Bacterial Levan-Derivatives: An Alternative Adhesive Biomaterial for Medical and Tissue Engineering Applications

Bioadhesives are important devices in both biomedical and tissue engineering applications. While medical adhesives and sealants require wound healing, robust adhesion and protection towards external harm, in tissue engineering the improvement of biomaterial/cell interactions is object of intense research to control cellular responses.

Herein, we present the construction of hybrid nanostructured multilayer films of chitosan (CHI) and a phosphonate‑levan derivative (Ph-levan). Levan is an unconventional fructose polymer produced by extremophilic microorganisms which exhibits hydroxyl groups that can form strong adhesive bonds with various substrates. The feasibility to construct hybrid CHI and (Ph-levan) multilayer films was first confirmed using a quartz-crystal microbalance. Films with 50 CHI/(Ph-levan) bilayers assembled on glass were shown to have a shear adhesive strength of 2.5 MPa, three times higher than a control of 50 CHI/alginate bilayers – two materials widely regarded as good natural adhesives (0.9 MPa). The biological performance was evaluated in vitro using L929 cells. After 24 hours, the mean cell area on (Ph-levan)-based films was around 110 cells.mm^-2, whereas the control showed lower cell adhesion, with only around 20 cells.mm^-2. The results demonstrate that the biological process of L929 cells adhesion was sensitive to Ph-levan incorporation in the multilayer surfaces. We believe that levan-based surfaces will lead to new findings in biomedical applications as surgical bandages and sealants and in tissue engineering cell/materials interactions, contributing to promote and control specific cellular responses related to their adhesion, metabolism and ideally stem cell differentiation mechanisms.