Injectable Boron Nitride-Hyaluronic Acid Hybrid Hydrogels to Facilitate Joint Motion: Mechanical and Tribological Characterization

Hexagonal boron nitride (hBN) is used as an additive in engineering applications such as polymers, ceramics, and coatings because of its anti-wear and lubrication performance. It has a high potential as a biomaterial, but it has not been evaluated to facilitate joint motion with its lubricating properties until now. In this study, the hypothesis that boron nitride nanoparticles (BNPs) and nanosheets (BNNSs) can facilitate movement in the joint region is evaluated for the first time. Hyaluronic acid-based hybrid hydrogels are designed to transport BN particles to the target area and pin-on-disc tests on cartilage pins paired with glass disks are conducted to determine the validity of the proposed hypothesis. The injectability, mechanical properties, and friction coefficients of hydrogels with the addition of increasing proportions of different hBN morphologies are monitored. As a result, hyaluronic acid has been found to be a suitable carrier for the injectability of boron nitride in biomedical applications. The amount and morphology of boron nitride are observed as two important parameters. A significant decrease in the friction coefficient (18.9%) is observed in the BNNS-doped hybrid hydrogel compared to the virgin hydrogel. hBN can be considered as a new therapeutic agent with the potential to facilitate joint mobility.