Unidirectional Polyvinylidene/Copper-Impregnated Nanohydroxyapatite Composite Membrane Prepared by Electrospinning with Piezoelectricity and Biocompatibility for Potential Ligament Repair.

Abstract

Ligament tears can strongly influence an individual's daily life and ability to engage in physical activities. It is essential to develop artificial scaffolds for ligament repairs in order to effectively restore damaged ligaments. In this experiment, the objective was to evaluate fibrous membranes as scaffolds for ligament repair. These membranes were created through electrospinning using piezoelectric polyvinylidene fluoride (PVDF) composites, which contained 1 wt.% and 3 wt.% of copper-impregnated nanohydroxyapatite (Cu-nHA). The proposed electrospun membrane would feature an aligned fiber structure achieved through high-speed roller stretching, which mimics the properties of biomimetic ligaments. Nanoparticles of Cu-nHA had been composited into PVDF to enhance the pirzoelectric β-phase of the PVDF crystallines. The study assessed the physicochemical properties, antibacterial activity, and biocompatibility of the membranes in vitro. A microstructure analysis revealed that the composite membrane exhibited a bionic structure with aligned fibers resembling human ligaments. The piezoelectric performance of the experimental group containing 3 wt.% Cu-nHA was significantly improved to 25.02 ± 0.68 V/g·m^-2 compared with that of the pure PVDF group at 18.98 ± 1.18 V/g·m^-2. Further enhancement in piezoelectric performance by 31.8% was achieved by manipulating the semicrystalline structures. Antibacterial and cytotoxicity tests showed that the composite membrane inherited the antibacterial properties of Cu-nHA nanoparticles without causing cytotoxic reactions. Tensile tests revealed that the membrane's flexibility of strain was adequate for use as artificial scaffolds for ligaments. In particular, the mechanical properties of the two experimental groups containing Cu-nHA were significantly enhanced compared with those of the pure PVDF group. The favorable piezoelectric and flexible properties are highly beneficial for ligament tissue regeneration. This study successfully developed PVDF/Cu-nHA piezoelectric fibers for a biocompatible, unidirectional piezoelectric membrane with potential applications as ligament repair scaffolds.