Efficient Capture of Circulating Tumor Cells Using Patterned ZnO Nanorod Arrays

This paper is to demonstrate an efficient cell capture assay based on employing patterned highly vertical zinc oxide (ZnO) nanorods. Hydrophilic properties of ZnO nanorods, as well as nano topographic nature of the outer surface of cells were exploited as separation mechanism. MCF-7 and MDA-MB-231 breast cancer cell lines were captured on the patterned or not patterned ZnO nanorods. For these substrates, significantly improved capture efficiency was achieved by patterning the nanorods surfaces. The capture efficiency of MCF-7 cell species increased from 0 to over 84 % through the conversion of flat substrates to patterned nanorods surfaces. Additionally, efficiency promotion was observed by increasing the incubation time from 1 hour to 4 hours for the MCF-7 cells, resulting in maximum capture efficiency of 98.4% in the case of patterned nanorods. However, MDA-MB-231 cancer cells, as invasive late-stage cell species, were expectantly found to show lower efficiencies, maximum of 86%. Intensively and strongly adhered breast cancer cells to nanorods with formed lamellipodia have been reported for proposed ZnO nanostructured substrates. Interestingly, both types of breast cell species depicted different cell areas, offering various focal adhesions. This allows for selective separation of not only the breast cancer cells from the normal blood species but also these two cell types while retaining viability.