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Surface Coatings Modulate the Differences in the Adhesion Forces of Eukaryotic and Prokaryotic Cells as Detected by Single Cell Force Microscopy
摘要： Single cell force microscopy was used to investigate the maximum detachment force (MDF) of primary neuronal mouse cells (PNCs), osteoblastic cells (MC3T3), and prokaryotic cells (Staphylococcus capitis subsp. capitis) from different surfaces after contact times of 1 to 5 seconds. Positively charged silicon nitride surfaces were coated with positively charged polyethyleneimine (PEI) or poly-D-lysine. Laminin was used as the second coating. PEI induced MDFs of the order of 5 to 20 nN, slightly higher than silicon nitride did. Lower MDFs (1 to 5 nN) were detected on PEI/laminin with the lowest on PDL/laminin. To abstract from the individual cell properties, such as size, and to obtain cell type-specific MDFs, the MDFs of each cell on the different coatings were normalized to the silicon nitride reference for the longest contact time. The differences in MDF between prokaryotic and eukaryotic cells were generally of similar dimensions, except on PDL/laminin, which discriminated against the prokaryotic cells. We explain the lower MDFs on laminin by the spatial prevention of the electrostatic cell adhesion to the underlying polymers. However, PEI can form long flexible loops protruding from the surface-bound layer that may span the laminin layer and easily bind to cellular surfaces and the small prokaryotic cells. This was reflected in increased MDFs after two-second contact times on silicon nitride, whereas the two-second values were already observed after one second on PEI or PEI/laminin. We assume that the electrostatic charge interaction with the PEI loops is more important for the initial adhesion of the smaller prokaryotic cells than for eukaryotic cells.
关键词： prokaryotic cells,poly-D-lysine,silicon nitride,laminin,cell adhesion,single cell force microscopy,surface coatings,polyethyleneimine,eukaryotic cells,maximum detachment force
更新于2025-11-21 11:24:58
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LITESEC-T3SS - Light-controlled protein delivery into eukaryotic cells with high spatial and temporal resolution
摘要： Many bacteria employ a type III secretion system (T3SS) injectisome to translocate proteins into eukaryotic host cells. Although the T3SS can efficiently export heterologous cargo proteins, a lack of target cell specificity currently limits its application in biotechnology and healthcare. In this study, we exploit the dynamic nature of the T3SS to govern its activity. Using optogenetic interaction switches to control the availability of the dynamic cytosolic T3SS component SctQ, T3SS-dependent effector secretion can be regulated by light. The resulting system, LITESEC-T3SS (Light-induced translocation of effectors through sequestration of endogenous components of the T3SS), allows rapid, specific, and reversible activation or deactivation of the T3SS upon illumination. We demonstrate the light-regulated translocation of heterologous reporter proteins, and induction of apoptosis in cultured eukaryotic cells. LITESEC-T3SS constitutes a new method to control protein secretion and translocation into eukaryotic host cells with unparalleled spatial and temporal resolution.
关键词： protein translocation,eukaryotic cells,optogenetics,type III secretion system,LITESEC-T3SS
更新于2025-09-23 15:21:01
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Optical Transfection
摘要： Strategies for the delivery of genes into eukaryotic cells fall into three categories: transfection by biochemical methods, transfection by physical methods, and virus-mediated transduction. “Optical transfection”—a physical transfection method—exploits the ability of light to create small transient pores in the plasma membrane of mammalian cells.
关键词： plasma membrane,laser,eukaryotic cells,Optical transfection,gene delivery
更新于2025-09-09 09:28:46