Sequence-programmable semiconducting peptide assemblies with tunable bandgap

Abstract

Semiconducting biomaterials with rationally controlled electronic properties hold great promise for next-generation functional platforms, yet achieving sequence-programmable bandgaps in peptide-based systems remains a significant challenge. Here, we present a sequence-driven design strategy for selfassembling aromatic peptide assemblies in which systematic variation of three aromatic amino acids — phenylalanine (F), tryptophan (W), and tyrosine (Y) — enables systematic modulation of both bandgap and nanostructure morphology. Density functional theory (DFT) calculations reveal that aromatic residue composition governs HOMO–LUMO energy levels, yielding bandgaps spanning approximately 1.0 to 5.0 eV. Coarse-grained molecular dynamics (CG-MD) simulations, corroborated by transmission electron microscopy (TEM), demonstrate that sequence identity governs self-assembled nanostructure morphology through π–π stacking interactions, establishing a direct sequence-to-structure relationship. Beyond electronic tunability, the intrinsic fluorescence of aromatic residues provides a sequence-dependent optical readout, with emission maxima shifting systematically across aromatic compositions. This work establishes a sequence-to-property design framework for electronically active peptide materials, offering rational guidelines for tailoring bandgap and photoluminescence toward targeted biosensing and optoelectronic applications.