Biosurface and Biotribology最新文献

In this study, a bioinspired hierarchical structure was formed with superomniphobicity on a 7075 aluminium alloy using laser ablation. The morphology and wetting characteristics of the biomimetic sample surface were characterised using scanning electron microscopy, laser confocal microscopy, and contact angle measurements. The effect of the liquid properties and surface structures on the rolling behaviour was investigated. The results suggest that the fabricated biomimetic sample surface was a hierarchical structure. The prepared sample had superomniphobicity and low adhesion properties, and the contact angles of six different liquid droplets on the sample surface reached or approached 150°. Specifically, the largest contact angle was 152°, and the average rolling angle was 7.7°. This multi-hydrophobic surface provides a valuable reference for the research study and use of a variety of solid–liquid contacts.

Excessive wear is a key issue affecting the performance of ultra-high molecular weight polyethylene (UHMWPE)-based artificial prosthesis. This work is focussed on the bio-tribology behaviours of UHMWPE when mating with different metal counterparts (iron-based 316L, Co-based Stellite-S21 and Stellite-S22). According to the ASTM F732 standard, two million cycles comparative wear tests were carried out under bovine serum lubrication. When coupled with S21, S22, and 316L metal counterparts, the obtained average wear factors of UHMWPE were 1.333 ± 0.192, 1.360 ± 0.160, and 1.190 ± 0.177 × 10⁻⁶ mm³/N · m, respectively. Initial surface roughness of the metal counterpart has shown an important role in controlling the volume of UHMWPE wear, especially the first one million cycles. Compared with 316L, CoCrMo-based counterparts possessed relative higher hardness and exhibited less rise in surface roughness caused by wear. For UHMWPE-on-metal bearings, random scratch, surface pit, and wear debris attachment were commonly seen, which suggested the coexistence of abrasion, third-body abrasion, and adhesion-based wear. In contrast, the metal counterpart was slightly scratched with no polymer transfer film formation. The work conducted in the present study gives useful knowledge regarding the UHMWPE-on-metal bearing design. With an intention to minimise wear, surface roughness of metal counterpart should be carefully controlled.

With one-third of patients having osteoarthritis predominantly in one compartment of the knee, unicompartmental knee spacers have been introduced as a less invasive alternative to total knee replacement. However, patients with the knee spacer implanted were seen to have persistent pain, resulting in high revision rates. A static finite element model of the knee and its interaction with a knee spacer implant at full extension and 90° flexion was used to investigate the tibio-femoral contact mechanics of the knee joint after a knee spacer surgery. Three different knee spacer designs (contoured, flat and C-shaped) were modelled and prescribed with cobalt-chrome, ultra-high molecular polyethylene and polyurethane material properties. The results suggested that a softer spacer is generally preferred as this helps in the conformity of knee spacer to the condyle, effectively distributing the load subjected to the implant. Flat spacers that result in high stresses resulting from lower contact areas should be avoided.

A fluorine-free and multifunctional superhydrophobic coating (r-MSC) was prepared by the one-step spraying method. The coating had superhydrophobic and low-adhesion properties with the water contact angle of 161.5° ± 1° and the sliding angle of 3.2° ± 0.5°. It could be prepared by spraying while maintaining superhydrophobic surface characteristics on any substrates. The coating owed outstanding mechanical durability and chemical stability. Moreover, the coating also possessed the ability of self-cleaning, anti-fouling, anti-icing, and flame retardant ability. Importantly, the presence of multifunctional coating endowed the substrate with both water-resistant and fireproof properties. Besides, it also showed excellent oil-water separation ability, which presented the oil-water separation efficiency of over 90% for different types of oils after 10 separation cycles. Furthermore, the coating could improve corrosion inhibition performance and the corrosion current density was reduced by two orders of magnitude from the polarization curve. The r-MSC had the advantages of simple preparation, fluorine-free, environmentally friendly and appropriate for large-area fabrication, which could be applied to various fields.

There are various walking pavements in daily life. Slip accidents will happen if required friction for safe walking is greater than available friction between the foot and ground surface. Existing researches mostly focus on horizontal or slope pavements, whereas the cross-slope walkways are less. A self-developed gait friction test platform was used to test friction, distribution of plantar pressure and spatiotemporal parameters of human walking under cross-slope condition. With the increase of cross-slope angles, the mediolateral friction increases (R ² = 0.972, P < 0.001), the anterior-posterior friction shows no significant change (R ² = 0.758, P = 0.017), the normal pressure decreases (R ² = 0.915, P = 0.007), and the high foot is more prone to slip and fall than low foot. Therefore, plantar pressure distribution of both feet was shifted to left. The gait cycle was prolonged (P < 0.001), swing period of both feet decreased (P = 0.029) and support period increased (P = 0.015) with the increase of cross-slope angle.

