Many research topics in the fields of condensed matter and the life sciences are based on small-angle X-ray and neutron scattering techniques. With the current rapid progress in source brilliance and detector technology, high data fluxes of ever-increasing quality are produced. In order to exploit such a huge quantity of data and richness of information, wider and more sophisticated approaches to data analysis are needed. Presented here isGENFIT, a new software tool able to fit small-angle scattering data of randomly oriented macromolecular or nanosized systems according to a wide list of models, including form and structure factors. Batches of curves can be analysed simultaneously in terms of common fitting parameters or by expressing the model parametersviaphysical or phenomenological link functions. The models can also be combined, enabling the user to describe complex heterogeneous systems.

The maturation of coronavirus SARS-CoV-2, which is the etiological agent at the origin of the COVID-19 pandemic, requires a main protease M^proto cleave the virus-encoded polyproteins. Despite a wealth of experimental information already available, there is wide disagreement about the M^promonomer-dimer equilibrium dissociation constant. Since the functional unit of M^prois a homodimer, the detailed knowledge of the thermodynamics of this equilibrium is a key piece of information for possible therapeutic intervention, with small molecules interfering with dimerization being potential broad-spectrum antiviral drug leads. In the present study, we exploit Small Angle X-ray Scattering (SAXS) to investigate the structural features of SARS-CoV-2 M^proin solution as a function of protein concentration and temperature. A detailed thermodynamic picture of the monomer-dimer equilibrium is derived, together with the temperature-dependent value of the dissociation constant. SAXS is also used to study how the M^prodissociation process is affected by small inhibitors selected by virtual screening. We find that these inhibitors affect dimerization and enzymatic activity to a different extent and sometimes in an opposite way, likely due to the different molecular mechanisms underlying the two processes. The M^proresidues that emerge as key to optimize both dissociation and enzymatic activity inhibition are discussed.

Thermal-induced conformational changes and protein–protein interactions of bovine serum albumin (BSA) in aqueous solution are assessed by small angle X-ray scattering (SAXS) at two pH values (7.4 and 9.0) and two ionic strengths (0.1 and 0.5). We demonstrate that Guinier analysis in two ranges of the modulus of the scattering vector allows protein melting and aggregation to be monitored simultaneously, thus providing insights into the mechanism of thermal-induced BSA aggregation. Results of the analysis suggest that at room temperature monomeric and dimeric BSA fractions are present in solution. For low concentrations (<10 mg mL⁻¹) the monomeric to dimeric fraction ratio is close to 6, the same value we obtained independently in size-exclusion chromatography experiments. For elevated concentrations (20 mg mL⁻¹ and 40 mg mL⁻¹) a decrease in the dimer fraction occurs. Following heating, dimer formation is observed prior to protein melting, while no higher order aggregates are observed in the 20–60 °C temperature range. In the vicinity of the BSA melting point, higher order aggregates appear and protein molecules exhibit an aggregation burst. Higher ionic strength makes the described effects more pronounced – dimer formation increases at lower temperatures, presumably due to partial screening of electrostatic interactions between protein molecules. Moreover, the melting temperature shifts to higher values upon increasing the protein concentration and pH, indicating that repulsive interactions stabilize the protein structure. The suggested model was verified by the assessment of parameters of protein–protein interaction potentials based on DLVO theory using the global fitting procedure.

Ethosome represents a smart transdermal vehicle suitable for solubilization and cutaneous application of drugs. Coenzyme Q10 is an endogenous antioxidant whose supplementation can counteract many cutaneous disorders and pathologies. In this respect, the present study describes the production, characterization, and cutaneous protection of phosphatidylcholine based ethosomes as percutaneous delivery systems for coenzyme Q10. CoQ10 entrapment capacity in ethosomes was almost 100%, vesicles showed the typical ‘fingerprint’ structure, while mean diameters were around 270 nm, undergoing an 8% increase after 3 months from production. An ex-vivo study, conducted by transmission electron microscopy, could detect the uptake of ethosomes in human skin fibroblasts and the passage of the vesicles through 3D reconstituted human epidermis. Immunofluorescence analyses were carried on both on fibroblasts and 3D reconstituted human epidermis treated with ethosomes in the presence of H₂O₂ as oxidative stress challenger, evaluating 4-hydroxynonenal protein adducts which is as a reliable biomarker for oxidative damage. Notably, the pretreatment with CoQ10 loaded in ethosomes exerted a consistent protective effect against oxidative stress, in both models, fibroblasts and in reconstituted human epidermis respectively.

Curcumin is a natural polyphenol able to bind the amyloid beta peptide, which is related to Alzheimer’s disease, and modify its self-assembly pathway. This paper focuses on a multi-disciplinary study that starts from the design of curcumin-like compounds with the key chemical features required for inhibiting amyloid beta aggregation, and reports the effects of these compounds on the in vitro aggregation of amyloid beta peptides. Chemoinformatic screening was performed through the calculation of molecular descriptors that were able to highlight the drug-like profile, followed by docking studies with an amyloid beta peptide fibril. The computational design underlined two different scaffolds that were easily synthesized in good yields. In vitro experiments, ranging from fluorescence spectroscopy and confocal microscopy up to small angle X-ray scattering, provided evidence that the synthesized compounds are able to modify the aggregation pattern of amyloid beta peptides both in the secondary structures, and in terms of the overall structure dimensions. The cytotoxic potential of the synthesized compounds was finally tested in vitro with a model neuronal cell line (LAN5). The overall view of this study suggests new concepts and potential difficulties in the design of novel drugs against diverse amyloidoses, including Alzheimer’s disease.