Ca9.95Li1.05(PO4)7 and β-Ca3(PO4)2 lamellar microstructure: multilayer 3D scaffolds for 3T3 cell viability studies

Abstract

This study proposes the development of a lamellar microstructure in multilayer ceramic scaffolds to investigate the influence of surface morphology on cell behavior. The scaffolds consist of tricalcium silicate (C3S) core and calcium phosphate outer coatings, where Ca ions are partially substituted with Li ions. The scaffolds were physicochemically characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy (FESEM/EDX) and Mercury Porosimetry. The scaffolds exhibited Ca2P2O7, β-Ca3(PO4)2, Ca9.95Li1.05(PO4)7, CaLi(PO4) and Li3(PO4) as main phases. The Ca2P2O7 phase in the outer layer was removed using a 30-s etching process, revealing a lamellar microstructure in the bulk. The compressive strength of the scaffolds was 1.2 ± 0.1 MPa for the control and 0.9 ± 0.1 MPa for the C30s scaffolds, while the corresponding microporosity values were 61 % and 72 %. In vitro bioactivity assays demonstrated hydroxyapatite-like (HA-like) precipitation on etched scaffolds after 14 days in simulated body fluid (SBF), unlike the untreated controls. Direct and indirect biological assays using 3T3 fibroblasts revealed significantly higher cell viability, adhesion, and proliferation on the scaffolds with the lamellar microstructure, futher enhanced by the HA-like coating. FESEM imaging confirmed cell colonization on the surface and within the internal lamellar framework, suggesting that this architecture supports cell infiltration and ECM formation. These findings highlight the functional relevance of the lamellar microstructure in promoting biointegration, positioning these scaffolds as promising candidates for bone tissue engineering.