Bioinspired, lignocellulosic surfaces with antimicrobial properties

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The project is focused on phenolic acid esters of cellulose and xylan representing biomimetic model compounds, which will be synthesized by advanced organic chemistry. Convenient strategies are adapted to polymer analogous reactions of polysaccharides with hydroxybenzoic- or hydroxycinnamic acids. Moreover, a regio-selective esterification of polysaccharides with phenolic acids is aimed and will be revealed by NMR spectroscopy or chromatographic methods. Selected combinations of cellulose or xylan and phenolic acids lead to soluble products depending on the degree of functionalization. Multilayer thin films on planar surfaces will be yielded from film-forming biopolymer derivatives as a model for lignocellulosic fibers inspired by nature. Phenylpropanoids are grafted by enzymatic polymerization to the phenolic anchor groups of the top layer. The characterization of physical properties will be performed by AFM, SEM, QCM-D, goniometry, ATR-IR-spectroscopy, as well as zeta potential measurements. Antimicrobial properties will be investigated by experiments with bacteria culture and subsequent live/dead staining. Biocompatibility will be evaluated by means of radical assays (antioxidative effects) and studies about fibrinogen adsorption with QCM-D (hemocompatibility). The intension of the project is to show structure property relationships between chemical structures and antimicrobial activity as well as biocompatibility. This work enables the design of novel bio-based antimicrobial, biocompatible surfaces, which can be transferred to pulp- and textile fibers. The molecular structure may be varied in terms of polysaccharide with phenolic acid moiety, degree of substitution and phenylpropanoide as well as reaction conditions (type of enzyme). The correlation between scalable material structures and antimicrobial activity as well as biocompatibility will be calculated from regression models. Moreover, this fundamental knowledge provides insights into lignification and opens novel prospects in the fields of biorefinery and development of bio-based composites possessing high strength.