Biosurface and Biotribology最新文献

The surface properties of biomaterials are the key factors for the success of artificial implants in the body. The creation of patterns on titanium alloys by laser surface texturing techniques can modify the surface to make it multifunctional. The evolution of the surface morphology of Ti6Al4V alloy textured by a nanosecond laser with 1064 nm wavelength in the air is studied. Laser surface texturing treatment is performed on the titanium alloy through different pulse numbers, power, pulse width and scan times to obtain different morphologies. The 2D cross-section profile shows that the morphology can be divided into three types in the evolution process of various pulse numbers, powers and pulse widths: bump-shaped, hump-shaped and crater-shaped. It is found that the effect of pulse width on morphology mainly depends on power. The effects of laser parameters on the height of bumps and the evolution of morphology are the main research points to analyse the topography evolution. The causes of bumps are also analysed. Energy dispersive spectrometer measures the area irradiated by the laser, and it is found that the oxygen content of the bump is up to 43.1%, which can speculate that the bump is the result of the oxidation reaction.

Moisture removal and water recovery from the air are vital for regulating indoor humidity and mitigating water scarcity. Most atmospheric water harvesters (AWH) focus primarily on increasing the moisture capture rate, but for it to be economical and sustainable, it is essential to consider the energy required to recover and harvest the captured water. Here, a mechanically flexible, biphilic sorption-based AWH made of green, environmentally friendly material is presented. It consists of a hygroscopic chitosan polymer embedded within a flexible, hydrophobic silica xerogel that can harvest 86.3 g water/g chitosan at 97% relative humidity and 25°C reaching saturation after 30 days (i.e. 2.88 g water/g chitosan/day). Roughly 88% of the sorbed moisture was recovered by mechanical squeezing (ca. 0.020 MPa) within 150 s. Repeated water harvesting experiments and uniaxial compression tests demonstrate that chitosan-silica xerogel is durable for long-term operations, providing a fast, reliable, and sustainable moisture removal and water harvesting tool.

To enhance the friction performance of resin-based friction materials, five types of specimens with different polymer ether ketone (PEEK) contents were fabricated and their physiomechanical behaviours were tested and, their tribological properties were investigated using a JF150F-II constant-speed tester. It was found that the addition of PEEK had a positive influence on the properties of the friction materials, and sample FM-3 (the shorthand of ‘Friction Materials-3’, containing 2 wt% PEEK) exhibited improved friction performance with a fade ratio and recovery ratio of 8.6% and 101.1% respectively. Among all samples, FM-4 (the shorthand of ‘Friction Materials-4’, containing 3 wt% PEEK) had the lowest specific wear rate with a value of 0.622 × 10⁻⁷ cm³ (N·m)⁻¹ at 350°C. The PEEK can fill the microcracks in the composite at a high temperature and can also cover the hard abrasive particles to prevent them from directly damaging the composite. The findings from this study afford a foundation for studies to further improve the properties of resin-based friction materials.

Chinese bamboo rats consume a diet that consists mainly mechanically demanding bamboo. The ability of the rats to process food depends on the capacity of their teeth to resist wear during biting and chewing. The mechanisms of the bamboo rat teeth were determined by investigating and correlating the structure and tribological properties of the teeth. The rat's incisor has a cutting-edge cusp and outer enamel iron pigmentation, making the teeth harder, more resistant to acid attacks, and improving the resistance to cracking. Additionally, the incisor is designed to self-sharpen. The complex morphology at the macroscale, and the three-dimensional fabric body formed by densely packed rods and inter-rods at the microscale of molar enamel benefit molar rapid capture and effective breaking of bamboo, resisting the high stresses required to process bamboo without wear. The results of the structure–function relations of bamboo rat teeth in this study may provide new ideas for improving plant cutting and grinding tools.

Polyvinyl alcohol (PVA) is a synthetic polymer that has been extensively studied for fabricating porous membranes via electrospinning for diverse biomedical applications. However, the poor mechanical properties of electrostatically spun PVA nanofiber membranes severely limit their application in the biomedical field. Therefore, porous, tough hybrid PVA-based fibrous membranes were prepared by introducing poly (1,8-octanediol citrate) (POC) into PVA fibrous membranes followed by sodium citrate treatment. The tensile modulus, fracture strength, and fracture toughness of the sodium citrate-treated PVA/POC (CPP) membranes achieve 119.81 ± 5.32 MPa, 10.34 ± 1.57 MPa and 401.51 ± 11.67 MJ m⁻², respectively, which were ∼60, ∼10, and ∼4 times higher than those achieved by the pristine PVA membrane. Moreover, the novel CPP membranes exhibited suitable biodegradation ratios and high cell/issue affinities, suggesting their potential biomedical applications in soft or hard tissue repair. This strategy, which provides porous structures, high mechanical properties and excellent biocompatibility, demonstrates a facile but effective approach for the development of advanced biomaterials.

