Biocompatible TiO2 nanoparticle-based cell immunoassay for circulating tumor cells capture and identification from cancer patients.

We demonstrate the isolation of circulating tumor cells (CTCs) with a biocompatible nano-film composed of TiO2 nanoparticles. Due to the enhanced topographic interaction between nano-film and cancer cell surface, cancer cells (HCT116) spiked into PBS and healthy blood can be recovered from the suspension, whose efficiencies were respectively 80 % and 50 %. Benifit from the biocompatibility of this nano-film, in-situ culture of the captured cancer cells is also available, which provides an alternative selection when the capture cell number was inadequate or the sample cannot be analyzed immediately. For the proof-of-concept study, we use this nano-film to separate the circulating tumor cells from the colorectal and gastric cancer patient peripheral blood samples and the captured CTCs are identified by a three-colored immunocytochemistry method. We investigated the cancer cells capture strength at the nano-bio interface through exposing the cells to fluid shear stress in microfluidic device, which can be utilized to increase the purity of CTCs. The result indicated that 50 % of the captured cells can be detached from the substrate when the fluid shear stress was 180 dyn cm(-2). By integration of this CTCs capture nano-film with other single cell analysis device, we expected to further explore their applications in genome sequencing based on the captured CTCs.