SEM imaging predicts quality of niosomes from maltodextrin-based proniosomes.

PURPOSE: The limits to surfactant loading of proniosomes were determined and a rationale developed for the observed relationship between the composition of proniosomes and the quality of reconstituted niosome suspension.
METHODS: A novel method for producing proniosomes with a maltodextrin carrier was recently developed, which provides for rapid reconstitution of niosomes with minimal residual carrier. A slurry of maltodextrin and surfactant was dried to form a free-flowing powder which could be rehydrated by addition of warm water. This method provided facile production of a wide range of proniosome compositions, and thus, allowed us to examine rehydration behavior for similar concentrations of surfactant over a wide range of film thickness. SEM images of proniosomes with various degrees of surfactant loading and images of pure surfactant were compared. Direct observation and particle size measurements by laser light scattering provided characterization of the final niosome preparations.
RESULTS: Successful rehydration of surfactant to produce niosomes from dried film requires that the film be as thin as possible to avoid the clumping and precipitation that occurs when pure, granular surfactant is hydrated directly. The appearance of a coarse, broken surface on the proniosomes correlates with inefficient rehydration and occurrence of aggregation and precipitate in the final niosome suspension.
CONCLUSIONS: These observations provide an indication of the requirements for dry proniosomes to yield niosome suspensions of high quality.