Structural Characterization of Biomaterials by Means of Small Angle X-rays and Neutron Scattering (SAXS and SANS), and Light Scattering Experiments

Abstract

Scattering techniques represent non-invasive experimental approaches and powerful tools for the investigation of structure and conformation of biomaterial systems in a wide range of distances, ranging from the nanometric to micrometric scale. More specifically, small-angle X-rays and neutron scattering and light scattering techniques represent well-established experimental techniques for the investigation of the structural properties of biomaterials and, through the use of suitable models, they allow to study and mimic various biological systems under physiologically relevant conditions. They provide the ensemble averaged (and then statistically relevant) information under in situ and operando conditions, and represent useful tools complementary to the various traditional imaging techniques that, on the contrary, reveal more local structural information. Together with the classical structure characterization approaches, we introduce the basic concepts that make it possible to examine inter-particles interactions, and to study the growth processes and conformational changes in nanostructures, which have become increasingly relevant for an accurate understanding and prediction of various mechanisms in the fields of biotechnology and nanotechnology. The upgrade of the various scattering techniques, such as the contrast variation or time resolved experiments, offers unique opportunities to study the nano- and mesoscopic structure and their evolution with time in a way not accessible by other techniques. For this reason, highly performant instruments are installed at most of the facility research centers worldwide. These new insights allow to largely ameliorate the control of (chemico-physical and biologic) processes of complex (bio-)materials at the molecular length scales, and open a full potential for the development and engineering of a variety of nano-scale biomaterials for advanced applications.

Methods of Liposomes Preparation: Formation and Control Factors of Versatile Nanocarriers for Biomedical and Nanomedicine Application

“…Small-Angle X-ray/Neutron Scattering (SAXS/SANS) and Diffraction Techniques Among the experimental methods, the small-angle X-ray scattering (SAXS), smallangle neutron scattering (SANS), and diffraction methods are the most widely used for a non-destructive characterization of the structural properties of liposomes [147][148][149][150]. Scattering techniques also provide the fundamental tools for investigating the main interactions of nanocarriers in different solution environments, and for investigating conformational modifications and structural transitions which are relevant for the prediction of the structurefunction relationship in many biological processes [151][152][153].…”

“…Small-angle neutron scattering (SANS) shares the same basic principles with SAXS. While SAXS spectra originates from the scattering of the electrons present in the materials system under investigation, and is sensitive to the hydrophilic region of a lipid bilayer, the SANS technique furnishes information on the lipids' hydrophobic tails region, as neutrons furnish a better "contrast" for that region [151][152][153]. Moreover, neutron diffraction measurements performed on (selectively) deuterated lipids furnish an important approach for the determination of the conformation of the lipid molecules at different positions [27,40].…”

Polymeric Composite of Magnetite Iron Oxide Nanoparticles and Their Application in Biomedicine: A Review

“…Small angle neutron scattering (SANS) is a valuable technique to study magnetic and internal structural properties in nanostructures ensembles. This technique is based on the direct interaction between neutrons and the atomic nuclei, which produce a scattering length associated with specific elements [115]. It is necessary to have adequate experimental conditions such as a sample with a solvent with scattering contrast variations, which allows identifying magnetic scattering or elemental composition of individual layers [116].…”

“…However, there are considerable penetration depth and the ability to manipulate local scattering contrast by deuterium labeling without significantly affecting the chemical interactions, resolution, and length scales suitable for polymer studies. Selective Deuterium is used when there is a weak scattering of the components of interest [115]. SANS analyzes interparticle interactions as a function of the nanoparticle volume fraction.…”

Nanostructures in Nanomedicine: Critical Issues and Perspectives

“…Those nanostructured system are based on the complex combinations of different (non-covalent) supramolecular interactions, that allow the formation of highly functional materials and devices with remarkable properties [49][50][51][52][53][54][55]. More specifically, supramolecular self-assembly between amphiphilic compounds allows the fabrication of a large variety of nanomaterials with emerging complex properties and various architectures [56][57][58][59]. These approaches have offered great potential to develop materials with improved therapeutic efficacy including target specificity, controlled drug release, lower therapeutic doses and minimum exposure to normal tissues [60,61].…”