Microwave-assisted synthesis of biocompatible europium-doped calcium hydroxyapatite and fluoroapatite luminescent nanospindles functionalized with poly(acrylic acid)

Langmuir. 2013 Feb 12;29(6):1985-94. doi: 10.1021/la304534f. Epub 2013 Jan 29.


Europium-doped calcium hydroxyapatite and fluoroapatite nanophosphors functionalized with poly(acrylic acid) (PAA) have been synthesized through a one-pot microwave-assisted hydrothermal method from aqueous basic solutions containing calcium nitrate, sodium phosphate monobasic, and PAA, as well as sodium fluoride in the case of the fluoroapatite particles. In both cases a spindlelike morphology was obtained, resulting from an aggregation process of smaller subunits which also gave rise to high specific surface area. The size of the nanospindles was 191 (32) × 40 (5) nm for calcium hydroxyapatite and 152 (24) × 38 (6) nm for calcium fluoroapatite. The luminescent nanoparticles showed the typical red luminescence of Eu(3+), which was more efficient for the fluoroapatite particles than for the hydroxyapatite. This is attributed to the presence of OH(-) quenchers in the latter. The nanophosphors showed negligible toxicity for Vero cells. Both PAA-functionalized nanophosphors showed a very high (up to at least 1 week) colloidal stability in 2-(N-morpholino)ethanesulfonic acid (MES) at pH 6.5, which is a commonly used buffer for physiological pH. All these features make both kinds of apatite-based nanoparticles promising tools for biomedical applications, such as luminescent biolabels and tracking devices in drug delivery systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylic Resins / chemistry*
  • Animals
  • Apatites / chemistry*
  • Biocompatible Materials / chemical synthesis
  • Biocompatible Materials / chemistry
  • Biocompatible Materials / toxicity
  • Buffers
  • Cell Survival / drug effects
  • Chemistry Techniques, Synthetic
  • Chlorocebus aethiops
  • Durapatite / chemistry*
  • Europium / chemistry*
  • Hydrogen-Ion Concentration
  • Kinetics
  • Luminescent Agents / chemistry
  • Microwaves*
  • Nanoparticles / chemistry*
  • Optical Phenomena
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry*
  • Organometallic Compounds / toxicity
  • Vero Cells


  • Acrylic Resins
  • Apatites
  • Biocompatible Materials
  • Buffers
  • Luminescent Agents
  • Organometallic Compounds
  • Europium
  • carbopol 940
  • Durapatite
  • fluorapatite