Designing nutritious food for the elderly population often requires significant quantities of leucine-rich whey proteins to combat malnutrition, yet high-protein formulations can cause mouth dryness and increased oral friction. This study investigated how various colloidal processing methods and compositions impact the in vitro oral tribological properties of protein-rich emulsions and emulsion-filled gels. Oil-in-water emulsions with oil fractions from 1 wt% to 20 wt% were prepared, alongside emulsion-filled gels containing whey protein isolate (WPI), hydrolysed whey protein (HWP), or a blend of both (10 wt% protein content). Two processing approaches were employed: creating emulsions with an initial 10 w% protein content (M1) and initially forming emulsions with 0.1 wt% protein content, then enriching to a final 10 wt% concentration (M2). The hypothesis was that formulations with HWP or method 2 (M2) would offer lubrication benefits by inducing droplet coalescence, aiding in the formation of a lubricating boundary tribofilm. Surprisingly, the tribological behavior of high-protein emulsions showed minimal dependence on oil droplet volume fraction. However, both HWP-based emulsions and those processed with M2 for WPI exhibited significant friction reduction, which may be attributed to the presence of coalesced oil droplets, supporting our hypothesis. Substituting 50 wt% of WPI with HWP in emulsion-filled gel boli resulted in very low friction coefficients in the boundary lubrication regime, suggesting oil droplet release from the gel matrix. These findings provide insights into designing high-protein foods with improved mouthfeel for the elderly population, necessitating further validation through sensory studies.

Gel lubrication is routinely used during gynecological examination to prevent or reduce pain, yet its impact on microbial composition during sampling remains unclear. This study aimed to investigate whether lubricating gel affects the microbial composition of vaginal samples. We included 31 pregnant women presenting during their third trimester to clinics or emergency room and collected 143 unique vaginal samples for 16S amplicon microbial analysis. Vaginal samples were obtained using sterile swabs under various conditions: without gel-immediately frozen (n = 30), with gel-immediately frozen, without gel-at room temperature (RT) for 5 h before freezing, with gel-at RT for 5 h before freezing, and additional sampling after 24 h without gel-immediate freezing. We found that sample collection with gel lubrication influenced specimen quality-half of the gel samples failing to meet processing limitation compared to those without gel. The effect of gel on testing quality dissipated after 24 h. However, when samples met post-sequencing filters, gel lubrication did not alter the microbial composition, individual taxa abundance or alpha and beta diversity. We recommend sampling either before gel exposure or 24 h after. These findings underscore the importance of considering sample collection methodologies in vaginal microbiome studies to ensure high-quality microbial data for accurate analysis.

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.

The fretting wear behaviors of silicone rubber under dry friction and different lubrication conditions are studied experimentally. Water, engine oil, dimethyl silicone oil (DSO), and dimethyl silicone oil doped with graphene oxide (DSO/GO) are selected as lubricants. Under the liquid lubrication conditions, the silicone rubber samples are always immersed in the same volume of lubricant. The contact model of a 440C steel ball and silicone rubber sample is the sphere-on-flat contact. The reciprocating fretting wear experiments are carried out using the reciprocating friction wear tester. A scanning electron microscope and three-dimensional white-light interference profilometer are used to detect the surface wear morphology and obtain the wear volume, respectively. The influences of normal force, lubrication condition, and displacement amplitude on fretting wear behavior are discussed. The fretting wear performances of silicone rubber under different fretting states and lubrication conditions are compared. The results show that for a small normal force, silicone rubber has the best wear resistance under DSO/GO lubrication. While for a large normal force, silicone rubber has the best wear resistance under engine oil lubrication.

