Use of naturally-occurring halloysite nanotubes for enhanced capture of cells from flow

The development of individualized treatments for cancer can be facilitated by more efficient methods for separating circulating tumor cells (CTC) from patient blood in such a way that they remain viable for live cell assays. We have previously shown that immobilized P-selectin protein can be used on the inner surface of a microscale flow system to induce leukemic cells and leukocytes to roll at different velocities and relative fluxes, thereby creating a means for rapid cell fractionation without inflicting cellular damage [1]. In this study a method for more efficient capture was developed. This enhancement was achieved by altering the nanoscale topography of the inner surface of selectin-coated MicroRenathane (MRE) microtubes using naturally occurring halloysite nanotubes. Immobilized nanotubes on the MRE tube surface provide enhanced capture by two means: (1) The surface area of the MRE tube inner surface is increased, allowing for more protein adsorption, and (2) the characteristic dimensions of the nanotubes allow for selectin proteins to be presented away from the surface, spanning the hydrodynamic lubrication layer that opposes cell contact with the surface. Comprehensive theoretical and experimental analyses of the nanotube coating has confirmed this, as well as show that the macroscale and microscale fluid dynamics in the MRE tube are unaltered by the coating. Consequently, halloysite nanotube coatings provide a straightforward engineering solution to an inherent fluidics obstacle, potentiating our ability to capture viable CTC for study, diagnosis, and treatment of cancer on a patient-to-patient basis.