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The service conditions of rubber seals are primarily in the dynamic sliding state, with a high coefficient of friction, which can seriously compromise the equipment’s safety and the services’ lifespan. Diamond-like carbon (DLC) films have been the ideal candidate for tribological modification of rubber surfaces due to their excellent tribological properties over the last two decades. This field can be widely discussed as a hard film on soft substrates, where the challenge is the mismatch of mechanical properties, leading to the exfoliation of DLC films in friction. Early work developed the DLC films with a segment structure to solve this critical issue, illustrating the possibility of wear-resistant rubber. In recent years, researchers have paid attention to further increasing the coated rubber’s lifetime in friction, focusing on adhesion. These research achievements were reviewed on the aspects of structurization, adhesion, and doping in this article. It proposed an alternative direction of understanding the surface wear mechanism for designing wear-resistant DLC films on rubber.

Although titanium and its alloys are broadly utilized in various biomedical applications, some challenges still exist, especially their poor hemocompatibility and insufficient surface bioactivity. In this work, to achieve in situ rapid reendothelialization and improve non-specific anti-biofouling, a novel strategy inspired by the endothelial function and the glycocalyx structure was proposed to construct a three-dimensional glycocalyx-like coating (TNTA-PEG-HR) on TA2 alloy by functionalizing TiO2nanotubes with 6-arm aminated polyethylene glycol (PEG), Arg-Glu-Asp-Val (REDV) peptide and heparin. The nanotubes were firstly fabricated by anodic oxidation and annealing treatment to imitate the three-dimensional structure of glycocalyx, followed by successively preparing the Zn2+-loaded polydopamine interlayer, grafting 6-arm PEG, and covalently immobilizing the complex of heparin and REDV. The biomimetic coating was exhaustively characterized and its impacts on hemocompatibility and cell behaviors were also evaluated. The results showed that TNTA-PEG-HR coating improved the hydrophilicity, promoted the adsorption of bovine serum albumin while inhibiting fibrinogen adsorption, effectively lessened the adhered and activated platelets, and suppressed human plasma α-granular membrane protein (GMP140) expression, resulting in the improvement of hemocompatibility. TNTA-PEG-HR coating accelerated endothelial cell (EC) adhesion and proliferation, and up-regulated VEGF and NO expression, thus facilitating the cytocompatibility and promoting rapid reendothelialization. Moreover, TNTA-PEG-HR coating significantly suppressed the adhesion and proliferative activity of smooth muscle cells (SMCs). This multifunctional coating provides a novel strategy for the blood-contacting materials to simultaneously achieve anti-biofouling, anticoagulation, and in situ rapid reendothelialization, representing a simple and convenient method of surface biofunctionalization for widespread clinical applications of titanium-based biomaterials.

Nanomaterials with unique nanotube arrays have attracted extensive attention in the field of blood-contacting biomaterials. In this study, the regular titanium dioxide nanotube arrays were first prepared on the pure titanium surface by anodic oxidation. Subsequently, copper ions (Cu2+) and strontium ions (Sr2+) were incorporated into the nanotubes by the chelation of dopamine to improve biocompatibility. The as-prepared TiO2nanotubes had an inner diameter of about 60 nm and an outer diameter of 90–110 nm, as well as a tube length of 4–6 µm. The following annealing treatment and the incorporation of Cu2+and Sr2+had little effect on the morphology and dimensions of the nanotubes, but can significantly improve the hydrophilicity, and promote the adsorption of bovine serum albumin concurrently inhibit the adsorption of fibrinogen, showing the effect of selective protein adsorption. At the same time, loading Cu2+and Sr2+can also effectively inhibit platelet adhesion and activation, promote endothelial cell growth, and upregulate the expression of vascular endothelial growth factor and nitric oxide. Therefore, the results of this study showed that the incorporation of Cu2+and Sr2+into the TiO2nanotubes can simultaneously improve the hemocompatibility and cytocompatibility of endothelial cells, which can enlarge the application of titanium-based biomaterials in cardiovascular devices such as a stent.

