Optimization of Piezoelectric Gamma-Phase Glycine Biocrystal Formation Using Electroanalytic Methods for Production of a Bone Healing Polymer-Nanomaterial-Glycine Composite

Piezoelectric materials find use in a broad array of technologies: functioning as actuators, transducers, and sensors. Further, piezoelectric materials have been developed with mechanical properties from low to high modulus: allowing incorporation into devices undergoing substantial deformation (<i>e.g.</i>, for biomedical applications such as bone growth, wound healing). However, traditional materials still see limitations on their use due to economic and application-specific constraints. Biomaterials, such as γ-phase glycine biocrystals, exist as biocompatible, biodegradable, renewable, and low-cost alternatives with tunable mechanical properties compliant to biomechanical forces. The presented study was designed to further characterize/optimize a coordinative interaction between aqueous glycine and poly(vinyl alcohol)-associated hydroxyl groups which is implicated in the nucleation and preferred interfacial growth of γ-phase glycine biocrystals. The relative coordinative behaviors of select organic moieties (-R), present as end-groups of (gold) electrode-modifying self-assembled monolayers (SAMs; alkane thiol derivatives: HS-(CH)_n-R), were studied <i>via</i> electroanalytical methods. Glycine adsorption was studied <i>in situ</i> through continuous measure of electrode potentials, along with voltametric measures of related transient/charging currents. Electrochemical impedance spectroscopy was similarly performed <i>in situ</i>, as well as at discrete time points throughout the crystallization process to assess film crystallinity. Results from these studies were fit to relevant physicochemical models (<i>e.g.</i>, adsorption isotherms, equivalent circuit models); related to crystal formation processes/behaviors; and utilized in the synthesis of low modulus, high-efficiency piezoelectric polymer/γ-glycine composites. These materials were further modified with antioxidant cerium oxide nanomaterials and utilized to induce growth and differentiation of bone cells, <i>in vitro</i>.