A new approach to prepare well-dispersed CaF2 nanoparticles by spray drying technique

作者：Sun Limin^*; Chow Laurence C; Bonevich John E; Wang Tongxin; Mitchell James W

来源：Journal of Biomedical Materials Research Part B: Applied Biomaterials , 2011, 98B(2): 223-229.

DOI：10.1002/jbm.b.31800

• calcium fluoride
• nanoparticle
• composite particle
• spray drying
• particle dispersion/agglomeration

Previously, nano-sized calcium fluoride (CaF2) particles were prepared using a spray drying method by simultaneously feeding Ca(OH)(2) and NH4F solutions to a two-liquid nozzle. The aim of the present study was to prepare better-dispersed nano-CaF2 particles by co-forming a soluble salt, sodium chloride (NaCl). NaCl of various concentrations were added to the NH4F solution, leading to formation of (CaF2+NaCl) composites with CaF2/NaCl molar ratios of 4/1, 4/4, and 4/16. Pure nano-CaF2 was also prepared as the control. Powder X-ray diffraction analysis showed that the products contained crystalline CaF2 and NaCl. Scanning electron microscopy examinations showed that both the CaF2/NaCl composite and pure CaF2 particles were about (50-800) nm in size and consisted of primary CaF2 particles of < 50 nm in size. BET surface area measurements showed similar primary particle sizes for all samples. Dynamic light scattering measurements showed that the washed (CaF2+NaCl) particles were much smaller than the pure CaF2 as the dissolution of NaCl "freed" most of the primary CaF2 particles, leading to a greater degree of particle dispersion. The well-dispersed nano-CaF2 may be expected to be a more effective anticaries agent than NaF by providing longer lasting elevations of fluoride concentrations in oral fluids.

• 出版日期2011-8