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1. Naphthalene‐Derived Secondary Organic Aerosols Interfacial Photosensitizing Properties

   https://doi.org/10.1029/2021GL093465  

   Wang, Xinke ; Gemayel, Rachel ; Baboomian, Vahe J. ; Li, Kangwei ; Boreave, Antoinette ; Dubois, Clement ; Tomaz, Sophie ; Perrier, Sebastien ; Nizkorodov, Sergey A. ; George, Christian ( July 2021 , Geophysical Research Letters)

   We investigated the photosensitizing properties of secondary organic aerosol (SOA) formed during the hydroxyl radical (OH) initiated oxidation of naphthalene. This SOA was injected into an aerosol flow tube and exposed to UV radiation and gaseous volatile organic compounds or sulfur dioxide (SO₂). The aerosol particles were observed to grow in size by photosensitized uptake of d‐limonene and β‐pinene. In the presence of SO₂, a photosensitized production (0.2–0.3 µg m⁻³ h⁻¹) of sulfate was observed at all relative humidity (RH) levels. Some sulfate also formed on particles in the dark, probably due to the presence of organic peroxides. The dark and photochemical pathways exhibited different trends with RH, unraveling different contributions from bulk and surface chemistry. As naphthalene and other polycyclic aromatics are important SOA precursors in the urban and suburban areas, these dark and photosensitized reactions are likely to play an important role in sulfate and SOA formation.

    

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2. Light-Activated Protoporphyrin IX-Based Polysilsesquioxane Nanoparticles Induce Ferroptosis in Melanoma Cells

   https://doi.org/10.3390/nano11092324  

   Vadarevu, Hemapriyadarshini ; Juneja, Ridhima ; Lyles, Zachary ; Vivero-Escoto, Juan L. ( September 2021 , Nanomaterials)

   The use of nanoparticle-based materials to improve the efficacy of photodynamic therapy (PDT) to treat cancer has been a burgeoning field of research in recent years. Polysilsesquioxane (PSilQ) nanoparticles with remarkable features, such as high loading of photosensitizers, biodegradability, surface tunability, and biocompatibility, have been used for the treatment of cancer in vitro and in vivo using PDT. The PSilQ platform typically shows an enhanced PDT performance following a cell death mechanism similar to the parent photosensitizer. Ferroptosis is a new cell death mechanism recently associated with PDT that has not been investigated using PSilQ nanoparticles. Herein, we synthesized a protoporphyrin IX (PpIX)-based PSilQ platform (PpIX-PSilQ NPs) to study the cell death pathways, with special focus on ferroptosis, during PDT in vitro. Our data obtained from different assays that analyzed Annexin V binding, glutathione peroxidase activity, and lipid peroxidation demonstrate that the cell death in PDT using PpIX-PSilQ NPs is regulated by apoptosis and ferroptosis. These results can provide alternative approaches in designing PDT strategies to enhance therapeutic response in conditions stymied by apoptosis resistance. 

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3. Quenching of ketone triplet excited states by atmospheric halides

   https://doi.org/10.1039/d0ea00011f  

   Gemayel, R. ; Emmelin, C. ; Perrier, S. ; Tomaz, S. ; Baboomian, V. J. ; Fishman, D. A. ; Nizkorodov, S. A. ; Dumas, S. ; George, C. ( January 2021 , Environmental Science: Atmospheres)

   null (Ed.)

   The photosensitized chemistry of three aromatic ketones (xanthone, flavone, and acetophenone) and also of secondary organic aerosol (SOA) arising from the photo-oxidation of naphthalene was investigated by means of transient absorption spectroscopy. Halide ions were selected to probe the reactivity of the generated triplet states. The quenching rate constants ranged from 10 9 M −1 s −1 with iodide ions to less than 10 5 M −1 s −1 with chloride ions. The halide-triplet state interactions produced the corresponding radical anion (X 2 ˙ − ) along with halogenated and more oxidized organic compounds as identified by liquid chromatography and mass spectrometry. Deoxygenated naphthalene SOA solutions showed strong transient absorption at 420 nm when excited at 355 nm, and were also quenched by iodide ions similar to the single compound experiments indicating that compounds in naphthalene SOA can act as photosensitizers. Combining the study of these individual and known photosensitizers with those formed in the atmosphere (in this case through the oxidation of naphthalene) demonstrates that tropospheric photosensitization may involve a large variety of compounds of primary or secondary nature and will introduce new, unconsidered chemical pathways that impact atmospheric multiphase chemistry. 

