Akanksha Raj1, Min Wang2, Chao Liu3, Liaquat Ali4, Niclas G Karlsson5, Per M Claesson6, Andra Dėdinaitė7. 1. KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science, Drottning Kristinas Väg 51, SE-10044 Stockholm, Sweden. Electronic address: rajaka@kth.se. 2. KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science, Drottning Kristinas Väg 51, SE-10044 Stockholm, Sweden. Electronic address: mwang@kth.se. 3. KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science, Drottning Kristinas Väg 51, SE-10044 Stockholm, Sweden. Electronic address: chaoliu@kth.se. 4. Medicinal Biochemistry and Microbiology, Institute of Biomedicine, University of Gothenburg, Medicinaregatan 9A, SE-40530 Gothenburg, Sweden. Electronic address: liaqat.ali@medkem.gu.se. 5. Medicinal Biochemistry and Microbiology, Institute of Biomedicine, University of Gothenburg, Medicinaregatan 9A, SE-40530 Gothenburg, Sweden. Electronic address: niclas.karlsson@medkem.gu.se. 6. KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science, Drottning Kristinas Väg 51, SE-10044 Stockholm, Sweden; SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, Box 5607, SE-114 86 Stockholm, Sweden. Electronic address: percl@kth.se. 7. KTH Royal Institute of Technology, School of Chemical Sciences and Engineering, Department of Chemistry, Surface and Corrosion Science, Drottning Kristinas Väg 51, SE-10044 Stockholm, Sweden; SP Technical Research Institute of Sweden, SP Chemistry, Materials and Surfaces, Box 5607, SE-114 86 Stockholm, Sweden. Electronic address: andra@kth.se.
Abstract
HYPOTHESIS: Synovial surfaces are lubricated by biomolecular aggregates that act in synergy, and lubricin is one key biolubricant. Its molecular structure allows extensive hydration and this is conducive to its lubrication performance. However, in order to fullfil its lubrication function it needs to be anchored and oriented on the surface in a proper way. We suggest that cartilage oligomeric matrix protein (COMP) is one of the biomolecules that promotes anchoring of lubricin in a fashion that facilitates lubrication. EXPERIMENTS: Weakly hydrophobic poly(methyl methacrylate) (PMMA) surfaces were coated by COMP and lubricin, individually and in combinations. Adsorption was investigated using a quartz crystal microbalance, and friction between the biopolymer-coated surfaces was determined by employing the atomic force microscope-colloidal probe technique. FINDINGS: It was found that COMP facilitated firm directed attachment of lubricin in a manner that resulted in low friction forces, significantly lower than what was achieved when lubricin was directly adsorbed to PMMA. Evidently, COMP provides means for lubricin to attach strongly and in a favourable conformation for efficient lubrication of this surface. We suggest that our findings can be extrapolated to cartilage surfaces, where co-localization of COMP and lubricin has been demonstrated.
HYPOTHESIS: Synovial surfaces are lubricated by biomolecular aggregates that act in synergy, and lubricin is one key biolubricant. Its molecular structure allows extensive hydration and this is conducive to its lubrication performance. However, in order to fullfil its lubrication function it needs to be anchored and oriented on the surface in a proper way. We suggest that cartilage oligomeric matrix protein (COMP) is one of the biomolecules that promotes anchoring of lubricin in a fashion that facilitates lubrication. EXPERIMENTS: Weakly hydrophobic poly(methyl methacrylate) (PMMA) surfaces were coated by COMP and lubricin, individually and in combinations. Adsorption was investigated using a quartz crystal microbalance, and friction between the biopolymer-coated surfaces was determined by employing the atomic force microscope-colloidal probe technique. FINDINGS: It was found that COMP facilitated firm directed attachment of lubricin in a manner that resulted in low friction forces, significantly lower than what was achieved when lubricin was directly adsorbed to PMMA. Evidently, COMP provides means for lubricin to attach strongly and in a favourable conformation for efficient lubrication of this surface. We suggest that our findings can be extrapolated to cartilage surfaces, where co-localization of COMP and lubricin has been demonstrated.