The human body involves a large number of systems subjected to contact stresses and thus experiencing wear and degradation. The limited efficacy of existing solutions constantly puts a significant financial burden on the healthcare system, more importantly, patients are suffering due to the complications following a partial or total system failure. More effective strategies are highly dependent on the availability of advanced functional materials demonstrating excellent tribological response and good biocompatibility. In this article, we review the recent progress in implementing two-dimensional (2D) materials into bio-applications involving tribological contacts. We further summarize the current challenges for future progress in the field.
The COVID-19 pandemic has raised the problem of efficient, low-cost materials enabling the effective protection of people from viruses transmitted through the air or via surfaces. Nanofibers can be a great candidate for efficient air filtration due to their structure, although they cannot protect from viruses. In this work, we prepared a wide range of nanofibrous biodegradable samples containing Ag (up to 0.6 at.%) and Cu (up to 20.4 at.%) exhibiting various wettability. By adjusting the magnetron current (0.3 A) and implanter voltage (5 kV), the deposition of TiO2 and Ag+ implantation into PCL/PEO nanofibers was optimized in order to achieve implantation of Ag+ without damaging the nanofibrous structure of the PCL/PEO. The optimal conditions to implant silver were achieved for the PCL-Ti0.3-Ag-5kV sample. The coating of PCL nanofibers by a Cu layer was successfully realized by magnetron sputtering. The antiviral activity evaluated by widely used methodology involving the cultivation of VeroE6 cells was the highest for PCL-Cu and PCL-COOH, where the VeroE6 viability was 73.1 and 68.1%, respectively, which is significantly higher compared to SARS-CoV-2 samples without self-sanitizing (42.8%). Interestingly, the samples with implanted silver and TiO2 exhibited no antiviral effect. This difference between Cu and Ag containing nanofibers might be related to the different concentrations of ions released from the samples: 80 μg/L/day for Cu2+ versus 15 μg/L/day for Ag+. The high antiviral activity of PCL-Cu opens up an exciting opportunity to prepare low-cost self-sanitizing surfaces for anti-SARS-CoV-2 protection and can be essential for air filtration application and facemasks. The rough cost estimation for the production of a biodegradable nanohybrid PCL-Cu facemask revealed ~$0.28/piece, and the business case for the production of these facemasks would be highly positive, with an Internal Rate of Return of 34%.
- MeSH
- antivirové látky chemie MeSH
- biokompatibilní potahované materiály chemie MeSH
- Cercopithecus aethiops MeSH
- COVID-19 prevence a kontrola přenos MeSH
- lidé MeSH
- měď chemie MeSH
- nanovlákna chemie MeSH
- polyestery chemie MeSH
- SARS-CoV-2 chemie MeSH
- titan chemie MeSH
- Vero buňky MeSH
- zlato chemie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Hyaluronan (HA) is widely used for eye drops as lubricant to counteract dry eye disease. High and low molecular weight HA are currently used in ophthalmology. However, a large portion of the current literature on friction and lubrication addresses articular (joint) cartilage. Therefore, eye drops compositions based on HA and its derivatized forms are extensively characterized providing data on the tribological and mucoadhesive properties. The physiochemical properties are investigated in buffers used commonly in eye drops formulations. The tribological investigation reveals that amphiphilic HA-C12 decreases the friction coefficient. At the same time, the combination of trehalose/HA or HAC12 enhances up to eighty-fold the mucoadhesiveness. Thus, it is predicted a prolonged residence time on the surface of the eye. The incorporation of trehalose enhances the protection of human keratinocytes (HaCaT) cells, as demonstrated in an in-vitro cell-desiccation model. The presence of trehalose increases the friction coefficient. Medium molecular weight HA shows significantly lower friction coefficient than high molecular weight HA. This research represents a first, wide array of features of diverse HA forms for eye drops contributing to increase the knowledge of these preparations. The results here presented also provide valuable information for the design of highly performing HA-formulations addressing specific needs before preclinic.
