Coherent x-ray scattering for discriminating bio-compatible materials in tissue scaffolds

Abstract

It has been shown that coherently scattered x-rays can be used to discriminate and identify specific components in a mixture of materials. To assess the feasibility of using coherent x-ray scatter (CXS) to characterize the material components within tissue scaffolds, we studied the CXS properties of the bio-compatible materials of polymers (polypropylene fumarate, polycaprolactone, epoxy, etc.), sugar and salt solutions at different concentration, and complex materials consisting of more than one polymer. We also investigated the effects of x-ray spectra on the CXS functions of polymers by measuring them with different x-ray source anodes. It is shown that the synthesized polymers with different portions of base polymers can be characterized with CXS. The polymerization process does not significantly change the CXS characteristics of the measured polymers. When protein is denatured, no substantial change in scatter was detected. Solutions of different concentration can be characterized and quantified by the CXS features corresponding to the solutes. The difference among CXS of solutions of different concentration makes it possible to image and trace fluids and their concentration changes in tissues or scaffolds. Our results show that CXS of complex specimens can be decomposed with the scatter functions of the component materials. By simulating a tissue scaffold with a phantom with several bio-compatible materials, we demonstrated that significant contrast can be achieved at proper scatter angles by measuring the coherent x-ray scatter, despite the low attenuation-based contrast between them. We conclude that use of x-ray scatter makes it possible to track and map the fate (e.g., its breakdown and/or removal) of specific components within tissue scaffolds.