Assessment of bacterial biotransformation of alkylnaphthalene lubricating base oil component 1-butylnaphthalene by LC/ESI-MS(/MS).

Alkylnaphthalene lubricating oils are synthetic Group V base oils that are utilized in wide-ranging industrial applications and which are composed of polyalkyl chain-alkylated naphthalenes. Identification of alkylnaphthalene biotransformation products and determination of their mass spectrometry (MS) fragmentation signatures provides valuable information for predicting their environmental fates and for development of analytical methods to monitor their biodegradation. In this work, laboratory-based environmental petroleomics was applied to investigate the catabolism of the alkylnaphthalene, 1-butylnaphthalene (1-BN), by liquid chromatography electrospray ionization MS data mapping and targeted collision-induced dissociation (CID) analyses. Comparative mapping revealed that numerous catabolites were produced from soil bacterium, Sphingobium barthaii KK22. Targeted CID showed unique patterns of production of even-valued deprotonated fragments that were found to originate from specific classes of bacterial catabolites. Based upon results of CID analyses of catabolites and authentic standards, MS signatures were proposed to occur through formation of distonic radical anions from bacterially-produced alkylphenol biotransformation products. Finally, spectra interpretation was guided by CID results to propose chemical structures for twenty-two 1-BN catabolites resulting in construction of 1-BN biotransformation pathways. Multiple pathways were identified that included aromatic ring-opening, alkyl chain-shortening and production of α,ß-unsaturated aldehydes from alkylated phenols. Until now, α,ß-unsaturated aldehydes have not been a class of compounds much reported from alkylated polycyclic aromatic hydrocarbon (APAH) and PAH biotransformation. This work provides a new understanding of alkylnaphthalene biotransformation and proposes MS markers applicable to monitoring APAH biotransformation in the form of alkylated phenols, and by extension, α,ß-unsaturated aldehydes, and toxic potential during spilled oil biodegradation.

Analysis of Tribology Properties of Trimethylolpropane-based Lubricant by Molecular Dynamics.

Currently, it is crucial for the lubricant formulation industry to explore cost-effective and environmentally friendly methodologies for analyzing the tribological properties of engine aviation lubricants under high-temperature and high-pressure operating conditions. This study demonstrates the feasibility of employing molecular dynamic simulations to gain essential insights into the evolution of the tribological properties of lubricants during operation. A three-layer molecular model was devised, comprising nickel aluminide molecules in the top and bottom layers, and polyol ester in the core. The impact of sliding velocities ranging from 20 km/h to 100 km/h was investigated under varying temperature and pressure conditions. Concentration, temperature and velocity profiles, radial distribution function, mean square displacement, and friction coefficient were calculated and analyzed in detail. Notably, the highest friction coefficients - ranging from 2.5 to 0.75 - were observed at the lowest temperature and pressure conditions tested. Conversely, other sections of the gas turbine exhibited substantially lower friction coefficients - ranging from 0 to 0.01.Simulations demonstrate that increasing pressure and temperature reduce polymer chain mobility, leading to stronger internal interactions within the lubricant. Consequently, lubricant adsorption onto metal surfaces decreases. Furthermore, the lubricant performs exceptionally well when its molecules encounter higher velocities and temperatures. Based on the results obtained, the research demonstrates that the presented technique provides both quantitative and qualitative tribological information essential for understanding a system molecular behavior, serving as a guiding framework for researchers in the field.

Box-Behnken design (BBD) for optimization and simulation of biolubricant production from biomass using aspen plus with techno-economic analysis.

