Sorption/release of diclofenac sodium in/from free-standing poly(acrylic acid)/poly(ethyleneimine) multilayer films

Polyelectrolyte multilayer films deposited onto various substrates have been used extensively as drug delivery systems. However, little attention has been paid to the release of drugs from free-standing polymeric films. Herein, we report the construction of thermal crosslinked free-standing poly(acrylic acid) (PAA)/branched poly(ethyleneimine) (PEI) multilayer films composed of 25 double layers [(PAAJPEI)(25)] and their use in sorption/release of diclofenac sodium (DS). The (PAA/PEI)(25) multilayer films were characterized by scanning electron microscopy, potentiometric titrations and Fourier transform infrared spectroscopy, while the sorption/release of DS was monitored by UV-Vis spectroscopy. The DS sorption equilibrium data were fitted with five isotherm models (Langmuir, Freundlich, Sips, Dubinin-Radushkevich, and Temkin). The maximum equilibrium sorption capacity, q(10), given by the Langmuir model was 32.42 mg DS/g. The Korsmeyer-Peppas semiempirical equation showed that the release of DS from the free-standing (PAA/PEI)(25) films proceeded by pseudo-Fickian dithision, irrespective of the releasing media. (C) 2016 Wiley Periodicals, Inc.