Ti-6Al-4V alloy is widely used in aircraft, automotive and biomedical applications due to its corrosion resistance, high strength-to-weight ratio (i.e., specific strength) and biocompatibility properties. Even though these characteristics are required in metal components used in total joint replacement surgeries, Ti-6Al-4V exhibits a poor tribological performance.

Different post-processing approaches (e.g., heat treatments, surface coating, and surface texturing) have been investigated to tackle this drawback. Laser texturing, for instance, has become an increasingly post-processing route for improving the corrosion resistance, tribological behaviour and biocompatibility of Ti-6Al-4V surfaces. In the work of Wang and collaborators (2022), they investigated those properties by creating a microgrooved surface on the alloy via UV nanosecond laser texturing.

An enhancement in corrosion resistance was found in laser texture surfaces, which might be due to a β → α phase transformation occurring in the surface motivated by laser ablation. On a similar note, the tribological performance of the surface treated material displayed an enhancement (i.e., reduction of coefficient of friction during dry sliding and decrease in wear volume generated). The authors attribute this phenomena to an augmentation in the surface hardness of the material also caused by laser texturing.

In vitro bioactivity, evaluated via BMSC adhesion, also followed the trend of the before-mentioned properties, with microgrooved surfaces showing the highest proliferation rate and adhesion number.

Header image reproduced from Wang (2022).

References:

Header Image: The surface morphology with the magnification of one thousand times of the four kinds of plant leaves: (a) Photinia serrulata, (b) Ginkgo, (c) Aloe vera and (d) Hypericum monogynum. (CC BY-NC-ND 4.0)

Throughout millions of years, organisms evolved in Nature due to a need of adaptation driven by different environmental conditions imposed. Functional systems with intricate properties arose from this continuous structural development leading to, for example, super hydrophobic and self-cleaning surfaces found in lotus leafs (referred as “lotus effect”). An understanding of role of the microstructural features in these systems may help elucidating how to tailor system with an appropriate surface wettability.

In order to tackle this need, Wang and co-workers (2016) studied the wettability properties of four different types of plants (P. serrulata, Ginkgo, Aloe vera, H. monogynum) exhibiting dissimilar microstructures by means of static contact angle for deionized water.

Their results provide an insightful understanding of surface wettability. Whilst minor corrugated and raised boundary microstructures portray the highest wettability (i.e., P. serrulata), increase in cross section corrugation diminishes the liquid/surface contact area and, therefore, intensifies hydrophobicity. Also, the L/W ratio seems to play a major role in surface wettability. Ginko, although displays a corrugated microstructure on the leaf, its large L/W ratio promotes diffusion of liquid, which consequently leads to a hydrophilic surface.

References:

Header image adapted from Liu, 2021. Left: Working mechanism of the fabricated TENG. Right: The short-circuit current of the TENG with different debris sizes.

Mechanically assisted corrosion of metal alloys in hip implants also releases solid particles as well as metal ions into the synovial fluid. Compared to metal ions/particles in blood particles at the surrounding tissues, far fewer studies had been reported on synovial fluid during in-vitro study. Moreover, the metal ions concentrations and the wear particles sizes reported in different studies have greater variations. Also, the Wear debris can either reside as solid particles or can dissolve and further enhance the ion content. Thus it is extremely desirable to produce a technique for in-situ wear debris characterization which might be significant in predicting wear rate and understanding the wear mechanism of implant bearings.

Based on the variety of material selection, device structure, and operating mode, biomedical sensors such as the Triboelectric nanogenerator (TENG) was developed as a newly emerging energy technology for monitoring the creation of wear debris in artificial joints where the artificial joint itself can be used as a TENG by the coupling of triboelectrification and electrostatic induction (Liu et al.2021). With the TENG, different micron sizes of wear debris can be separated based on different voltage amplitude. However, the developed method is highly sensitive to test medium and did not provide any rationale in lubricant containing environment which needs further modification.

