Characterization of crystal structure and mechanical properties of polycaprolactone-hydroxyapatite-collagen nanofiber for scaffold anterior cruciate ligament (ACL) applications

Recently, it was found that the case of knee injuries could reach a prevalence of 48 per 1000 peoples in one year, with 9% being categorized as Anterior Cruciate Ligament (ACL) injuries. The most common cause of ACL injuries is sports activities. Several strategies were used to heal this injury, such as a treatment, up to autographs bone graft surgery. Current research developments lead to the use of artificial ligaments to heal the ACL injuries which have many advantages over autografts. Thus, this present study aims to fabricate the artificial ligament using hydroxyapatite (HA)/collagen/polycaprolactone (PCL) nanofiber composites. Here, we try to determine the effect of variations of HA, collagen, and PCL compositions in the nanofiber composites by studying their crystal structure and mechanical properties (tensile strength). We use variations of PCL: HA: collagen compositions about of 50:45:5, 50:40:10, 50:35:15, 50:30:20, and 50:25:25 wt%, respectively, in the 10% w/v of solution concentrations. In this present research, the nanofiber was fabricated by using electrospinning method with a voltage of 23 kV, while, the distance between the needle and the collector of about of 15 cm. The XRD and tensile strength tests were used to study the effects of PCL: HA: collagen compositions. In the XRD test, we found that the PCL peaks were detected at 2θ = 21° and 23° and HA was found at 2θ = 31°. The PCL crystal size is found to be 47.82-86.87 nm and the degree of crystallinity is 24.31-36.87%. In the mechanical test, the Ultimate Tensile Strength (UTS) value was obtained in the range of 0.942 MPa-2.864 MPa. It was found that the PCL could increase the tensile strength. However, the obtained UTS value is still far from the UTS of the original human ACL value.