in healthcare: plasma-activated cream (PAC). PAC offers a versatile lipid-based platform for medical applications that transcends the traditional boundaries of plasma application by its flexible integration into a variety of treatment forms: as a cream base for transdermal applications, oil base for injectables, or incorporation with other biologics and lipid-soluble compounds. In this study, we reveal the novel method of creating PAC by infusing a lipophilic base with plasma-activated species, specifically focusing on nitric oxide (NO) and its related compounds (NOx). By measuring NOx concentrations before and after plasma treatment, we successfully validated the use of gliding-arc plasma to synthesize PAC. The NOx concentration rose from a baseline of 0 mg/L to an average of 2.0 mg/L post-treatment, indicative of successful infusion of plasma-activated species into PAC. This preliminary experiment unveils a novel pathway for incorporating plasma's beneficial effects into a lipid-based cream and shows the potential for PAC to act as NO storage. PAC not only brings forth new possibilities in wound-healing and antimicrobial treatments but also lays the groundwork for further exploration of plasma's role in enhancing drug delivery and NO storage. 

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3. Single-Step Synthesis Process for High-Entropy Transition Metal Boride Powders Using Microwave Plasma

   https://doi.org/10.3390/ceramics4020020  

   Storr, Bria; Kodali, Deepa; Chakrabarty, Kallol; Baker, Paul A.; Rangari, Vijaya; Catledge, Shane A. (June 2021, Ceramics)

   null (Ed.)

   A novel approach is demonstrated for the synthesis of the high entropy transition metal boride (Ta, Mo, Hf, Zr, Ti)B2 using a single heating step enabled by microwave-induced plasma. The argon-rich plasma allows rapid boro-carbothermal reduction of a consolidated powder mixture containing the five metal oxides, blended with graphite and boron carbide (B4C) as reducing agents. For plasma exposure as low as 1800 °C for 1 h, a single-phase hexagonal AlB2-type structure forms, with an average particle size of 165 nm and with uniform distribution of the five metal cations in the microstructure. In contrast to primarily convection-based (e.g., vacuum furnace) methods that typically require a thermal reduction step followed by conversion to the single high-entropy phase at elevated temperature, the microwave approach enables rapid heating rates and reduced processing time in a single heating step. The high-entropy phase purity improves significantly with the increasing of the ball milling time of the oxide precursors from two to eight hours. However, further improvement in phase purity was not observed as a result of increasing the microwave processing temperature from 1800 to 2000 °C (for fixed ball milling time). The benefits of microwave plasma heating, in terms of allowing the combination of boro-carbothermal reduction and high entropy single-phase formation in a single heating step, are expected to accelerate progress in the field of high entropy ceramic materials. 

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4. Two‐step Two‐intermediate Photorelease Bolm‐McCulla Reaction: Dual Release of Nitrene and Atomic Oxygen Reactive Intermediates

   https://doi.org/10.1111/php.13485  

   Rashid, Mahir; Baker, Devora D.; Greer, Alexander (July 2021, Photochemistry and Photobiology)

   Abstract This article is a highlight of the paper by Isor et al. in this issue ofPhotochemistry and Photobiology. It describes the photolysis of a dibenzothiophene sulfoximine (bearingN‐phenyl imino andS‐oxide groups) to produce two reactive intermediates in tandem. The sulfoximine undergoes a S–N and S–O photocleavage to release phenyl nitrene and atomic oxygen [O(³P)]. The phenyl nitrene dimerizes to azobenzene or is trapped by diethylamine to reach an azepine. From there, atomic oxygen arises in a secondary photolysis of dibenzothiophene sulfoxide. A computational analysis also reveals that the S–N bond is labile for initial nitrene release, with the secondary release of atomic oxygen by S–O cleavage. Whether future sulfoximine scaffolds can produce the reverse order release of O(³P) then nitrene, or release both simultaneously, is yet to be established. Nonetheless, molecules with dual‐intermediate release, such as coupled photoaffinity labeling and cellular oxidation, are worth pursuing. 

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5. Photoinduced Nitric Oxide Exchange in the Diazeniumdiolate Siderophore, Pandorachelin

   https://doi.org/10.1021/acschembio.5c00484  

   Susman, Melanie; Makris, Christina; Butler, Alison (September 2025, ACS Chemical Biology)

   C-diazeniumdiolate siderophores are a small class of photoactive bacterial Fe(III) chelators. Driven by genome mining, we discovered a new C-type diazeniumdiolate siderophore, pandorachelin, produced by the rhizospheric bacterium, Pandoraea norimbergensis DSM 11628. The biosynthetic gene cluster encoding the production of pandorachelin is conserved across several Pandoraea species. Pandoraea spp. are environmentally widespread and are increasingly prevalent clinical pathogens, spurring new interest in their metabolites. UV irradiation photolytically cleaves the N–N bonds within the diazeniumdiolate-containing graminine constituents of pandorachelin. With EPR spin trapping, we directly detect nitric oxide released from the two C-diazeniumdiolate ligands of pandorachelin upon UV irradiation. Additionally, we show that nitric oxide can react with the intermediates during the photoreaction to re-construct the diazeniumdiolate groups via exchange of the distal NO, and thereby recover Fe(III)-binding capacity. The photochemistry of this class of siderophores points to a broader biological role, both in their propensity to release the biological signaling molecule, nitric oxide, and in their ability to undergo photoinduced NO exchange. 

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