Figure 1. Schematic of DNAo flexor. Above the LCST, the PNIPAM chains on both sides of the hinge become hydrophobic, causing the two arms of
origami to fold due to hydrophobic interactions. Once the temperature is lowered below the LCST, PNIPAM rehydrates thereby unfolding the origami
structure. A gold nanoparticle and fluorescent molecule are fixed on opposite ends of the plate DNAo to give optical responses to its actuation.


Figure 2. Reaction scheme, design, and characterization of the origami. a) PNIPAM–DNA staple preparation to form the DBCO-staple azide-terminated
PNIPAM strand using strain-promoted azide-alkyne cycloaddition (spAAC). b) PAGE gel of unmodified and modified DNA staples shows 100%
conversion. c) Snapshot of DNAo flexor structure from simulation (CanDo) showing PNIPAM sites (dashed circles). d) Agarose gel electrophoresis of
PNIPAM-functionalized DNAo shows 3.1 ± 0.1% reduced electrophoretic mobility over unfunctionalized DNAo.


Figure 3. Surface-enhanced fluorescence of PNIPAM-actuated DNAo. a) Interaction between Cy5 and 16 nm Au NP placed on opposite arms of the
DNA flexor. During closure, an increased emission intensity (red) is seen, which is absent when the PNIPAM or NP are omitted (blue, green, and
black). b) FDTD simulations of point dipole emitter approaching Au NP also show that emission enhancement and quantum efficiency depend also
on nanoparticle size (2R = 10–20 nm). Observed doubling of emission implies distance between NP and dye drops to 3–7 nm.


Figure 4. DLS from cycling DNA flexor between open and closed states. a) DNAo flexor without PNIPAM shows only gradual change in effective DLS
size with temperature (2 × 10-3 m MgCl2). b) DNAo flexor with PNIPAM gives clear transition above 32 °C due to PNIPAM collapse and closing of the
flexor, increasing effective size and narrowing distribution (2 × 10-3 m MgCl2). c) At 11 × 10-3 m MgCl2, repeated cycling confirms increased size in
closed state with narrower size distribution. d) At 20 × 10-3 m MgCl2, the cold state appears larger due to formation of aggregates between the origamis;
however, these aggregates are broken up at 40 °C and the closed flexor remains unchanged after multiple cycles, despite differences in the aggregated
open state (solid lines 40 °C, dashed 25 °C).