Development of a novel NiCu nanoparticle-loaded polysaccharide-based hydrogel for 3D printing of customizable dressings with promising cytotoxicity against melanoma cells.

Polysaccharide hydrogels and metal alloy nanoparticles have already found use in a range of biomedical applications. Nickel-copper nanoparticles (NiCu NPs) are particularly promising due to their tunable properties, such as ferromagnetism, biocompatibility, and antimicrobial activity. At the same time, polysaccharide hydrogels made of polymer mixtures such as alginate and methylcellulose with incorporated metal alloy nanoparticles are reported in the scientific literature. In view of this, in this work, NiCu NPs are combined with polysaccharide hydrogels and 3D printed to construct geometrically customizable dressings with tailorable properties for melanoma treatment. This novel combination exploits the intrinsic magnetic properties of NiCu NPs and the same time builds on their less known properties to improve the mechanic stability of 3D printed materials, both contributing to a previously not reported application as potent cytotoxic dressing against melanoma cells. The dressings were evaluated in terms of their physico-chemical characteristics, and their potential application, namely melanoma cell cytotoxicity. While all dressings exhibited similar degradation profiles regardless of composition, the addition of NiCu NPs had an effect on the hydrophilicity, swelling rates, and topographical properties of the dressings. Compression results showed that the presence of NPs increased the stiffness of the dressings, while the ultimate tensile strength was highest at 0.31 MPa for the dressings with 0.5 wt% NPs. We show that although the base formulation of the dressings is biocompatible with skin-derived cells, dressings loaded with NPs exhibit promising antimelanoma activity. Extracts obtained from dressings containing 0.5 wt% NPs reduced melanoma cell viability to 61% ± 11% and 40% ± 2% after 24 h and 72 h of soaking, respectively. Furthermore, extracts of dressings with 1 wt% NPs reduced melanoma cell viability to less than 15% within the first 24 h. By adjusting the NP content, the mechanical properties, surface roughness, and wettability can be tuned so that the dressings can be functionally customized. In addition, by using 3D printing as a fabrication process, the shape and composition of the dressings can be tailored to the patient's needs. The dressings also remained intact after soaking in simulated physiological solution for 14 days, indicating their suitability for long-term topical application.

An Experimental and Computational Study of the High-Velocity Impact of Low-Density Aluminum Foam.

The study presents the results of an experimental and computational study of the high-velocity impact of low-density aluminum foam into a rigid wall. It is shown that the aluminum foam samples deformed before hitting the rigid wall because of the high inertial forces during the acceleration. During the impact, the samples deformed only in the region contacting the rigid wall due to the high impact velocity; the inertial effects dominated the deformation process. However, the engineering stress-strain relationship retains its typical plateau shape until the densification strain. The experimental tests were successfully reproduced with parametric computer simulations using the LS-DYNA explicit finite element code. A unique computational lattice-type model was used, which can reproduce the randomness of the irregular, open-cell structure of aluminum foams. Parametric computer simulations of twenty different aluminum foam sample models with randomly generated irregular lattice structures were carried out at different acceleration levels to obtain representative statistical results. The high strain-rate sensitivity of low-density aluminum foam was also observed. A comparison of experimental and computational results during aluminum foam sample impact shows very similar deformation behavior. The computational model correctly represents the real impact conditions of low-density aluminum foam and can be recommended for use in similar high-velocity impact investigations.

Multifunctional hybrid structures made of open-cell aluminum foam impregnated with cellulose/graphene nanocomposites.

This work focuses on exploring combinations of disintegrated bacterial cellulose nanofibres (BC) with graphene oxide (GO) (reduced and non-reduced) and phase change materials (PCMs) prepared in the form of foam-like structures. The presence of GO remarkable improves the fire-retardancy and provides dimensional stability to the foams while PCMs gives thermal energy storage capacity. The foams were exposed to methyltrimethoxysilane (MTMS) vapour to become hydrophobic which was confirmed by measuring water absorption capacity and water contact angle. To extend the multifunctionality of these nanocomposite foams, a selected composition was impregnated into an open-cell aluminium foam creating a hybrid structure (Al-BC/GO) with higher mechanical properties (increase in stress of 100 times) and high sound absorption coefficient (near 1 between 1000-4000 Hz). The low thermal conductivity confirms that this hybrid structure is a thermal insulator. These advantages highlight the potential applications of the proposed materials e.g. construction, automotive and aeronautical sectors.

Indirect Reconstruction of Pore Morphology for Parametric Computational Characterization of Unidirectional Porous Iron.

This paper addresses the problem of reconstructing realistic, irregular pore geometries of lotus-type porous iron for computer models that allow for simple porosity and pore size variation in computational characterization of their mechanical properties. The presented methodology uses image-recognition algorithms for the statistical analysis of pore morphology in real material specimens, from which a unique fingerprint of pore morphology at a certain porosity level is derived. The representative morphology parameter is introduced and used for the indirect reconstruction of realistic and statistically representative pore morphologies, which can be used for the generation of computational models with an arbitrary porosity. Such models were subjected to parametric computer simulations to characterize the dependence of engineering elastic modulus on the porosity of lotus-type porous iron. The computational results are in excellent agreement with experimental observations, which confirms the suitability of the presented methodology of indirect pore geometry reconstruction for computational simulations of similar porous materials.