- MeSH
- adhezivita MeSH
- buněčné linie keratinocytů HaCaT MeSH
- filtrace MeSH
- hlen účinky léků MeSH
- kyselina hyaluronová chemická syntéza chemie farmakologie MeSH
- lékové transportní systémy * MeSH
- lidé MeSH
- lubrikace * MeSH
- nefelometrie a turbidimetrie MeSH
- oči účinky léků MeSH
- oční roztoky farmakologie MeSH
- protonová magnetická rezonanční spektroskopie MeSH
- reologie MeSH
- sterilizace MeSH
- tření MeSH
- viskozita MeSH
- vysoušení MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Regeneration of large bone defects caused by trauma or tumor resection remains one of the biggest challenges in orthopedic surgery. Because of the limited availability of autograft material, the use of artificial bone is prevalent; however, the primary role of currently available artificial bone is restricted to acting as a bone graft extender owing to the lack of osteogenic ability. To explore whether surface modification might enhance artificial bone functionality, in this study we applied low-pressure plasma technology as next-generation surface treatment and processing strategy to chemically (amine) modify the surface of beta-tricalcium phosphate (β-TCP) artificial bone using a CH4/N2/He gas mixture. Plasma-treated β-TCP exhibited significantly enhanced hydrophilicity, facilitating the deep infiltration of cells into interconnected porous β-TCP. Additionally, cell adhesion and osteogenic differentiation on the plasma-treated artificial bone surfaces were also enhanced. Furthermore, in a rat calvarial defect model, the plasma treatment afforded high bone regeneration capacity. Together, these results suggest that amine modification of artificial bone by plasma technology can provide a high osteogenic ability and represents a promising strategy for resolving current clinical limitations regarding the use of artificial bone.
- MeSH
- biokompatibilní materiály metabolismus MeSH
- buněčná diferenciace fyziologie MeSH
- fosforečnany vápenaté metabolismus MeSH
- kostní náhrady metabolismus terapeutické užití MeSH
- krysa rodu rattus MeSH
- osteogeneze fyziologie MeSH
- regenerace kostí fyziologie MeSH
- transplantace kostí metody MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Úvod a cíl práce: Tribologické metody nacházejí široké uplatnění nejen na poli technických věd, ale stále častěji také v oblasti humánní a veterinární medicíny. Sledování opotřebení biologických a protetických materiálů je dnes již běžnou součástí protokolů zkoušek u kloubních náhrad. I z tohoto pohledu je využití tribologie v zubním lékařství logickým krokem při vývoji a zátěžovém sledování řady materiálů používaných u výkonů záchovné a protetické stomatologie, ale také v oblasti dentální hygieny při čištění, včetně depuračních technik. Výsledky: Jako klíčové se jeví vytvoření odpovídajících podmínek pro simulaci kontaktu v prostředí, které se co nejvíce přiblíží reálným poměrům v ústní dutině. Vedle optimalizace zátěže je žádoucí následné vyhodnocení vhodnou defektoskopickou metodou, která tak doplňuje vlastní tribologii. Závěr: Tento komplexní přístup umožňuje již v rámci vývoje získat cenné informace o vlastnostech nového materiálu a případně jej modifikovat.
Introduction and aim: Tribological methods are widely used not only in the field of technical sciences, but increasingly also in the field of human and veterinary medicine. Monitoring the wear of biological and prosthetic materials is now a common part of test protocols for joint replacements. From this point of view, the use of tribology in dentistry is a logical step in the development and stress monitoring of a number of materials used in restorative and prosthetic dentistry, but also in the field of dental hygiene in cleaning, including depuration techniques. Results: The creation of appropriate conditions for the simulation of contact in an environment that is as close as possible to the real conditions in the oral cavity seems to be crucial. In addition to stress-stain optimization, a subsequent evaluation by a suitable defectoscopic method is desirable to complement the issue of tribology. Conclusion: This comprehensive approach makes it possible to obtain valuable information on the properties of the new material through its development and, if necessary, to modify it.
