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search.filters.applied.f.access: openAccess × End date: 2019 × Start date: 2010 × Subject: HeLa cell line × Subject: human × WGL Institute: IFWD ×

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    Ultracompact three-dimensional tubular conductivity microsensors for ionic and biosensing applications
    (Washington, DC : American Chemical Society, 2014) Martinez-Cisneros, C.S.; Sanchez, S.; Xi, W.; Schmidt, O.G.
    We present ultracompact three-dimensional tubular structures integrating Au-based electrodes as impedimetric microsensors for the in-flow determination of mono- and divalent ionic species and HeLa cells. The microsensors show an improved performance of 2 orders of magnitude (limit of detection = 0.1 nM for KCl) compared to conventional planar conductivity detection systems integrated in microfluidic platforms and the capability to detect single HeLa cells in flowing phosphate buffered saline. These highly integrated conductivity tubular sensors thus open new possibilities for lab-in-a-tube devices for bioapplications such as biosensing and bioelectronics.
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    Rolled-up functionalized nanomembranes as three-dimensional cavities for single cell studies
    (Washington, DC : American Chemical Society, 2014) Xi, W.; Schmidt, C.K.; Sanchez, S.; Gracias, D.H.; Carazo-Salas, R.E.; Jackson, S.P.; Schmidt, O.G.
    We use micropatterning and strain engineering to encapsulate single living mammalian cells into transparent tubular architectures consisting of three-dimensional (3D) rolled-up nanomembranes. By using optical microscopy, we demonstrate that these structures are suitable for the scrutiny of cellular dynamics within confined 3D-microenvironments. We show that spatial confinement of mitotic mammalian cells inside tubular architectures can perturb metaphase plate formation, delay mitotic progression, and cause chromosomal instability in both a transformed and nontransformed human cell line. These findings could provide important clues into how spatial constraints dictate cellular behavior and function.
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    Carbonate-based Janus micromotors moving in ultra-light acidic environment generated by HeLa cells in situ
    (London : Nature Publishing Group, 2016) Guix, Maria; Meyer, Anne K.; Koch, Britta; Schmidt, Oliver G.
    Novel approaches to develop naturally-induced drug delivery in tumor environments in a deterministic and controlled manner have become of growing interest in recent years. Different polymeric-based microstructures and other biocompatible substances have been studied taking advantage of lactic acidosis phenomena in tumor cells, which decrease the tumor extracellular pH down to 6.8. Micromotors have recently demonstrated a high performance in living systems, revealing autonomous movement in the acidic environment of the stomach or moving inside living cells by using acoustic waves, opening the doors for implementation of such smart microengines into living entities. The need to develop biocompatible motors which are driven by natural fuel sources inherently created in biological systems has thus become of crucial importance. As a proof of principle, we here demonstrate calcium carbonate Janus particles moving in extremely light acidic environments (pH 6.5), whose motion is induced in conditioned acidic medium generated by HeLa cells in situ. Our system not only obviates the need for an external fuel, but also presents a selective activation of the micromotors which promotes their motion and consequent dissolution in presence of a quickly propagating cell source (i.e. tumor cells), therefore inspiring new micromotor configurations for potential drug delivery systems.