Abstract
At present, one of the main limitations of three-dimensional (3D) bioprinting in tissue engineering stems from a scarcity of biomaterials tailored for specific applications. Widely used hydrogels offer an optimal printability and a suitable environment for cell growth; however, they lack the mechanical strength required for non-soft tissues, for example, cartilage, tendons, and meniscus. This work investigated the physicochemical, mechanical, and biological characteristics of a 3D-printed polycaprolactone (PCL) reinforced with multiwalled carbon nanotubes (MWCNT) and "bamboo-like" carbon nanotubes (BCNT) with the following w/w % concentrations: 0.005%, 0.01%, 0.02%, and 0.2%. The materials were analyzed with subsequent techniques: Scanning electron microscopy, nanoindentation, parallel plate rheometry, and differential scanning calorimetry. Biological evaluations were performed with normal human articular chondrocytes by confocal microscopy and proliferation assay. The study revealed that the carbon nanotubes (CNT) addition improved the rheological properties of the material by increasing the setting temperature. Moderate enhancement was observed in terms of mechanical properties. The most significant difference was noted in cell adhesion and proliferation. Pure PCL did not facilitate cell growth and mainly apoptotic cells were observed on its surface. The addition of 0.01% MWCNT resulted in enhanced adhesion and proliferation; however, the morphology of the cells remained spherical, signifying a suboptimal surface for proliferation. Interestingly, PCL reinforced with 0.02% BCNT displayed excellent facilitation of cellular adhesion and proliferation, which is uncharacteristic of pure PCL. In summary, this study investigated the potential of CNT-reinforced PCL for 3D bioprinting and tissue engineering, highlighting key physicochemical, mechanical, and biological aspects of this biomaterial.