The growing concern and limitations for existing lubricants have driven the need for biolubricants, extensively proposed as the most suitable and sustainable lubricating oils. Biolubricant refers to lubricants that quickly biodegrade and are non-toxic to humans and aquatic habitats. Over the last decade, there has been a significant increase in the production of biolubricants due to the rising demand for replacing petroleum-based lubricants with those derived from renewable sources like vegetable oils and lipase that are used in various applications. In this study biodiesel (FAME) produced from blending animal fats and waste cooking was used as a raw material with ethylene glycol for biolubricant production using a transesterification reaction in the presence of calcium oxide which considers the newest and novel part as there is no production of biolubricant from animal fats and waste cooking oil in previous researches. The reaction parameters of biolubricant production were optimized using response surface methodology (RSM) with the aid of Box Behnken Design (BBD) to study the effect of independent variables on the yield of biolubricant. These variables are temperature ranging from (100-150 °C), reaction time ranging from 1 to 4 h, and FAME (Fatty Acid Methyl Ester) to alcohol molar ratio ranging from (2:1) to (4:1). The highest biolubricant yield is 91.56% at a temperature of 141 °C, a FAME/alcohol molar ratio of 2:1, and 3.3 h. Various analyses were performed on the produced biolubricant at the optimum conditions. The results include a pour point of -9 °C, a flash point of 192 °C, a kinematic viscosity at 40 °C of 10.35 cSt, a viscosity index of 183.6, an ash content of 0.76 wt.%, and a carbon residue of 1.5 wt.%, comparing favorably with the ISO VG 10 standard. The production process of biolubricant was simulated with Aspen Plus version 11 using a Non-Random Two-Liquid (NRTL) fluid package. The simulation results indicated that the production process can be applied on an industrial scale. Economic analysis was performed on the biolubricants production plant. The total capital investment was $12.7 M with a payback period of 1.48 years and an internal rate of return (IRR) of 67.5% indicating the suitability and profitability of the biolubricant production.

Size-Controllable and pH-Sensitive Whey Protein Microgels as High-Performance Aqueous Biolubricants.

Developing efficient aqueous biolubricants has become a significant focus of research due to their prevalence in biotribological contacts and enormous potential in soft matter applications. In this study, size-controllable, pH-sensitive whey protein microgels were prepared using a water-in-water emulsion template method from protein-polysaccharide phase separation. The granular hydrogel from the protein microgels exhibited superior lubricity, obtaining 2.7-fold and 1.7-fold reductions in coefficient of friction (µ) compared to native protein and human saliva (µ = 0.30 compared to 0.81 and 0.52, respectively). The microgels also exhibited outstanding load-bearing capabilities, sustaining lubrication under normal forces up to 5 N. Microgels with a smaller size (1 µm) demonstrated better lubricating performance than 6 and 20 µm microgels. The exceptional lubricity was from a synergistic effect of the ball-bearing mechanism and the hydration state of the microgels. Particularly at pH 7.4, the hydration layer surrounding highly negative charges contributed to the electrostatic repulsion among the swollen microgels, leading to an improved buffer ability to separate contact surfaces and effective rolling behavior. Such pH-dependent repulsion was evidenced using a surface forces apparatus that the adhesion between the whey protein-coated surfaces and protein-mica surfaces decreased from 4.49 to 0.97 mN/m and from 7.89 to 0.36 mN/m, respectively, with pH increasing from the isoelectronic point to 7.4. Our findings fundamentally elucidated the tribo-rheological properties and lubrication mechanisms of the whey protein microgels with excellent biocompatibility and environmental responsiveness, offering novel insights for their food and biomedical applications requiring aqueous biolubrication.

Comparison of Eco-Friendly Ionic Liquids and Commercial Bio-Derived Lubricant Additives in Terms of Tribological Performance and Aquatic Toxicity.

Approximately half of the lubricants sold globally find their way into the environment. The need for Environmentally Acceptable Lubricants (EALs) is gaining increased recognition. A lubricant is composed of a base oil and multiple functional additives. The literature has been focused on EAL base oils, with much less attention given to eco-friendly additives. This study presents the tribological performance and aquatic toxicity of four short-chain phosphonium-phosphate and ammonium-phosphate ionic liquids (ILs) as candidate anti-wear and friction-reducing additives for EALs. The results are benchmarked against those of four commercial bio-derived additives. The four ILs, at a mere 0.5 wt% concentration in a synthetic ester, demonstrated a 30-40% friction reduction and >99% wear reduction, superior to the commercial baselines. More impressively, all four ILs showed significantly lower toxicity than the bio-derived products. In an EPA-standard chronic aquatic toxicity test, the sensitive model organism, Ceriodaphnia dubia, had 90-100% survival when exposed to the ILs but 0% survival in exposure to the bio-derived products at the same concentration. This study offers scientific insights for the future development of eco-friendly ILs as lubricant additives.

