Tough Bonding of PVA Hydrogel-on-Textured Titanium Alloy with Varying Texture Densities in Swollen State.

Cartilage defects in large joints are a common occurrence in numerous degenerative diseases, especially in osteoarthritis. The hydrogel-on-metal composite has emerged as a potential candidate material, as hydrogels, to some extent, replicate the composition of human articular cartilage consisting of collagen fibers and proteoglycans. However, achieving tough bonding between the hydrogel and titanium alloy remains a significant challenge due to the swelling of the hydrogel in a liquid medium.

In vitro drug release and cartilage interface lubrication properties of biomimetic polymers.

Osteoarthritis is a degenerative disease that is widely found in the elderly population, with a trend towards a younger age group in recent years. In the early stages of arthritis, patients are treated with hyaluronic acid injections and anti-inflammatory drugs. However, it has been found that hyaluronic acid can only play a supportive role and does not have a lubricating effect, and due to the absence of blood vessels, nerves, and lymphatic vessels in the articular cartilage, the oral anti-inflammatory drugs cannot reach the interface of the inflammatory joints adequately, and the drug utilisation rate is low.

A lubricant and adhesive hydrogel cross-linked from hyaluronic acid and chitosan for articular cartilage regeneration.

Trauma-induced articular cartilage damages are common in clinical practice. Hydrogels have been used to fill the cartilage defects and act as extracellular matrices for cell migration and tissue regeneration. Lubrication and stability of the filler materials are essential to achieve a satisfying healing effect in cartilage regeneration.

Improved Interfacial Interactions of Dip Coatings by In Situ Introducing Silica to Enhance Corrosion Resistance and Metal Bonding Strength.

Corrosion is an irreversible phenomenon in nature that has been a major source of metal degradation. We herein provide a unique approach for embedding nanoparticles into epoxy resins via hydrogen bonding adsorption of in situ hydrophilic silica. Based on this adsorption action, a super-anticorrosive epoxy-based Teflon (MEP-PTFE) coating for usage on metals such as aluminum alloys was developed utilizing one-step dip coating, with promising engineering and public applications.

Silver/Polypyrrole-Functionalized Polyurethane Foam Embedded Phase Change Materials for Thermal Energy Harvesting.

Conversion of solar energy into thermal energy stored in phase change materials (PCMs) can effectively relieve the energy dilemma and improve energy utilization efficiency. However, facile fabrication of form-stable PCMs (FSPCMs) to achieve simultaneously energetic solar-thermal, conversion and storage remains a formidable challenge. Herein, we report a desirable solar-thermal energy conversion and storage system that utilizes paraffin (PW) as energy-storage units, the silver/polypyrrole-functionalized polyurethane (PU) foam as the cage and energy conversion platform to restrain the fluidity of the melting paraffin and achieve high solar-thermal energy conversion efficiency (93.

A tannic acid-reinforced PEEK-hydrogel composite material with good biotribological and self-healing properties for artificial joints.

Polyetheretherketone (PEEK) is widely considered as a promising material for joint implants but it still has limitations involving high friction and wear. To mimic the cartilage-subchondral bone structure in natural joints, a polyvinyl alcohol (PVA) hydrogel layer was fabricated on the PEEK substrate to provide a lubrication mechanism. In addition, tannic acid was applied to form dynamic hydrogen bonds with PVA molecules, for the purpose of strengthening the hydrogel layer and endowing it with self-healing ability.

Bio-inspired surface modification of PEEK through the dual cross-linked hydrogel layers.

The biocompatible high-performance material PEEK (polyetheretherketone) is an attractive implant material, however, its hydrophobicity and high friction coefficients severely hinder its biomedical applications. Thus, it is inferred from the recent advances in surface modification technology, achieving the biomimetic natural joint lubrication systems on PEEK still remains a challenge. In view of the above, herein we proposed a novel two-step strategy to fabricate a "soft (dual cross-linked hydrogel) layer-hard (PEEK) substrate" texture that mimics the structure and function of soft cartilage on the hard basal bone in joints.

