  Chirality is a ubiquitous phenomenon in the natural world. Many biomolecules
without inversion symmetry such as amino acids and sugars are chiral molecules.
Measuring and controlling molecular chirality at a high precision down to the
atomic scale are highly desired in physics, chemistry, biology, and medicine,
however, have remained challenging. Herein, we achieve all-optical
reconfigurable chiral meta-molecules experimentally using metallic and
dielectric colloidal particles as artificial atoms or building blocks to serve
at least two purposes. One is that the on-demand meta-molecules with strongly
enhanced optical chirality are well-suited as substrates for surface-enhanced
chiroptical spectroscopy of chiral molecules and as active components in
optofluidic and nanophotonic devices. The other is that the bottom-up-assembled
colloidal meta-molecules provide microscopic models to better understand the
origin of chirality in the actual atomic and molecular systems.
  Keywords: opto-thermoelectric tweezers; optical chirality; metamolecules;
bottom-up assembly
