MTS Assay for 3T3-L1 Cell Viability

For the MTS assay, 2×10⁵ 3T3-L1 cells were seeded in each of the wells of a 24-well plate and fed with culture medium overnight. A porous polyester Transwell™ insert with a pore size of 0.4 µm was placed in each well of the 24-well plate. Then, tested hydrogels were placed into the Transwell™ insert. The 3T3-L1 cells were then exposed to test hydrogels or laser wavelength of 520 nm (1.0 mW), 808 nm (1.5 mW), or 980 nm (1.5 mW) for different periods of irradiation for 24, 48, or 72 h incubation. The CellTiter 96^® AQueous One solution cell proliferation assay system (Promega, Madison, WI, USA) was used to evaluate cell proliferation and observation of the optical density (OD) of formazan at 490 nm, quantified cell viability. The reagent contained a tetrazolium compound 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and inner salt (MTS), and the reduction of MTS achieved by untreated cells was set at 100%, and that of test cells was expressed as a percentage of untreated cells.14 (link)–16 (link) Data are shown as the mean ± the standard deviation for six independent experiments.