Biodegradable artificial leukocyte for targeted drug delivery

Selectins are suitable biological molecules for target delivery of anti-inflammatory drugs due to their site-specific expression on endothelial cells during inflammation. A target drug delivery system using porous, biodegradable, poly-lactic-co-glycolic-acid (PLGA) microspheres coated with leukocyte functional ligand, Sialyl Lewis^x, has been developed. We attached biotinylated-Sialyl-Lewis^x to avidin-linked PLGA microspheres via carbodiiamide chemistry, and our in vitro assays showed that they display rolling adhesion to selectin-coated surfaces under hydrodynamic flow. The rolling velocity of these artificial leukocytes is similar to that displayed by leukocytes rolling on P- or E-selectin coated surfaces. We can tune rolling velocity, and hence residence time of capsules on surfaces, by changing the density of Sialyl Lewis^x on the microsphere surfaces.