(261a) Design and Engineering of Biohybrid Materials for Organic Electronics: From Supramolecular Assembly to Single Molecule Charge Transport

A grand challenge in the field of bioelectronics is to develop soft, deformable materials with hierarchical structures that possess a wide range of functionality. In order to address this challenge, new chemistries are critically required to generate robust bio-electronic interfaces between traditionally disparate materials. In this talk, I will discuss recent work in our group that focuses on biohybrid materials such as pi-conjugated oligopeptides that can be engineered for precise supramolecular assembly and charge transport applications. In the first part of the talk, I will describe the equilibrium and non-equilibrium assembly of pi-conjugated peptides using a combination of experiments and analytical modeling. In a series of experiments, pi-conjugated peptides are guided to assemble under reaction-dominated or diffusion-dominated conditions. Our results show that the morphology of self-assembled peptide fibers is controlled by the assembly kinetics. We further developed an analytical reaction-diffusion model to describe oligopeptide assembly, and experimental results are compared to the reaction-diffusion model across a range of parameters (Damkohler number). Moreover, we use microrheology to study the sol-gel transition of these materials during assembly, with direct measurement of modulus and photophysical properties during the sol-gel transition. In situ confocal fluorescence microscopy and in situ fluorescence lifetime imaging microscopy (FLIM) are also used to characterize peptides during the assembly process. In the second part of the talk, I will discuss the direct measurement of the electron transport properties and conductance of single molecules and oligomers. Here, we measure the conductance of single biomolecules and sequence-defined synthetic oligomers using a scanning tunneling microscope-break junction technique (STM-BJ). Using this approach, we characterize the electron transport properties of new classes of conjugated oligomers and biohybrid materials by varying primary monomer sequence. In this way, our work provides fundamental information underlying electron and charge transport behavior, which will be used to inform future design of molecular electronics materials.