A new
hemofiltration system was developed to continuously capture
circulating tumor cells (CTCs) from a large volume of whole blood
using a column that was packed with antifouling zwitterionized silica
microspheres. The silica microspheres were modified with sulfobetaine
silane (SBSi) to inhibit fouling, resist clogging, and give a high
surface wettability and prolonged operation time. Packed microspheres
with different diameters formed size-controllable interstitial pores
that effectively captured CTCs by ligand-free size selection. For
optimized performance of the hemofiltration system, operational factors,
including the size of microspheres, flow rate, and cross-sectional
area of the column, were considered with respect to the removal rate
for colorectal cancer cells and the retention rate for white blood
cells and red blood cells. The captured CTCs were collected from the
column by density sedimentation. A large quantity of colorectal cancer
cells was spiked into sheep blood, and the sample was circulated for
5 h with a total operational volume of 2 L followed by collection
and culture in vitro. The results showed that the proposed hemofiltration
device selectively removed abundant CTCs from in vitro circulatory
blood. The viable cells were harvested for amplification and potential
applications for precision medicine.