Nanotechnology is becoming increasingly important for products used in our daily lives, such as the masses of titanium dioxide nanoparticle agglomerates (TiO2 NPs) used in the pharmaceutical industry, for cosmetic products, or for pigments. Meanwhile, a serious lack of detailed information concerning the interaction between the nanomaterials and cells limits their biological and medical applications. Sensing technology is very important for understanding these interactions. We have shown that TiO2 NPs induce heat shock protein 70B' (HSP70B') mRNA [Okuda-Shimazaki et al., 2010. Int J Mol Sci 11:2383–2392]. In the current work, sensor cells for detection of cellular responses to NPs were prepared by transfecting an HSP70B' promoter–reporter plasmid. First, to find suitable cells for detection, five different mammalian cell lines were chosen as potential sensor cells. The results showed TiO2 NP response in some cell lines, although different sensor cells had different TiO2 NP response levels, as heat shock response ability is important for the detection. Then, we studied the TiO2 NP time-course response and dose response. The results indicated that our sensor cells can detect TiO2 NP cellular responses. Our work should aid in understanding the interactions between bio-nanomaterials and cells. Biotechnol. Bioeng. 2012; 109: 3112–3118. © 2012 Wiley Periodicals, Inc.