Non-Uniform Electric Field Manipulation of Chromogenic Peptide Amphiphile Assemblies

This work investigates the influence of dielectrophoretic forces on the structural features and the resulting aggregates of a chromogenic model system, peptide-diacetylene (D₃GV-DA) amphiphiles. Here, we systematically investigate how non-uniform electric fields impact the (i) peptide-directed supramolecular assembly stage and (ii) topochemical photopolymerization stage of polydiacetylenes (PDAs) in a quadrupole-based dielectrophoresis (DEP) device, as well as the (iii) manipulation of D₃GV-DA aggregates in a light-induced DEP (LiDEP) platform. The conformation-dependent chromatic phases of peptide-PDAs are utilized to probe the chain-level effect of DEP exposure after the supramolecular assembly or after the topochemical photopolymerization stage. Steady-state spectroscopic and microscopy analyses show that structural features such as the chirality and morphologies of peptidic 1-D nanostructures are mostly conserved upon DEP exposure, but applying mild, non-uniform fields at the self-assembly stage is sufficient for fine-tuning the chromatic phase ratio in peptide-PDAs and manipulating their aggregates via LiDEP. Overall, this work provides insights into how non-uniform electric fields offer a controllable approach to fine-tune or preserve the molecularly preset assembly order of DEP-responsive supramolecular or biopolymeric assemblies, as well as manipulate their aggregates using light projections, which have future implications for the precision fabrication of macromolecular systems with hierarchical structure-dependent function.