(595b) Design of a Molecular-Recognition Material for Capture and Release of Phosphate

As many resources are being unsustainably depleted as the global population exponentially rises, society is turning towards wastewater as a new source for reclaiming valuable nutrients. Novel materials need to be engineered to sequester and recycle these valuable resources for reuse, with phosphate as a key target for reuse as a fertilizer. This work specifically aims to design a new material based on biologically-inspired peptide amphiphiles (PAs) that can molecularly recognize, sequester and recycle phosphate out of water. To perform these functions, we are synthetically manipulating the natural ability of proteins to specifically bind to ions and small molecules based on their molecular sequence and secondary structure. Thus, we have incorporated phosphate-binding amino acid sequences into the peptide “headgroup” of PAs, which are conjugated to an alkyl “tail.” These molecules then spontaneously self-assemble into supramolecular structures that display the binding sequence to the aqueous environment. We have also programed these PA micelles to entangle and physically bind to each other, creating a dense, gelled network of molecular-recognition structures that will retain phosphate at high pH and controllably release phosphate at low pH, as water is flowed through the hydrogel. In our work thus far, we used solid-phase-peptide synthesis to successfully synthesize two systems of PAs, incorporating an elucidated phosphate-binding amino acid sequence into the headgroup of the PAs. Fundamental self-assembly and structural properties were then characterized. We determined the critical micelle concentrations and used scattering and electron microscopy techniques to validate that these systems self-assemble into worm-like micelles at the binding pH, which is the desired architecture to form a crosslinked hydrogel that is able to capture and release phosphate.