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Author: Kuehne, Alexander J.C. × End date: 2019 × Publisher: Weinheim : Wiley-VCH × WGL Institute: DWI ×

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    Anti-Stokes Stress Sensing: Mechanochemical Activation of Triplet-Triplet Annihilation Photon Upconversion
    (Weinheim : Wiley-VCH, 2019) Yildiz, Deniz; Baumann, Christoph; Mikosch, Annabel; Kuehne, Alexander J.C.; Herrmann, Andreas; Göstl, Robert
    The development of methods to detect damage in macromolecular materials is of paramount importance to understand their mechanical failure and the structure–property relationships of polymers. Mechanofluorophores are useful and sensitive molecular motifs for this purpose. However, to date, tailoring of their optical properties remains challenging and correlating emission intensity to force induced material damage and the respective events on the molecular level is complicated by intrinsic limitations of fluorescence and its detection techniques. Now, this is tackled by developing the first stress-sensing motif that relies on photon upconversion. By combining the Diels–Alder adduct of a π-extended anthracene with the porphyrin-based triplet sensitizer PtOEP in polymers, triplet–triplet annihilation photon upconversion of green to blue light is mechanochemically activated in solution as well as in the solid state. © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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    Conjugated Polymer Nanoparticles toward In Vivo Theranostics – Focus on Targeting, Imaging, Therapy, and the Importance of Clearance
    (Weinheim : Wiley-VCH, 2017) Kuehne, Alexander J.C.
    Conjugated polymer nanoparticles are highly fluorescent colloids with tunable emission colors ranging from the visible deep into the near infrared spectrum. Conjugated polymer nanoparticles are easy to prepare, tunable in their size, and virtually nonbleachable. Conjugated polymer particles can also be designed to give off heat upon irradiation. All these properties make conjugated polymer particles ideal materials for biomedical fluorescence and photoacoustic imaging as well as for theranostic applications. Here, different examples of surface functionalization to attach pathological homing devices, imaging modalities, as well as the emerging possibilities for therapeutic measures are discussed. Furthermore, clearance of the particles is considered, which is important to ultimately apply the materials for in vivo theranostics. Due to the conjugated backbone of the conjugated polymers, established degradation strategies, as known from hydrophilic nonconjugated polymer carriers, cannot be applied. Bioinspired strategies and potential pathways for degradation and clearance via structural changes upon triggers such as pH, oxidation, and temperature are also discussed in this progress report. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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    Compartmentalized Jet Polymerization as a High-Resolution Process to Continuously Produce Anisometric Microgel Rods with Adjustable Size and Stiffness
    (Weinheim : Wiley-VCH, 2019) Krüger, Andreas J.D.; Bakirman, Onur; Guerzoni, Luis P.B.; Jans, Alexander; Gehlen, David B.; Rommel, Dirk; Haraszti, Tamás; Kuehne, Alexander J.C.; De Laporte, Laura
    In the past decade, anisometric rod-shaped microgels have attracted growing interest in the materials-design and tissue-engineering communities. Rod-shaped microgels exhibit outstanding potential as versatile building blocks for 3D hydrogels, where they introduce macroscopic anisometry, porosity, or functionality for structural guidance in biomaterials. Various fabrication methods have been established to produce such shape-controlled elements. However, continuous high-throughput production of rod-shaped microgels with simultaneous control over stiffness, size, and aspect ratio still presents a major challenge. A novel microfluidic setup is presented for the continuous production of rod-shaped microgels from microfluidic plug flow and jets. This system overcomes the current limitations of established production methods for rod-shaped microgels. Here, an on-chip gelation setup enables fabrication of soft microgel rods with high aspect ratios, tunable stiffness, and diameters significantly smaller than the channel diameter. This is realized by exposing jets of a microgel precursor to a high intensity light source, operated at specific pulse sequences and frequencies to induce ultra-fast photopolymerization, while a change in flow rates or pulse duration enables variation of the aspect ratio. The microgels can assemble into 3D structures and function as support for cell culture and tissue engineering. © 2019 DWI – Leibniz Institute for Interactive Materials. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim