The Sequence-Specific Cellular Uptake of Spherical Nucleic Acid Nanoparticle Conjugates

摘要

We investigated the sequence-dependent cellular uptake of spherical nucleic acid nanoparticle conjugates (SNAs). This process occurs by interaction with class A scavenger receptors (SR-A) and caveolae-mediated endocytosis. It is known that linear poly(guanine) (poly G) is a natural ligand for SR-A, and it has been proposed that interaction of poly G with SR-A is dependent on the formation of G-quadruplexes. Since G-rich oligonucleotides are known to interact strongly with SR-A, we hypothesized that SNAs with higher G contents would be able to enter cells in larger amounts than SNAs composed of other nucleotides, and as such we measured cellular internalization of SNAs as a function of constituent oligonucleotide sequence. Indeed, SNAs with enriched G content show the highest cellular uptake. Using this hypothesis, we chemically conjugated a small molecule (camptothecin) with SNAs to create drug-SNA conjugates and observed that poly G SNAs deliver the most camptothecin to cells and have the highest cytotoxicity in cancer cells. Our data elucidate important design considerations for enhancing the intracellular delivery of spherical nucleic acids.