Chondrocyte senescence and reduced lubrication play pivotal roles in the pathogenesis of age-related osteoarthritis (OA). In the present study, highly lubricated and drug-loaded hydrogel microspheres are designed and fabricated through the radical polymerization of sulfobetaine (SB)-modified hyaluronic acid methacrylate using microfluidic technology. The copolymer contains a large number of SB and carboxyl groups that can provide a high degree of lubrication through hydration and form electrostatic loading interactions with metformin (Met@SBHA), producing a high drug load for anti-chondrocyte senescence. Mechanical, tribological, and drug release analyses demonstrated enhanced lubricative properties and prolonged drug dissemination of the Met@SBHA microspheres. RNA sequencing (RNA-seq) analysis, network pharmacology, and in vitro assays revealed the extraordinary capacity of Met@SBHA to combat chondrocyte senescence. Additionally, inducible nitric oxide synthase (iNOS) has been identified as a promising protein modulated by Met in senescent chondrocytes, thereby exerting a significant influence on the iNOS/ONOO-/P53 pathway. Notably, the intra-articular administration of Met@SBHA in aged mice ameliorated cartilage senescence and OA pathogenesis. Based on the findings of this study, Met@SBHA emerges as an innovative and promising strategy in tackling age-related OA serving the dual function of enhancing joint lubrication and mitigating cartilage senescence.

BACKGROUND: Speculum lubrication may help to reduce the pain experienced during Pap-smear collection and hence increase uptake of cervical cancer screening and repeat testing, but there are fears of its interference with cytological results.
OBJECTIVE: To determine and compare the adequacy of cervical cytology smears and the mean pain scores of women undergoing cervical cancer screening with or without speculum lubrication.
METHODS: This was a randomised controlled study of 132 women having cervical cancer screening at a tertiary hospital in Nigeria. Sixty-six participants were randomly assigned to the \'Gel\' and \'No Gel\' groups, respectively. Pap smears were collected from each participant with a lubricated speculum (\'Gel group\') or a non-lubricated speculum (\'No Gel group\'). The primary outcome measures were the proportion of women with unsatisfactory cervical cytology smears and the mean numeric rating scale pain scores, while the secondary outcome measures were the proportion of women who were willing to come for repeat testing and the cytological diagnosis of Pap-smear results.
RESULTS: The baseline socio-demographic variables were similar in both groups. There was no significant difference in the proportion of unsatisfactory cervical smear results between the two groups (13.6% vs. 21.2%, p = 0.359). However, the mean pain scores were significantly lower in the gel group than in the no gel group (45.04 vs. 87.96; p<0.001). An equal proportion of the participants in each group (90.9% vs. 90.9%; p > 0.999) were willing to come for repeat cervical smears in the future.
CONCLUSIONS: Speculum lubrication did not affect the adequacy of cervical smears but significantly reduced the pain experienced during pap smear collection. Also, it did not significantly affect the willingness to come for repeat cervical smears in the future.
BACKGROUND: The trial was registered with the Pan-African Clinical Trial Registry with a unique identification and registration number: PACTR2020077533364675.

Lubricin, a lubricating glycoprotein abundant in synovial fluid, forms a low-friction brush polymer interface in tissues exposed to sliding motion including joints, tendon sheaths, and the surface of the eye. Despite its therapeutic potential in diseases such as osteoarthritis and dry eye disease, there are few sources available. Through rational design, we developed a series of recombinant lubricin analogs that utilize the species-specific tissue-binding domains at the N- and C-termini to increase biocompatibility while replacing the central mucin domain with an engineered variant that retains the lubricating properties of native lubricin. In this study, we demonstrate the tissue binding capacity of our engineered lubricin product and its retention in the joint space of rats. Next, we present a new bioprocess chain that utilizes a human-derived cell line to produce O-glycosylation consistent with that of native lubricin and a purification strategy that capitalizes on the positively charged, hydrophobic N- and C-terminal domains. The bioprocess chain is demonstrated at 10 L scale in industry-standard equipment utilizing commonly available ion exchange, hydrophobic interaction and size exclusion chromatography resins. Finally, we confirmed the purity and lubricating properties of the recombinant biolubricant. The biomolecular engineering and bioprocessing strategies presented here are an effective means of lubricin production and could have broad applications to the study of mucins in general.