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4. A five-coordinate cobalt bis(dithiolene)–phosphine complex [Co(pdt) 2 (PTA)] (pdt = phenyldithiolene; PTA = 1,3,5-triaza-7-phosphaadamantane)

   https://doi.org/10.1107/S2056989020005447  

   Williams, DaShawn ; Brannon, Jacob P. ; Chandrasekaran, Perumalreddy ; Stieber, S. Chantal ( May 2020 , Acta Crystallographica Section E Crystallographic Communications)

   The title compound, bis(1,2-diphenyl-2-sulfanylideneethanethiolato-κ 2 S , S ′)(1,3,5-triaza-7-phosphaadamantane-κ P )cobalt(II) dichloromethane hemisolvate, [Co(pdt) 2 (PTA)]·0.5C 2 H 4 Cl 2 or [Co(C 14 H 10 S 2 ) 2 (C 6 H 12 N 3 P)]·0.5C 2 H 4 Cl 2 , contains two phenyldithiolene (pdt) ligands and a 1,3,5-triaza-7-phosphaadamantane (PTA) ligand bound to cobalt with the solvent 1,2-dichloroethane molecule located on an inversion center. The cobalt core exhibits an approximately square-pyramidal geometry with partially reduced thienyl radical monoanionic ligands. The supramolecular network is consolidated by hydrogen-bonding interactions primarily with nitrogen, sulfur and chlorine atoms, as well as parallel displaced π-stacking of the aryl rings. The UV–vis, IR, and CV data are also consistent with monoanionic dithiolene ligands and an overall Co II oxidation state. 

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5. FAP‐Targeted Photodynamic Therapy Mediated by Ferritin Nanoparticles Elicits an Immune Response against Cancer Cells and Cancer Associated Fibroblasts

   https://doi.org/10.1002/adfm.202007017  

   Zhou, Shiyi ; Zhen, Zipeng ; Paschall, Amy V. ; Xue, Lijun ; Yang, Xueyuan ; Bebin Blackwell, Anne‐Gaelle ; Cao, Zhengwei ; Zhang, Weizhong ; Wang, Mengzhe ; Teng, Yong ; et al ( November 2020 , Advanced Functional Materials)

   Cancer‐associated fibroblasts (CAFs) are present in many types of tumors and play a pivotal role in tumor progression and immunosuppression. Fibroblast‐activation protein (FAP), which is overexpressed on CAFs, has been indicated as a universal tumor target. However, FAP expression is not restricted to tumors, and systemic treatment against FAP often causes severe side effects. To solve this problem, a photodynamic therapy (PDT) approach is developed based on ZnF₁₆Pc‐loaded and FAP‐specific single chain variable fragment (scFv)‐conjugated apoferritin nanoparticles, or αFAP‐Z@FRT. αFAP‐Z@FRT PDT efficiently eradicates CAFs in tumors without inducing systemic toxicity. When tested in murine 4T1 models, the treatment elicits anti‐cancer immunity, causing suppression of both primary and distant tumors, that is, the abscopal effect. Treatment efficacy is enhanced when αFAP‐Z@FRT PDT is used in combination with anti‐PD1 antibodies. Interestingly, it is found that the PDT treatment not only elicits a cellular immunity against cancer cells, but also stimulates an anti‐CAFs immunity. This is supported by an adoptive cell transfer study, where T cells taken from 4T1‐tumor‐bearing animals treated with αFAP PDT retard the growth of A549 tumors established on nude mice. Overall, this approach is unique for permitting site‐specific eradication of CAFs and inducing a broad spectrum anti‐cancer immunity.

    

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