Characterization of free-standing multilayer membranes made of chitosan and alginate

Objective. Free-standing films have increasing applications in the biomedical field as drug delivery systems, for wound healing and tissue regeneration. In this work, we produced free-standing multilayer membrane made of chitosan (CHI) and alginate (ALG), by detaching a polyelectrolyte multilayer film from its underlying substrate without any postprocessing step. The morphology and the chemical properties of the CHI/ALG multilayer films were characterized.

Methods. In this work, the buildup of free-standing multilayer films made of CHI and ALG was investigated. Several conditions were tested to follow the film growth in order to get thick films. The CHI/ALG free-standing films were characterized by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and by scanning electron microscopy (SEM). Permeability tests were performed using FITC-dextran, with several molecular weights, as a drug model molecule.

Results and Discussion. The produced membranes can be detached from an underlying inert substrate without any postprocessing step. Permeability experiments on these membranes revealed that the permeation of FITC-dextran depended greatly on its molecular weight.

Conclusions. The production of free-standing films permits the direct experimental determination of many physical properties of fundamental significance such as ion permeation and mechanical properties that can be tuned for real-world applications. These free-standing films are easy detachable, easy to handle, stable in the presence of physiological solutions and biocompatible, demonstrating potential for applications in tissue engineering and regenerative medicine.