Self-assembled polysaccharide nanofibers for biophotonics, tissue engineering, and bionanoprotonics

The ability to precisely manipulate, localize, and assemble biological and bioinspired molecules into organized structures has contributed to great advances in bionanotechnology. These advances include bioelectronics, biophotonics, tissue engineering, and regenerative medicine. For these applications, chitin is particularly appealing. Chitin is a naturally abundant polysaccharide, which is mechanically stable, biodegradable, nontoxic, and physiologically inert. Here, I will present our efforts to create nanoscale structures and devices using self-assembled chitin nanofibers. First, I will discuss a novel nanofabrication approach based on a “chitin nanofiber ink”, which self-assembles into ultrafine (3nm) nanofibers upon drying. This ink is coupled with airbrushing, replica molding, and microcontact printing to manufacture chitin nanofiber structures with size control across length scales. Second, I will describe applications of these structures in biocompatible photonic devices and scaffolds for tissue engineering. Preliminary results in engineering neural networks and aligned cardiac tissue will be presented. Third, I will introduce the first biopolymer field effect transistor with protons (H+) as charge carriers. In a chitin derivative (maleic chitosan) nanofibers, H+ hop along the hydrated nanofiber hydrogen bond network following the Grotthuss mechanism. The H+ flow is measured with PdHx proton transparent contacts and this flow is turned on or off by an electrostatic potential applied to a gate electrode. Since in nature, protonic (H+) and ionic (not electronic) currents are used to communicate information across cell membranes, these biocompatible protonic devices may represent a versatile biotic- abiotic interface for bionanoelectronics.