[en] Full text: Materials as hydroxyapatite nanoparticles can be functionalized to enhance the specificity of these nanoparticles in many types of tumors. The surfaces of HA can be functionalized with folic acid (FA)¹ , since many cancer cells show overexpression of folate receptors. Furthermore, folate molecule can be aminated, making possible the linkage of other therapeutic molecules on HA nanoparticles surfaces.The functionalization processes of nanomaterials can improve physico-chemical characteristics of nanoparticles surfaces while maintaining its bulk characteristics². Considering that the tumor regions shows acidic pH while normal tissues show basic pH, the study on the releasing behavior of folate from HA nanoparticles in different media conditions is important to predict if this material can be used as a drug delivery system for cancer treatment.The doping process of HA nanoparticles with copper allows theranostic applications for this material due to its beta and positron emissions. In this study, HA-Cu nanoparticles were synthesized by hydrothermal method using CuCl₂.2H₂O, the obtained material was functionalized with aminated folic acid in different pH conditions. The stability of the chemical interactions between hydroxyapatite and folate were investigated in aqueous suspensions at different time intervals and different media and pH conditions. The synthesized materials were characterized by XRD, EDX, ICP-AES, FTIR, UV-vis, TGA and CHN.The results indicate stable chemical interactions in FA/HA-Cu samples, with no significant releasing of Cu and FA in neutral pH, suggesting that this material can act as theranostic agent for many types of cancer and justifying the continuity of this work with studies of incorporation and controlled release of chemotherapeutic drugs. References: Cipreste, M. F. et al.RSC Adv.6, 76390–76400 (2016); 2. L. Treccani. et al. Acta Biomater., 2013, 9, 7115–7150. (author)