Polycaprolactone Hybrid Scaffold Loaded With N,O-Carboxymethyl Chitosan/Aldehyde Hyaluronic Acid/Hydroxyapatite Hydrogel for Bone Regeneration

Hydrogels have emerged as potential materials for bone grafting, thanks to their biocompatibility, biodegradation, and flexibility in filling irregular bone defects. In this study, we fabricated a novel NAH hydrogel system, composed of N,O-carboxymethyl chitosan (NOCC), aldehyde hyaluronic acid (AHA), and hydroxyapatite (HAp). To improve the mechanical strength of the fabricated hydrogel, a porous polycaprolactone (PCL) matrix was synthesized and used as a three-dimensional (3D) support template for NAH hydrogel loading, forming a novel PCL/NAH hybrid scaffold. A mixture of monosodium glutamate (M) and sucrose (S) at varied weight ratios (5M:5S, 7M:3S, and 9M:1S) was used for the fabrication of 3D PCL matrices. The morphology, interconnectivity, and water resistance of the porous PCL scaffolds were investigated for optimal hydrogel loading efficiency. The results demonstrated that PCL scaffolds with porogen ratios of 7M:3S and 9M:1S possessed better interconnectivity than 5M:5S ratio. The compressive strength of the PCL/NAH hybrid scaffolds with 9M:1S (561.6 ± 6.1 kPa) and 7M:3S (623.8 ± 6.8 kPa) ratios are similar to cancellous bone and all hybrid scaffolds were biocompatible. Rabbit models with tibial defects were implanted with the PCL/NAH scaffolds to assess the wound healing capability. The results suggest that the PCL/NAH hybrid scaffolds, specifically those with porogen ratio of 7M:3S, exhibit promising bone healing effects.