Poly(acrylic acid)-coated MNPs (fluidMAG-PAS; 200 nm, denoted as PAA-MNPs), green fluorescent PAA-MNP (nano-screenMAG-PAS, 200 nm), and carboxymethyl-dextran-coated MNPs (fluidMAG-CMX; 200 nm, denoted as CMX-MNPs) were purchased from Chemicell (Berlin, Germany). Poly-L-lysine (PLL)-coated maghemite nanoparticles (PLL-MNPs, 79 nm) with positive and negative ζ-potentials were prepared and characterized as described previously.31 (link) Minimum essential media (MEM) and trypsin-EDTA were purchased from Gibco BRL (Grand Island, NY, USA). Penicillin/streptomycin/amphotericin B (PSA) was purchased from Upstate (Lake Placid, NY, USA). Fetal bovine serum (FBS), ammonium persulfate, potassium thiocyanate, cytochalasin D, and blebbistatin were purchased from Sigma-Aldrich (St. Louis, MO, USA). Wheat germ agglutinin (WGA), rhodamine-phalloidin, Alexa Fluor 568 goat anti-mouse secondary antibody, and 4’,6-diamidino-2-phenylindole (DAPI) were purchased from Thermo Fisher Scientific (Waltham, MA, USA). Mouse anti-vinculin antibody was purchased from Santa Cruz Biotechnology, Inc. (Dallas, TX, USA). Six-well flexible-bottomed culture plates coated with collagen I (BioFlex® plates) were purchased from Flexcell® International Corporation (Burlington, NC, USA).