As biodegradable orthopedic implant materials, magnesium alloys have been attracted enough attentions recently. However, too fast degradation in vivo, limited biocompatibilities, and insufficient antibacterial properties are three main challenges at present. In order to solve these problems, a multifunctional composite coating of Chi(Zn/BMP2)/HA was constructed on AZ31B magnesium alloy surface, successively by the alkali heating treatment, self-assembly of 16-phosphonyl-hexadecanoic acid, in situimmobilization of Chi(Zn/BMP2) (chitosan, zinc ions, and bone morphogenetic protein 2), and the deposition of HA (hydroxyapatite). The results of ATR-FTIR (attenuated total reflection Fourier transform infrared spectrum) spectra and elemental compositions confirmed that 16-phosphonyl-hexadecanoic acid, Chi(Zn/BMP2), and HA were successfully immobilized on the surface. Compared with Mg, Mg-OH, Mg-16, and Mg-Chi(Zn/BMP2), Mg-Chi(Zn/BMP2)/HA with the concave–convex structure surface significantly enhanced the hydrophilicity and corrosion resistance. On the other hand, Mg-Chi(Zn/BMP2)/HA coating also showed excellent biocompatibilities, which not only significantly promoted the osteoblast adhesion and proliferation, but also upregulated ALP and OCN expression of osteoblasts. Furthermore, due to the synergistic antibacterial effect of zinc ions and chitosan, Mg-Chi(Zn/BMP2)/HA showed a good antibacterial property against Escherichia coli(E. coli). Therefore, it can be said that the method used in this work has a good application prospect in improving the corrosion resistance, biocompatibility of magnesium alloys, and inhibiting infections against E. coli.

In recent years, intracranial thrombectomy stent has been an important method to treat ischemic stroke caused by acute thrombosis. In this paper, a new intracranial thrombectomy stent with a fish scale-like structure was designed and its mechanical properties were studied by a finite element method. The porosity of all stents was more than 80%. The space occupation ratio (SOR) of the stents increased linearly with the increase of strut thickness, while the strut width had little effect on SOR. The maximum equivalent stress and strain, the directional deformation and overall radial load of the stent decreased with the increase of strut thickness, however, the strut width has little impact on these parameters. The stents with 0.2 mm strut width and the thickness of 0.15 and 0.20 mm had better radial load performance, and the stent with 0.2 mm strut width and 0.15 mm strut thickness had better contact performance with the vessel wall and displayed better flexibility. Therefore, the present study provides a theoretical basis for the design of new intracranial thrombectomy stent.

Abstract

Magnesium alloy is considered as one of the ideal cardiovascular stent materials owing to its good mechanical properties and biodegradability. However, the in vivorapid degradation rate and the insufficient biocompatibility restrict its clinical applications. In this study, the magnesium alloy (AZ31B) was modified by combining the surface chemical treatment and in-situ self-assembly of 16-phosphonyl-hexadecanoic acid, followed by the immobilization of chitosan-functionalized graphene oxide (GOCS). Heparin (Hep) and GOCS were alternatively immobilized on the GOCS-modified surface through layer by layer (LBL) to construct the GOCS/Hep bioactive multilayer coating, and the corrosion resistance and biocompatibility were extensively explored. The results showed that the GOCS/Hep bioactive multilayer coating can endow magnesium alloys with an excellent in vitrocorrosion resistance. The GOCS/Hep multilayer coating can significantly reduce the hemolysis rate and the platelet adhesion and activation, resulting in an excellent blood compatibility. In addition, the multilayer coating can not only enhance the adhesion and proliferation of the endothelial cells, but also promote the vascular endothelial growth factor (VEGF) and nitric oxide (NO) expression of the attached endothelial cells on the surfaces. Therefore, the method of the present study can be used to simultaneously control the corrosion resistance and improve the biocompatibility of the magnesium alloys, which is expected to promote the application of magnesium alloys in biomaterials or medical devices, especially cardiovascular stent.

