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    Synthesis and Self-Assembly Behavior of Double Ullazine-Based Polycyclic Aromatic Hydrocarbons
    (Stuttgart : Georg Thieme, 2021) Richter, Marcus; Borkowski, Michał; Fu, Yubin; Dmitrieva, Evgenia; Popov, Alexey A.; Ma, Ji; Marszalek, Tomasz; Pisula, Wojciech; Feng, Xinliang
    Polycyclic aromatic azomethine ylides (PAMY, 1) are versatile building blocks for the bottom-up synthesis of nitrogen-containing polycyclic aromatic hydrocarbons (N-PAHs). Although the chemistry of PAMY was already established few years ago, the cycloaddition of a double PAMY building block has not been reported so far. In this work, we demonstrate the first cycloaddition of a PAMY-dimer (6), which opens the access to three different alkyl ester-substituted N-PAHs with a laterally extended double ullazine scaffold (DU-1, DU-2 and DU-3). Interestingly, the cyclic voltammetry of DU-1-3 exhibited three reversible oxidation waves, which confirmed the electron-rich nature of the double ullazine scaffold. Furthermore, in-situ spectroelectrochemistry study of ethylhexyl ester-substituted DU-3 revealed the formation of different cationic species with new absorption bands up to 1689 nm. Additionally, the influence of the attached substituents on the film formation and supramolecular organization in the thin films were investigated by polarized optical microscopy and grazing incidence wide-angle X-ray scattering.
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    Sperm Micromotors for Cargo Delivery through Flowing Blood
    (Washington, DC : American Chemical Society, 2020) Xu, Haifeng; Medina-Sánchez, Mariana; Maitz, Manfred F.; Werner, Carsten; Schmidt, Oliver G.
    Micromotors are recognized as promising candidates for untethered micromanipulation and targeted cargo delivery in complex biological environments. However, their feasibility in the circulatory system has been limited due to the low thrust force exhibited by many of the reported synthetic micromotors, which is not sufficient to overcome the high flow and complex composition of blood. Here we present a hybrid sperm micromotor that can actively swim against flowing blood (continuous and pulsatile) and perform the function of heparin cargo delivery. In this biohybrid system, the sperm flagellum provides a high propulsion force while the synthetic microstructure serves for magnetic guidance and cargo transport. Moreover, single sperm micromotors can assemble into a train-like carrier after magnetization, allowing the transport of multiple sperm or medical cargoes to the area of interest, serving as potential anticoagulant agents to treat blood clots or other diseases in the circulatory system.
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    Medical Imaging of Microrobots: Toward In Vivo Applications
    (Washington, DC : American Chemical Society, 2020) Aziz, Azaam; Pane, Stefano; Iacovacci, Veronica; Koukourakis, Nektarios; Czarske, Jürgen; Menciassi, Arianna; Medina-Sánchez, Mariana; Schmidt, Oliver G
    Medical microrobots (MRs) have been demonstrated for a variety of non-invasive biomedical applications, such as tissue engineering, drug delivery, and assisted fertilization, among others. However, most of these demonstrations have been carried out in in vitro settings and under optical microscopy, being significantly different from the clinical practice. Thus, medical imaging techniques are required for localizing and tracking such tiny therapeutic machines when used in medical-relevant applications. This review aims at analyzing the state of the art of microrobots imaging by critically discussing the potentialities and limitations of the techniques employed in this field. Moreover, the physics and the working principle behind each analyzed imaging strategy, the spatiotemporal resolution, and the penetration depth are thoroughly discussed. The paper deals with the suitability of each imaging technique for tracking single or swarms of MRs and discusses the scenarios where contrast or imaging agent's inclusion is required, either to absorb, emit, or reflect a determined physical signal detected by an external system. Finally, the review highlights the existing challenges and perspective solutions which could be promising for future in vivo applications.