Read this interesting article using the below link:

This article was written by MM Raihan as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Raihan is researching In-situ Measurement of Nano-scale Wear Utilising Advanced Sensors at the University of Leeds, UK.

Replacement of the human joints when diseased or damaged during trauma is an incredibly effective operation. Every year, orthopaedic surgeries effectively restore physical function and relieve pain for millions of Europeans. However, despite great surgical achievements and uniform pain alleviation after total joint replacement, there is still significant heterogeneity in functional progress after joint replacement.

Besides, physical condition, poor mental health has been identified as a key parameter impacting early recovery. The patients who are being waiting for hip replacement or already done so, need mental health support apart from just focusing on pain relief. In a study on 900 patients in UK, 72% showed deterioration in their mental health before and after the surgery. Poor functional performance have been linked to inadequate mental health, such as anxiety and depression, as well as poor coping skills and social support.

According to data from the Swedish Hip Arthroplasty Register, depression and anxiety levels were strong predictors of pain alleviation and patient satisfaction. Thus an appropriate assessment of emotional health has been suggested that may enable a modification in the way patients are managed. The emotional support can help to improve the pain tolerance of the patients. It was also observed that patients with limited pain tolerance, whether they have good or bad emotional health, are more likely to report lower postoperative gains. Thus anyone with arthritis who is awaiting or had surgery should not be left alone. Apart from the emotional support, personalised self-management support, signposting to financial support and advice have been recommended. Teams of clinicians, including physical therapists, behavioural psychologists, and other support specialists, may get involved in such activities.

More study is required to establish perioperative postoperative techniques that simultaneously promote the physical and emotional health of the patients in order to ensure maximal functional gain following technically successful surgery.

References

1. https://www.versusarthritis.org/news/2021/june/we-are-calling-for-more-support-for-those-waiting-for-joint-replacement-surgery/
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3808180/

This article was written by MM Raihan as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Raihan is researching In-situ Measurement of Nano-scale Wear Utilising Advanced Sensors at the University of Leeds, UK.

High-impact sports are generally discouraged after surgery including surfing, Rugby, martial arts, and football due to significant risk of falling. In contrast, Golf, cycling, hiking, and swimming (avoid breaststroke) are all recommended as low-impact activities. There is lack of evidence available about surfing following hip resurfacing arthroplasty (HRA) or total hip arthroplasty (THA).

Vanlommel et al. thus undertook a study in a single surgeon series to evaluate the quality and viability of resuming this intense sport after HRA, with the hypothesis that return to surfing is viable after HRA. They examined 45 patients who had practised surfing prior to the beginning of pain and hip surgery. For 37 (82%) patients, complete clinical and radiological follow-up was done including several questionnaires. The results were amazing. More than 80% of patients commenced surfing within the first 6 months after surgery. During surfing, 21 patients (72%) were completely pain free. More than 80% of patients began surfing within 6 months of their surgery. 21 patients (72%) were fully pain-free when surfing.

Wait don’t go for surfing right now if you have just undergone HRA or THA surgery. This study is a short term evaluation. A prospective study based on preclinical laboratory simulation and high quality clinical study such as the High-Activity Arthroplasty Score remains necessary to let you go enjoy surfing.

To read the interesting article, follow the provided link

This article was written by MM Raihan as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers. Raihan is researching In-situ Measurement of Nano-scale Wear Utilising Advanced Sensors at the University of Leeds, UK.

Fluids, including liquids and gases, fall into two categories: Newtonian fluids and non-Newtonian fluids. A key difference between these two fluids is that they respond differently to the applied forces. The rheology of non-Newtonian fluids changes dramatically under processing conditions, however, that of Newtonian fluid remains constant.

Newtonian fluids: These fluids obey Newton’s law of viscosity and have a linear correlation between the rate of angular deformation and shear stress. In such fluids, viscosity remains constant regardless of shear rate. Water, air, glycerine, gasoline, alcohol can be taken as examples of these Newtonian fluids.