Titanium dioxide nanotube arrays are widely used in biomaterials due to their unique tubular structure and tunable biocompatibility. In the present study, titanium oxide nanotube arrays with different diameters were prepared on the titanium surface by anodization, followed by zinc doping using hydrothermal treatment to enhance the biocompatibility. Both the nanotube dimensions and zinc doping had obvious influences on the hydrophilicity, protein adsorption, blood compatibility, and endothelial cell behaviors of the titanium surface. The increase of the diameter and zinc doping can improve the hydrophilicity of the titanium surface. The increase of nanotube diameter could reduce the albumin adsorption while increasing the fibrinogen adsorption. However, zinc doping can simultaneously promote the adsorption of albumin and fibrinogen, and the effect was more obvious for albumin. Zinc doping can significantly improve the blood compatibility of the titanium oxide nanotubes because it cannot only increase the activity of cyclophosphate guanylate (cGMP) but also significantly reduce the platelets adhesion and hemolysis rate. Moreover, it was also found that both the smaller diameter and zinc doping nanotubes can enhance the endothelial cell adhesion and proliferation as well as up-regulate the expression of NO and VEGF. Therefore, the zinc doped titanium dioxide nanotube array can be used to simultaneously improve the blood compatibility and promote endothelialization of the titanium-based biomaterials and implants, such as intravascular stents.

Implantation of a scaffold into the body in a safe and convenient manner remains a challenge in the repair of patient bone defect. In the present study, a strategy for fabrication of the redox-sensitive nanofibers with a core–shell structure that can deliver the growth factors in a tunable manner is presented. Poly(ethylene oxide) (PEO) and bone morphogenetic protein 2 (BMP-2) forms the inner core region, and a mixture of poly(epsilon-caprolactone) (PCL) and redox-responsive c-6A PEG–PCL nanogel with −S–S– bond forms the outer shell. The redox-sensitive shell of the nanofibers can respond the change of the GSH (glutathione) concentration and thus regulate the BMP-2 release behavior in vitro and in vivo. In vitro cytotoxicity results indicated that the redox-sensitive nanofiber had good osteoinduction. The in vivo results demonstrated that the nanofibers exhibited a capacity of prompting new bone generation in the bone defect. Therefore, the redox-responsive nanofiber in the present study may be of great potential for application in bone reconstruction.

The development of a facile and versatile strategy to endow surfaces with synergistically anti-inflammatory, antimicrobial, and anticoagulant functions is of particular significance for blood-contacting biomaterials and medical devices. In this work, we report a simple and environmentally friendly “one-pot” method inspired by byssal cuticle chemistry, namely, [Fe(dopa)3] coordination chemistry for assembly of copper ions (Cu2+) and plant polyphenol (tannic acid)/catecholamine (dopamine or norepinephrine) to form metal–phenolic/catecholamine network-based coatings. This one-pot method enabled us to easily develop a multifunctional surface based on the combination of the characteristic functions of metal ions and plant polyphenol or catecholamine. The residual phenolic hydroxyl groups on the coatings imparted the modified surface with excellent antioxidant and anti-inflammatory functions. The robust chelation of copper ions to the metal–phenolic/catecholamine networks provided not only durable antibacterial property but also glutathione peroxidase like catalytic capability to continuously and controllably produce antithrombotic nitric oxide by catalyzing endogenous S-nitrothiol. The biological functions of such coatings could be well regulated by adjusting the ratios of the feed concentration of Cu2+ions to plant polyphenol or catecholamine. We envision that our simple, multifunctional, and bioinspired coating strategy can hold great application promise for bioengineering blood-contacting devices.

Surface biomimetic modification with extra-cellular matrix (ECM)-derived biomolecules is an emerging potential method of accelerating the healing of vascular stent lesions. However, insufficient capacity of the constructed biofunctional layer in maintaining its long-term efficiency and preventing thrombus and neointimal hyperplasia continue to be major limitations in clinical application. On the basis of the structure and function of ECM, in this study, we constructed a novel stromal cell-derived factor-1α (SDF-1α)/laminin-loaded nanocoating on the 316L stainless steel (SS) surface to provide improved function in modulation of vascular remodeling. The modified surface was found to control delivery of biomolecules and exhibit promising potential to provide stage-adjusted treatment after injury. An in vitrobiocompatibility study suggested that the constructed layer may effectively prevent thrombosis formation by inhibiting platelet adhesion and activation, while accelerating endothelium regeneration by inducing endothelial cell (EC) migration and endothelial progenitor cell (EPC) aggregation. An in vivoanimal test further demonstrated that the nanocoating may prevent thrombus and neointimal hyperplasia after implantation for 3 months. Therefore, the ECM-inspired nanocoating described in this study is a promising novel approach for vascular stent surface modification.

