Abstract: OBJECTIVE To improve uptake and cytotoxicity of the drug on MCF-7 cells by developing a poly (N-isopropylacrylamide) (PNIPAm) nanogel for Quercetin (Que) METHODS The PNIPAm nanogel was optimized by an orthogonal design and its structure was confirmed by FT-IR. A single factor experiment was used to optimize the formulation of quercetin-loaded nanogel (Que-PNIPAm). The particle size， surface morphology and drug loading were characterized and the in vitro release behavior was investigated. Cytotoxicity of MCF-7 cells induced by Que-PNIPAm was investigated by CCK-8 method. The qualitative and quantitative cellular uptake studies were investigated by fluorescence microscope and flow cytometry， respectively. The mechanism of cellular uptake was investigated by the inhibitor method. RESULTS The particle size and drug loading of Que-PNIPAm were measured as (166.1±2.87)nm and 3.18%， respectively. Nanogel exhibited spherical morphology and uniform size distribution observed by electron microscopy. Compared to free Que， Que-PNIPAm significantly increased inhibition rate of MCF-7 cells. Que-PNIPAm also showed higher cell uptake efficiency and more effective antitumor activity at 42 ℃. Colchicine and 2-deoxyglucose have an inhibitory effect on MCF-7 cells uptake. CONCLUSION The prepared nanogel shows small particle size， thermosensitive property， which could significantly enhance the capacity of cellular uptake and tumor cytotoxicity. The mechanism of cellular uptake demonstrates tubulin is involved in the internalization of the nanogel into MCF-7 cells.