Polydopamine-modified 3D-printed polycaprolactone scaffolds for promoting bone regeneration

Abstract

Polycaprolactone (PCL) is one of the most widely used three-dimensional (3D) printing materials with excellent biocompatibility and mechanical properties. However, its hydrophobic nature hinders cell adhesion and proliferation. Polydopamine (PDA) has been shown to promote proliferation and induce osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) on polymer surfaces. Despite this, the impact of varying PDA coating thicknesses on the osteogenic differentiation of BMSCs has been minimally explored. In this paper, PCL scaffolds were fabricated using 3D printing technology, and PDA-coated PCL scaffolds (PDA-PCL-0, PDA-PCL-3, PDA-PCL-6, PDA-PCL-24) were prepared by immersing the scaffolds in an aqueous dopamine solution for fixed time points (0, 3, 6, 24 h) under constant shaking. The scaffolds were characterized and subjected to physicochemical performance tests to evaluate their effects on BMSC proliferation, adhesion, and osteogenic differentiation. The results showed that PDA-PCL-6 scaffolds exhibited significant immunomodulatory properties, promoting BMSC proliferation, adhesion, and osteogenic differentiation more effectively than the other groups. In vivo validation experiments, including micro-computed tomography, hematoxylin and eosin staining, Masson staining, and immunohistochemical analysis of bone morphologenetic protein 2 (BMP-2) and type I collagen (COL-I), confirmed that PDA-PCL-6 scaffolds significantly enhanced bone regeneration, histocompatibility, and hemocompatibility compared to uncoated scaffolds at 1, 2, and 3 months postoperation. In conclusion, our results indicate that a PDA coating obtained through 6-h immersion significantly enhances the biocompatibility and osteoinductive properties of PCL scaffolds, providing a promising strategy for bone defect repair.

Keywords

3D printing / Bone regeneration / Polycaprolactone / Polydopamine