Altered Cell Mechanics from the Inside: Dispersed Single Wall Carbon Nanotubes Integrate with and Restructure Actin

Abstract

With a range of desirable mechanical and optical properties, single wall carbon nanotubes (SWCNTs) are a promising material for nanobiotechnologies. SWCNTs also have potential as biomaterials for modulation of cellular structures. Previously, we showed that highly purified, dispersed SWCNTs grossly alter F-actin inside cells. F-actin plays critical roles in the maintenance of cell structure, force transduction, transport and cytokinesis. Thus, quantification of SWCNT-actin interactions ranging from molecular, sub-cellular and cellular levels with both structure and function is critical for developing SWCNT-based biotechnologies. Further, this interaction can be exploited, using SWCNTs as a unique actin-altering material. Here, we utilized molecular dynamics simulations to explore the interactions of SWCNTs with actin filaments. Fluorescence lifetime imaging microscopy confirmed that SWCNTs were located within ~5 nm of F-actin in cells but did not interact with G-actin. SWCNTs did not alter myosin II sub-cellular localization, and SWCNT treatment in cells led to significantly shorter actin filaments. Functionally, cells with internalized SWCNTs had greatly reduced cell traction force. Combined, these results demonstrate direct, specific SWCNT alteration of F-actin structures which can be exploited for SWCNT-based biotechnologies and utilized as a new method to probe fundamental actin-related cellular processes and biophysics.

Validation of an Algorithm to Quantify Changes in Actin Cytoskeletal Organization

“…Recently, an algorithmic approach was used to quantify filament length and number; however, this was validated using artificially generated filament networks. 25 In collaboration with CSIRO, we have developed an algorithm for analyzing actin cytoskeletal organization in a cell-based system using two tumor cell lines, the U2OS osteosarcoma cells and SK-N-SH neuroblastoma cells. These cell lines have been extensively studied and have a well-defined cytoskeleton, making them ideal for imaging.…”

Distribution of single wall carbon nanotubes in the Xenopus laevis embryo after microinjection

“…There have been reports in the literature by our group (Holt et al, 2010(Holt et al, , 2012c(Holt et al, , 2015Shams et al, 2014;Yaron et al, 2011) and others (Dulinska-Molak et al, 2014;Kaiser et al, 2008;Rodriguez-Fernandez et al, 2012;Sargent et al, 2012;Villegas et al, 2014;Zhang et al, 2011) that have shown high levels of cellular exposure to SWCNTs can alter subcellular components, including F-actin structures. Even though SWCNTs were present in X. laevis embryos at high local concentrations (up to~2 mg ml -1 ), there were no gross alterations to subcellular morphologies, including F-actin and endoplasmic reticulum.…”

Myosin-II mediated traction forces evoke localized Piezo1 Ca2+ flickers

“…Upon seeding, cells bind to fibronectin via cellular integrins and take up the geometry of the island. We selected the shape of our substrate islands based on previous traction force measurements in micropatterned cells [39][40][41]45 , which show that in cells constrained to a square shape, traction forces are highest at the vertices, moderately high at edges, and minimal in the middle of the cell (Fig. 3A).…”