Doubly crosslinked biodegradable hydrogels based on gellan gum and chitosan for drug delivery and wound dressing.

Biopolymer-based hydrogels with sustained drug release capability and antibacterial activity have exhibited great potential in clinical application in drug delivery and wound healing. In this study, a new type of composite wound dressing hydrogel aiming at avoiding wound infection was developed through embedding drug loaded gellan gum microspheres (GMs) into a doubly crosslinked hydrogel, which was constructed by Schiff-base crosslinking of oxidized gellan gum (OG) (pre-crosslinked by calcium ion) and carboxymethyl chitosan (CMCS). The gelation time, swelling index, degradation rate and mechanical properties of the blank hydrogel was optimized by varying the ratios of CMCS/OG (w/w) with fixed OG/calcium (w/w) ratio.

Multilayers of poly(ethyleneimine)/poly(acrylic acid) coatings on Ti6Al4V acting as lubricated polymer-bearing interface.

To achieve an efficient lubricated interface on titanium alloy (Ti6Al4V) alloy, polyelectrolyte multilayer (PEM) polymer coatings, based on poly(ethyleneimine)/poly(acrylic acid) (PEI/PAA), were fabricated on the surface of Ti6Al4V alloy substrates using the layer-by-layer (LbL) assembly technique. Their composition and morphology were confirmed by Fourier-transform infrared/attenuated total reflectance (FTIR/ATR) spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The tribological properties were investigated by a ball-on-disk rotating tribometer using deionized water, saline, and calf serum.

Superhydrophobic Surface with Stepwise Multilayered Micro- and Nanostructure and an Investigation of Its Corrosion Resistance.

We develop a fluorine-free preparation of the superhydrophobic surface on an aluminum alloy with anticorrosion performance and mechanical robustness. The surface morphology, chemical composition, and water repellency were determined with SEM, CLSM, EDS, FT-IR, TG, and contact-angle measurements, respectively. The aluminum matrix superhydrophobic surface (STA-PDMS-ZnO sample) was able to display excellent repellency to water with a WCA of 152° and a WSA of 2°.

Lyophobic slippery surfaces on smooth/hierarchical structured substrates and investigations of their dynamic liquid repellency.

Slippery surfaces were prepared by infusing lubricant into smooth or hierarchical-structured superhydrophobic surfaces (SHS) to compare different surface-free energies. The surfaces obtained showed good repellency towards liquids with various values of surface tension/molecular polarity/viscosity, including hexane, tetradecane, water, ethylene glycol and viscous engine oil. The lyophobicity could be realized on a relatively smooth surface, indicating that the first principle of preparing a lyophobic slippery surface is to perform a low surface-free energy modification.

Magnetic and self-healing chitosan-alginate hydrogel encapsulated gelatin microspheres via covalent cross-linking for drug delivery.

In order to broaden the abilities of injectable hydrogel scaffolds, a self-healing chitosan/alginate hydrogel encapsulated with magnetic gelatin microspheres (MGMs) was prepared for anti-cancer drug delivery and soft tissue engineering. The hydrogel was formulated by cross-linking carboxyethyl chitosan (CEC) and oxidized alginate (OAlg) via the Schiff-base reaction. To strengthen the mechanical and biological capabilities of hydrogel, MGMs containing 5-fluorouracil (5-Fu) were prepared by an emulsion cross-linking method.

Covalently polysaccharide-based alginate/chitosan hydrogel embedded alginate microspheres for BSA encapsulation and soft tissue engineering.

Hydrogels based scaffolds are very promising materials for a wide range of medical applications including tissue engineering and drug delivery. This study reports a covalently cross-linked composite hydrogel embedded with microspheres basing natural polysaccharides as a protein delivery system for soft tissue engineering. This biodegradable composite hydrogel derived from water-soluble chitosan and alginate derivatives upon mixing, without addition of chemical cross-linking agents.

Biodegradable Nanoglobular Magnetic Resonance Imaging Contrast Agent Constructed with Host-Guest Self-Assembly for Tumor-Targeted Imaging.

