Selenium-doped nanostructure has been considered as an attractive approach to enhance the antibacterial activity of calcium phosphate (cap) materials in diverse medical applications. in this study, the selenium-doped biphasic calcium phosphate nanoparticles (SeB-NPs) were first synthesized. Then, silver was in situ incorporated into SeB-NPs to obtain nanostructured composite nanoparticles (Ag SeB-NPs). Both SeB-NPs and Ag SeB-NPs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS), and Raman spectra. The results confirmed that the SeO 3 2− was doped at the po 4 3− position and silver nanoparticles were deposited on the surface of SeB-NPs. Next, Transmission Electron Microscopy (TEM) analysis displayed that the prepared Ag SeB-NPs had a needlecluster-like morphology. CCK-8 analysis revealed SeB-NPs and Ag SeB-NPs had good cytocompatibility with osteoblasts. the antibacterial activity of the prepared Ag SeB-NPs was confirmed by using Gramnegative E. coli and Gram-positive S. aureus. The above results manifested the significance of the final Ag SeB-NPs for biomedical applications. Tissue engineering has been widely used in bone graft and dentistry due to a large number of patients require grafting resulting from congenital conditions, trauma, and tumor resection, and so on 1-3. Mineralized tissues, such as bone, tooth enamel, dentin, and cementum, are enriched with significant amounts of ionic substitutions, including sodium, potassium, and carbonate groups. These elements can affect the functionality of related tissues 4,5. Calcium phosphate (CaP) based nanoparticles, including hydroxyapatite (Ca 10 (PO 4) 6 (OH) 2 , HA), β-tricalcium phosphate (Ca 3 (PO 4) 2 , β-TCP), tetracalcium phosphate (Ca 4 (PO 4) 2 O; TTCP), biphasic calcium phosphate (BCP), and so forth, were well-known in implant surgery because of their excellent biocompatibility, biodegradability, and tunable physicochemical properties. Compared to HA or β-TCP, biphasic calcium phosphate (BCP) composed of HA and β-TCP, performed better mechanical properties, higher biological activity, and adjustable degradation rate 6-10. Bacteria attached to the implanted medical devices or scaffold can cause healthcare-associated infections, such as the formation of biofilm, which further results in local inflammation and infection. Therefore, the scaffold with excellent antibacterial properties provides an overwhelming advantage in the clinic stage 11,12. Many metal nanoparticles, such as silver (Ag), zinc oxide (ZnO), and titanium dioxide (TiO 2), performed strong antibacterial properties and low toxicity towards mammalian cells, some of these nanoparticles have been widely applied in a range of areas 13-20. Silver (Ag) is stable in the body fluids and can be used in antibacterial implants due to silver can easily binds to bacterial DNA and RNA, resulting in bacteria death 21. However, the antibacterial effect of nanoparticles was influenced...