In recent years, several papers have been published on delivery of chemically active materials and their controlled release mechanism. Since the performance of drug delivery systems is determined by drug loading and releasing properties, there is still a need for new drug delivery technologies for various active molecules. Layer-by-Layer (LbL) self-assembly method has been known since 1990’s for its water-based, environmental-friendly and practical features compared to other coating techniques in the literature (CVD, LB, etc.). However, it is not possible to coat hydrophobic molecules/ drugs directly to surface by LbL technique. Either chemical modification or encapsulation by an amphiphilic polymer is required for water-dispersible form. Although several release kinetics of various encapsulated molecules have been studied under different conditions in the literature, there is not sufficient information about controlled release mechanisms of loaded nanospheres through thin film systems. Therefore, it is intended to study thin film engineering of phthalocyanine-based molecules by LbL method via regularly repeating coating structure and nano-surface topography.<br/>In this study, thin film coatings containing encapsulated hydrophobic phthalocyanine are developed. Encapsulation is acquired by co-solvent evaporation technique. Thin films are fabricated by dip-spin and spray layer-by-layer (LbL) technique. Hence, it is possible to obtain multilayer thin films with nanosphere structures by LbL self-assembly. Material amount and release mechanism on absorbable gelatin sponge are controlled. Encapsulated material amount in the film system and LbL desorption of encapsulated material through film system are quantitatively determined with respect to pH change by quarzt-crystal microbalance (QCM-D) measurements. Depending on the absorbance and fluorescence spectra of photoactive material, distribution of nanospheres on surface is monitored by confocal microscopy in the visible range. Besides, film growth is observed by ultraviolet-visible spectroscopy. Surface topography of thin films and nanosphere structure are investigated by scanning electron microscopy (SEM). Thickness and roughness analysis are made by surface profiler and atomic force microscopy (AFM) respectively. Developed thin film coatings provide promising results to be used in medical applications such as in-vitro photodynamic therapy for skin cancer patients in near future.

Thin film engineering of hydrophobic phthalocyanine containing nanospheres by layer-by-layer (LbL) method

256th National Meeting (2018)

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