Gold and Hydroxyapatite Nano-Composite Scaffolds for Anterior Cruciate Ligament Reconstruction: In Vitro Characterization

Current anterior cruciate ligament (ACL) graft replacement materials often fail due to the lack of biological integration. While many newly developed extracellular matrix based scaffolds show good biocompatibility they often do not entice cellular remodeling and the rebuilding of a functional ligament. We have proposed the conjugation of gold nanoparticles (AuNP) and hydroxyapatite nanoparticles (nano-HAp). to acellular tissue to enhance cell attachment and proliferation while maintaining an improved degradation resistance and open microstructure. We are the first to investigate the double conjugation of AuNP and nano-HAp onto decellularized tissue to improve the tissue remodeling response. Decellularized porcine diaphragm was crosslinked with two types of nano-HAp and amine-functionalized AuNP with 1-ethyl-3-(3-dimethlaminopropyl) carbodiimide (EDC) crosslinker. Scaffolds were characterized using electron microscopy, differential scanning calorimetry, and fibroblast assays. Results demonstrated that scaffolds with nano-HAp have increased thermal stability at low levels of crosslinking. The open microstructure of the scaffold was not compromised allowing for cell migration while still providing increased degradation resistance. The addition of <200 nm nano-HAp decreased cell viability compared to scaffolds without nanoparticles, but the addition of AuNP to scaffolds showed enhanced cell viability in the presence of <200 nm nano-HAp. The addition of <40 nm nano-HAp showed an increase in cell viability compared to scaffolds crosslinked without nanoparticles. It is concluded that attaching AuNP and <40nm nano-HAp to extracellular matrices may improve overall properties.