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The incorporation of nanoparticles into metallic biomaterials has been recognized as a significant approach to improve their bioactivity for biomedical applications. In this study, friction stir processing (FSP) was employed to incorporate TiO2 nanoparticles as bioactive reinforcement into the β titanium alloy Ti–35Nb–2Ta–3Zr (TNTZ) matrix to construct an integrated micro-nano composite layer. The effect of different TiO2 contents on the osteogenic capacity of rat bone marrow stromal stem cells (BMSCs) was studied. The TiO2/TNTZ composite layer exhibited a refined grain structure with a mean grain size of approximately 10 μm and a characteristic surface morphology of pronounced peaks and valleys with enhanced RSkw and RKur values. Moreover, TiO2/TNTZ significantly promoted the adhesion, proliferation, and spreading of BMSCs, upregulated the expression of genes related to osteogenesis (ALP and Runx2) up to nearly 1.5 times, and enhanced the expression of ALP and OCN (P

Gradient materials can achieve both external strengthening and internal toughening, which has great potential to break the strong plastic tradeoff. Titanium carbide (TiC) particle is conducive to form a wearable surface in biomedical Titanium (Ti) alloy. In this work, gradient TiC/Ti6Al4V composites were successfully prepared by friction stir processing (FSP). Microstructure, texture and mechanical properties of the material were systematically characterized. Scanning electron microscopy (SEM) showed that the equiaxed grains near the machined surface were transformed into elongated grains inside. The results of energy spectrum analysis (EDS) showed that there was element aggregation near TiC particles. X-ray diffraction (XRD) indicated martensitic transformation in the stir zone and in the transition zone. The results of nano indentation showed that the hardness of stir zone was higher. In order to promote recrystallization and improve the hardness of the transition zone, high temperature rapid heat treatment was carried out after FSP. When the sample was heated at 700 °C and cooled in the furnace, the hardness increased to the maximum. In the process of rapid heating, the dissolution of elements near TiC particles also led to the increase of hardness. This study provides a new idea for surface modification of gradient titanium alloy by using FSP method to improve its mechanical properties.

Osteogenic differentiation and antibacterial property are two-core requirements for bone implants, but typically they are not compatible. Zinc (Zn) as a common bioactive material is widely used in the medical field. A balance between antibacterial and osteogenic activity can be achieved at appropriate Zn concentration. In this study, the TNTZ/Zn micro/nano-composites were prepared by doping Zn nanoparticles onto Ti-35Nb-2Ta-3Zr (TNTZ) surface through the friction stir processing (FSP) technique. The results of material characterization revealed the homogeneous distribution of Zn, the presence of α″ martensite, and the increase in microhardness in the stir zone. Due to the solid metallurgical bonding between Zn NPs and substrate, Zn ions were released slowly and may be biologically responsive through body fluid corrosion. In terms of biological activity, the expression of adhesion-related protein vinculin and osteogenic differentiation genes were up-regulated by TNTZ/Zn, which improved the early adhesion and osteogenic differentiation of bone marrow stromal stem cells. Besides, TNTZ/Zn presented excellent antibacterial properties, and direct contact with the fine grain surface containing Zn NPs may be the dominant mechanism. TNTZ/Zn micro/nano-composites have excellent mechanical properties, osteogenic differentiation and antibacterial properties, providing an efficient strategy for titanium alloy surface modification and showing tremendous potential in dental applications.

It is known that the microbiome affects human physiology, emotion, disease, growth, and development. Most humans exhibit reduced appetites under high temperature and high humidity (HTHH) conditions, and HTHH environments favor fungal growth. Therefore, we hypothesized that the colonic mycobiota may affect the host’s appetite under HTHH conditions. Changes in humidity are also associated with autoimmune diseases. In the current study mice were fed in an HTHH environment (32°C ± 2°C, relative humidity 95%) maintained via an artificial climate box for 8 hours per day for 21 days. Food intake, the colonic fungal microbiome, the feces metabolome, and appetite regulators were monitored. Components of the interleukin 17 pathway were also examined. In the experimental groups food intake and body weight were reduced, and the colonic mycobiota and fecal metabolome were substantially altered compared to control groups maintained at 25°C ± 2°C and relative humidity 65%. The appetite-related proteins LEPT and POMC were upregulated in the hypothalamus (p < 0.05), and NYP gene expression was downregulated (p < 0.05). The expression levels of PYY and O-linked β-N-acetylglucosamine were altered in colonic tissues (p < 0.05), and interleukin 17 expression was upregulated in the colon. There was a strong correlation between colonic fungus and sugar metabolism. In fimo some metabolites of cholesterol, tromethamine, and cadaverine were significantly increased. There was significant elevation of the characteristic fungi Solicoccozyma aeria, and associated appetite suppression and interleukin 17 receptor signaling activation in some susceptible hosts, and disturbance of gut bacteria and fungi. The results indicate that the gut mycobiota plays an important role in the hypothalamus endocrine system with respect to appetite regulation via the gut-brain axis, and also plays an indispensable role in the stability of the gut microbiome and immunity. The mechanisms involved in these associations require extensive further studies.

We investigated the tensile and superelastic behaviors of Ti-35Nb-2Ta-3Zr processed by double-faced friction stir processing that results in a roughly 2 times higher yield strength with an elongation of 37%. The friction stir processed specimens exhibited different superelasticity as loading cycle increased. To assess the strength and deformation of gradient structure, in situ micro compression tests were conducted on stir zone and heat affected zone, revealing higher strength in stir zone and better ductility in heat affected zone. The combination of stir zone and heat affected zone could increase the strength and maintain the ductility of the specimen simultaneously.