A Research Paper Published in ACS Omega

In the published paper, the importance of the first layer on the properties of biocompatible polyelectrolyte multilayers built-up from chitosan and carboxymethylcellulose prepared by the layer-by-layer method was examined. It is known that the use of polyelectrolyte poly(ethyleneimine) as the first layer during the construction of multilayers can significantly influence their properties. However, the toxicity of poly(ethyleneimine) has not yet been fully investigated, which is an obstacle for the potential application of the mentioned nanomaterials. In this paper, a non-toxic and biocompatible replacement of poly(ethyleneimine) is proposed in such a way that a more concentrated solution of chitosan is applied for the preparation of the first layer which leads to the formation of nanofilms with improved properties compared to nanofilms containing poly(ethyleneimine) as the first layer. In this way, the use of chitosan as the first layer is twofold: to obtain nanofilms with improved properties and to make the prepared nanofilms non-toxic so that they can be applied as protective layers on fruit. In addition, it was shown that the addition of sodium chloride to polyelectrolyte solutions from which nanofilms are made affects the preparation and properties of the resulting films in a specific way. The above result can be explained by the assumption that polyelectrolyte multilayers built from chitosan and carboxymethylcellulose in the examined conditions are not stabilized only by electrostatic interactions, but that also hydrogen bonds significantly affect the stabilization of such nanofilms.

The research was performed as a part of the Croatian-Slovenian bilateral research project Modulation of fruit polyphenolic profile by sustainable postharvest physical treatments (APPLPEMs, IPS-2020-01-6126) funded by the Croatian Science Foundation.