Non-Newtonian fluids: These fluids do not obey Newton’s law of viscosity and the viscosity declines or enhances respective to the type of fluid under applied shear. The five ways, describing how non-Newtonian fluids behave, are explained as follows (figure 1):

• Dilatant: The viscosity of the fluid increases with an increase in shear stress. Quicksand and mud slurry are two examples of dilatant fluids.
• Pseudoplastic: The viscosity of the fluid decreases with an increase in shear stress. Blood and ketchup are two examples of pseudoplastic fluids.
• Bingham plastic: These fluids, like oil paint, have a linear relationship between the rate of angular deformation and shear stress. The difference between these fluids and Newtonian ones is that they have internal yield stress making them a time-dependent relation.
• Rheopectic: The viscosity of the fluid increases with an increase in shear stress and the relation is time-dependent. Gypsum paste can be taken as an example.
• Thixotropic: The viscosity of the fluid decreases with an increase in shear stress and the relation is time-dependent. Paint and glue are two examples of thixotropic fluids.

References

[1] Newtonian and Non-Newtonian Fluids | Newton’s Law of Viscosity (apsed.in)

This article was written by Mahdieh Mosayebias part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Mahdieh is researching the Design of Self Lubricating Prothesis at ETH Zurich, Switzerland.

It’s really hard to miss out on the news about football players wearing Zorro’s masks during the games. When Son Heung-min showed up at the Qatar World Cup as South Korea face Brazil, wearing that shining, chic, black face mask, everyone on the internet was talking about it. Actually, many football players have been seen wearing similar masks to the match, including Croatian player Joško Gvardiol and Tunisia’s Ellyes Skhiri as in the cover picture. So, what are these face masks for and how are they made?

Protective face masks have been loved by many athletes who have recently fractured a nose or an eye socket but are eager to get back to the pitch as soon as possible. The 3D surface imaging, 3D modelling, and 3D printing technology enable the design process to be accurate and customisable, 100% specific to the face of the athletes. The masks are designed to be lightweight, comfortable and unobtrusive, but provide incredible strength to protect fractured bones or prevent future injury.

References:

Header Image Adapted from: https://www.theguardian.com/football/2022/nov/28/why-are-world-cup-players-wearing-strange-face-masks-on-the-pitch

https://www.technologyinmotion.com/orthotics/sports-facemask/

This post was written by Esperanza Shi as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Esperanza is researching the Optimisation of Scanning Strategies for 3D Printed Artificial Joints at Imperial College London, UK.

Generative text AI tools, such as ChatGPT, have recently garnered significant attention due to its ability to provide comprehensive responses and eloquent answers across many domains of knowledge. Whilst it represents a significant technological advancement, it has been met with both positive and negative reviews. Elon Musk wrote that “ChatGPT is scary good”. It has also received widespread criticism particularly around efficacy and integrity from educators, academics and journalists plus many more.

But how should we embrace these tools? Professor Michael Bryant asks ChatGPT ‘What are the current research challenges in biotribology?’

Biotribology is the study of friction, wear, and lubrication of biological systems, including joints, implants, and prosthetics. Some of the current research challenges in biotribology include:

1. Understanding the complex interactions between biological tissues and synthetic materials: One of the major challenges in biotribology is to understand the complex interactions between biological tissues and synthetic materials used in implants and prosthetics. This requires a deep understanding of the mechanical, chemical, and biological properties of both the biological tissues and the synthetic materials.

2. Developing advanced testing methods: Biomechanical testing of biological tissues is challenging due to their complex nature. Developing advanced testing methods that can accurately measure friction, wear, and lubrication in biological systems is a critical research challenge.

3. Designing and developing better implant materials: Developing new materials and coatings for implants that can better mimic the natural properties of biological tissues is another important research challenge. This can help improve the biocompatibility, durability, and longevity of implants.

4. Improving lubrication of joint replacements: The lubrication of joint replacements is a critical factor in their performance and longevity. Developing better lubrication strategies and materials is a key research challenge in biotribology.

5. Studying the effects of aging and disease: Aging and disease can significantly impact the friction, wear, and lubrication of biological systems. Studying the effects of aging and disease on biotribology can provide valuable insights into the development of better treatments and therapies for patients.

