Preparation of amino acid nanoparticles at varying saturation conditions in an aerosol flow reactor
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Nanoparticle formation of five amino acids, glycine, l-proline, l-valine, l-phenylalanine, and l-leucine was studied. The aim was to explore factors determining nanoparticle formation and crystallinity. The amino acid nanoparticles have been prepared at different saturation conditions in the aerosol reactor. In a condensed state, the particles were formed by droplet drying. The raise in temperature induced the sublimation of amino acids from the aerosol particles. The amino acid vapor was condensed by physical vapor deposition in a rapid cooling process. The diffusion coefficients and nucleation rates of amino acids have been calculated to understand particle formation. Upon the vapor deposition, amino acids formed crystalline nanoparticles except in the case l-phenylalanine according to X-ray diffraction. The crystal polymorph of glycine in the nanoparticles depended on the applied reactor temperature. The preference of crystallographic orientation varied in both the particle formations from condensed and vapor phase. l-Valine, l-phenylalanine, and l-leucine formed leafy-looking particles. These results could be utilized in the fabrication of nano-sized asperities on drug particle surfaces to reduce forces between particles and accordingly increase particle dispersion in dry powder inhalers.
KeywordsAerosol Nanoparticles Amino acid Physical vapor deposition
We thank the Academy of Finland (project no. 133407 and 140362) for financial support.
- Amelin AG (1972) Theoretical foundation of mist formation at the vapor condensation. Khimiya, MoscowGoogle Scholar
- Budavari S (ed) (1989) The Merck Index 11th. Merck & Co, RahwayGoogle Scholar
- Gonda I (1981) Study of the effect of polydispersity of aerosols on regional deposition in the respiratory tract. J Pharm Pharmacol 33(suppl.):52PGoogle Scholar
- Hickey AJ, Concessio NM, Van Oort MM, Platz RM (1994) Factors influencing the deagglomeration of dry powders as aerosols. Pharm Technol 18:58–82Google Scholar
- Incropera FP, DeWitt DP (2002) Fundamentals of heat and mass transfer, 5th edn. Wiley, New York, pp 846–847Google Scholar
- Lähde A, Raula J, Kauppinen EI (2008c) Production of l-leucine nanoparticles under various conditions using an aerosol flow reactor method. J Nanomater, Article ID 680897Google Scholar
- Lechuga-Ballesteros D, Kuo M-C (2001) Dry powder compositions having improved dispersivity. WO 01/32144Google Scholar
- Lide DR (ed) (2003) CRC handbook of chemistry and physics, 84th edn. CRC Press, Boca RatonGoogle Scholar
- Reid RR, Prausnitz JM, Poling BE (1987) The properties of gases and liquids, 4th edn. McGraw-Hill, New YorkGoogle Scholar
- Staniforth JN (1997) Improvements in or relating to powders for use in dry powder inhalers. WO 97/03649Google Scholar