**2.2. Sample preparation**

Different types of calcium phosphate salts were mixed in different proportions using various chemicals as part of the liquid phase to identify the best composition with respect to their mechanical properties (**Table 1**). All samples were mixed using mortar and pestle under ambient conditions (room temperature and atmospheric pressure). The powder phase was mixed thoroughly until all the salts were uniformly dispersed. To this, the liquid phase was added in small quantities and triturated until the mixture became a thick, moldable paste.

The most suitable formulation was achieved when tetracalcium phosphate (TTCP provided by CaP Biomaterials) and dicalcium phosphate (DCPA provided by Sigma-Aldrich, St. Louis, MO.) were used as the solid phase and chitosan lactate (CL) was used as the setting liquid. An equimolar ratio of TTCP and DCPA was mixed and to this 10% w/v solution of CL was added. This mixture was thoroughly mixed using mortar and pestle to form a soft mass. The soft mass could then be set in different mold shapes depending on the assay or test being performed.

#### *2.2.1. Sample preparation for SEM*

Scanning electron microscopy (SEM) was used to analyze the surface of CPCs. Specimens fractured during compression test were taken for SEM imaging. S4800 Field Emission SEM, HITACHI was used for our research. Gold nanolayer (about 3 nm) was laid over specimens before analyzing using SEM.


**Table 1.** Control and experimental groups use in osteoconductive studies.
