Biosurface and Biotribology最新文献

Selenium (Se), a well-known essential element in human health, plays a vital role in regulating metabolism owing to its antioxidative nature. However, organic Se compounds are toxic and cannot be used for biomedical applications. Selenium nanoparticles (SeNPs) exhibit low biological toxicity and high bioavailability; however, they are prone to aggregation and are extremely unstable, thereby diminishing their bioactivity and bioavailability. To overcome these limitations, ultra-small, highly stable, and bioactive SeNPs were synthesised based on an in-situ hybridisation strategy by using polyphenol-grafted-chitosan (GA-CS) to control and restrict crystal growth of Se nanoparticles. The resultant GA-CS@nSe exhibited an average particle size of ∼30 nm and was highly stable in aqueous solutions. In addition, GA-CS@nSe displayed improved biocompatibility and enhanced antioxidative activity. Taken together, the authors provide a basis for polyphenol-mediated construction of Se-based particles with increased bioactivity.

To improve the tribological characteristics of dimples on the surface of 45 steel, the dimples were filled with MoS₂ and MoS₂ modified by dopamine (MoS₂ @ DA), and ball-disk friction and wear tests were conducted. Specifically, the dimple filling gap, abrasion depth, and surface cross-sectional area of 45 steel were measured. The wear morphology of the friction ball and exfoliation of MoS₂ in the dimples and the bending characteristics of the specimens were studied. The surface friction coefficient of MoS₂ @ DA-filled specimen was 17.9% lower than MoS₂-filled specimen, and the dimple filling gap was 70.1% lower, the surface abrasion depth was 5.8% lower, and the abrasion cross-sectional area was 17.7% smaller. Moreover, the bending strength of the MoS₂ @ DA specimen was 3.27 times greater than that of the MoS₂ specimen, and the exfoliation of MoS₂ was slowed by filling with the MoS₂ @ DA. Finally, the tribological characteristics were also superior for the specimens prepared with MoS₂ @ DA.

Because of their tissue-like mechanical performances, high biocompatibility, and adjustable functionality, hydrogels have become increasingly attractive materials for promoting wound healing. Chronic wounds include burn, diabetic, and infected wounds. Unlike common incision wounds, chronic wounds are more challenging to heal. To meet the clinical needs, multifunctional hydrogels should be fabricated and investigated. To guide future studies on the fabrication of hydrogel-based chronic wound dressings, a review of advanced multifunctional hydrogels is necessary. Various hydrogels with advanced properties, such as antibacterial, antioxidant, bioadhesive, anti-inflammatory, and wound healing properties, that can be used for skin burn wounds and diabetic wounds are summarised. Lastly, the prospects of advanced hydrogels for wound healing are elaborated.

In order to solve the problem of excessive degradation rate and insufficient biocompatibility of magnesium-based bone implants, a polyphenol (EGCG) induced hydroxyapatite (HA) coating was prepared on the surface of AZ31 alloy. The physical and chemical properties and corrosion resistance of the coating were analysed in depth, and its biocompatibility was preliminarily explored in vitro. The results showed that the polyphenol (EGCG) conversion coating constructed on the AZ31 could successfully induce the formation of HA by complexing the phenolic hydroxyl group with calcium ions. The electrochemical and long-term immersion experiments showed that the corrosion resistance of EGCG/HA composite coating was significantly improved. The self-corrosion current density, hydrogen evolution and the increase of pH value of AZ31-EGCG/HA were significantly lower than those of AZ31. On the basis of inhibiting the excessive corrosion of the substrate, the composite coating significantly improves the compatibility of pre-osteoblasts, supports the adhesion and spreading and effectively reduces the haemolysis rate to less than 5%. The preparation method of the coating is simple, low cost and suitable for complex shape surfaces, which can significantly improve the corrosion resistance and biocompatibility of the AZ31 substrate. It is expected to provide a solution for the surface modification of magnesium-based bone implants.

Inspired by the excellent wear resistance and lubrication of articular joints, a novel bionic interfacial system was proposed by combining thixotropic hydrogel with surface porous Ultrahigh Molecular Weight Polyethylene (UHMWPE). Thixotropic hydrogel, synthesised by gelatin, alginate sodium, tannic acid and weak crosslinking by Ca²⁺ (Gel-TA-Alg@Ca²⁺), was used as a lubricant due to its shear-thinning when loaded, then the recovery viscosity to be benefitted for reserving in surface pores on UHMWPE when unloaded. Surface porous UHMWPE was fabricated by using hydroxyapatite particles as porogen to control its porosity, pore size, surface roughness and surface energy (PE-HA). Gel-TA-Alg@Ca²⁺ significantly reduced average coefficients of friction and wear factors compared to those under normal saline and calf serum solution lubricating after reciprocating tribological testing. Notably, Gel-TA-Alg@Ca²⁺ still maintained thixotropy and was stored in surface pores of UHMWPE even after tribological testing for 7200 min. Thus, durable lubrication could be realised due to the synergistic effect of surface porous structure and thixotropy. Stribeck curves showed the characterisations of mixed, elastohydrodynamic and hydrodynamic, but without boundary lubrications for PE-30HA under three lubricants. The present results might provide the potential application to construct the durable lubrication bionic articular joint interfacial system for artificial joints.

Experimental in vitro simulation can be used to predict the wear performance of total knee replacements. The in vitro simulation should aim to replicate the in vivo loading, motion and environment experienced by the joint, predicting wear and potential failure whilst minimising test artefacts. Experimental wear simulation can be sensitive to environmental conditions; the environment temperature is one variable which should be controlled and was the focus of this investigation. In this study, the wear of an all-polymer (PEEK-OPTIMA™ polymer-on-UHMWPE) total knee replacement and a conventional cobalt chrome-on-UHMWPE implant of similar initial surface topography and geometry were investigated under elevated temperature conditions. The wear was compared to a previous study of the same implants under simulator running temperature (i.e. without heating the test environment). Under elevated temperature conditions, the wear rate of the UHMWPE tibial inserts was low against both femoral component materials (mean <2 mm³/million cycles) and significantly lower (p < 0.05) than for investigations at simulator running temperature. Protein precipitation from the lubricant onto the component articulating surfaces is a possible explanation for the lower wear. This study highlights the need to understand the influence of different variables including environmental temperature to minimise the test artefacts during wear simulation which may affect the wear rates.

The authors previously developed a scaffold-free tissue-engineered construct (TEC) from mesenchymal stem cells (MSCs). Although the TEC exhibited even cell distribution and was successfully applied for cartilage repair in animal models, it is unsuitable for relatively large-scale cartilage defects due to its small size. To solve the problem, the authors recently developed a novel biomaterial, a centrifugally compressed cell-collagen combined construct (C⁶) from a mixture of MSCs and atelocollagen, both of which are subjected to centrifugation. The results of the previous study indicated that C⁶ exhibited high cell viability (70 %) and sufficient cell distribution similar to that of the TEC. In the present study, the morphology and gene expression of C⁶ were investigated. Histological examination indicated that C⁶ is six times thicker (approximately 1 mm) than the TEC after a 7-day culture. The C⁶ remained unchanged in scale with increased cell density after a 21-day culture. Scanning electron microscopic observation indicated that C⁶ exhibited interconnected and porous microstructures, while the TEC had close-knit microstructures. Reverse transcriptase-polymerase chain reaction analysis indicated that the expression of sex-determining region Y-box 9 and runt-related transcription factor 2 was significantly higher in C⁶ than that in TEC.

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.