Gadolinium-based macromolecular magnetic resonance imaging (MRI) contrast agents (CAs) have attracted increasing interest in tumor diagnosis. However, their practical application is potentially limited because the long-term retention of gadolinium ion in vivo will induce toxicity. Here, a nanoglobular MRI contrast agent (CA) PAMAM-PG- g-s-s-DOTA(Gd) + FA was designed and synthesized on the basis of the facile host-guest interaction between β-cyclodextrin and adamantane, which initiated the self-assembly of poly(glycerol) (PG) separately conjugated with gadolinium chelates by disulfide bonds and folic acid (FA) molecule onto the surface of poly(amidoamine) (PAMAM) dendrimer, finally realizing the biodegradability and targeting specificity.

Injectable polysaccharide hydrogel embedded with hydroxyapatite and calcium carbonate for drug delivery and bone tissue engineering.

To meet the progressive requirements for bone regeneration purpose, injectable hydrogels have attracted increasing attention in tissue regeneration and local drug delivery applications. In this study, we report a facile method to prepare injectable and degradable polysaccharide-based hydrogels doubly integrated with hydroxyapatite (HAp) nanoparticles and calcium carbonate microspheres (CMs) under physiological condition. The mechanism of cross-linking is attributed to the Schiff-base reaction between amino and aldehyde groups of carboxymethyl chitosan (CMCS) and oxidized alginate (OAlg), respectively.

Construction of lubricant composite coating on Ti6Al4V alloy using micro-arc oxidation and grafting hydrophilic polymer.

To improve the tribological properties of Ti6Al4V alloy to realize the application in artificial joints, a novel composite coating was designed and fabricated on its surface through the combination of two different surface modification techniques-micro-arc oxidation (MAO) and grafting hydrophilic polymer. The characterizations of morphologies and composition of MAO layer were examined using scanning electron microscopy (SEM), energy dispersive spectroscope (EDS) and X-ray diffraction (XRD). It was found that a TiO layer displaying uniform porous structure formed on the surface based on the optimal MAO parameters of an oxidation voltage of 450 V and an oxidation time of 60 min.

Improving surface wettability and lubrication of polyetheretherketone (PEEK) by combining with polyvinyl alcohol (PVA) hydrogel.

Poor surface wettability and relative high friction coefficients of pristine polyetheretherketone (PEEK) have limited its application in orthopedic implants. In this study, inspired by the structure of natural articular cartilage, we presented a novel method to fabricate a "soft-on-hard" structure on the surface of pristine PEEK specimens, which combined a soft polyvinyl alcohol (PVA) hydrogel layer and a three-dimensional porous layer with PEEK substrates. A variety of analytical methods were used to evaluate their properties, our results demonstrated that the hydrogel layer could be seamlessly connected with substrate, and the hydrogel-covered PEEK owned a highly hydrophilic surface, a very low water contact angle of 7° could be obtained.

A poly(ε-caprolactone)-poly(glycerol)-poly(ε-caprolactone) triblock copolymer for designing a polymeric micelle as a tumor targeted magnetic resonance imaging contrast agent.

Gadolinium-based macromolecular contrast agents (CAs) with favorable biocompatibility, targeting specificity, and high relaxivity properties are desired for magnetic resonance imaging (MRI) of tumors. Herein, a novel triblock polymeric micelle based on poly(glycerol) (PG) and poly(ε-caprolactone) (PCL) was designed as a nanocarrier to fabricate a tumor targeted contrast agent (CA). Through conjugating gadolinium chelates and folic acid (FA) molecules to the PG block, a triblock-micelle contrast agent (T-micelle) formed from self-assembly demonstrated a low critical micelle concentration (CMC) of 6 mg L and a hydrodynamic diameter of about 250 nm.

Gadolinium-based nanoscale MRI contrast agents for tumor imaging.

