Polymer-Driven Co-Assembly of Achiral and Chiral Nanoparticles into Plasmonic Nanoclusters with Quantitatively Modulated Optical Chirality.

Chiral plasmonic nanoassemblies demonstrate enhanced chiral optical activity through plasmonic mode coupling, holding transformative potential for applications in sensing, catalysis, and quantum-optical technologies. However, the mechanisms underlying this enhancement-particularly the roles of structural geometry, plasmonic coupling, and chiral field amplification-remain incompletely elucidated. A significant challenge persists in designing coupled nanoassemblies with precisely controlled nanostructures to systematically investigate chirality enhancement. Departing from conventional approaches that incorporate chiral molecules, we present the co-assembly of achiral and chiral plasmonic nanoparticles (NPs) into AB-type nanoclustersand the correlation between inherent plasmonic chirality and the quantity of hotspots. Complementary polymer-grafted achiral nanospheres and chiral nano arrows assemble into stable AB clusters through a combination of electrostatic interactions and hydrogen bonding. The coordination number (n) of AB can be tuned from 2 to 7 by adjusting polymer configurations through modulation of solution pH. The g-factor of AB exhibits a linear increase with the n value of AB. Simulation results indicate that the enhanced optical chirality arises from the increase in electric field strength due to the increasing number of hotspots within the NP assemblies.