Keramische Werkstoffe und Bauteile/Advanced Ceramics, Universität Bremen, Am Biologischen Garten 2, IW 3, Raum 2140, 28359, Bremen, Germany.
MAPEX Center for Materials and Processes, University of Bremen, Am Fallturm 1, 28359, Bremen, Germany.
Bioprocess Biosyst Eng. 2022 Jan;45(1):171-185. doi: 10.1007/s00449-021-02650-3. Epub 2021 Oct 18.
Immobilizing microorganisms inside 3D printed semi-permeable substrates can be desirable for biotechnological processes since it simplifies product separation and purification, reducing costs, and processing time. To this end, we developed a strategy for synthesizing a feedstock suitable for 3D bioprinting of mechanically rigid and insoluble materials with embedded living bacteria. The processing route is based on a highly particle-filled alumina/chitosan nanocomposite gel which is reinforced by (a) electrostatic interactions with alginate and (b) covalent binding between the chitosan molecules with the mild gelation agent genipin. To analyze network formation and material properties, we characterized the rheological properties and printability of the feedstock gel. Stability measurements showed that the genipin-crosslinked chitosan/alginate/alumina gels did not dissolve in PBS, NaOH, or HCl after 60 days of incubation. Alginate-containing gels also showed less swelling in water than gels without alginate. Furthermore, E. coli bacteria were embedded in the nanocomposites and we analyzed the influence of the individual bioink components as well as of the printing process on bacterial viability. Here, the addition of alginate was necessary to maintain the effective viability of the embedded bacteria, while samples without alginate showed no bacterial viability. The experimental results demonstrate the potential of this approach for producing macroscopic bioactive materials with complex 3D geometries as a platform for novel applications in bioprocessing.
将微生物固定在 3D 打印的半透性基质内对于生物技术过程是可取的，因为它简化了产品分离和纯化，降低了成本和处理时间。为此，我们开发了一种策略，用于合成适用于 3D 生物打印的机械刚性和不溶性材料的原料，其中嵌入了活细菌。该加工路线基于高度填充颗粒的氧化铝/壳聚糖纳米复合材料凝胶，该凝胶通过（a）与藻酸盐的静电相互作用和（b）壳聚糖分子与温和的凝胶剂京尼平之间的共价键合得到增强。为了分析网络形成和材料性能，我们对原料凝胶的流变性能和可打印性进行了表征。稳定性测量表明，在孵育 60 天后，京尼平交联的壳聚糖/藻酸盐/氧化铝凝胶不会在 PBS、NaOH 或 HCl 中溶解。含藻酸盐的凝胶在水中的溶胀也比不含藻酸盐的凝胶少。此外，将大肠杆菌嵌入纳米复合材料中，并分析了各个生物墨水成分以及打印过程对细菌活力的影响。在这里，添加藻酸盐是维持嵌入细菌有效活力所必需的，而不含藻酸盐的样品则没有细菌活力。实验结果表明，该方法具有生产具有复杂 3D 几何形状的宏观生物活性材料的潜力，可作为生物加工中新型应用的平台。