- Klíčová slova
- tribologie, opotřebení,
- MeSH
- lidé MeSH
- testování materiálů * MeSH
- tření MeSH
- zubní materiály * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
PURPOSE OF THE STUDY By 7th December 2016, 4,755 Bicon-Plus cups in total were implanted in the Czech Republic. Some of them have been continuously re-operated, while the most frequent reason of failure is polyethylene wear and aseptic loosening. The present study is focused on surface analysis of retrieved polyethylene Bicon-Plus cups and the determination of the roughness of their bearing surfaces. MATERIAL AND METHODS In this study, we had 13 high molecular weight polyethylene cups with the average time in situ of 8.11 years (3.6-13.7, SD 3.2) before the retrieval. The study population was composed of 3 men, 10 women, with the mean age of 53.31 years. An optical scanning method, based on the principle of active triangulation, was used to determine wear rate. The rate of wear was identified by means of an obtained scan subsequently processed with the use of the GOM Inspect software. The roughness of surfaces was analysed with the application of Contour GT-X8 profiler using the principle of phase shifting interferometry. Measurements of surface topography of the retrieved cups were performed on the entire bearing surfaces. For the individual surface changes, a typical range of surface roughness, describing the particular wear character, was determined. By means of morphology analysis of the tested implants, three areas were identified: unworn area; area representing the worn part of the cup; and the area roughened by parallel grooving. The total surface roughness was evaluated as an arithmetic mean of the measured values. Subsequently, the values were sorted based on frequency and were classified into categories defining the particular wear mechanisms. RESULTS Wear rate of the retrieved acetabular cups was evaluated based on the wear direction vector and the size of linear wear. The average linear wear was equal to 0.13 mm/year (ranging from 0.26 to 2.29 mm/year), and the mean value of total volumetric material loss was 44.37 mm3/year (the range being from 51.80 to 1,119.7 mm3/year). Using the optical profilometer, a map of roughness distribution of the individual cups was obtained. For each implant, 76 values of roughness were evaluated. With the respect to average roughness, the samples were sorted to various categories describing: surface polishing; abrasiveadhesive wear; surfaces with preserved grooving; substantial plastic deformation. DISCUSSION The results clearly showed an increase of wear depending on implant survival; however, the tendency is not linear. This fact can be attributed to a larger amount of abrasive particles, causing an increase of wear or occurrence of surface wear in terms of micro cracks and oxidation degradation of polyethylene. This study indicates that geometry, positioning, and cup alignment during the implantation have a fundamental impact on the cup durability. Further correlation, which was observed in the case of the cup with prevailing roughness in the range from 0.1 to 0.3 μm, is a relatively wide wear vector angle determined with the use of the optical method. Considering the implants with the longest survival time with no loosening of the acetabular cup, the mean angle of direction vector was 56.8° (SD 2.1°). CONCLUSIONS The present study provides the results of morphology analysis of the retrieved Bicon-Plus cups. In general, relatively high wear rate, mainly of abrasive-adhesive character was identified. The dependence between wear and implant in situ longevity was not clearly linear, which suggests the influence of other parameters on the polyethylene wear rate. An important role of implant positioning on survival was also revealed. Moreover, it seems that it can be a more important parameter than the characteristics of the patient. Key words: total hip arthroplasty, Bicon-Plus cup, retrieval analysis, surface analysis, wear measurement, roughness, deformation, survivorship.
- MeSH
- analýza selhání vybavení MeSH
- kyčelní protézy * MeSH
- lidé středního věku MeSH
- lidé MeSH
- náhrada kyčelního kloubu přístrojové vybavení MeSH
- polyethylen MeSH
- povrchové vlastnosti MeSH
- protézy - design MeSH
- selhání protézy * MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
Závěrečná zpráva o řešení grantu Interní grantové agentury MZ ČR
1 svazek : ilustrace ; 30 cm
The main problem concerning total hip arthroplasty (THA) is aseptic loosening and periprosthetic osteolysis, both are related to the type and rate of joint surface wear. Wear is not a primary function of joint materials but is a result of the interaction of various factors and conditions. These factors and conditions can be simulated at least partially in vitro and analyzed using optic colorimetric interferometry. The composition of joint fluid, pressure, speed and other parameters of the experiment will evolve from the real situation. Therefore analysis of real joint effusions acquired during reoperation/ implantation of THA is part of the proposed study. Results of the project will be exploitable in the construction of joint implants (material and constructive engineering), in clarifying differences in wear rates, survival of implants, and also in understanding the biologic reactions around THA. Therefore, the proposed project is fully in accordance with the R&D program MH Czech Republic.
Největším problémem totální endoprotézy (TEP) kyčle je aseptické uvolnění a periprotetická osteolýza, které jsou podmíněny typem a rychlostí otěru kloubních povrchů. Opotřebení není primární funkcí artikulačních materiálů, nýbrž důsledkem interakcí řady faktorů a podmínek. Tyto faktory a podmínky je možné dílem simulovat in vitro a studovat pomocí optické kolorimetrické interferometrie. Složení kloubní kapaliny, tlakové, rychlostní a další parametry experimentu budou vycházet z reálné situace. Proto je součástí navrhovaného projektu také analýza reálné kloubní kapaliny získané v průběhu reoperace/implantace TEP kyčle. Výstupy projektu budou využitelné při výrobě kloubních implantátů (materiálové a konstrukční inženýrství), při vysvětlení rozdílů v rychlosti opotřebení, přežití implantátu, resp. při pochopení biologických reakcí kolem TEP.
