Multilayer thin films of Zinc (II) Phthalocyanine loaded Poly(D, L-lactide-co-glycolide) nanocapsules by layer-by-layer self assembly

Systematic design and controlled distribution of drug loaded nanoparticles in molecular level are highly challenging by traditional techniques. In this study, encapsulation of photodynamically active hydrophobic molecule, zinc (II) phthalocyanine, by biocompatible and biodegradable copolymer poly (D, L- lactide-co-glycolide) is achieved by co-solvent evaporation method. The average size of the drug-loaded nanoparticles is obtained below 100 nm for the first time for thin film assembly with 86% yield which is stated as crucial for the efficiency of drug delivered. These nanospheres are further studied for multilayer thin film coatings by dip-spin layer-by-layer self-assembly. As a scalable and controlled method, LbL offered a uniform distribution of hydrophobic photosensitizers ZnPc loaded PLGA capsules below 10 nm precisely. Light absorbance-transmittance spectroscopy and quartz-crystal microbalance measurements are performed for thin film growth and adsorption kinetics, respectively. Besides, the thickness of layers, the stability of thin film structures and homogeneous distribution of nanoparticles on the surface are controlled and investigated by surface profiler, dynamic light scattering, and scanning electron microscopy measurements respectively. Prepared multilayer thin film coatings are promising candidates for tumors on the skin or just under the skin by photodynamic therapy applications.