Influence of dicephalic ionic surfactant interactions with oppositely charged polyelectrolyte upon the in vitro dye release from oil core nanocapsules

The electrostatic interactions between dicephalic-type surfactants: cationic, N,N-bis[3.3'-(trimethylammonio) propyl]dodecanamide dimethylsulphate (C-12(TAPAMS)(2)) and anionic, disodium N-dodecyliminodiacetate (C-12(COONa)(2)) with oppositely charged polyelectrolytes, natural, lambda-carrageenan (CAR) and synthetic, poly(diallyldimethylammonium chloride) (PDADMAC) were investigated at the oil/water interface by interfacial tension measurements to obtain the most stable anchor layer of polymeric shells of nanocapsules obtained via LbL method. All nanocarriers coated with further lambda-carrageenan/poly-L-lysine (CAR/PLL) bilayers were created on the nanoemulsion templates loaded with hydrophobic cyanine-type photosensitizer, IR-786. To evaluate progress of the layer-by-layer deposition of polyelectrolytes on the liquid core and nanocapsules' stability, zeta potential measurements were used. Size (<100 nm) and morphology of the obtained nanoproducts were examined by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM) techniques. The in vitro release profile features were studied spectrophotometrically and interpreted in terms of diffusion-controlled processes, proving that selection for the first shell layer of an appropriate ionic surfactant and polyelectrolyte type and their strong interactions are the most desirable features for fabrication of long sustained nanocapsules encapsulating a hydrophobic photosensitizer. (C) 2011 Elsevier B.V. All rights reserved.