Sequence-Defined Polymer Brushes as Patternable Surface Modification Monolayers for Semiconductor/Bio Interfaces

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. Conventional surface functionalization methods such as silane chemistries and self-assembled monolayers (SAMs) may offer only a limited level of customization, while polymer brushes offer a wider range of chemistries and maintain compatibility with lithographic techniques. Here we developed a class of bioinspired, sequence-defined polymers–polypeptoids, as designer polymer brushes for surface modification of lithographic substrates. The polypeptoid brushes are demonstrated to be compatible with both lithographic patterning workflows and processes involving biomolecules. We designed polypeptoids with a hydroxyl group that enables efficient melt grafting onto silicon substrates to form 1–2 nm monolayers under lithographically relevant conditions. Chemical contrast patterns consisting of polypeptoid and poly(methyl methacrylate) brushes were generated with length scales defined by electron-beam lithography, which display selective adsorption of biomolecular building blocks such as DNA origami, with the polypeptoid brush grafted regions exhibiting much higher affinity to DNA origami compared to commonly used SiO₂ surfaces. We further show that the polypeptoid brush affinity to DNA origami can be tuned by manipulating monomer chemistry and sequence within the polypeptoid chains.