On-demand bactericidal and self-adaptive antifouling hydrogels for self-healing and lubricant coatings of catheters.

Catheter-related infections are one of the most common nosocomial infections with increasing morbidity and mortality, and robust antibacterial or antifouling catheter coatings remain great challenges for long-term implantation. Herein, multifunctional hydrogel coatings were developed to provide persistent and self-adaptive antifouling and antibacterial effects with self-healing and lubricant capabilities. Polyvinyl alcohol (PVA) with ß-cyclodextrin (ß-CD) grafts (PVA-Cd) and 4-arm polyethylene glycol (PEG) with adamantane and quaternary ammonium compound (QAC) terminals (QA-PEG-Ad) were crosslinked through host-guest recognitions between adamantane and ß-CD moieties to acquire PVEQ coatings. In response to bacterial infections, QACs exhibit reversible transformation between zwitterions (pH 7.4) and cationic lactones (pH 5.5) to generate on-demand bactericidal effect. Highly hydrophilic PEG/PVA backbones and zwitterionic QACs build a lubricate surface and decrease the friction coefficient 10 times compared with that of bare catheters. The antifouling hydrated layer significantly inhibits blood protein adsorption and platelet activation and reveals negligible hemolysis and cytotoxicity. The dynamic host-guest crosslinking achieves full self-healing of cracks in PVEQ hydrogels, and the mechanical profiles were recovered to over 90 % after rejuvenating the broken hydrogels, exhibiting a long-term stability after mechanical stretching, twisting, knotting and compression. After subcutaneous implantation and local bacterial infection, the retrieved PVEQ-coated catheters display no tissue adhesion and 3 log folds lower bacterial number than that of bare catheters. PVEQ coatings effectively prevent the repeated bacterial infections and there are few inflammatory reactions in the surrounding tissue, while substantial lymphoid infiltration and inflammatory cell aggregation occur in muscle tissues around the bare catheter. Thus, this study demonstrates a catheter coating strategy by on-demand bactericidal, self-adaptive antifouling, self-healing and lubricant hydrogels to address medical devices-related infections. STATEMENT OF SIGNIFICANCE: It is estimated over two billion peripheral intravenous catheters are annually used in hospitals around the world, and catheter-associated infection has become a great clinical challenge with rapidly rising morbidity and mortality. Surface coating is considered a promising approach, but substantial challenges remain in the development of coatings that simultaneously satisfy both anti-fouling and antibacterial attributes. Even more, few attempts have been made to design mechanically robust coatings and reversible antibacterial or antifouling capabilities, which are critical for long-term medical implants. To address these challenges, we propose a concise strategy to develop hydrogel coatings from commercially available poly(ethylene glycol) and polyvinyl alcohol. In addition to self-healing and lubricant capabilities, the reversible conversion between zwitterionic and cationic lactones of quaternary ammonium compounds enables on-demand bactericidal and self-adaptive antifouling effects.

Performance evaluation of nano-graphene lubricating oil with high dispersion and low viscosity used in diesel engines.

The basic tribological experiments have reported that nano-graphene lubricating oil has excellent anti-friction and anti-wear properties, which has been widely concerned. However, the real anti-friction effect of nano-graphene lubricating oil and its impact on engine power performance, economic performance and emission performance remain to be proved. This has seriously hindered the popularization and application of nano-graphene lubricating oil in the engine field. In this paper, nano-graphene powder was chemically grafted to prepare nano-graphene lubricating oil with high dispersion stability. The influence of nano-graphene on physicochemical properties of lubricating oil was studied, and the influence of nano-graphene on engine power performance, economic performance and emission performance was explored. The results show that after modification, the dispersion of nano-graphene in lubricating oil is improved. Compared with pure lubricating oil, the addition of nano-graphene makes the kinematic viscosity of lubricating oil slightly lower, and has little effect on the density, flash point, pour point and total acid value of lubricating oil. The reversed towing torque of nano-graphene lubricating oil is reduced by 1.82-5.53%, indicating that the friction loss decreases. The specific fuel consumption of the engine is reduced, which indicates that the fuel economic performance is improved. Engine HC+NOX, CH4, CO2 emissions do not change much, but particulate matter (PM) emissions increase by 8.85%. The quantity concentration of nuclear particles, accumulated particles and total particles of nano-graphene lubricating oil are significantly higher than that of pure lubricating oil. And the increase of the quantity concentration of accumulated particles is more obvious than that of nuclear particles, and the larger the load, the more obvious this phenomenon. In order to apply nano-graphene lubricating oil to the engine, it is also necessary to further study its impact on the post-processing system, adjust the control strategy of the post-processing system and then test and calibrate.

