Assessment of Methacrylated Poly(ε-Caprolactone)/Silanized Hydroxyapatite Composite Resin for High-Resolution Scaffolds via Vat Photopolymerization 3D Printing

Abstract

High-resolution, biocompatible scaffolds are essential for reproducible tissue engineering and remain challenging to fabricate with vat photopolymerization due to cure-depth control and limited bioactivity of neat polymers. This work investigated the mechanical, surface, and biological properties, as well as the high-resolution 3D printability, of methacrylated poly(ε-caprolactone) (PCLMA) composite resins incorporating silanized hydroxyapatite (HAp-Si) and a photoabsorber additive. Formulations of PCLMA, PCLMA10 (10% HAp), PCLMA10S (10% HAp-Si), and PCLMA10SOr (10% HAp-Si + 0.1% Orange II) were prepared. NMR confirmed successful functionalization of PCLMA and HAp-Si. Cured samples were characterized by wettability (contact angle) and Shore A hardness. Mechanical compression tests were performed on 3D-printed cylindrical samples, while in vitro biological assays, including cell adhesion, were performed using human primary fibroblasts. The incorporation of HAp-Si enhanced the mechanical properties, with PCLMA10S exhibiting higher performance compared to PCLMA. Biological assays further demonstrated cell adhesion, underscoring the potential bioactivity and biocompatibility on HAp/HAp-Si-containing surfaces. Complex Gyroid scaffolds were 3D printed to assess high-resolution printability. Importantly, the inclusion of Orange II enabled well-defined pore architectures, overcoming printability limitations observed in formulations without the photoabsorber. These findings highlight the potential of tailored PCLMA-based composite resins for mechanical, biocompatible, and precise structured scaffolds, for tissue engineering applications.