title: Calcium phosphate nanoparticles functionalized with a dimethacrylate monomer.
abstract: The synthesis of calcium phosphate nanoparticles may include modifying agents to tailor particle size, reduce agglomeration and add specific functionalities. This study describes the synthesis of dicalcium phosphate dihydrate (DCPD) nanoparticles functionalized with triethylene glycol dimethacrylate (TEGDMA), added to one of the reacting solutions, with the purpose of reducing agglomeration and improving the compatibility with vinyl-based resin matrices. The nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA), transmission electronic microscopy (TEM), dynamic light scattering (DLS), and surface area (BET). As controls, proprietary DCPD nanoparticles and nanoparticles synthesized without the addition of TEGDMA ("bare") were subjected to the same analytical methods. XRD revealed a similar crystalline structure of the synthesized materials in comparison to the proprietary nanoparticles. The presence of a TEGDMA layer was confirmed by elemental analysis and TGA, corresponding to a mass fraction of 8.5%. FTIR analysis of the functionalized nanoparticles revealed the suppression of some absorbance bands found in the neat TEGDMA. A chemisorption mechanism between TEGDMA and the surface of primary particles by ion-dipole interaction involving TEGDMA oxyethylene, and also an interaction mechanism between the particle surface and terminal-CH3 groups are proposed. Functionalized nanoparticles showed 3 to 11 times higher surface area than the controls, in agreement with DLS data, indicating lower agglomeration.
authors.affiliation: University of São Paulo, School of Dentistry, Department of Biomaterials and Oral Biology, Av. Prof. Lineu Prestes, 2227, 05508-000 São Paulo, SP, Brazil. Electronic address: marcela-cr@hotmail.com.
authors.forename: Marcela Charantola
authors.initials: MC
authors.lastname: Rodrigues
authors.affiliation: University of São Paulo, Department of Chemical Engineering, Av. Prof. Lineu Prestes, 580, Bloco 18, 05508-000 São Paulo, SP, Brazil. Electronic address: hewer@iq.usp.br.
authors.forename: Thiago Lewis Reis
authors.initials: TL
authors.lastname: Hewer
authors.affiliation: University of São Paulo, Institute of Physics, Department of Applied Physics, Rua do Matão Travessa R #187, 05508-090 São Paulo, SP, Brazil. Electronic address: gbrito@if.usp.br.
authors.forename: Giancarlo Espósito de Souza
authors.initials: GE
authors.lastname: Brito
authors.affiliation: University of São Paulo, School of Dentistry, Department of Biomaterials and Oral Biology, Av. Prof. Lineu Prestes, 2227, 05508-000 São Paulo, SP, Brazil. Electronic address: vearana@usp.br.
authors.forename: Victor Elias
authors.initials: VE
authors.lastname: Arana-Chavez
authors.affiliation: University of São Paulo, School of Dentistry, Department of Biomaterials and Oral Biology, Av. Prof. Lineu Prestes, 2227, 05508-000 São Paulo, SP, Brazil. Electronic address: rrbraga@usp.br.
authors.forename: Roberto Ruggiero
authors.initials: RR
authors.lastname: Braga
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry*; D008027:Light; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry*; D012542:Scattering, Radiation; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; C494366:calcium phosphate, dibasic, dihydrate
keywords: Calcium phosphate; Nanoparticles; Synthesis