Grafting of cationic molecules to hyaluronic acid improves adsorption and cartilage lubrication.

Synovial fluid lubricates articular joints by forming a hydrated layer between the cartilage surfaces. In degenerative joint diseases like osteoarthritis (OA), the synovial fluid is compromised, which leads to less effective innate lubrication and exacerbated cartilage degeneration. Studies over the years have led to the development of partially or fully synthetic biolubricants to reduce the coefficient of friction with cartilage in knee joints. Cartilage-adhering, hydrated lubricants are particularly important to provide cartilage lubrication and chondroprotection under high normal load and slow speed. Here, we report the development of a hyaluronic acid (HA)-based lubricant functionalized with cationic branched poly-L-lysine (BPL) molecules that bind to cartilage via electrostatic interactions. We surmised that the electrostatic interactions between the BPL-modified HA molecules (HA-BPL) and the cartilage facilitate localization of the HA molecules to the cartilage surface. The number of BPL molecules on the HA backbone was varied to determine the optimal grafting density for cartilage binding and HA localization. Collectively, our results show that our HA-BPL molecules adhered readily to cartilage and were effective as a lubricant in cartilage-on-cartilage shear measurements where the modified HA molecules significantly reduce the coefficient of friction compared to phosphate-buffered saline or HA alone. This proof-of-concept study shows how the incorporation of cartilage adhering moieties, such as cationic molecules, can be used to enhance cartilage binding and lubrication properties of HA.

Bioinspired film-terminated ridges for enhancing friction force on lubricated soft surfaces.

Enhancing friction force in lubricated, compliant contacts is of particular interest due to its wide application in various engineering and biological systems. In this study, we have developed bioinspired surfaces featuring film-terminated ridges, which exhibit a significant increase in lubricated friction force compared to flat samples. We propose that the enhanced sliding friction can be attributed to the energy dissipation at the lubricated interface caused by elastic hysteresis resulting from cyclic terminal film deformation. Furthermore, increasing inter-ridge spacing or reducing terminal film thickness are favorable design criteria for achieving high friction performance. These findings contribute to our understanding of controlling lubricated friction and provide valuable insights into surface design strategies for novel functional devices.

Effect of Instrument Lubricant on Mechanical Properties of Restorative Composite.

OBJECTIVES: Using a wetting resin or adhesive system as an instrument lubricant when placing composite layers is commonly practiced to improve handling. This study investigated whether instrument lubricants affected strength, stiffness, or hardness. METHODS: Composite beams (TPH Spectra) were fabricated using a stainless steel mold (25×2.5×2 mm) in two steps, where the second half (12.5 mm) was added and cured against a cured first half (n=15). The composite surface at the open end of the first half was smoothed using an instrument lubricated with wetting resin (Ultradent) or universal adhesive (ScotchBond Universal), enough to prevent sticking, or without lubrication. An additional beam of each group was characterized using scanning electron microscopy. Monolithic specimens were also fabricated. After 24 hour storage (37°C, 100% humidity), the beams' flexural strength and stiffness were determined by four-point bending. Vickers surface hardness was measured on 24-hour composite samples in 2 mm deep acrylic cavities, cured after the surface was smoothed with the two instrument lubricants or no lubricant (n=10). Hardness was remeasured after finishing with a series of contouring and polishing discs. Data were statistically analyzed using ANOVA followed by Student-Newman-Keuls post hoc test at 0.05 significance level. RESULTS: There were significant differences (p<0.001) in flexural strength and stiffness among groups. While strength and stiffness were not affected by using a wetting resin as instrument lubricant, use of a universal adhesive increased strength and stiffness significantly, achieving monolithic values. Scanning electron micrographs showed less porosities at the interface when using instrument lubricants. Surface hardness was significantly reduced in groups in which instrument lubricants were used, but finishing/polishing restored original hardness (p<0.001). CONCLUSIONS: Lubricating an instrument with a wetting agent did not adversely affect physical or surface properties, provided the surface was finished and polished. If a universal adhesive was used as lubricant, the strength and stiffness of a layered composite could be increased, reaching monolithic values.

