PREPARATION OF NIOSOME VESICLES FROM NON-IONIC SURFACTANTS BY HYDRODYNAMIC FOCUSING
Catherine T. Lo1, Andreas Jahn2, Wyatt N. Vreeland1, and Laurie E. Locascio1
1Biochemical Science Division, NIST Gaithersburg, MD 20899
2Semiconductor Electronics Division, NIST, Gaithersburg, MD 20899
Formation of noisome vesicles from non-ionic surfactants (i.e. sorbitan monoesters SPAN 60 and 80) was studied using hydrodynamic focusing technique in microfluidic formats. These nanoscaled, multilamellar vesicles bear the same properties as liposomes and are an inexpensive alternative to liposomes as drug carrier systems . However, traditional laboratory methods for noisome preparation require bulk mixing of two liquid phases and are not well-controlled, often resulting in niosome population with high polydispersity and inconsistent drug loading. We, therefore, utilized engineering principles and advantages available at the microscale to precisely control the fluid flow and mixing of liquids, to formulate niosomes with reproducible size, size distribution, and drug encapsulation.
Niosomes in this study were composed of SPAN, cholesterol, and dicetyl phosphate dissolved in isopropyl alcohol in the molar ratio of 47.5:47.5:5.0. The alcohol stream was hydrodynamically focused between two streams of phosphate buffered saline, to direct the formation of vesicles in a microfluidic channel. The laminar flow in the microchannel enabled controlled diffusive mixing at the two liquid interfaces where the surfactant assembled into vesicles . The niosomes formed by the microfluidic process were characterized using asymmetric field-flow fractionation combined with light scattering. We observed that the vesicle size and size distribution are tunable by adjusting the flow rate ratio (between the aqueous and alcohol streams) of the microfluidic system.
 T. Yoshioka et al., Internat. Journal of Pharm., 105, 1-6, (1994)
 A. Jahn et al., Langmuir, 23, 11, 6289-6293, (2007)
Mentors’ Names: Wyatt N. Vreeland
Laurie E. Locascio
Biochemical Science Division (831)
Chemical Science and Technology Laboratory
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