Chemosensitization of Hey cells to docetaxel after exposure to YSA-targeted, siRNA loaded nanogels. A. Hey cells were plated onto 96-well plates (1 × 104 cells/well) and allowed to adhere overnight at 37°C and 5% CO2. The medium was removed, and the cells were washed with PBS followed by replacement of the medium. Wells were set up in triplicate to include several concentrations of YSA-targeted, siRNA-loaded nanogels (1 to 1000 μg/mL). The cells were incubated with the nanogels for four hours. The cells were washed with PBS, the medium replaced, and the cells incubated for an additional 48 hours before addition of docetaxel in order to allow reduction of EGFR expression. Docetaxel was then added, and cells were incubated with the taxane for an additional 96 hours. The percent cytotoxicity (Tox 8 assay) was assessed compared to untreated cells. B. Chemosensitization of Hey cells treated with the highest dose of YSA-targeted, siRNA-loaded nanogels (1000 μg/mL) and increasing concentrations of docetaxel are compared to controls: Unloaded YSA-conjugated nanogels (YSA-pNIPMAm), unloaded pNIPMAm nanogels (pNIPMAm), YSA peptide alone, and untreated cells. Results represent the mean of two independent experiments; error bars represent standard deviation. All cells treated with siRNA-loaded, targeted nanogels were significantly different from controls at all doses of docetaxel except where noted [see Additional file 3, Tables S1-S4].