## 4 Conclusions  
The goal of this study was to explore the effects of orthophosphate (OP) and cellulose derivatives on MgO/SiO\({}_{2}\) formulations for producing 3D-printed bioceramics. These formulations recently raised growing interest in additive manufacturing technology and were demonstrated as efficient starting materials for the preparation of clinoenstatite and forsterite bioceramics. However, the preparation of complex structures through 3D printing has only recently been explored for such cements, and even though some additives were already reported as essential for the obtainment of an extrudable ink, their effect on such formulations has been left unexplored so far. Here, we meticulously characterized magnesium silicate hydrate (M-S-H) cements containing various admixtures, which served as the basis for developing 3D printing inks. Upon calcination, these inks yielded Mg\({}_{2}\)SiO\({}_{4}\)-biologically relevant ceramics. Our findings indicate that sodium orthophosphate can be utilized in M-S-H pastes as a water-reducing admixture with retardant properties, extending the setting times and maintaining sufficient fluidity for easy extrusion during printing. Furthermore, when used in conjunction with OP, HPMC and CMC did not alter the hardening times of the MgO/SiO\({}_{2}\) cement pastes but acted as beneficial suspension aids. The presence of cellulose derivatives, already used as viscosity modifiers in other cementitious systems,  
Figure 7: AFM maps of the printed bioceramics HPMC_5 (**A**), HPMC_10 (**B**), CMC_5 (**C**), and CMC_10 (**D**).  
notably influenced the water dynamics within the cement formulations, thereby impacting their printability.  
The printing parameters for these cement pastes were carefully adjusted, and selected formulations were successfully 3D printed and converted into forsterite biocercamics. Confocal Raman mapping highlighted the influence of cellulose on the formation of different ceramic phases. Both AFM and SEM analyses confirmed the achievement of homogeneously rough surfaces with excellent interlayer adhesion. Additionally, gas porosimetry and compressive strength tests underscored the porous nature of the materials and suggested that these samples could be appropriate for biological applications, particularly as scaffolds for cancellous bone.  
This study not only enhances our understanding of the interplay between additives and cement pastes in 3D printing but also sets the stage for future work aimed at refining these biocercamic formulations. By further optimizing the interactions of components and printing parameters, we can advance towards tailored biomedical applications, potentially leading to breakthroughs in personalized medicine and implantable scaffold technologies.  
Conceptualization, M.B. and M.T.; investigation, L.C. and M.T.; formal analysis, L.C., M.B. and M.T.; writing--original draft preparation, L.C. and M.T.; writing--review and editing, M.B. and M.T.; funding acquisition, M.B. and M.T. All authors have read and agreed to the published version of the manuscript.  
This research was funded by CSGI (Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase) and MIUR-Italy (\"Progetto Dipartimenti di Eccellenza 2018-2022\" and \"Dipartimenti di Eccellenza 2023-2027 DICUS 2.0\" allocated to Department of Chemistry \"[PERSON]\", University of Florence). The research was also funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 \"Dalla ricerca all'impresa\"--Call for tender No. 341 of 15/03/2022 of Italian Ministry of Research funded by the European Union--NextGenerationEU, Project title \"3A-ITALY - Made-in-Italy circolare e sostenibile\", CUP: B83C22004890007.  
Not applicable.  
The data presented in this study are available in the article.  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.