Regulation of the Liquid–liquid Phase-Separated Droplets of Biomacromolecules by Butterfly-Shaped Gold Nanomaterials

Liquid–liquid phase-separated (LLPS) droplets play key roles in regulating protein behaviors, such as enzyme compart-mentalization, stress response, and disease pathogenesis, in living cells. The manipulation of the droplet for-mation/deformation dynamics is the next target of nano-biotechnology, although the required nanodevices for controlling the dynamics of liquid–liquid phase separation, LLPS, have not been invented. Here, we propose a butterfly-shaped gold nanobutterfly (GNB) as a nanodevice for manipulating the droplet-formation/deformation dynamics of LLPS. GNBs are moderate, symmetrical gold nanomaterials (average diameter = ~30 nm) bearing two concaves and resembling a butter-fly. Their growth process is analyzed via their time-lapse electroscopic images and time-lapse ultraviolet/visible/near-infrared (NIR) spectroscopy, as well as the application of solution additives in protein science. These nanomaterials are synthesized via the seed-mediated method with an efficiency of ~70%. Interestingly, the GNBs stabilized the LLPS droplet of adenosine triphosphate (ATP)/poly-L-lysine, whereas other two gold nanoparticles with different shapes (spherical and rod-shaped) did not, indicating that the concave of the GNBs interacts with the precursor of the droplets. The NIR-laser irradiation of the GNBs facilitates the on-demand deformation of the droplets via the localized-heat effect. This but-terfly-shaped nanodevice represents a future strategy for manipulating the dynamics of LLPS.