Adsorption of colloidal particles from a bulk solution onto a perfectly planar substrate has been extensively exploited as a way to obtain ordered two-dimensional (2D) phases, called 2D colloidal crystals (2DCC). Even if these crystals have plenty of applications in the fields of biology, biomedicine and materials science, many questions still remain regarding the dynamics of their formation, such as how monomer-monomer interactions affect the assembly dynamics and the final assembled structure.

To gain insights on the fundamental assembly mechanisms, we engineered blunt-end trimeric DNA macromolecules that are able to form extensive semi-crystalline surface networks through pi-pi stacking of terminal bases upon adsorption on a mica surface. We are able to track the early stages of nucleation and growth of these trimeric DNA macromolecules through images obtained by high-speed atomic force microscopy (HS-AFM) to derive the fundamental mechanisms behind the nucleation, growth and error-correction kinetics in 2DCCs.

Using the unique programmability provided by DNA-nanotechnology, we show we can tune the monomer-monomer interactions by modifying the end-group affinity and the flexibility of the particles and relate the molecular monomer design to changes in network formation. We then combined our observations with Monte Carlo simulations of trimeric patchy particles to further estimate the range of physical energies involved in the experiments. Our findings contribute to the understanding of the fundamental mechanisms behind the formation of 2DCC and provide insights on the design of molecular building blocks in bottom-up nanotechnology.