C-Star structures were designed using NU-PACK. Sequences are shown in Tables and of the SI. The nitrilotriacetic acid (NTA) functionalized strand was purchased from Eurogentec, and purified by the supplier using high-performance liquid chromatography (HPLC). All other oligonucleotides were purchased from Integrated DNA Technologies (IDT). Non-functionalized strands were purified by the supplier using standard desalting, while cholesterol-functionalized strands were purified by HPLC. Cy3 and Black Hole Quencher R -2 functionalized strands used for characterizing responsive C-stars (see SI) were purified by HPLC. As received dehydrated DNA was reconstituted in TE buffer (10 mM Tris, 1 mM EDTA, pH 8.0, Sigma Aldrich). All buffers were syringe-filtered through 0.22 µm pore size polyethersulfone filters (Millex) prior to use. The concentration of reconstituted DNA strands was determined by measuring absorbance at 260 nm using a ThermoScientific Nanodrop 2000 UV-Vis spectrophotometer. Extinction coefficients for all strands were provided by the supplier.