Gold and platinum bimetallic nanoparticles, Au@PtNPs, have gained attention due to their plasmonic properties. The controlled synthesis of Au@PtNPs involves complex parameters, and the resulting synergy between Au and Pt introduces possibilities for tailoring their properties. This study explores the effects of key-parameters of synthesis (gold core diameters, reaction time, and Pt concentration) on the final properties of Au@PtNPs. Gold nanoparticles of varying diameters were synthesized and used as cores for the reduction of hexachloroplatinic acid, forming a surrounding shell of Pt nanoparticles. The parameters were systematically tuned to understand their impact on morphology, dimension, stability, and plasmonic properties of Au@PtNPs. Increasing Pt precursor concentration resulted in thicker and denser Pt shells, broadening the localized surface plasmon resonance (LSPR) band and improving Au@PtNPs stability. These properties are essential for applications such as photothermal treatment. The synthesis achieved satisfactory products within just 1 h of Pt4+ reduction at mild temperature without using surfactants. Only limited changes in plasmonic properties were observed after 4 h of synthesis, suggesting an optimal reaction period. Manipulating Au core diameter provided LSPR band control, with smaller cores exhibiting greater broadening towards the infrared region. This systematic exploration provided valuable insights for understanding key-parameters governing the synthesis and properties of Au@PtNPs. AuPtNPs PtNPs keyparameters key gold time acid morphology dimension stability shells (LSPR treatment Pt4 surfactants period control region

Hydroxyapatite (HA) nanopowders are attracting interest for surface application to ceramic biomaterials. In this study, we developed innovative and new viable synthesis routes of calcium phosphate nanopowders from the natural calcium carbonate of chicken eggshells. Following the four routes, alternative co-precipitation, vacuum process, brushite, and calcination, we obtained the HA samples, which were then characterized by different methods. The X-ray diffraction /Rietveld method showed the HA phases, monetite and brushite crystallinity with greater symmetry, and nanoscale. Transmission electron microscopy showed the morphology of nanoparticles functionalized nanoparticles smaller than 100 nm in routes A, B and D, and Fourier-transform infrared spectrophotometry and Raman spectroscopy identified the classic chemical groups of calcium phosphates by four routes mainly groups (PO4)3- and (CO3-). Scanning electron microscopy analysis revealed a good surface topography to future cell biointeraction in A, B and D routes, and thermogravimetric analysis showed the mass loss profile inherent to each synthesis route with slot at 200 °C. Hence, the eggshell HA and brushite and the specific monetite nanoparticles with different morphology can be prepared from the four new possible and viable routes using different methods.