Hydrophilic polymers are very useful in biomedical applications. In this study, biocompatible polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) polymers end-capped with succinimidyl groups were either modified or synthesised and attached to polyvinylchloride surfaces. The modified surfaces were evaluated with cell adhesion and bacterial adhesion. 3T3 mouse fibroblast cells and three bacteria species were used to evaluate surface adhesion activity. Results showed that the modified surface exhibited significantly reduced 3T3 cell adhesion with a 50%–69% decrease for PEG and a 64%–81% for PVP, as compared to unmodified polyvinylchloride. The modified surface also showed significantly reduced bacterial attachment with 22%–78%, 18%–76% and 20%–75% decrease for PEG and 22%–76%, 18%–76% and 20%–73% for PVP to Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, respectively, as compared to unmodified polyvinylchloride. It seems that an appropriate chain length or molecular weight (neither the longest nor the shortest chain length) determines the lowest cell and bacterial adhesion in terms of PEG. On the other hand, a mixture of polymers with different chain lengths exhibited the lowest cell and bacterial adhesion in terms of PVP.

Corrosion and wear play significant roles in the aseptic loosening of artificial hip joints for the long-term service. In this present study, tribo-corrosion tests were carried out through a reciprocating ball-on-plate system to evaluate the corrosion and wear properties of CoCrMo, Ti6Al4V and Ti15Mo alloys in a simulated body fluid (SBF) solution. It was found that the tribo-corrosion behaviours of CoCrMo/Al₂O₃ and Ti15Mo/Al₂O₃ systems had significant wear-corrosion synergistic interaction, and wear-induced corrosion was dominant. For Ti6Al4V/Al₂O₃ systems, their wear mechanism under SBF lubrication was a combination of abrasive, adhesive and fatigue wear. While the wear mechanism of the Ti15Mo/Al₂O₃ system under synergistic interaction was a combination of abrasive and adhesive wear. Finally, it was suggested that the Ti15Mo alloy would be the better alternative for metal implant applications compared with the CoCrMo alloy for the consideration of both wear and potential poisonous ions such as Co(III) and Cr(VI).

In general, tooth wear is difficult to be noticed until it leads to toothache in vivo. Developing a dynamic dental wear monitoring system to predict tooth wear in daily life is a necessity. The translation between complex surface wear morphology and corresponding digital signal source is a technical limitation to develop this kind of monitoring system. Microwear texture analysis has been widely employed in predicting diet by a palaeontologist. The main question is whether the microwear texture analysis has potential development space to develop a sensor for monitoring tooth wear. According to obtained results, the microwear texture analysis had enough sensitivity to display the surface morphology variations for different chewing foods and various angles. The corresponding sensitive digital signal of tooth microwear surface morphology makes it possible to develop a dental microwear sensor.

Understanding material-protein interactions is the basis for regulating material-blood interactions, which is a common topic of interest for medical material developers. In recent years, researchers have conducted extensive studies on (1) the structural characteristics of the plasma protein adsorption layer on the material surface, including the evolution of the protein adsorption layer and its typical binary structure. (2) Influence factors of the protein adsorption layer formation include protein factors (e.g., isoelectric point, structural stability), material factors (e.g., wettability, surface charge, morphology, size), and environmental factors. (3) Effects of some common plasma proteins in the protein adsorption layer on material-blood interactions. Here, we review the important research results in this field, hoping to provide a reference for future development of advanced blood contact materials.

Slippage is a common phenomenon between laparoscopic graspers and tissues during minimally invasive surgery, which may lead to inefficient surgical operations, prolonged operation time, and increased patient suffering. The stability factors related to the friction behaviour between laparoscopic graspers and the large intestine, including bio-surface liquids, pulling angle, and surface profile of graspers, were studied. The friction behaviour at the large intestine–grasper interface was tested using a UMT-II tribometer under the conditions of clamping force of 1–4 N, sliding displacement of 15 mm, and sliding velocity of 2 mm/s to simulate the grasping and pulling operations of soft tissue. The results showed that the bio-surface liquid (serum) of the large intestine significantly decreased the friction coefficient, thus reducing the grasping efficiency. A pulling angle of 15° could generate the peak frictional force and enhance the grasping stability. The frictional force increased with the ratio of the profile surface area of the grasper. These results demonstrate that the grasping stability can be improved by changing either the bio-surface liquid condition or the pulling angle. In addition, a grasper with a larger profile surface area can also prevent slippage due to its significant influence on the pressure distribution and actual contact area for tissue retention.