Bottlebrush Polymers for Articular Joint Lubrication: Influence of Anchoring Group Chemistry on Lubrication Properties.

The role of carboxylic, aldehyde, or epoxide groups incorporated into bottlebrush macromolecules as anchoring blocks (or cartilage-binding blocks) is investigated by measuring their lubricating properties and cartilage-binding effectiveness. Mica modified with amine groups is used to mimic the cartilage surface, while bottlebrush polymers functionalized with carboxylic, aldehyde, or epoxide groups played the role of the lubricant interacting with the cartilage surface. We demonstrate that bottlebrushes with anchoring blocks effectively reduce the friction coefficient on modified surfaces by 75-95% compared to unmodified mica. The most efficient polymer appears to be the one with epoxide groups, which can react spontaneously with amines at room temperature. In this case, the value of the friction coefficient is the lowest and equals 0.009 ± 0.001, representing a 95% reduction compared to measurements on nonmodified mica. These results show that the presence of the functional groups within the anchoring blocks has a significant influence on interactions between the bottlebrush polymer and cartilage surface. All synthesized bottlebrush polymers are also used in the preliminary lubrication tests carried out on animal cartilage surfaces. The developed materials are very promising for future in vivo studies to be used in osteoarthritis treatment.

Biophysical impact of lubricating base oil aerosols on natural pulmonary surfactant film.

Lubricating base oils have been extensively employed for producing various industrial and consumer products. Therefore, their environmental and health impacts should be carefully evaluated. Although there have been many reports on pulmonary cytotoxicity and inflammatory responses of inhaled lubricating base oils, their potential influences on pulmonary surfactant (PS) films that play an essential role in maintaining respiratory mechanics and pulmonary immunity remains largely unknown. Here a systematic study on the interactions between an animal-derived natural PS and aerosols of water and representative mineral and vegetable base oils is performed using a novel biophysical assessing technique called constrained drop surfactometry capable of providing in vitro simulations of normal tidal breathing and physiologically relevant temperature and humidity in the lung. It was found that the mineral oil aerosols can impose strong inhibitions to the biophysical property of PS film, while the airborne vegetable oils and water show negligible adverse effects within the studied concentration range. The inhibitory effect is originated from the strong hydrophobicity of mineral oil, which makes it able to disrupt the interfacial molecular ordering of both phospholipid and protein compositions and consequently suppress the formation of condensed phase and multilayer scaffolds in a PS film. ENVIRONMENTAL IMPLICATION: Understanding the biophysical influence of airborne lubricating base oils on pulmonary surfactant (PS) films can provide new insights into the environmental impacts and health concerns of various industrial lubricant products. Here a comparative study on interactions between an animal-derived natural PS film and the aerosols of water and representative mineral and vegetable base oils under the true physiological conditions was conducted in situ using constrained drop surfactometry. We show that the most frequently used mineral base oil can cause strong inhibitions to the PS film by disrupting the molecular ordering of saturated phospholipids and surfactant-associated proteins at the interface.

Potential of Powder Rheology for Detecting Unforeseen Cross-Contamination of Foreign Active Pharmaceutical Ingredients.

Unexpected cross-contamination by foreign components during the manufacturing and quality control of pharmaceutical products poses a serious threat to the stable supply of drugs and the safety of customers. In Japan, in 2020, a mix-up containing a sleeping drug went undetected by liquid chromatography during the final quality test because the test focused only on the main active pharmaceutical ingredient (API) and known impurities. In this study, we assessed the ability of a powder rheometer to analyze powder characteristics in detail to determine whether it can detect the influence of foreign APIs on powder flow. Aspirin, which was used as the host API, was combined with the guest APIs (acetaminophen from two manufacturers and albumin tannate) and subsequently subjected to shear and stability tests. The influence of known lubricants (magnesium stearate and leucine) on powder flow was also evaluated for standardized comparison. Using microscopic morphological analysis, the surface of the powder was observed to confirm physical interactions between the host and guest APIs. In most cases, the guest APIs were statistically detected due to characteristics such as their powder diameter, pre-milling, and cohesion properties. Furthermore, we evaluated the flowability of a formulation incorporating guest APIs for direct compression method along with additives such as microcrystalline cellulose, potato starch, and lactose. Even in the presence of several additives, the influence of the added guest APIs was successfully detected. In conclusion, powder rheometry is a promising method for ensuring stable product quality and reducing the risk of unforeseen cross-contamination by foreign APIs.

