• Non-covalent Interactions in Peptide Hydrogels: A Mechanism for Mechanical and Structural Control

      Joyner, Katherine Angel; Yu, Yihua Bruce (2013)
      Hydrogels are a unique class of materials lying at the interface of biology and engineering. In the development of this class of materials, understanding the underlying molecular mechanisms that dictate mechanical and structural properties is critical. Non- covalent interactions have been shown here to specifically modulate the properties of peptide hydrogels. A pair of oppositely charged peptides, that when mixed together self-assemble in to a hydrogel network were used in these studies. It was demonstrated using NMR signal decay, that electrostatic interactions are the primary contributions to peptide assembly into a hydrogel network. A decrease of electrostatic interactions results in a decrease in mechanical strength. Also, the ability for hydrogels to form elongated fibrous networks was prevented with the decrease in electrostatic interactions. We further investigated the role of peptide terminal chemistries in hydrogel design. With simple chemical modifications (N-termini acetyl- (COCH3) and amino- (NH2); C-terminal -carboxyl (COOH) and -amide (NH2)) regulation of the mechanical and structural properties was demonstrated. Generally the mechanical strength and fiber structure did not vary, however gelation kinetics and fiber characteristics were directly related to changes in peptide terminal chemistries. These results show the utility of non - covalent interactions in modulating peptide hydrogel structural and mechanical properties in the development of biomedical materials. We additionally examined the chromatographic analysis and separation involved in the development of peptide-based biomaterials through comparison of fluorocarbon and hydrocarbon columns and eluents in the retention and separation of non-fluorinated analytes. The results from these studies showed that fluorocarbon columns displayed the best separation and have a significant potential for use in development.