Bioinspired, lignocellulosic surfaces with antimicrobial properties

该项目的重点是代表仿生模型化合物的纤维素酯和木聚糖酚酸酯，这两种化合物将由高级有机化学合成。方便的策略适用于多糖与羟基苯甲酸或羟基肉桂酸的聚合物类似反应。此外，还研究了多糖与酚酸的区域选择性酯化反应，并将通过核磁共振波谱或层析方法进行揭示。根据功能化程度的不同，选择纤维素或木聚糖和酚酸的组合可产生可溶产品。生物聚合物的成膜衍生物将在平面上形成多层薄膜，作为受自然启发的木质纤维的模型。苯丙烷类化合物通过酶聚合接枝到顶层的酚类锚基上。物理性质的表征将通过AFM、扫描电子显微镜、QCM-D、测角、ATR-IR光谱以及Zeta电位测量来执行。抗菌性能将通过细菌培养和随后的活/死染色实验进行研究。生物相容性将通过自由基测定(抗氧化效果)和QCM-D对纤维蛋白原吸附的研究(血液相容性)进行评估。该项目的目的是展示化学结构与抗菌活性以及生物相容性之间的结构、性质和关系。这项工作使新型生物基抗菌、生物相容性表面的设计成为可能，这种表面可以转移到纸浆和纺织纤维上。分子结构可以根据酚酸部分的多糖、取代度和苯丙酸以及反应条件(酶的类型)而变化。可伸缩材料结构和抗微生物活性以及生物相容性之间的相关性将从回归模型中计算出来。此外，这些基础知识为木质化提供了洞察力，并在生物精炼和开发具有高强度的生物基复合材料领域开辟了新的前景。

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.