Gadolinium-based nanoscale magnetic resonance imaging (MRI) contrast agents (CAs) have gained significant momentum as a promising nanoplatform for detecting tumor tissue in medical diagnosis, due to their favorable capability of enhancing the longitudinal relaxivity (r) of individual gadolinium ions, delivering to the region of interest a large number of gadolinium ions, and incorporating different functionalities. This mini-review highlights the latest developments and applications, and simultaneously gives some perspectives for their future development.

Improved biotribological properties of PEEK by photo-induced graft polymerization of acrylic acid.

The keys of biomaterials application in artificial joints are good hydrophilicity and wear resistance. One kind of the potential bio-implant materials is polyetheretherketone (PEEK), which has some excellent properties such as non-toxic and good biocompatibility. However, its bioinert surface and inherent chemical inertness hinder its application.

Semi-degradable porous poly (vinyl alcohol) hydrogel scaffold for cartilage repair: Evaluation of the initial and cell-cultured tribological properties.

Tissue engineering for articular cartilage repair has shown success in ensuring the integration of neocartilage with surrounding tissue, but the rapid restoration of biomechanical and biotribological functions remains a significant challenge. Poly (vinyl alcohol) (PVA) hydrogel is regarded as a potential articular cartilage replacement for its fair mechanical strength and low surface friction, while its lack of bioactivity limits its utility. Combining the advantages of tissue engineering materials and PVA hydrogel, we developed a semi-degradable porous PVA hydrogel through addition of ploy (lactic-co-glycolic acid) (PLGA) microspheres and salt-leaching technique.

Poly(glycerol) Used for Constructing Mixed Polymeric Micelles as T MRI Contrast Agent for Tumor-Targeted Imaging.

There was much interest in the development of nanoscale delivery vehicles based on polymeric micelles to realize the diagnostic and therapeutic applications in biomedicine. Here, with the purpose of constructing a micellar magnetic resonance imaging (MRI) contrast agent (CA) with well biocompatibility and targeting specificity, two types of amphiphilic diblock polymers, mPEG-PG(DOTA(Gd))-b-PCL and FA-PEG-b-PCL, were synthesized to form mixed micelles by coassembly. The nanostructure of the resulting micellar system consisted of poly(caprolactone) (PCL) as core and poly(glycerol) (PG) and poly(ethylene glycol) (PEG) as shell, simultaneously modified with DOTA(Gd) chelates and folic acid (FA), which afforded functions of MRI contrast enhancement and tumor targeting.

Preparation of linear poly(glycerol) as a T contrast agent for tumor-targeted magnetic resonance imaging.

Macromolecular contrast agents (CAs) labeled with targeting molecules are gaining remarkable interest as promising materials overcoming the defects of small-molecule CAs. Designed on the basis of biocompatible poly(glycerol) (PG), a linear macromolecular contrast agent (CA) was synthesized with a composition of PG as a backbone and partial hydroxyl connected with gadolinium labeled poly(l-lysine) dendrons, where folic acid was also conjugated. This linear CA exhibited higher relaxivity (7.

Swelling, mechanical and friction properties of PVA/PVP hydrogels after swelling in osmotic pressure solution.

The potential of polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) hydrogels as articular cartilage replacements was in vitro evaluated by using a macromolecule-based solution to mimic the osmotic environment of cartilage tissue. The effects of osmotic pressure solution on the morphology, crystallinity, swelling, mechanical and friction properties of PVA/PVP hydrogels were investigated by swelling them in non-osmotic and osmotic pressure solutions. The results demonstrated that swelling ratio and equilibrium water content were greatly reduced by swelling in osmotic solution, and the swelling process was found to present pseudo-Fickian diffusion character.

Mechanically robust superhydrophobic steel surface with anti-icing, UV-durability, and corrosion resistance properties.

A superhydrophobic steel surface was prepared through a facile method: combining hydrogen peroxide and an acid (hydrochloric acid or nitric acid) to obtain hierarchical structures on steel, followed by a surface modification treatment. Empirical grid maps based on different volumes of H2O2/acid were presented, revealing a wettability gradient from "hydrophobic" to "rose effect" and finally to "lotus effect". Surface grafting has been demonstrated to be realized only on the oxidized area.