Fig. 7: Directional motions of DNA liquid condensates (composed of Y_2x4) with localized UV–Vis photoswitching.

a–c, Push-swimming at low switching frequencies. a Illustration of the motion driven by the switched irradiation localized within a region of interest (ROI). The condensate is pushed forward by a UV-spread DNA microflow, which was directed backward while unfurling from the aft end and reversed forward upon switching to Vis. A displacement between two consecutive switching moments, t_i and \({t}_{i-1}\), is represented as Δr_i. Advances of the condensate interface for 11 successive operations, lasting up to completely crumbling, are plotted in (b) a two-dimensional (2D) map. A time-evolving displacement \(\left(\Delta x,\Delta y\right)={\sum }_{i}\Delta {{{{\boldsymbol{r}}}}}_{i}\). For clarity, several of them are rotated around the start point (0, 0). Markers are colored according to a yellow-to-orange color bar that represents an elapsed time normalized by their time durations. c Time-sequential images of push-swimming in the first operation (#1) captured at four consecutive UV–Vis alterations. d–f Pull-swimming at intermediate switching frequencies. d Illustration of pull-swimming. By quickly switching to Vis before the UV-discharged DNA diffuses away, the reversed flow can pull the condensate toward the ROI over a finite distance. In (e) a 2D plot of the advances of the condensate interface observed in 10 successive operations, a cyan-to-purple color bar (left) corresponds to the normalized elapsed time for pull-swimming. f Time-sequential images of pull-swimming in the third operation (#3) captured when a condensate opened (UV) and closed (Vis) its fore end, with multiple UV–Vis switching intervals. g Scatter plot of maximum net displacements \({L}_{\max }\) for a range of the switching frequencies f. A net displacement \(L\left(t\right)\) is obtained through \(L\left(t\right)=|{\sum }_{i}\Delta {{{{\boldsymbol{r}}}}}_{i}|\). Time evolutions of the data points in the shaded range \(L(t)\) are further plotted in (h). Cargo transport using i push- and j pull-swimming of liquid condensates comprising cross-linked motif Y_2x4/L’₀/Y₀ (Supplementary Table 18). Blue triangles point to Y₀ gel-state condensates serving as cargo. (c, i, j) Yellow triangles point to immobile nearby DNA liquid condensates as reference objects. Irradiation intensities: (UV, 360–370 nm) 3.3 mW cm^–2, (Vis, 460–495 nm) 7.0 mW cm^–2. Temperatures: (b, e) 36.2°C; (i) 41.5°C; (j) 36.8°C. Scale bars: (c, f, j) 50 µm; (i) 20 µm. Source data are provided as Source Data files.