Review on Cutting Fluids: Formulation, Chemistry and Deformulation.

This comprehensive review offers a chemical analysis of cutting fluids, delving into both their formulation and deformulation processes. The study covers a wide spectrum of cutting fluid formulations, ranging from simple compositions predominantly comprising oils, whether mineral or vegetable, to emulsions. The latter involves the integration of surfactants, encompassing both nonionic and anionic types, along with a diverse array of additives. Concerning oils, the current trend leans towards the use of vegetable oils instead of mineral oils for environmental reasons. As vegetable oils are more prone to oxidation, chemical alterations, the addition of antioxidant may be necessary. The chemical aspects of the different compounds are scrutinized, in order to understand the role of each component and its impact on the fluid's lubricating, cooling, anti-wear, and anti-corrosion properties. Furthermore, the review explores the deformulation methodologies employed to dissect cutting fluids. This process involves a two-step approach: separating the aqueous and organic phases of the emulsions by physical or chemical treatments, and subsequently conducting a detailed analysis of each to identify the compounds. Several analytical techniques, including spectrometric or chromatographic, can be employed simultaneously to reveal the chemical structures of samples. This review aims to contribute to the improvement of waste treatment stemming from cutting fluids. By gathering extensive information about the formulation, deformulation, and chemistry of the ingredients, there is a potential to enhance the waste management and disposal effectively.

The development status and future trends of lubricant additives technology: Based on patents analysis.

In order to reveal the current status and future trends of lubricant additives, this study analyzes the structured and unstructured data of 77701 lubricant additive patents recorded by Patsnap. The results show that China is the country with the largest number of patents in this field, and the United States is the main exporting country of international technology flow; the current research and development of lubricant additives is dominated by multifunctional composite additives; environmentally friendly additive compositions are the current research hotspot; and more environmentally friendly and economically degradable additives have more development potential in the future. Overall, this study provides a comprehensive understanding of the research and application of lubricant additives and contributes to the future development of the lubricant industry.

Cartilage-Inspired, High-Strength, and Heat-Tolerant Lubricating Hydrogels by Macrophase Separation.

Hydrogels are considered as a potential cartilage replacement material based on their structure being similar to natural cartilage, which are of great significance in repairing cartilage defects. However, it is difficult for the existing hydrogels to combine the high load bearing and low friction properties (37 °C) of cartilage through sample methods. Herein, we report a facile and new fabrication strategy to construct the PNIPAm/EYL hydrogel by using the macrophase separation of supersaturated N-isopropylacrylamide (NIPAm) monomer solution to promote the formation of liposomes from egg yolk lecithin (EYL) and asymmetric template method. The PNIPAm/EYL hydrogels possess a relatively high compressive strength (more than 12 MPa), fracture energy (9820 J/m2), good fatigue resistance, lubricating properties, and excellent biocompatibility. Compared with the PNIPAm hydrogel, the friction coefficient (COF 0.046) of PNIPAm/EYL hydrogel is reduced by 50%. More importantly, the COF (0.056) of PNIPAm/EYL hydrogel above lower critical solution temperature (LCST) does not increase significantly, exhibiting heat-tolerant lubricity. The finite element analysis further proves that PNIPAm/EYL hydrogel can effectively disperse the applied stress and dissipate energy under load conditions. This work not only provides new insights for the design of high-strength lubricating hydrogels but also lays a foundation for the treatment of cartilage injury as a substitute material.

Natural product of angelica essential oil developed as a stable Pickering emulsion for joint interface lubrication.

