Characterization of Wrinkle Formation in a Polymeric Drug Coating by Atomic Force Microscope and Grazing Incidence Small-Angle X-Ray Scattering

Surface structure of polymeric drug delivery coating plays an important role on controlled drug release. To get a full picture of the qualitative and quantitative properties, two complementary techniques are used namely, atomic force microscopy (AFM) and grazing incidence small-angle X-ray scattering (GISAXS). The surface texture and grain size are characterized by AFM, while GISAXS gives deeper insights into structural changes of a larger area of the studied thin films.


Drug release from polymeric composite thin films is promising for buccal/transdermal pharmaceutical applications due to the enhanced bioavailability. There is a growing demand for smart drug delivery systems and for corresponding appropriate characterization methods to study stability and release behavior. The surface morphology has a strong impact on dissolution and delivery properties as well as the long term stability of the drug delivery system.

Here we used a combined approach of atomic force microscopy (AFM) and grazing-incidence small-angle X-ray scattering (GISAXS) to investigate the structural properties of iCVD (initiated Chemical Vapor Deposition)-coated clotrimazole films as a drug delivery system. The present drug delivery system consists of clotrimazole as the active pharmaceutical ingredient (API), an antifungal medication which is typically administered orally, and poly(2-hydroxyethyl methacrylate) (pHEMA) as the top barrier layer. pHEMA is a hydrogel which builds a protective barrier in dry state and enables drug delivery (diffusion of API) in wet state. By analyzing thin-film samples of varying drug layer thickness with an atomic force microscopy and a SAXS system we identified structural differences.

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