Computational and experimental methods were applied to investigate the self-assembly and gelation of C13-dipeptides. A modified aggregation propensity (APS) was introduced to correlate the effects of side chains of amino acids on the tendency to aggregate. From the experimental results, the ranges of 0.156<APS<0.250 seemed to be a proper region for the C13-dipeptides to form hydrogels, while other molecules with higher or lower APS were insoluble or dissociated. As observed from molecular dynamics simulations, the C13-dipeptides firstly form small aggregates through hydrophobic interactions and then rearranged through electrostatic attractions and hydrogen bonds for self-assembly. The C13-dipeptides tended to be anti-parallel packed as shown by hydrogen bonding analyses. Experimental observations and analyses on the structures of C13-dipeptide hydrogels matched the computational conclusions very well. From the 5 selected gelators, i.e. C13-GW, C13-VY and C13-WT, strong - stacking was observed. For C13-WS strong hydrogen bonding was found, and in C13-WY both of strong pi-pi interactions and hydrogen bonds were found. It takes around 90 minutes or longer for C13-dipeptides to form hydrogels and those formed by C13-WY and C13-WS had weak water holding capacities, which might be due to strong intermolecular hydrogen bonding. From rheological studies the C13-dipeptides formed strong chemical gels that were stabilized by strong interactions between the molecular aggregates. These gelators exhibit the potentials to be environmentally-friendly substitutes for the common functionalized peptide gelators.
ASJC Scopus subject areas
- Polymers and Plastics
- Materials Chemistry
Hu, T., Zhang, Z., Hu, H., Euston, S. R., & Pan, S. (2019). A comprehensive study on self-assembly and gelation of C13-dipeptides – from design strategies to functionalities. Biomacromolecules. https://doi.org/10.1021/acs.biomac.9b01386