Tracking Aggregation and Fibrillation of Globular Proteins Using Terahertz and Far-Infrared Spectroscopies

Partially unfolded proteins can self-assemble to form insoluble protein fibrils with diameters in the nanometer scale. These are of particular interest in healthcare because of their presence in diseases such as Alzheimer's disease and type-II diabetes. Tracking the formation of protein fibrils has far-reaching benefits for research into treatment of these diseases. Current optical techniques that track fibrillation either limit samples to their aqueous form or are slow to conduct. We present in this work terahertz and far-infrared (FIR) spectroscopic analyses of fibrils made from three globular proteins. We track the fibrillation process over an extended period to show that mature fibrils have distinct absorbance properties that are not solely caused by scattering. Results also show that FIR spectroscopy can provide information about fibril structures that is otherwise missed by optical techniques.