Nanoparticle coatings for enhanced capture of flowing cells in microtubes

Recently, a flow-based selectin-dependent method for the capture and enrichment of specific types of cells (CD34+ hematopoetic stem and progenitor cells and human leukemia HL60) from peripheral blood was demonstrated. However, these devices depend on a monolayer of selectin protein, which has been shown to have a maximum binding efficiency as a function of surface area. A novel surface coating of colloidal silica nanoparticles was designed that alters the surface roughness resulting in increased surface area. The nanoparticles were adhered using either an inorganic titanate resinous coating or an organic polymer of poly-L-lysine. Using Alexa Fluor 647 conjugated P-selectin, an increase in protein adsorption of up to 35% when compared to control was observed. During perfusion experiments using P-selectin-coated microtubes, we observed increased cell capture and greatly decreased rolling velocity at equivalent protein concentration compared to nonparticle control. Atomic force microscopy showed increased surface roughness consistent with the nanoparticle mean diameter, suggesting a monolayer of particles. These results support the coating's potential to improve existing cell capture implantable devices for a variety of therapeutic and scientific uses.