This study presents new insights into the potential role of polyelectrolyte interfaces in regulating low friction and interstitial fluid pressurization of cartilage. Polymer brushes composed of hydrophilic 3-sulfopropyl methacrylate potassium salt (SPMK) tethered to a PEEK substrate (SPMK-g-PEEK) are a compelling biomimetic solution for interfacing with cartilage, inspired by the natural lubricating biopolyelectrolyte constituents of synovial fluid. These SPMK-g-PEEK surfaces exhibit a hydrated compliant layer approximately 5 μm thick, demonstrating the ability to maintain low friction coefficients (μ ∼ 0.01) across a wide speed range (0.1-200 mm/s) under physiological loads (0.75-1.2 MPa). A novel polyelectrolyte-enhanced tribological rehydration mechanism is elucidated, capable of recovering up to ∼12% cartilage strain and subsequently facilitating cartilage interstitial fluid recovery, under loads ranging from 0.25 to 2.21 MPa. This is attributed to the combined effects of fluid confinement within the contact gap and the enhanced elastohydrodynamic behavior of polymer brushes. Contrary to conventional theories that emphasize interstitial fluid pressurization in regulating cartilage lubrication, this work demonstrates that SPMK-g-PEEK\'s frictional behavior with cartilage is independent of these factors and provides unabating aqueous lubrication. Polyelectrolyte-enhanced tribological rehydration can occur within a static contact area and operates independently of known mechanisms of cartilage interstitial fluid recovery established for converging or migrating cartilage contacts. These findings challenge existing paradigms, proposing a novel polyelectrolyte-cartilage tribological mechanism not exclusively reliant on interstitial fluid pressurization or cartilage contact geometry. The implications of this research extend to a broader understanding of synovial joint lubrication, offering insights into the development of joint replacement materials that more accurately replicate the natural functionality of cartilage.

This study investigates the rheological, morphological, and mechanical properties of melt-processed polylactide/ethylene vinyl alcohol (70PLA/30EVOH) blend composites containing 0.25, 0.5, and 1 wt.% of graphene oxide (GO) nanoplates. Thermodynamic-based suggested the localization of nanoparticles in EVOH, SEM studies showed that the introduction of GO to the blend increased dispersed droplet size, which was attributed to the localization of GO within EVOH, as confirmed by TEM. The rheology results indicated a decrease in the elasticity for the composite containing 0.25 wt.% of GO compared to the neat blend, which was attributed to the sliding effect of the added GO nanoplatelets. However, samples containing higher amounts of GO nanoplatelets exhibited more excellent elasticity than the neat blend. The increased elasticity was suggestively attributed to the dominance of hydrodynamic interactions, the physical network of added nanoplatelets, and polymer/GO interactions over the sliding role of the GO nanoplatelets at higher loadings. In addition, the effect of the order of mixing was investigated, and the premixing of PLA and GO exhibited a decrease in the droplet radius compared to the neat blend. It was ascribed to the localization of GO nanosheets in the PLA and interface, which was confirmed by rheological results and mechanical assessments.

The tribological behaviour of articular cartilage plays a key role in joint motion; however, there is a gap in research on the effect of hyperuricemic joint fluid on cartilage friction behaviour in acute gouty arthritis. In this study, we carried out a fixed-load scratch experiment to compare the friction and wear of articular cartilage under the lubrication of gouty arthritis arthritic fluid and normal human arthritic fluid, and the results showed that the cartilage friction coefficient of patients with acute gouty arthritis was significantly larger than that of normal human beings, and that the cartilage friction coefficient decreased with the elevation of normal load and sliding speed, and the change with the sliding speed varied more differently from that of normal human beings, and that the cartilage surface wear was more severe after prolonged friction. The wear and tear of the cartilage surface is more severe after prolonged friction. Patients with gouty arthritis should reduce the sudden speed changes such as fast running and variable speed running to maintain the stability of the cartilage surface friction coefficient.