title: Bioinspired lubricating films of cellulose nanofibrils and hyaluronic acid.
abstract: The development of materials that combine the excellent mechanical strength of cellulose nanofibrils (CNF) with the lubricating properties of hyaluronic acid (HA) is a new, promising approach to cartilage implants not explored so far. A simple, solvent-free method to produce a very lubricating, strong cellulosic material by covalently attaching HA to the surface of CNF films is described in this work. A detailed analysis of the tribological properties of the CNF films with and without HA is also presented. Surface and friction forces at micro/nanoscale between model hard surfaces (glass microspheres) and the CNF thin films were measured using an atomic force microscope and the colloid probe technique. The effect of HA attachment, the pH and the ionic strength of the aqueous medium on the forces was examined. Excellent lubrication was observed for CNF films with HA attached in conditions where the HA layer was highly hydrated. These results pave the way for the development of new nanocellulose-based materials with good lubrication properties that could be used in biomedical applications.
authors.affiliation: Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland. Electronic address: juanjose.valledelgado@aalto.fi.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Valle-Delgado
authors.affiliation: Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland.
authors.forename: Leena-Sisko
authors.initials: LS
authors.lastname: Johansson
authors.affiliation: Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland. Electronic address: monika.osterberg@aalto.fi.
authors.forename: Monika
authors.initials: M
authors.lastname: Österberg
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D017276:Friction; D005898:Glass / Q000737:chemistry; D006820:Hyaluronic Acid / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D054327:Lubricants / Q000737:chemistry*; D008153:Lubrication; D008422:Materials Testing / Q000379:methods; D018625:Microscopy, Atomic Force; D008863:Microspheres; D057139:Nanofibers / Q000737:chemistry*; D009994:Osmolar Concentration; D056951:Photoelectron Spectroscopy; D015203:Reproducibility of Results; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D054327:Lubricants; D014867:Water; D002482:Cellulose; D006820:Hyaluronic Acid
keywords: Cellulose nanofibrils; Colloid probe technique; Hyaluronic acid; Lubrication; Thin films