Highly improved aqueous lubrication of polymer surface by noncovalently bonding hyaluronic acid-based hydration layer for endotracheal intubation.

Hydration lubrication is the key responsible for the exceptionally low boundary friction between biosurfaces. However, it is a challenge to settle a hydration layer on a polymer surface via a noncovalent manner. Herein, we develop a highly lubricated coating absorbed onto the polymer surface via intermolecular association of hyaluronic acid (HA)-based micelles. A poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymer (Pluronic, F127) is recruited to complex with HA and further self-assembled to form a thick micelle layer. High water-retaining capacity of the HA/F127 coating enables the decorated surface with excellent hydrophilicity and boundary lubrication, where the coefficient of friction in aqueous media is reduced by 60% compared with the bare polymer surface. The HA/F127 coating suppresses nonspecific protein adsorption and exhibits good biocompatibility. More remarkably, an in vivo cynomolgus monkey model, demonstrates the utility of the HA/F127 coating in alleviating or preventing complications of endotracheal intubation, such as foreign irritation, airway mucosal damage, and inflammatory response. This cost-effective and scalable approach is suitable to manufacture interventional devices especially disposable medical devices with highly lubricated surface.

Surface Epitaxial Crystallization-Directed Nanotopography for Accelerating Preosteoblast Proliferation and Osteogenic Differentiation.

Surface nanotopography provides a physical stimulus to direct cell fate, especially in the case of osteogenic differentiation. However, fabrication of nanopatterns usually suffers from complex procedures. Herein, a feasible and versatile method was presented to create unique nanosheets on a poly(ε-caprolactone) (PCL) substrate via surface epitaxial crystallization. The thickness, periodic distance, and root-mean-square nanoroughness of surface nanosheets were tunable by simply altering the PCL concentration in the growth solution. Epitaxial nanosheets possessed an identical composition as the substrate, being a prerequisite to revealing the independent effect of biophysical linkage on the osteogenic mechanism of the patterned surface. Preosteoblasts' response to the epitaxial nanosheets was examined in the aspect of preosteoblast proliferation and osteogenic differentiation. The expression of alkaline phosphatase, collagen type I, osteopontin, and osteocalcin as well as mineralization was significantly promoted by the epitaxial nanosheets. Acceleration of osteogenic differentiation was attributed to activating the TAZ/RUNX2 signaling pathway. The findings demonstrate that surface epitaxial crystallization is a feasible approach to design and construct nanotopography for bone tissue engineering.

Promoting osteoblast proliferation on polymer bone substitutes with bone-like structure by combining hydroxyapatite and bioactive glass.

Mimicking the structural features of natural bone has been demonstrated to bring pronounced advantages for mechanical reinforcement of polymeric orthopedic substitutes that are composed of bioinert polymer matrix and bioactive fillers. However, to trigger effective bone formation and implant integration, the bioactivity of bone substitutes plays a vital role. We hypothesized that the use of hydroxyapatite (HA) and bioactive glass (BG), compared to the use of HA alone, could improve the biological properties of polymer-based bone substitutes. Herein, high-density polyethylene (PE) composites loaded with HA and BG were fabricated using a modified injection molding machine that can provide intense shear flow to regulate the hierarchical structure of the composites. Morphological observation revealed that bone-like structures were formed in both HA/PE and BG/HA/PE composites, showing highly oriented interlocked shish kebabs. In addition, the bioactive fillers were distributed uniformly. Osteoblast proliferation was promoted by the combination of HA and BG. The mechanism was the upregulation of Runx2 expression (1.51 ±â€¯0.17) with BG and the activation of the TAZ/YAP (1.41/0.64) signaling pathway, which accelerated the generation of ossification-related proteins. BG can regulate microRNA to promote the mRNA expression of Runx2. The silencing of Runx2 expression can inhibit BG-induced osteoblast proliferation. These results suggest that the BG/HA/PE composites having a bone-like structure have high potential as bone substitutes to repair large bone defects.

Enhanced oxidation stability of highly cross-linked ultrahigh molecular weight polyethylene by tea polyphenols for total joint implants.

Despite being currently state-of-the-art to prevent the oxidation of irradiated ultrahigh molecular weight polyethylene (UHMWPE) bearings, vitamin E (VE) poses concerns in the loss of cross-linking efficiency and is limited to be used at very low concentrations. It thus emphasizes the urgent demand for more efficient stabilizers. In this study, oxidation stability of highly cross-linked UHMWPE was demonstrated to be enhanced by tea polyphenols, such as lipid-soluble tea polyphenols (lsPPT), epigallocatechin gallate (EGCG), and lipid-soluble epigallocatechin gallate (lsEGCG). These antioxidants were blended with UHMWPE granules and consolidated by compression molding prior to E-beam irradiation. The presence of tea polyphenols substantially prolonged oxidation induction time of the irradiated UHMWPE before and after accelerated aging. Especially, lsEGCG was significantly superior to VE in terms of stabilizing capacity. Explained by the hydrogen donation mechanism, tea polyphenols with multiple phenolic hydroxyls could scavenge more radiation-induced free radicals than VE with only one phenolic hydroxyl, which was verified by the electron spin resonance spectra. Intriguingly, tea polyphenols showed less inhibitive effect on the cross-link density of irradiated UHMWPE than VE. Besides, there is no significant difference in crystallinity, mechanical performance as well as in vitro biocompatibility between the irradiated UHMWPE stabilized by tea polyphenols and VE. These findings highlight tea polyphenols, especially lsEGCG, are promising alternatives to extend the life span of UHMWPE implants.