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- ItemImproved imaging of magnetically labeled cells using rotational magnetomotive optical coherence tomography(Basel : MDPI AG, 2017) Cimalla, P.; Walther, J.; Mueller, C.; Almedawar, S.; Rellinghaus, B.; Wittig, D.; Ader, M.; Karl, M.O.; Funk, R.H.W.; Brand, M.; Koch, E.In this paper, we present a reliable and robust method for magnetomotive optical coherence tomography (MM-OCT) imaging of single cells labeled with iron oxide particles. This method employs modulated longitudinal and transverse magnetic fields to evoke alignment and rotation of anisotropic magnetic structures in the sample volume. Experimental evidence suggests that magnetic particles assemble themselves in elongated chains when exposed to a permanent magnetic field. Magnetomotion in the intracellular space was detected and visualized by means of 3D OCT as well as laser speckle reflectometry as a 2D reference imaging method. Our experiments on mesenchymal stem cells embedded in agar scaffolds show that the magnetomotive signal in rotational MM-OCT is significantly increased by a factor of ˜3 compared to previous pulsed MM-OCT, although the solenoid's power consumption was 16 times lower. Finally, we use our novel method to image ARPE-19 cells, a human retinal pigment epithelium cell line. Our results permit magnetomotive imaging with higher sensitivity and the use of low power magnetic fields or larger working distances for future three-dimensional cell tracking in target tissues and organs.
- ItemA novel patch micro electrode array for sensing ionic membrane currents(Amsterdam [u.a.] : Elsevier, 2011) Aryasomayajula, A.; Perike, S.; Hensel, R.; Posseckardt, J.; Gerlach, G.; Funk, R.H.W.Ionic membrane currents play an important role during regeneration of nerve cells, embryonic development and wound healing processes. Measuring the intracellular ion currents across the cell membrane is important in understanding the cellular functions related to the ion activities. A novel patch micro electrode array (p-MEA) for measuring the ionic membrane currents without poisoning the cells due to emitting metal ions is described in this paper. Results on biocompatibility of the device are presented. We discuss the fabrication and working principle of p-MEA.