Yinglun Ma, Jennifer Delgado, Cuizheng Zhang, Taokun Luo, Y Y Kim, Kathleen Ngo, Hanwen Zhang, Chad A. Mirkin
Spherical nucleic acids (SNAs) are examples of how nucleic acid structures can impact important biological functions. Herein, we explore how well-defined DNA nanostructures assembled on the surface of preformed SNAs can influence important processes like cellular uptake. Three different DNA nanostructures, which vary in clustering and/or topology, were studied with three different cell lines (NIH-3T3, HaCaT, RAW 264.7). All three structures exhibited higher cellular uptake than conventional SNAs, with one structure (TX motif SNA) exhibiting a 5-fold increase after 4 h of incubation. Increased DNA clustering and DNA crossover numbers correlate with enhanced Ca 2+ binding and, ultimately, higher uptake primarily through clathrin- and macropinocytosis-mediated pathways (caveolae-mediated pathways have been observed with traditional ssSNAs). Ca 2+ content within SNA structures facilitates uptake by making the structure less negatively charged and increasing interactions with Ca 2+ -binding proteins. This work shows how structural manipulation of the SNA shell can control and optimize its biological function.