(638c) Sequence-Defined Polymer Brushes for Surface Nanopatterning Towards Directed Biomolecular Assemblies

Control over semiconductor/bio interfaces is a key enabler for biological nanofabrication pathways and new applications at the intersection of semiconductor technology and synthetic biology. While current efforts have largely centered around conventional surface functionalization strategies such as silane chemistries and self-assembled monolayers (SAMs), polymer brushes have emerged as versatile surface modification layers, expanding the design space to control surface properties at the nanoscale. But to a large extent, they have not yet been tailored to interface between semiconductor processing and synthetic biology.

Here we developed a class of bioinspired, sequence-defined polymers–peptoids, as designer polymer brushes, to modify surface properties and create surface contrast patterns on lithographic substrates. These peptoid brushes allow precise control over molecular weight, side-chain chemistry, and sequence on the monomer level, and are demonstrated to be compatible with both lithographic workflows and processes involving biomacromolecules. We designed and synthesized peptoids with a hydroxyl group that enables efficient melt grafting onto silicon substrates under lithographically relevant conditions. Chemical contrast patterns with length scales defined by e-beam lithography were then generated via either patterning a grafted peptoid brush monolayer, or grafting peptoid brushes to prepatterned regions. Using peptoid and other polymer brushes, we created nanoscale surface contrast patterns that display selective adsorption of biomolecular building blocks such as DNA origami, which preferentially binds to the peptoid brush grafted regions. We further show that peptoid brush affinity to DNA origami, which is much higher compared to commonly used SiO₂ surfacefor DNA origami binding, can be tuned by manipulating monomer chemistry and sequence within the peptoid chains.

This surface nanopatterning strategy with sequence-defined peptoid brushes allows fine-tuning of surface properties and surface functionalization with diverse chemical groups. Building upon this platform, we are employing peptoid brushes as a bridge material to connect between lithographically patterned surfaces and biomolecular building blocks, establishing pathways towards large-area nanopatterning integrating the accuracy of top-down lithography with the molecular precision and bio-functionality afforded by biomolecular assemblies.