It is a good job BioTrib is working across all of these domains to address the current research challenges highlighted by ChatGPT. What will be interesting to see is how these changes with time as the field advances. Certainly some of these challenges have been of focus to researchers for many a year.

This article was written by ChatGPT and BioTrib Lead Scientist, Professor Michael Bryant.

Alginate is widely used as a biomaterial in 3D bioprinting due to its biocompatibility, biodegradability, high accessibility, shear thinning behavior, and cross-linking speed. The rheological properties of the bioink are the key factor influencing printability (ability to form and maintain the design shape), therefore investigations are conducted to enhance the weak mechanical properties of alginate gel in order to obtain hybrid hydrogels with high printability. Indeed, when using 3D bioprinting, the objective is to obtain a multilayer construction that retains its mechanical stability over time and, in order to produce relevant in vitro tissue models, the final goal is to match the native mechanical properties of the tissue.

In the review ‘Alginate based hydrogel inks for 3D bioprinting of engineered orthopedic tissues’, Murab et al. provide an overview of the different parameters such as printing method, concentration of alginate and crosslinker, and shape of the printed structures on the properties of the alginate-based printed construct. Specifically, they reviewed different strategies used in the last few years to increase the mechanical and biological performances of alginate-based hydrogels for bioprinting of bone and cartilage. For example, the advantageous properties of alginate and type I collagen have been combined to create a lattice structure with improved mechanical properties and higher expression of cartilage-specific genes in primary rat articular cartilage chondrocytes compared to the alginate control.

Another example of cartilage tissue engineering using alginate combined the latter with polycaprolactone (PCL) to create a stable PCL support scaffold with bioprinted alginate in between. The resulting construct exhibits good mechanical stability and the goat cartilage cells embedded in alginate were found to have high viability with the production of a cartilage-like matrix. Although encouraging results are presented in the literature, there is still a long way to go to use the alginate-based hydrogels for in vitro orthopedic models.

References

Murab, Sumit, et al. “Alginate based hydrogel inks for 3D bioprinting of engineered orthopedic tissues.” Carbohydrate Polymers (2022): 119964.

This article was written by Marie Moulin as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Marie is researching the Bioprinting of Bone and Cartilage at Uppsala University, Sweden.

The fabrication of functional constructs that mimic the physiological characteristics of tissues would represent a major breakthrough for the creation of complex in vitro models or for regenerative medicine. Current 3D biofabrication technologies, such as stereolithography or extrusion bioprinting, are used to attempt to achieve this goal by combining cells and biomaterials according to a specific architecture, layer by layer. This additive manufacturing method limits the ability to create clinically relevant sized constructs, as the printing time for centimeter-sized constructs is too high to preserve cell viability (cells remain in the cartridge and construct, outside of an optimal culture environment). Volumetric bioprinting is a promising technology that could produce clinically relevant sized living constructs in less than a minute.

This emerging technology uses the principle of medical tomography in reverse, projecting a 2D patterned optical light field into a volume of photopolymer, which causes cross-linking in the area where the light exposure builds up to produce a 3D construct. Paulina Nuñez Bernal et al. described in 2019 the utilisation of this technic to create a 3D meniscus-shaped construct with high resolution, high cell density, and cell viability (>85%). To do so, a gelatin-based photoresponsive hydrogel (gelMA) containing chondroprogenitor cells (ACPCs) was used. Over time, the cells in the printed constructs synthesized fibrocartilage ECM, which increased the mechanical properties of the meniscus to a compressive modulus value comparable to that of native fibrocartilage. This achievement using volumetric bioprinting could be promising for the future of knee joint repair.

References

Bernal, Paulina Nuñez, et al. “Volumetric bioprinting of complex living‐tissue constructs within seconds.” Advanced materials 31.42 (2019): 1904209.

This article was written by Marie Moulin as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.

Marie is researching the Bioprinting of Bone and Cartilage at Uppsala University, Sweden.