Lab on a fabric

Abstract

This thesis presents two different methods for isolating circulating tumor cells (CTCs) with the mass-producible and low-cost polyester fabric sheets: High-throughput viable CTC isolation based on size and deformability and highly-sensitive CTC isolation based on immune-affinity binding on graphene oxide (GO) coating. CTC isolation method based on size and deformability enables the capture of heterogeneous CTCs, regardless of their surficial protein expressions. Slots with curved walls, which are naturally formed due to the cross-sectional shape of the polyester monofilaments, reduce 21.6% of stress applied to the cells when compared to the conventional slots with straight walls. As a result, 86% of cancer cells remained viable after the isolation process conducted at the flow rate of 25 mL/h. The slots with curved walls also prevent cells from clogging the filter, thus successfully releasing over 92% of the captured cancer cells. We applied our fabric sheets to 11 human blood samples obtained from 9 breast cancer patients and 2 healthy volunteers. The number of CTCs found from patients’ samples was closely related with the expression level of the proliferation marker Ki-67 in the primary tumor. However, the present method resulted in a relatively low CTC capture efficiency of 60-65%. We have enhanced the CTC capture efficiency by selective increase of cancer cell size. Hypo-osmotic cell swelling increases the size of epithelial-like and mesenchymal-like cancer cells maximum 26% and 16%, respectively, while increasing the size of leukocytes only 9% at the osmolality of 190mOsm/kg. Meanwhile, over 90% of cancer cells remained viable at the given osmolality. Consequently, capture efficiency increased by 9-12% with negligible decrease in specificity and viability. We processed 1mL of 10 human blood samples obtained from 6 colorectal cancer patients and 4 healthy volunteers, in both hypotonic and isotonic conditions. The CTC detection rate and the number of CTCs were increased in hypotonic condition compared to isotonic condition. Therefore, we have demonstrated that the present method is appropriate for the rapid and low-cost cancer diagnosis. In the immunoaffinity-based CTC isolation, we functionalized the stack of three fabric sheet layers with GO, to increase the density of anti-EpCAM antibodies. The fabric sheet layers with GO modification resulted in CTC capture efficiency of 75-80%, which was 10-25% higher compared to the fabric sheet layers without GO modification. Meanwhile, only 140 leukocytes were captured in 1mL of human blood samples. We performed the clinical study using 10 human blood samples obtained from 7 colorectal cancer patients and 3 healthy volunteers. The GO-coated fabric sheet layers successfully isolated 4-42 CTCs/mL from all cancer patients, while none of the cancerous cells were found in healthy volunteers’ samples. The GO-functionalized fabric sheet layers, capable of highly-sensitive and highly-selective CTC isolation, are feasible for clinical CTC applications. In summary, we have designed, manufactured, and characterized two different versions of CTC isolation devices made of mass-producible fabric sheets and demonstrated clinical application using human blood samples. The newly developed fabric sheets, producible by well-established and cost-effective textile manufacturing process, result in a simple and novel platform for viable CTC analysis.