Poly(d,l-lactic acid) nanoparticle preparation and colloidal characterization
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Nano size-ranged poly(d,l-lactic acid) (PLA) particles were obtained from 2 and 10 w% PLA solution in water-saturated ethyl acetate by the emulsification-diffusion method. An increase in the PLA solution concentration resulted in an increase of the particle mean size from ca 260 nm to 530 nm with a broadening of the distribution. After fractionation by centrifugation, the particle mean size was 980 nm. The Pluronic F68 used in the formulations at concentration ranging from 0.5 to 5% w/v, was shown to adsorb at the interface at 0.5 mg/m2 for both particle sizes. The molecular occupied area of 24 nm2/molecule suggested an expanded conformation of the surfactant at the interface, though an incomplete coverage could not be excluded. Coagulation kinetics measurements revealed a critical coagulation concentration (CCC) of 1.5 M sodium chloride, indicating a steric stabilization of the colloids by the adsorbed triblock copolymer. Nonetheless, variations in zeta potential with increasing salt concentration were observed, suggesting that the surface carboxylate groups were still accessible for further modifications.
KeywordsNanoparticles Emulsification-diffusion Surface charge Colloidal stability
The authors are grateful to C. Novat and CMEABG (University Claude Bernard, Lyon) for scanning electron microscopy and to Fondation Mérieux for funding T.T.
- 2.Alonso MJ (1996) Drugs Pharm Sci 77:203Google Scholar
- 6.Stainmesse S, Orecchioni AM, Nakache E, Puisieux F, Fessi H (1995) Colloid Polym Sci 273:505Google Scholar
- 8.Leroux JC, Allémann E, Doelker E, Gurny R (1995) Eur J Pharmaceut Biopharmaceut 41:14Google Scholar
- 11.Choi SW, Kwon HY, Kim WS, Kim JH (2002) Colloids Surf: A Physicochem Eng Asp 201:283Google Scholar
- 12.Le Ray AM, Vert M, Gautier JC, Benoit JP (1994) J Pharmaceut Sci 83:845Google Scholar
- 13.Hunter RJ (1981) Zeta potential in colloid science principles and applications. Academic Press, LondonGoogle Scholar
- 14.Kayes JB, Rawlins DA (1979) Colloid Polym Sci 257:622Google Scholar
- 15.Alexandridis P, Hatton TA (1995) Colloids Surf: A Physicochem Eng Asp 96:1Google Scholar
- 17.Eversole WG, Boardman WW (1941) J Chem Phys 9:798Google Scholar
- 19.Coombes AGA, Scholes PD, Davies MC, Illum L, Davis SS (1994) Biomater 15:673Google Scholar