- MeSH
- biokompatibilní materiály MeSH
- kolorimetrie MeSH
- kyčelní protézy MeSH
- lubrikace MeSH
- náhrada kyčelního kloubu MeSH
- povrchové vlastnosti MeSH
- reoperace MeSH
- rozhraní kost/implantát MeSH
- synoviální tekutina MeSH
- Konspekt
- Ortopedie. Chirurgie. Oftalmologie
- NLK Obory
- ortopedie
- NLK Publikační typ
- závěrečné zprávy o řešení grantu IGA MZ ČR
The aim of the present paper is to provide a novel experimental approach enabling to assess the thickness of lubricant film within hip prostheses in meaning of the contribution of particular proteins. Thin film colorimetric interferometry was combined with fluorescent microscopy finding that a combination of optical methods can help to better understand the interfacial lubrication processes in hip replacements. The contact of metal femoral head against a glass disc was investigated under various operating conditions. As a test lubricant, the saline solution containing the albumin and γ-globulin in a concentration 2:1 was employed. Two different mean speeds were applied, 5.7 and 22mm/s, respectively. The measurements were carried out under pure rolling, partial negative and partial positive sliding conditions showing that kinematic conditions substantially affects the formation of protein film. Under pure rolling conditions, an increasing tendency of lubricant film independently on rolling speed was detected, while the total thickness of lubricant film can be attributed mainly to albumin. When the ball was faster than the disc (negative sliding), a very thin lubricant film was observed for lower speed with no significant effect of particular proteins. The increase in sliding speed led to the increase of film thickness mainly caused due to the presence of γ-globulin. On the contrary, when the disc was faster than the ball (positive sliding), the film formation was very complex and time dependent while both of the studied proteins have shown any qualitative change during the test, however the effect of albumin seems to be much more important. Since a very good agreement of the results was obtained, it can be concluded that the approach consisting of two optical methods can provide the fundamental information about the lubricant film formation in meaning of particular proteins while the simultaneous presence of other constituents in model synovial fluid.
PURPOSE OF THE STUDY: The wear of articular surfaces is considered one of the most important factors limiting the life of total hip arthroplasty (THA). It is assumed that the particles released from the surface of a softer material induce a complex inflammatory response, which will eventually result in osteolysis and aseptic loosening. Implant wear is related to a friction coefficient which depends on combination of the materials used, roughness of the articulating surfaces, internal clearance, and dimensions of the prosthesis. MATERIAL AND METHODS: The selected parameters of the bearing couples tested were studied using an experimental device based on the principle of a pendulum. Bovine serum was used as a lubricant and the load corresponded to a human body mass of 75 kg. The friction coefficient was derived from a curve of slowdown of pendulum oscillations. Roughness was measured with a device working on the principle of interferometry. Clearance was assessed by measuring diameters of the acetabular and femoral heads with a 3D optical scanner. The specimens tested included unused metal-on-highly cross-linked polyethylene, ceramic-on-highly cross-linked polyethylene and ceramic-on-ceramic bearing couples with the diameters of 28 mm and 36 mm. For each measured parameter, an arithmetic mean was calculated from 10 measurements. RESULTS: 1) The roughness of polyethylene surfaces was higher by about one order of magnitude than the roughness of metal and ceramic components. The Protasul metal head had the least rough surface (0.003 μm). 2) The ceramic-on-ceramic couples had the lowest clearance. Bearing couples with polyethylene acetabular liners had markedly higher clearances ranging from 150 μm to 545 μm. A clearance increased with large femoral heads (up to 4-fold in one of the couple tested). 3) The friction coefficient was related to the combination of materials; it was lowest in ceramic-on-ceramic surfaces (0.11 to 0.12) and then in ceramic-on-polyethylene implants (0.13 to 0.14). The friction coefficient is supposed to increase with a decreasing femoral head diameter. However, in the bearing couples with polyethylene liners manufactured by one company, paradoxically, the friction coefficient slightly increased with an increase in femoral head size from 28 mm to 36 mm. 4) The lowest friction moment (< 3.5 Nm) was found for ceramic-on-ceramic implants 28 mm in diameter; the highest values were recorded in metal-on-polyethylene bearing couples 36 mm in diameter (> 7 Nm). DISCUSSION: Although our study confirmed that the bearing couples produced by different manufacturers varied to some extent in the parameters studied, in our opinion, this variability was not significant because it was not within an order of magnitude in any of the tests. CONCLUSIONS: The study showed that both the friction coefficient and the friction moment are affected more by the combination of materials than by the diameter of a femoral head. The best results were achieved in ceramic-on-ceramic implants.
A simple two-step method for the selective preparation of anomerically pure 1α- and 1β-(indol-2-yl)deoxyribose derivatives was developed. The synthesis was based on the Sonogashira reaction of 1α- and 1β-ethynyldeoxyribose and 2-haloanilines followed by a Pd-complex catalyzed cyclization to the corresponding indolyldeoxyribosides.
