Novel Boundary Lubrication Mechanisms from Molecular Pillows of Lubricin Brush-Coated Graphene Oxide Nanosheets

Langmuir. 2022 May 10;38(18):5351-5360. doi: 10.1021/acs.langmuir.1c02970. Epub 2022 Apr 24.

Abstract

There are numerous biomedical applications where the interfacial shearing of surfaces can cause wear and friction, which can lead to a variety of medical complications such as inflammation, irritation, and even bacterial infection. We introduce a novel nanomaterial additive comprised of two-dimensional graphene oxide nanosheets (2D-NSCs) coated with lubricin (LUB) to reduce the amount of tribological stress in biomedical settings, particularly at low shear rates where boundary lubrication dominates. LUB is a glycoprotein found in the articular joints of mammals and has recently been discovered as an ocular surface boundary lubricant. The ability of LUB to self-assemble into a "telechelic" brush layer on a variety of surfaces was exploited here to coat the top and bottom surfaces of the ultrathin 2D-NSCs in solution, effectively creating a biopolymer-coated nanosheet. A reduction in friction of almost an order of magnitude was measured at a bioinspired interface. This reduction was maintained after repeated washing (5×), suggesting that the large aspect ratio of the 2D-NSCs facilitates effective lubrication even at diluted concentrations. Importantly, and unlike LUB-only treatment, the lubrication effect can be eliminated over 15 rinsing cycles, suggesting that the LUB-coated 2D-NSCs do not exhibit any binding interactions with the shearing surfaces. The effective lubricating properties of the 2D-NSCs combined with full reversibility through rinsing make the LUB-coated 2D-NSCs an intriguing candidate as a lubricant for biomedical applications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Friction
  • Glycoproteins* / chemistry
  • Graphite
  • Lubricants*
  • Lubrication
  • Mammals

Substances

  • Glycoproteins
  • Lubricants
  • graphene oxide
  • lubricin
  • Graphite