Wear Behavior Characterization of Hydrogels Constructs for Cartilage Tissue Replacement

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Orthopedics

Background:

• Human articular cartilage exhibits zonal variations impacting its mechanical properties and wear resistance.
• Hydrogel constructs offer potential for articular cartilage replacement, but their wear behavior requires thorough characterization.
• Mimicking the zonal architecture of native cartilage is critical for developing effective hydrogel-based replacements.

Purpose of the Study:

• To characterize the wear behavior of hydrogel constructs designed for human articular cartilage replacement.
• To investigate the influence of poly (ethylene glycol) diacrylate (PEGDA) concentration and graphene oxide (GO) incorporation on hydrogel wear performance.
• To evaluate the suitability of micro-computer tomography (µ-CT) and Raman spectroscopy for assessing hydrogel structure and composition after wear testing.

Main Methods:

• Fabrication of hydrogel constructs using PEGDA and gellan gum (GG) to mimic superior (SUP) and deep (DEEP) cartilage layers.
• Wear testing of hydrogel constructs using a four-station displacement control knee joint simulator in bovine calf serum.
• Analysis of hydrogel properties including surface roughness, density uniformity (via µ-CT), and chemical composition (via Raman spectroscopy).

Main Results:

• Hydrogels with 15% w/v PEGDA exhibited superior wear resistance compared to those with 10% w/v PEGDA, showing less roughness increase and density loss.
• The inclusion of graphene oxide (GO) alongside 15% w/v PEGDA further enhanced the stability and preserved the structural integrity of the hydrogel constructs.
• Raman spectroscopy confirmed the loss of unreacted PEGDA due to washout, with the extent of loss inversely correlated to the degree of photo-crosslinking, highlighting its critical role in wear behavior.

Conclusions:

• The wear behavior of hydrogel constructs is significantly influenced by PEGDA concentration and the degree of photo-crosslinking.
• Incorporating GO, particularly with higher PEGDA concentrations, enhances the durability of hydrogels for cartilage replacement applications.
• µ-CT and Raman spectroscopy are effective tools for characterizing the structural and compositional changes in hydrogels subjected to wear, providing valuable insights for material design.