Biophysical Society Thematic Meeting | Singapore

Mechanobiology of Disease

Poster Abstracts

44-POS Board 44 Optical Measurements on the Variations of Neuronal Cell Membrane Roughness in Response to External Treatments Chia-Wei Lee 1 , Huei-Jyuan Pan 1 , Lan-Ling Jang 1 , Chau-Hwang Lee 1,2,3 . 1 Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan, 2 Institute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan, 3 Department of Physics, National Taiwan University, Taipei 10617, Taiwan. Living cells exhibit many topographic features that depend heavily on membrane properties as well as cytoskeleton configurations. Membrane roughness measured by atomic force microscopy (AFM) was long proposed as a diagnostic parameter for determining the status of a cell under external physical or chemical stimulations. However, the imaging speed of AFM is far below the requirement of high-content screening. In this study, we proposed to use a wide-field optical profiling technique, non-interferometric wide-field optical profilometry (NIWOP), to quantify the membrane roughness of mouse neuroblastoma cells (N2a). The NIWOP technique can acquire membrane roughness of all cells in a field of view within a few seconds. This speed is much more adequate for obtaining statistical results in a reasonable period. We treated the N2a cells by 10 uM paclitaxel (Taxol), and found that the membrane roughness was significantly decreased. A similar trend was observed on fixed cells by using scanning electron microscopy (SEM). Membrane stiffness increased by Taxol and microtubule translocation might both take parts in this result. We also found that the membrane roughness showed transient increase under the hypertonic condition with 75 mM sucrose in the culture medium. Meanwhile, treatments of oppositely charged gold nanoparticles (AuNPs, 30 nm) were also executed. Positively charged AuNPs decreased the membrane roughness, while negatively charged AuNPs showed insignificant effects. We also confirmed that the adsorption efficiency of positively charged AuNPs on cell membranes was much higher than that of negatively charged AuNPs by using SEM. In conclusion, we demonstrated that wide-field optical profilometry could acquire the membrane roughness of a group of living cells in a few seconds. The membrane roughness reflected the variations in cytoskeleton configurations, membrane tension, as well as the membrane affinity of nanoparticles.

86