Open Access

The laser welding of Cu–Al alloys for battery applications in the automotive industry presents significant challenges due to the high reflectivity of copper. Inadequate bonding and low mechanical strength may occur when the laser radiation is directed toward the copper side in an overlap configuration welding. To tackle these challenges, a laser surface treatment technique is implemented to enhance the absorption characteristics and overcome the reflective nature of the copper material. However, elevating the surface roughness and heat-energy input over threshold values leads to heightened temperature and extreme weld. This phenomenon escalates the formation of detrimental intermetallic compounds (IMC), creating defects like cracks and porosity. Metallurgical analysis, which is time-consuming and expensive, is usually used in studies to detect these phases and defects. However, to comprehensively evaluate the weld quality and discern the impact of surface structure, adopting a more innovative approach that replaces conventional cross-sectional metallography is essential. This article proposes a model based on the image feature extraction of the welds to study the effect of the laser-based structure and the other laser parameters. It can detect defects and identify the weld quality by weld classification. However, due to the complexity of the photo features, the system requires image processing and a convolutional neural network (CNN). Results show that the predictive model based on trained data can detect different weld categories and recognize unstable welds. The project aims to use a monitoring model to guarantee optimized and high-quality weld series production. To achieve this, a deeper study of the parameters and the microstructure of the weld is utilized, and the CNN model analyzes the features of 1310 pieces of weld photos with different weld parameters.

The dragonfish is a voracious predator of the deep sea with an arsenal of tools to hunt prey and remain concealed. In contrast to its dark pigmented skin, the dragonfish is equipped with transparent teeth. Here, we establish the structure, composition, and mechanical properties of the transparent teeth for the first time. We find the enamel-like layer to consist of nanocrystalline hydroxyapatite domains (∼20 nm grain size) embedded in an amorphous matrix, whereas in the dentin layer the nanocrystalline hydroxyapatite coats nanoscale collagen fibrils forming nanorods. This nanoscale structure is responsible for the much-reduced Rayleigh light scattering, which is further ensured by the sufficiently thin walls. Here, we suggest that the nanostructured design of the transparent dragonfish teeth enables predatory success as it makes its wide-open mouth armed with saber-like teeth effectively disappear, showing no contrast to the surrounding blackness of the fish nor the background darkness of the deep sea.

Pseudomonas aeruginosa (PA) is a major healthcare concern due to its tolerance to antibiotics when enclosed in biofilms. Tobramycin (Tob), an effective cationic aminoglycoside antibiotic against planktonic PA, loses potency within PA biofilms due to hindered diffusion caused by interactions with anionic biofilm components. Loading Tob into nano-carriers can enhance its biofilm efficacy by shielding its charge. Polyion complex vesicles (PIC-somes) are promising nano-carriers for charged drugs, allowing higher drug loadings than liposomes and polymersomes. In this study, a new class of nano-sized PIC-somes, formed by Tob-diblock copolymer complexation is presented. This approach replaces conventional linear PEG with brush-like poly[ethylene glycol (methyl ether methacrylate)] (PEGMA) in the shell-forming block, distinguishing it from past methods. Tob paired with a block copolymer containing hydrophilic PEGMA induces micelle formation (PIC-micelles), while incorporating hydrophobic pyridyldisulfide ethyl methacrylate (PDSMA) monomer into PEGMA chains reduces shell hydrophilicity, leads to the formation of vesicles (PIC-somes). PDSMA unit incorporation enables unprecedented dynamic disulfide bond-based shell cross-linking, significantly enhancing stability under saline conditions. Neither PIC-somes nor PIC-micelles show any relevant cytotoxicity on A549, Calu-3, and dTHP-1 cells. Tob's antimicrobial efficacy against planktonic PA remains unaffected after encapsulation into PIC-somes and PIC-micelles, but its potency within PA biofilms significantly increases.

