Preparation of Mammalian Cell and Bacterial Samples

RAW264.7 (ATCC TIB-71) cell line, Shigella sonnei (S. sonnei; ATCC 29930), Staphylococcus aureus (S. aureus; ATCC 25923), and Listeria monocytogenes (L. monocytogenes; ATCC 19117) were purchased from America Type Culture Collection (ATCC; Manassas, VA). Fetal bovine serum (FBS) and Dulbecco’s modified Eagle’s medium (DMEM) with high glucose were obtained from Thermo Fisher Scientific (South Logan, UT). CO2-independent medium (1×) was from Life Technologies (Carlsbad, CA). Penicillin-streptomycin (50×), casein (from bovine milk), Tween 20, mineral oil (molecular biology grade), and biocytin (> 98%) were from Sigma-Aldrich (St. Louis, MO). Tryptic soy broth (TSB) was from Merck (Darmstadt, Germany). 96-well culture plates (flat bottom) and 100 mm Ø culture dishes were from Corning (Tewksbury, MA). The ‘Dip and Read’ optical fiber sensor (coated with streptavidin) and Kinetics Buffer (10×) were from ForteBio (San Francisco, CA). Mouse TNF-a cytokine ELISA kit, standard mouse TNF-a recombinant protein, rabbit antibody specific to anti-mouse TNF-a (K0113001), and biotinylated rabbit antibody to anti-mouse TNF-a (K0113002) were from Koma Biotechnology (Seoul, Korea). Other reagents were of analytical grade.