Hydroxyapatite (HA) has been widely used as bone grafts due to its chemical and structural similarities to the mineral phase of hard tissues. Applying the combination of osteogenic proteins with HA materials can accelerate bone regeneration in defective areas. The aim of the study was investigating the treatment of HA particles with different amino acids such as serine (Ser), asparagine (Asn), aspartic acid (Asp) and arginine (Arg) to enhance the adsorption ability of HA carrier for delivering therapeutic proteins in body. Results: The crystallinity of HA reduced when amino acids were added during HA preparation. Depending on the types of amino acid, the specific surface area of the amino acid-functionalized HA particles varied from 105 to 149 m2/g. Bovine serum albumin (BSA) and lysozyme were used as model proteins for adsorption study. The protein adsorption onto the surface of amino acid-functionalized HA depended on the polarities of HA particles, whereby positively charged Arg-HA had higher affinity towards BSA (0.269 mg/m2) compared to lysozyme (0.133 mg/m2). Alternatively, the binding affinity of lysozyme (0.2 mg/m2) onto the negatively charged Asp-HA was higher compared to BSA (0.129 mg/m2). The amino acids functionalized-HA particles that had higher proteins adsorption demonstrated a lower protein release rate.