Exosomes, which are lipid membrane-bound nanovesicles (50-150 nm in diameter), have aroused extensive attention for their potential applications in invasive molecular and stand for a new therapeutic delivery system. However, they are limited by poor targeting ability and a lack of efficient isolation techniques. Here, we present a three-dimensional nanostructured microfluidic chip, in which arrays of micropillars were functionalized with crisscrossed multiwall carbon nanotubes by chemical deposition, to capture exosomes with high efficiency through a combination of a specific recognition molecule (CD63) and the unique topography of the nanomaterials. As is proven, this nanostructured interface substantially made the immuno capturing of exosomes more efficient. A high percentage of intact vesicles <150 nm were readily purified. As a further application, we added functionality to the exosomes by a chemical editing approach for targeted drug delivery. Donor cells were labeled chemically with dual ligands (biotin and avidin) in the phospholipid membrane and encapsulated drugs in the cytosol. Though the engineered donor cells secreted exosomes, the dual ligands, together with the drugs, were inherited by the exosomes, which were then isolated with the microfluidic chip. Then, the isolated exosomes were used as drug delivery vehicles and showed strong targeting abilities to tumor cells and highly efficient receptor-mediated cellular uptake when exposed to recipient cells. Thus, the anticancer effect of chemotherapeutic drugs was improved significantly. It suggested that this platform could provide a useful tool for isolating intact exosomes with high efficiency and exploiting their natural carrier function to deliver chemotherapeutic drugs to tumor cells with increased efficacy and targeting capacity.
Keywords: drug delivery; dual ligands; exosome; microfluidic chip; scalable separation; tumor targeting.