Small-angle X-ray scattering characterization of a β-amyloid model in phantoms

Abstract

Objective We present a method to prepare an amyloid model at scalable quantities for phantom studies to evaluate small-angle x-ray scattering systems for amyloid detection. Two amyloid models were made from a plasma protein with and without heating. Both models mimic the β-sheet structure of the β-amyloid (βA) plaques in Alzheimer’s disease. Amyloid detection is based on the distinct peaks in the scattering signature of the β-sheet structure. We characterized the amyloid models using a spectral small-angle x-ray scattering (sSAXS) prototype with samples in a plastic syringe and within a cylindrical polymethyl methacrylate (PMMA) phantom.

Results sSAXS data show that we can detect the scattering peaks characteristic of amyloid β-sheet structure in both models around 6 and 13 nm⁻¹. The βA model prepared without heating provides a stronger signal in the PMMA phantom. The methods described can be used to prepare models in sufficiently large quantities and used in samples with different packing density to assess the performance of βA quantification systems.