Advanced BioS ceramics with integrated optical thermometry for smart scaffolds

Abstract

This study reports the development of a smart scaffold with photothermal properties designed for 3D tissue engineering platforms. BioS scaffolds were fabricated via 3D printing (NS), sintered (S), and analyzed to assess the incorporation and behavior of Egyptian blue (EB) powder within a ceramic matrix. X-ray diffraction (XRD) confirmed the successful synthesis of EB. The EB powder was thoroughly characterized for its photothermal properties, exhibiting strong optical absorption and photoluminescence, making it a promising candidate for optical thermometry. Fourier transform infrared spectroscopy (FTIR) revealed structural differences between NS- and S-scaffolds following 3D printing. High-temperature sintering of BioS ceramic paste with EB densified the material and potentially induced phase transformations. Micro-computed tomography (µCT) analysis of grain size distribution indicated structural modifications between NS- and S-scaffolds. XRD identified calcium and sodium silicate as the predominant phases, with shifts in EB diffraction peaks after sintering. Scanning electron microscopy (SEM) revealed significant surface morphology changes, corroborating the µCT and XRD findings. The near-infrared (NIR) emission band of EB was utilized to develop a novel strategy for a ratiometric fluorescence thermometer based on a single emission band (²B₂g→²B₁ g). The EB powder exhibited a maximum relative sensitivity of 0.45% K^-1 at 293 K, while the NS- and S-scaffolds demonstrated sensitivities of 0.39% K^-1 and 0.30% K^-1, respectively. Hemolysis assays confirmed the hemocompatibility of the scaffolds, with red blood cell lysis below 1%. These findings support the safe application of these smart scaffolds in cell culture and biomedical research. Overall, this study provides new insights into developing a more physiologically relevant environment for in vitro cell culture assays by demonstrating the feasibility of integrating photoluminescent and thermosensitive properties– key features of smart materials–into biocompatible ceramic scaffolds. This approach advances the potential for real-time, in vitro monitoring and evaluation in biomedical applications.