Assessment of Methacrylated Poly(ε‐Caprolactone)/Silanized Hydroxyapatite Composite Resin for High‐Resolution Scaffolds via Vat Photopolymerization <scp>3D</scp> 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.