Development of high-performance joint injection lubricants has become the focus in the field of osteoarthritis treatment. Herein, natural product of angelica essential oil combined with the graphene oxide were prepared to the stable Pickering emulsion as a biological lubricant. The tribological properties of the Pickering emulsion under different friction conditions were studied. The lubricating mechanism was revealed and the biological activities were evaluated. Results showed that the prepared Pickering emulsion displayed superior lubrication property at the Ti6Al4V biological material interface. The maximum friction reduction and anti-wear abilities of the Pickering emulsion were improved by 36% and 50% compared to water, respectively. This was primarily due to the action of the double-layer lubrication films composed of the graphene oxide and angelica essential oil molecules. It was worth noting that the friction reduction effect of the Pickering emulsion at the natural cartilage interface was higher about 19% than that of HA used in clinic for OA commonly. In addition, the Pickering emulsion also displayed antioxidant activity and cell biocompatibility, showing a good clinical application prospect in the future.

Selection of lubricant type and concentration for orodispersible tablets.

Lubricants are essential for most tablet formulations as they assist powder flow, prevent adhesion to tableting tools and facilitate tablet ejection. Magnesium stearate (MgSt) is an effective lubricant but may compromise tablet strength and disintegratability. In the design of orodispersible tablets, tablet strength and disintegratability are critical attributes of the dosage form. Hence, this study aimed to conduct an in-depth comparative study of MgSt with alternative lubricants, namely sodium lauryl sulphate (SLS), stearic acid (SA) and hydrogenated castor oil (HCO), for their effects on the tableting process as well as tablet properties. Powder blends were prepared with lactose, sodium starch glycolate or crospovidone as the disintegrant, and a lubricant at different concentrations. Angle of repose was determined for the mixtures. Comparative evaluation was carried out based on the ejection force, tensile strength, liquid penetration and disintegratability of the tablets produced. As the lubricant concentration increased, powder flow and tablet ejection improved. The lubrication efficiency generally decreased as follows: MgSt > HCO > SA > SLS. Despite its superior lubrication efficacy, MgSt is the only lubricant of four evaluated that reduced tablet tensile strength. Tablet disintegration time was strongly determined by tensile strength and liquid penetration, which were in turn affected by the lubricant type and concentration. All the above factors should be taken into consideration when deciding the type and concentration of lubricant for an orodispersible tablet formulation.

Self-Lubricating, Living Contact Lenses.

The increasing prevalence of dry eye syndrome in aging and digital societies compromises long-term contact lens (CL) wear and forces users to regular eye drop instillation to alleviate discomfort. Here a novel approach with the potential to improve and extend the lubrication properties of CLs is presented. This is achieved by embedding lubricant-secreting biofactories within the CL material. The self-replenishable reservoirs autonomously produce and release hyaluronic acid (HA), a natural lubrication and wetting agent, long term. The hydrogel matrix regulates the growth of the biofactories and the HA production, and allows the diffusion of nutrients and HA for at least 3 weeks. The continuous release of HA sustainably reduces the friction coefficient of the CL surface. A self-lubricating CL prototype is presented, where the functional biofactories are contained in a functional ring at the lens periphery, outside of the vision area. The device is cytocompatible and fulfils physicochemical requirements of commercial CLs. The fabrication process is compatible with current manufacturing processes of CLs for vision correction. It is envisioned that the durable-by-design approach in living CL could enable long-term wear comfort for CL users and minimize the need for lubricating eye drops.

Bioinspired Bottlebrush Polymers Effectively Alleviate Frictional Damage Both In Vitro and In Vivo.

Bottlebrush polymers (BB) have emerged as compelling candidates for biosystems to face tribological challenges, including friction and wear. This study provides a comprehensive assessment of an engineered triblock BB polymer's affinity, cell toxicity, lubrication, and wear protection in both in vitro and in vivo settings, focusing on applications for conditions like osteoarthritis and dry eye syndrome. Results show that the designed polymer rapidly adheres to various surfaces (e.g., cartilage, eye, and contact lens), forming a robust, biocompatible layer for surface lubrication and protection. The tribological performance and biocompatibility are further enhanced in the presence of hyaluronic acid (HA) both in vitro and in vivo. The exceptional lubrication performance and favorable interaction with HA position the synthesized triblock polymer as a promising candidate for innovative treatments addressing deficiencies in bio-lubricant systems.