Biomimetic Surfaces Containing Self-Assembled Monolayers of a Lipid-Resembling Thiol (di-LA-PC) Generate Covalently...

Bioinorganic surfaces are uniquely advantageous for studying the assembly, structure, and function of complex biological molecules that form and function at interfaces. We previously used chemically functionalized inorganic surfaces to investigate the structure of amyloid fibrils and the mechanism of their formation. These fibril structures have long been associated with diseases such as Alzheimer's, Parkinson's, and type II diabetes, but basic understanding of chemical environment, molecular interactions, and the mechanism of fibril formation remains unknown. Here, we report an approach that involves fabricating well-characterized biomimetic surfaces that induce fibril growth in a highly controlled chemical environment: a biomimetic surface that attaches a synthetic alkyne-containing peptide through self-assembled monolayers (SAM) constructed with lipid-resembling thiols, 1,2-dilipoyl-sn-glycero-3-phosphorylcholine (di-LA-PC), and shorter azide-alkanethiols on planar Au surfaces. We attached these model peptides through a Cu-catalyzed click reaction and demonstrated subsequent peptide nucleation and the growth of fibrils on these membrane-mimicking substrates. The height, width, and length of individual fibril polymorphs on these surfaces were measured with atomic force microscopy (AFM) imaging. SAM and fibril molecular structures were characterized by using attenuated total internal reflection Fourier transform infrared spectroscopy (ATR-FTIR). As the surface coverage of di-LA-PC on the surface was increased from 0 to 20%, shorter and more sparse fibrils were observed because of the greater disruption in the planar SAM surface from the bulky di-LA-PC thiols. Our results have significant implications for the importance of cellular surface topography and heterogeneity in fundamental aspects of the mechanism of fibrilization.