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1. Organic Near‐Infrared‐Emitting Nanoparticles for X‐Ray Bioimaging: A Nontoxic Alternative Harnessing Förster Resonance Energy Transfer‐Based Sequential Energy Transfer

   https://doi.org/10.1002/adpr.202300296  

   Jones, Haley_W ; Bandera, Yuriy ; Foulger, Isabell_K ; Luzinov, Igor ; Foulger, Stephen_H ( April 2024 , Advanced Photonics Research)

   In the efforts to generate a less toxic X‐Ray bioimaging contrast agent, a fully organic, radioluminescent nanoparticle system that emits in the near‐infrared (NIR) region when excited with an X‐Ray source is synthesized using a two‐step process. First, red‐emitting nanoparticles are fabricated by the emulsion copolymerization of styrene and propargyl acrylate with anthracene, naphthalimide, and rhodamine B methyl methacrylate derivatives. Subsequently, the nanoparticles are modified with silicon phthalocyanine and indocyanine green derivatives via a copper(I)‐catalyzed azide/alkyne cycloaddition “click” reaction. By coupling an organic scintillator with four Förster resonance energy transfer‐pairing dyes, X‐Ray‐induced, multiple, sequential energy transfer is exploited to convert ionizing radiation from an X‐Ray source into NIR light, which is optimal for biomedical imaging. Proof‐of‐concept imaging studies show that the X‐Ray‐induced indocyanine green fluorescence from the particulate system can be visualized through porcine tissue. Additionally, toxicity studies in human embryonic kidney cells indicate that the particles are nontoxic and applicablein vivo.

    

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2. Hydrogel Films Encapsulating Fully Organic Scintillating Crystalline Colloidal Arrays with Tunable Emission

   https://doi.org/10.1364/IPRSN.2021.JTu1A.34  

   Mell, Sarah ; Jones, Haley W. ; Bandera, Yuriy ; Foulger, Stephen H. ( January 2021 , OSA Advanced Photonics Congress 2021)

   Radioluminescent copolymer nanoparticles that self-assembled into a crystalline colloidal array due to electrostatic repulsion were encapsulated within hydrogels. The rejection wavelength of the gels was tuned through drying and swelling the system.

    

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3. Dynamic Emission Tuning of X‐ray Radioluminescent Crystalline Colloidal Arrays: Coupling the Optical Stop Band with Sequential Förster Resonance Energy Transfers

   https://doi.org/10.1002/adom.201801142  

   Burdette, Mary K. ; Bandera, Yuriy P. ; Gray, Gary M. ; Foulger, Stephen H. ( November 2018 , Advanced Optical Materials)

   X‐ray radiation exhibits diminished scattering and a greater penetration depth in tissue relative to the visible spectrum and has spawned new medical imaging techniques that exploit X‐ray luminescence of nanoparticles. The majority of the nanoparticles finding applications in this field incorporate metals with high atomic numbers and pose potential toxicity effects. Here, a general strategy for the preparation of a fully organic X‐ray radioluminescent colloidal platform that can be tailored to emit anywhere in the visible spectrum through a judicious choice in donor/acceptor pairing and multiple sequential Förster resonance energy transfers (FRETs) is presented. This is demonstrated with three different types of ≈100 nm particles that are doped with anthracene as the scintillating molecule to “pump” subsequent FRET dye pairs that result in emissions from ≈400 nm out past 700 nm. The particles can be self‐assembled in crystalline colloidal arrays, and the radioluminescence of the particles can be dynamically tuned by coupling the observed rejection wavelength with the dyes' emission.

    

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4. Enhanced radioluminescence of yttrium pyrosilicate nanoparticles via rare earth multiplex doping

   https://doi.org/10.1039/d2nr02417a  

   Zhang, Eric ; Bandera, Yuriy ; Dickey, Ashley ; Kolis, Joseph W. ; Foulger, Stephen H. ( August 2022 , Nanoscale)

   A series of multi-doped yttrium pyrosilicate (YPS) nanoparticles were synthesized using a high temperature multi-composite reactor, and used to explore the radioluminescent properties that have potential for biological applications. The luminescent activators explored in this work were cerium, terbium, and europium. A series of mono-doped YPS nanoparticles were synthesized that have optical and X-ray luminescent properties that span the entire visible spectrum. Energy transfer experiments were investiagted to increase the photo- and X-ray luminescence of terbium and europium. Cerium was used as a sensitizer for terbium where X-ray luminescence was enhanced. Similar results were also obtained using cerium as a sensitizer and terbium as an energy bridge for europium. By leveraging different energy transfer mechanisms X-ray luminescence can be enhanced for YPS nanoparticles. 

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5. The effect of residual palladium on the performance of organic electrochemical transistors

   https://doi.org/10.1038/s41467-022-35573-y  

   Griggs, Sophie ; Marks, Adam ; Meli, Dilara ; Rebetez, Gonzague ; Bardagot, Olivier ; Paulsen, Bryan D. ; Chen, Hu ; Weaver, Karrie ; Nugraha, Mohamad I. ; Schafer, Emily A. ; et al ( December 2022 , Nature Communications)

   Abstract Organic electrochemical transistors are a promising technology for bioelectronic devices, with applications in neuromorphic computing and healthcare. The active component enabling an organic electrochemical transistor is the organic mixed ionic-electronic conductor whose optimization is critical for realizing high-performing devices. In this study, the influence of purity and molecular weight is examined for a p-type polythiophene and an n-type naphthalene diimide-based polymer in improving the performance and safety of organic electrochemical transistors. Our preparative GPC purification reduced the Pd content in the polymers and improved their organic electrochemical transistor mobility by ~60% and 80% for the p- and n-type materials, respectively. These findings demonstrate the paramount importance of removing residual Pd, which was concluded to be more critical than optimization of a polymer’s molecular weight, to improve organic electrochemical transistor performance and that there is readily available improvement in performance and stability of many of the reported organic mixed ionic-electronic conductors. 

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