Selective laser melting of nickel-titanium alloy (SLM-NiTi) can precisely control the size of the sample molding structure and has attracted extensive attention due to its special superelasticity and shape memory effect. However, the biological inertness and poor corrosion resistance of SLM-NiTi alloy limit their wide application as biomedical implant materials. In this study, polycaprolactone (PCL) coating was prepared on SLM-NiTi alloy by dipping and pulling method, and the effects of alkali heat pretreatment on the morphology, adhesion, corrosion resistance, long-term stability and biomineralisation of the PCL coatings were investigated. The results showed that PCL coating can substantially improve the performance of SLM-NiTi alloy, and the PCL coating after alkali heat pretreatment has higher adhesion (increased from 1,747 to 2,498 mN) and lower corrosion current density (reduced by about an order of magnitude compared to PCL coating alone). In addition, the necessary stability, biomineralisation and biocompatibility ability of coatings were also further improved. Therefore, the alkali heat pretreated PCL-coated SLM-NiTi alloy has good application prospects in implants due to its superior properties.

Despite numerous published studies on the wear of dental composites, few have considered the influence of temperature on the two-body wear process. Additionally, no previous work has considered the influence of temperature on dominant wear mechanisms during the consumption of hot substances, hence the focus of this study. Reciprocating wear tests were carried out at varying artificial saliva lubricant temperatures (37 and 57°C) and material loss was quantified using profilometry. The wear tracks were analysed using FIB/SEM/TEM. Results reveal that the wear rate of a dental composite can significantly increase with temperature, with fatigue/delamination and ploughing acting as dominant mechanisms.

Hydrogels exhibit a performance similar to that of the extracellular matrix and are compatible with human tissues and organs. Stimuli-responsive hydrogels that can respond smartly to a variety of stimuli have recently attracted extensive interest for biomedical applications. The response of these hydrogels to various single/multiple stimuli shows great potential for drug delivery, biosensors, wound dressing, cancer therapy, and tissue engineering. This review summarises the recent advances in the design of different stimuli-responsive hydrogels and their biomedical applications. We herein describe the mechanisms underlying the stimulus–response, and summarise the strategies for fabricating stimuli-responsive hydrogels that can respond to single or multiple stimuli from endogenous (i.e. pH, enzymes, glucose, and reactive oxygen species) or exogenous (i.e. magnetic and electric fields, temperature, and photo) sources. The current challenges faced by stimuli-responsive hydrogels are discussed and an outlook on future research directions is provided.

Wet adhesion has widespread applications in the fields of wearable electronics, medical devices and intelligent robots. In nature, many organisms have evolved with unique wet adhesion properties to adapt to complex habitats and climb in wet environments without falling. Tree frogs, as crawling masters in tropical rain forests, are representative of wet adhesion and give novel inspirations to design artificial wet adhesive materials by mimicking their specialised hexagonal structures and/or mucus composition. In this review, we first overview the research progress of tree frog toe pads from the perspective of toe pad structure and adhesion mechanism. Then, wet adhesive materials inspired by tree frog toe pads are systematically summarised from (i) the typical polymers, (ii) the preparation approaches, (iii) the adhesion test methods and (iv) the typical artificial adhesion surfaces. Third, various applications of bioinspired wet adhesive surfaces are highlighted. Finally, we present future challenges and opportunities to develop tree frog-inspired wet adhesive materials.

Hydrogels have been considered as potential candidates for cartilage replacement due to their high-water content, extreme network hydration, excellent biocompatibility and tunable mechanical properties. Currently, the development of high-performance cartilage-inspired hydrogel lubrication materials has become a hot topic in the field of biomedical materials. This review focusses on the recent development of cartilage-inspired high-strength hydrogels from the viewpoints of bionic surface/interface and biotribology. Specifically, the composition structure and extraordinary lubrication mechanism of the natural articular cartilage are overviewed first. Subsequently, some of the novel biomimetic design strategies for preparing high strength cartilage hydrogels with various network structures are summarised in detail, while systematic evaluation of lubrication properties and mechanisms are discussed. Furthermore, new surface modification means for improving the lubrication feature of high strength cartilage hydrogel materials are presented. In addition, in order to demonstrate the application potential of cartilage hydrogels in clinical, several bonding methods to decorate hydrogels onto surfaces of natural bone tissues or artificial joint materials are introduced. Finally, current challenges and future research directions are discussed for cartilage-inspired hydrogel lubrication materials.