Macromolecular pHPMA-Based Nanoparticles with Cholesterol for Solid Tumor Targeting: Behavior in HSA Protein Environment.

Nanoparticles (NPs) that form by self-assembly of amphiphilic poly(N-(2-hydroxypropyl)-methacrylamide) (pHPMA) copolymers bearing cholesterol side groups are potential drug carriers for solid tumor treatment. Here, we investigate their behavior in solutions of human serum albumin (HSA) in phosphate buffered saline. Mixed solutions of NPs, from polymer conjugates with or without the anticancer drug doxorubicin (Dox) bound to them, and HSA at concentrations up to the physiological value are characterized by synchrotron small-angle X-ray scattering and isothermal titration calorimetry. When Dox is absent, a small amount of HSA molecules bind to the cholesterol groups that form the core of the NPs by diffusing through the loose pHPMA shell or get caught in meshes formed by the pHPMA chains. These interactions are strongly hindered by the presence of Dox, which is distributed in the pHPMA shell, meaning that the delivery of Dox by the NPs in the human body is not affected by the presence of HSA.

Data analysis of the influence of microstructure, composition, and loading conditions on stress corrosion cracking behavior of Mg alloys.

Stress corrosion cracking (SCC) can be a crucial problem in applying rare earth (RE) Magnesium alloys in environments where mechanical loads and electrochemical driven degradation processes interact. It has been proven already that the SCC behavior is associated with microstructural features, compositions, loading conditions, and corrosive media, especially in-vivo. However, it is still unclear when and how mechanisms acting on multiple scales and respective system descriptors predictable contribute to SCC for the wide set of existing Mg alloys. In the present work, suitable literature data along SCC of Mg alloys has been analyzed to enable the development of a reliable SCC model for MgGd binary alloys. Pearson correlation coefficient and linear fitting are utilized to describe the contribution of selected parameters to corrosion and mechanical properties. Based on our data analysis, a parameter ranking is obtained, providing information on the SCC impact with regard to ultimate tensile strength (UTS) and fracture elongation of respective materials. According to the analyzed data, SCC susceptibility can be grouped and mapped onto Ashby type diagrams for UTS and elongation of respective base materials tested in air and in corrosive media. The analysis reveals the effect of secondary phase content as a crucial materials descriptor for our analyzed materials and enables better understanding towards SCC model development for Mg-5Gd alloy based implant.

Dissolution of iron oxide nanoparticles inside polymer nanocapsules.

The structure of poly(organosiloxane) nanocapsules partially filled with iron oxide cores of different sizes was revealed by small angle X-ray scattering and X-ray diffraction. The nanocapsules are synthesized by the formation of a poly(organosiloxane) shell around iron oxide nanoparticles and the simultaneous partial dissolution of these cores. Due to the high scattering contrast of the iron oxide cores compared to the polymer shell, the particle size distribution of the cores inside the capsules can be measured by small angle X-ray scattering. Additional information can be revealed by X-ray diffraction, which gives insights into the formation of the polymer network and the structure of the iron oxide cores. The study shows how the crystallinity and size of the nanoparticles as well as the shape and width of the size distribution can be altered by the synthesis parameters.