Biomechanical Evaluation of an Injectable Alginate / Dicalcium Phosphate Cement Composites for Bone Tissue...

Current bone repair strategies often rely on synthetic cements that must balance mechanical strength with biocompatibility. While dicalcium phosphate (DCP) cements are known for their biocompatibility, their mechanical properties and injectability remain limitations. Prior research has shown that DCP cements degrade in simulated body fluids, but the rate and impact on cellular behavior are not fully understood. No prior work had resolved how varying amounts of sodium alginate (SA) could modify the degradation and mechanical performance of DCP cements. This gap motivated an investigation into the effects of SA on the structural and biological properties of DCP composites. The study aimed to address whether SA could improve injectability and biocompatibility without compromising mechanical integrity. Understanding the interplay between SA concentration and cement behavior is essential for advancing injectable bone fillers. The need for a material that supports cell viability while maintaining structural stability is a key challenge in bone tissue engineering. This study sought to explore a potential solution by combining DCP with SA in varying proportions.

The goal of this research was to evaluate how sodium alginate (SA) influences the mechanical, structural, and biological performance of dicalcium phosphate (DCP) cements. Specifically, the study aimed to determine whether adding SA could improve injectability and setting time while maintaining mechanical strength. The motivation stemmed from the need for injectable bone cements that degrade at a controlled rate and support cell growth. Researchers focused on the impact of different SA concentrations on the cement's microstructure and degradation behavior. They also sought to assess the cytocompatibility of the composites with dental pulp stem cells (DPSCs). The study aimed to identify the optimal SA concentration that balances mechanical properties with biocompatibility. By characterizing the cements using XRD, SEM, and FTIR, the team aimed to understand how SA affects the cement's crystallinity and morphology. The ultimate objective was to develop a composite material that could be used as a bone filler with improved performance over traditional DCP cements.

The study used a microwave-assisted wet precipitation system to synthesize beta-tricalcium phosphate (β-TCP) particles. X-ray diffraction (XRD) was used to confirm the phase purity of the β-TCP. Scanning electron microscopy (SEM) was employed to examine the particle morphology and size. Fourier-transform infrared spectroscopy (FTIR) was used to identify the functional groups present in the β-TCP. DCP cement was prepared by mixing monocalcium phosphate monohydrate (MCPM) and β-TCP with water. Sodium alginate (SA) was dissolved in water at varying concentrations (0.5%, 1%, 2%, and 3%) to create SA/DCP composites. The cements were analyzed using XRD, SEM, FTIR, and thermogravimetric analysis (TGA) to assess their structural and thermal properties. In vitro biodegradation was tested in simulated body fluid (SBF) over 21 days. Setting time and injectability were measured using standard methods. Cell viability and morphology were evaluated using MTT assays and fluorescence microscopy with dental pulp stem cells (DPSCs).

XRD analysis confirmed that both pure DCP and SA/DCP cements matched the Monetite phase. SEM images showed that adding SA reduced the size of DCP particles, suggesting that SA inhibits particle growth. The setting time and injectability of the cements improved as the SA concentration increased. In simulated body fluid (SBF), the 2.0% SA/DCP composite showed the highest cumulative weight loss (26.52%) after 21 days. The release of Ca²⁺ ions increased with higher SA content. Mechanical strength of all cements was highest after 3 days in SBF but decreased with prolonged immersion. MTT assays revealed that all cements supported cell viability, with values higher than the control group. Fluorescence microscopy showed that cells maintained normal morphology when cultured in cement extracts. These findings suggest that SA enhances the biodegradation and injectability of DCP cements without compromising biocompatibility.

The study demonstrated that sodium alginate (SA) significantly affects the microstructure, mechanical properties, and biocompatibility of dicalcium phosphate (DCP) cements. The addition of SA improved injectability and reduced particle size, as shown by SEM and XRD. The 2.0% SA/DCP composite exhibited the highest degradation rate in simulated body fluid (SBF), with a 26.52% weight loss after 21 days. Mechanical strength was highest after 3 days but declined over time. All cements supported cell viability and maintained normal cell morphology. The researchers propose that SA/DCP composites could be suitable for bone tissue engineering applications. The findings suggest that SA enhances the performance of DCP cements without compromising biocompatibility. The study supports the potential use of SA/DCP as an injectable bone filler. The results align with the hypothesis that SA improves the functional properties of DCP cements.