Biosurface and Biotribology最新文献

Severe lesions in vessels need to be treated with implantable interventional devices such as vascular stents, which should be anti-coagulantion, anti-proliferation and promoting endothelialisation. Nitric oxide (NO), as a physiological gas signalling molecule, play an important role in revascularisation. Catalysing the release of NO from endogenous donors has already been widely favoured to treatment strategy for lesioned vessels. In this work, a series of copper-loaded coatings (titanium nanotube (TNT)/PDA-Cu) was fabricated by TNTs combined with polydopamine and ions, which achieve controlled in situ catalytic release of NO. This strategy could effectively immobilised copper ions on TNTs, and promoted the proliferation of endothelial cells and inhibited growth of smooth muscle cells (SMCs) via the performance of NO, as well as restrain the platelet adhesion. With the multiple function, TNT/PDA-Cu provides a promise approach for promoting endothelialisation, anti-coagulation and inhibition of SMC proliferation via copper-loaded coatings on TNTs.

Chitosan has good biocompatibility, in vivo biodegradability and certain physiological activity, which can be used as a drug carrier to stabilise and protect drug components, causing the promotion of drug absorption and controlling drug release. Using graphene oxide (GO) as a cross-linking agent, the functional groups in its lamellar structure can interact effectively with the functional groups in chitosan molecules, leading to enhanced mechanical properties and optimize the controlled drug-release behaviour. GO/chitosan composite films were prepared by the solution mixing method with various GO content and exhibit many hydrogen bonds between the GO and chitosan. There were no obviously agglomerated GO particles in the surface of composite films, and the lamellar structure can be observed in the cross section of the composite films. Differential thermal analysis (DTA) indicated that the addition of GO increased the stability of the chitosan film. The baicalin-loaded GO/Chitosan also exhibited pH dependent release behaviour, with an increasing release amount and rate at lower pH medium. In addition, the result of biological evaluations showed that the GO/Chitosan films had good cytocompatibility in vitro and histocompatibility at appropriate GO concentrations. This investigation offered a new pH-dependent drug carrier potentially applied for tumour and atherosclerosis treatment.

Reduction of energy consumption and improvement of cruising speed are greatly necessary for underwater vehicles. Previously, regular riblets have been machined and the drag reduction has been verified; however, the riblet parameters are not adjusted like the denticles of sharkskin, which adapt quickly to the complex changing fluid flow. To achieve an improved drag reduction effect on the complicated shape surface, a simple, low-cost, and timesaving stretching approach was proposed to adjust the riblet parameters on the underwater vehicle surface by controllable deformation. Nature latex rubber membrane with regular micro-riblets was prepared as a stretching flexible film, and the spacing and height of the micro-riblets were adjusted by adaptive control of the stretching ratio. The circulating water channel experiment verified the effectiveness and feasibility of the self-adaptive drag reduction by the controllable deformation method. The results demonstrated that the drag reduction rate of the controllable deformation bionic fish skin was 4.26% compared with a smooth surface at 0.25 m/s with an angle of attack of 0°, which is better than any other angle. The controllable deformation bionic fish skin provides a feasible method for the drag reduction of complex surface adaptive underwater vehicles.

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.