Highly rigid & transparent supramolecular fibrils of tyrosine

Various peptides and amino acids can self-assemble into fibrils in a solution environment both in vivo and in vitro. These fibrils can aggregate as amyloids in the organs of individuals with certain genetic mutations, and can also be assembled in-vitro for their potential application as bioinspired and biocompatible material. Here, we present our study of the mechanical properties of self-assembled fibrils of enantiomers of tyrosine, one of the essential amino acids found in living systems. We have observed that Young's modulus of fibrils of L-tyrosine, the biologically relevant enantiomer, can be as high as 43 GPa with a point stiffness of about 454 N m(-1) making these fibrils to be one of the highly rigid bioinspired structures. We have also observed that films of highly rigid L-tyrosine fibrils also have high optical transmittance of 65% while films of enantiomer D-tyrosine fibrils and fibrils of an equimolar mixture of D- and L-tyrosine are opaque. This suggests that individual amino acids can self-assemble into highly rigid fibrils and opens up avenues for using amino acids for constructing mechanically robust structures with varying optical properties.