Magnetic millifluidic fractionation of a heterogeneous cell culture for statistically relevant ananlysis of age-dependent population development

磁性纳米粒子是种类最多的纳米材料之一，由于它们可以在磁场作用下处理并从复杂的混合物中分离出来，因此受到越来越多的工业关注。这一创新项目的目标是开发一种微流控分离工艺，允许对单一酵母种群进行分级。这使得研究外源应激源对酵母的生理特性的影响取决于它们的年龄。为了可靠地说明酵母细胞的年龄和异质性对食品工业生产的影响，我们将用微流体池对酵母进行磁性分类。酵母细胞的分裂会导致母细胞上的芽痕。因此，芽痕的数量与细胞的生成直接相关。芽痕中含有大量的甲壳素，因此甲壳素也是细胞生成的指标。为了根据细胞年龄分离细胞，磁性纳米颗粒通过His-Tag系统与含有甲壳素结合结构域(ChBD)的蛋白质可逆地功能化，通过ChBD结合到芽痕上。这种MNP与芽痕的结合起到了磁性标记的作用。酵母细胞在通过流动细胞时受到磁场的影响，因此根据它们的磁性进行分级。磁场的排列、流动的几何形状和流速有助于根据MNP含量和团聚大小进行分级。酵母细胞按年龄进行分级将有助于回答有关胁迫相关基因在单个细胞中的表达以及细胞年龄对发酵性能影响的基本问题。此外，还可以研究依赖于生理特性的种群动态。回答这些问题具有很大的科学意义，因为确定酵母细胞的年龄是非常困难的，这一研究将为更深入地了解异质和均质细胞系统铺平道路。

Magnetic nanoparticles are among the most diverse nanomaterials and gain increasing industrial interest since they can be processed with magnetic fields and separated from complex mixtures. The goal of this innovative project is to develop a millifluidic separation process which allows the fractionation of singular yeast populations. This allows to investigate the influence of exogenous stressors on the physiological properties of yeasts depending on their age. Yeast will be classified magnetically according to cell age with a millifluidic flow cell in order to give a reliable statement on the influence of cell age and heterogeneity of yeast cells on the production in the food industry.Cell division of yeast cells leads to a bud scar on the mother cell. Thus, the number of bud scars directly correlates with the cell generation. Bud scars contain significant amounts of chitin which is therefore an indicator for cell generation as well. To separate the cells according to their cell age, magnetic nanoparticles, which are functionalized reversibly via a His-tag system with a protein containing chitin binding domain (ChBD), are bound to the bud scars through the ChBD. This binding of MNP to the bud scars acts as a magnetic marker. Yeast cells are affected by magnetic fields while passing the flow cell and thus fractionated according to their magnetic properties. The arrangement of the magnetic field, the flow geometry and the flow rate facilitate a fractionation depending on the MNP content and agglomeration size.The fractionation of yeast cells according to their age will help to answer fundamental questions on the expression of stress relevant genes in singular cells and the influence of the cell age on the fermentation performance. Furthermore, the population dynamic in dependence of the physiological properties can be investigated. To answer these questions is of great scientific interest since it is very difficult to determine the age of yeast cells and this investigation will pave the way to a deeper understanding of heterogeneous and homogeneous cell systems.