Search

The formation, characterization, photo-protective properties and release profiles of folic acid-loaded nanolaminated films were investigated by UV-visible spectroscopy, FTIR, Raman and SEM microscopy. Food-grade alginate/chitosan nanolaminates were obtained by the layer-by-layer technique and folic acid (FA) was incorporated by post-diffusion. The FA concentration of loading solutions and immersion time significantly affected the FA content in nanolaminates. The maximum FA loading was reached using FA solutions at 10 mg/mL for 30 min (54.4 μg/cm2), or 12.5 mg/mL for 120 min (≈70 μg/cm2). Nanolaminates containing FA were more stable under ultraviolet light exposure than non-encapsulated FA. The rate and concentration of FA released from nanolaminates were greater at buffer pH 7 than at pH 3, which might play a key role in the delivery and bioavailability of nutraceuticals. These results provide important information for the design of nanolaminates containing hydrophilic active compounds for food applications. This research was supported by the Ministerio de Ciencia e Innovación throughout the projects AGL2009-11475 and MINECO ALG2012-35635. Author Acevedo-Fani also thanks to the University of Lleida for the pre-doctoral grant.

We have prepared a chitosan polymer modified with gallic acid in order to develop an efficient protection strategy biological membranes against photodamage. Lipid bilayers were challenged with photoinduced damage by photosensitization with methylene blue, which usually causes formation of hydroperoxides, increasing area per lipid, and afterwards allowing leakage of internal materials. The damage was delayed by a solution of gallic acid in a concentration dependent manner, but further suppressed by the polymer at very low concentrations. The membrane of giant unilamellar vesicles was covered with this modified macromolecule leading to a powerful shield against singlet oxygen and thus effectively protecting the lipid membrane from oxidative stress. The results have proven the discovery of a promising strategy for photo protection of biological membranes.

International audience; Low-temperature crystalline deposition techniques are important, especially for coating polymer films that cannot tolerate high temperatures. In this work, crystalline anatase titanium dioxide (TiO2) thin films were deposited by reactive radio-frequency (RF) magnetron sputtering on unheated poly(ethylene terephthalate) (PET) films. The stability of the polymer film under UV-light irradiation in air was then studied. With only a TiO2 layer the polymer film was degraded by in-air, UV radiation. However, a transparent bilayer coating, consisting of a TiO2 layer on top of an ultra-thin sputtered alumina (Al2O3) layer, on the PET film effectively protected the polymer layer from photo-oxidation. Furthermore, the top anatase TiO2 layer has very good photo-catalytic activity, as shown by its ability to photo-degrade rhodamine B dye solution. The combination of these two properties allows photo-stable and transparent polymer/ceramic layered media with a self-cleaning surface.