It has been widely recognized that functional groups on biomaterial surfaces play important roles in blood compatibility. To construct an effective antithrombotic bio-interface onto the poly(ether sulfone) (PES) membrane surface, bio-functional groups of sodium carboxylic (–COONa), sodium sulfonic (–SO3Na) and amino (–NH2) groups were introduced onto the PES membrane surface in three steps: the synthesis of PES with carboxylic (–COOH) groups (CPES) and water-soluble PES with sodium sulfonic (–SO3Na) groups and amino (–NH2) groups (SNPES); the introduction of carboxylic groups onto the PES membrane by blending CPES with PES; and the grafting of SNPES onto CPES/PES membranes viathe coupling of amino groups and carboxyl groups. The physical/chemical properties and bioactivities were dependent on the proportions of the additives. After introducing bio-functional groups, the excellent hemocompatibility of the modified membranes was confirmed by the inhibited platelet adhesion and activation, prolonged clotting times, suppressed blood-related complement and leukocyte-related complement receptor activations. Furthermore, cell tests indicated that the modified membranes showed better cytocompatibility in endothelial cell proliferation than the pristine PES membrane due to the synergistic promotion of the functional groups. To sum up, these results suggested that modified membranes present great potential in fields using blood-contacting materials, such as hemodialysis and surface endothelialization.

A series of novel temperaturesensitive microgels were prepared through precipitation polymerization using MPTMS as the comonomer as well as the crosslinker. APS acted as the initiator to initiate the radical copolymerization of NIPAAm and MPTMS, at the same time, the acid environment resulting from the decomposition of APS catalyzed the hydrolysiscondensation of the siloxane groups to generate crosslinking points. The experimental results revealed that the microgels exhibited temperature sensitivity and the phase transition temperature was approximately 31 °C. An increase of SDS concentration or a decrease of MPTMS content resulted in a reduction of the final hydrodynamic diameters of the microgels.

The increasing demand for higher-quality medical care has resulted in the obsolescence of traditional biomaterials. Medical care is currently transitioning from an era depending on single-functional biomaterials to one that is supported by multifunctional and stable biomaterials. Herein, long-lasting multifunctional poly(ether sulfone) thin films (MPFs) containing heparin-mimic groups and a quaternary ammonium compound (QAC) were prepared via semi-interpenetrating polymer network (SIPN) strategy. The MPFs, with rough surface and inner finger-like macrovoid, had better hydrophilicity and anti-protein fouling ability, as revealed by scanning electron microscopy (SEM), atomic force microscope (AFM) and water contact angle (WCA) and protein adsorption tests. The results of platelet adhesion and activation, and clotting time confirmed that the hemocompatibility of the MPFs was significantly improved. From cell culture and germ-culture test, it was noted that the overall trend of human umbilical vein endothelial cell (HUVEC) proliferation was enhanced by a combination of heparin-mimic groups and QAC, whereas the growth of Escherichia coli(E. coli) and Staphylococcus aureus(S. aureus) was significantly prohibited. In addition, the MPFs were capable of modulating the expression level of basic fibroblast growth factor (bFGF) and transforming growth factor-beta1 (TGF-β1) in fibroblast, which was beneficial to controlling the formation of hypertrophic scar. In summary, the MPFs had potential to be used in the field of wound management and the study might help guide the design of surface structure of wound dressing.

Nitrogen-doped diamond-like carbon (N-DLC) films were synthesized by plasma immersion ion implantation and deposition (PIII-D) at room temperature (RT). During the process of deposition, N2flow was changed from 0 to 10 sccm. Lifshitz–van der Waals/acid–base (LW-AB) approach was employed to study the surface electronic state of the films, X-ray photoelectron spectroscopic (XPS) and valence band spectra (VBS) were used to study chemical bonds and electron structure information inside the films. Bandgap of the films were calculated by the data from ultraviolet spectrophotometer. The results showed that synthesized films were n-type semiconductors and doping of nitrogen element will affect the accepted–electron capability of the film. The change tendency of the bandgap coincides with that of the ratio of acidic to alkaline component of the polar acid-alkali surface energy. There was much sp hybrid electronic state existed in the films, which mainly sp2C=C/C=Nand sp3C–C/C–Nbonds.