Understanding the mechanisms behind crystal nucleation and growth is a
fundamental requirement for the design and production of bespoke nanomaterials with
controlled sizes and morphologies. Herein, we select gold (Au) nanoparticles as the
model system for our study due to their representative applications in biology,
electronics and optoelectronics. We investigate the radiation-induced in situ growth of
gold (Au) particles using liquid cell transmission electron microscopy (LCTEM) and
study the growth kinetics of non-spherical Au structures. Under controlled electron
fluence, liquid flow rate and Au3+ ion supply, we show the favoured diffusion-limited
growth of multi-twinned nascent Au seed particles into branched structures when using
thin liquid cells (100 nm and 250 nm) in LCTEM, whereas faceted structures (e.g.,
spheres, rods, and prisms) formed when using a 1 µm thick liquid cell. In addition, we
observed that anisotropic Au growth could be modulated by Au-binding amyloid fibrils,
which we ascribe to their capability of regulating Au3+ ion diffusion and mass transfer
in solution. We anticipate that this study will provide new perspectives on the shapecontrolled synthesis of anisotropic metallic nanomaterials using LCTEM.