Cobaltocenium-containing polymers, an emerging class of materials, have historically been challenging to prepare due to their chemical robustness. In this work, we introduce a novel and highly efficient method for their preparation based on methacrylate-containing block copolymers (BCPs), allowing segment-selective introduction of functional moieties. The catalyst-free and quantitative hydroamination reaction we introduce has proven successful for the post-modification of amine-containing polymers with cobaltocenium. To demonstrate the versatility of this method, we successfully synthesized a series of BCPs consisting of polystyrene and a 5 to 20 wt% poly(tert-butyl aminoethyl methacrylate) (PtBAEMA) segment by living anionic polymerization. The selective functionalization with ethynyl-cobaltocenium hexafluorophosphate results in adjustable 5 to 40 wt% cobaltocenium units in the polymer as part of the PtBAEMA block segment. The success was monitored by IR spectroscopy, and the quantitative incorporation of the cobaltocenium moiety was verified by 1H NMR, UV-Vis spectroscopy, and TGA. DSC proved the block-selective cobaltocenium introduction by an additional glass transition temperature at 154 °C, and the strong microphase separation character of the amphiphilic BCPs leads to lamellar structures in the bulk state, as proven by TEM investigations. Finally, the water contact angle on polymer films is compared, showing polarity inversion and tunability upon conversion of hydrophilic amine to hydrophobic cobaltocenium hexafluorophosphate moieties. This successful synthesis and characterization of cobaltocenium-containing BCPs not only paves the way for a new class of metallopolymers but also offers functionalization possibilities for a variety of other responsive moieties, providing access to functional BCPs.

Over the past decade, increasing evidence suggested that cells are capable of establishing long distance communication routes with different function defined as Tunneling Nanotubes (TNTs). TNTs are thin, dynamic, long membrane protrusions that allow the intercellular exchanges of signal clues, molecules, organelles and pathogens. The presence of TNTs has been observed in several types of cancer, glioblastoma (GBM) included, where they emerge to steer a more malignant phenotype [1]. GBM is the most common malignant tumour of Central Nervous System (CNS), representing about 82% of cases of all malignant gliomas [2]. An innovative strategy that could represent a potential therapeutic approach is the targeting of tumour cells communication. Therefore, we are studying TNTs in GBM, to deepen both their structural and genesis features in order to exploit them to improve the intercellular distribution of nanomedicines in close and far away cells, thus reaching isolated tumour niches that are hardly targeted by simple drug diffusion in the brain parenchyma. Until now, different types of nanoparticles have been identified within TNTs. Very little is known about the role of fundamental physical parameters of nanoparticles such as size, charge, shape in determining their penetration across the BBB and their transfer between cells by TNTs. Considering that, TNTs thickness is in the range of 0.2-1 μm, it can be speculated that the size should not be a critical parameter while positively charged NPs could trigger the formation of TNTs due to a higher toxicity compared to those that are negatively charged. At the best of our knowledge, no data are available about the effect of NPs shape on the transfer efficiency between TNTs. For this purpose, spherical, discoidal and deformable nanoparticles were synthetized in order to evaluate if the nanoparticles shape could influence their ability to be transferred via TNTs. These nanoparticles were evaluated in 2D and 3D in vitro models composed of human GBM cells, carrying the EGFRvIII mutation and resistant to temozolomide [3]. The results showed that a single GBM cell is able to form more than one TNT and that TNTs are dynamic and transient structures. They can be actin or actin and α-tubulin positive, they can have a length between 20-100 μm with a thickness of 200-600 nm. Moreover, GBM TNTs are efficient in allowing the intercellular transport of the three different types of nanoparticles tested, in a bidirectional vesicles-free way. Nanoparticles were followed inside TNTs and their average and maximum velocity was evaluated. Moreover, through a co-culture assay it has been demonstrated that the shape affects the efficiency of the nanoparticles exchange via TNTs because the discoidal ones were those transferred most efficiently, in comparison to the other two nanoparticles. Additionally, we address the presence of the TNTs in 3D-tumour organoids. GBM cells grown in a 3D scaffold better recapitulate the features of patient-derived cells, in comparison to 2D culture conditions. Results confirmed the localization of nanoparticles in the TNTs. Finally, the blood-brain barrier permeability of nanoparticles was measured in vitro in a transwell system and the results showed that discoidal nanoparticles displayed the highest endothelial permeability (~ 1.4x10-5 cm/min) with respect to the other nanoparticles tested. These results make TNTs promising tools for the delivery of drug-loaded discoidal nanoparticles between close and distant cells. This potential is relevant because communication modalities play key roles in driving GBM therapy resistance. Since the formation of TNTs occur also in other type of tumours, these findings can be also exploited in other context. References [1] Pinto G, “Patient-derived glioblastoma stem cells transfer mitochondria through tunneling nanotubes in tumor organoids”, Biochem J., vol. 478, no. 1, pp. 21-39, 2021. [2] Vollmann-Zwerenz A, “Tumor Cell Invasion in Glioblastoma”, Int J Mol Sci, vol. 21, no. 6, pp. 1932, 2020. [3] Taiarol L, “Givinostat-Liposomes: Anti-Tumor Effect on 2D and 3D Glioblastoma Models and Pharmacokinetics”, Cancers, vol. 14, no. 12, pp. 2978, 2022.