A highly crosslinking network combined with a fullerene-like structure is disclosed in a hydrogenated amorphous carbon film. The very soft carbon film exhibits super-low friction and excellent wear resistance even under a Hertzian contact pressure comparable to its hardness under vacuum, which is an extraordinary tribological behavior in the filed of solid lubrication films or coatings.

implants, e.g., blood contacting implants such as heart valves and stents, load bearing joints and ophthalmic surgery. [1][2][3] However, many in vitro experiments on biocompatibility and tribology showed contradictory results, due to different experimental setup and different fl uids used as lubricants. [4][5][6][7] The low tribological properties of DLC in air or vacuum could not be adapted to load bearing joints operated in biological fl uids, which would be one of the major restrictions on its application for coating material of biological implants where lubrication is of great importance. Fortunately, surface functionalization of DLC fi lms is a practicable and effective method to solve the key problems. However, there were few reports on surface functionalization of DLC fi lms to give DLC required biological properties. Hamers and Garrido used photochemical process to generate a monolayer of amine groups on nanocrystalline diamond surfaces and then DNA or proteins was covalently attached, leading to stable biologically active surfaces. [ 8,9 ] In this paper, mussel inspired catechol and following polymer brushes would be presented to functionalize DLC fi lm to meet its aqueous lubrication.Generally, water is not a good lubricant for the friction system of some inorganic materials because it is very hard to form stable boundary fi lm due to low viscosity. However, the extremely low friction properties supported by water lubrication were found in some biological surfaces, for example, the vitreous body of eyes, the organs of human body and synovial joints, such as hip, knee and fi nger joints. [ 10 ] The effi ciency is attributed to the complex structure of self-adaptive cartilage [ 11 ] combined with synergetic effects of self-assembled structure of biological additives (such as phospholipids, hyaluronan (HA), lubricins) and bottle-brushes-like glycoproteins. The biomolecules in synovial fl uid can immobilize onto surfaces of cartilage and combine large amounts of water molecules to aid lubrication. [12][13][14][15] For instance, HA-aggrecans complexes showed much better boundary lubrication properties than the HA alone, because of the fl uid hydration sheaths strongly bound to the highly charged segments on the aggrecans. [ 16 ] Over the last decades, some artifi cial methods have been employed to mimic the excellent bio-lubrication. Water-soluble polymers [ 17 ] and polymer brushes grafted from fl at surfaces [ 18 ] are two effective approaches to reduce friction in aqueous medium. HA, a linear Diamond-like carbon (DLC) fi lm has emerged as a promising material for biomedical applications, but its low tribological properties in air could not be adapted in water and biological fl uids. Herein, mussel-inspired catechol adhesive is presented to functionalize DLC fi lm and then polymer brushes are grafted by surface initiated atom transfer radical polymerization (SI-ATRP) to mimic excellent biological lubrication of articular cartilage. Macroscopic tribological evaluation demonstrates low and stable friction c...

Poly(vinyl alcohol)/poly(N-vinyl pyrrolidone) (PVP)/chitosan hydrogels were prepared by a lowtemperature treatment and subsequent 60 Co ␥-ray irradiation and then were medicated with ciprofloxacin lactate (an antibiotic) and chitosan oligomer (molecular weight ϭ 3000 g/mol). The gel content, swelling ratio, tensile strength, and crystallinity of the hydrogels were determined. The effects of the chitosan molecular weight, the low-temperature treatment procedure, and the radiation dosage on the hydrogel properties were examined. The molecular weight of chitosan was lowered by the irradiation, but its basic polysaccharide structure was not destroyed. Repeating the low-temperature treatment and ␥-ray irradiation caused effective physical crosslinking and chemical crosslinking, respectively, and contributed to the mechanical strength of the final hydrogels. The incorporation of PVP and chitosan resulted in a significant improvement in the equilibrium swelling ratio and elongation ratio of the prepared hydrogels. The ciprofloxacin lactate and chitosan oligomer were soaked into the hydrogels. Their in vitro release behaviors were examined, and they were found to follow diffusion-controlled kinetics.