The Principle Behind the Bioinert Surface Technology
No Cell Attachment
The Bioinert surface is a thin polyol hydrogel layer that is covalently bound to the ibidi Polymer Coverslip #1.5. In contrast to standard ultra-low attachment (ULA) coatings, Bioinert is completely non-adherent and allows no binding of any biomolecule, even in long-term experiments. Therefore, the Bioinert technology provides a stable passivation in cell-based assays for several days or even weeks.
No Cell-Substrate Interactions
Bioinert creates an environment in which cell-cell interactions dominate over cell-substrate interactions. In fact, the latter are completely blocked. The stability of the Bioinert surface allows for long-term experiments on the very same dish—for several days and even weeks—without the adhesion of any proteins. Even if your cells require medium with a high fetal calf serum concentration, Bioinert prevents any cell or protein from adhering to the surface.
No Prior Preparation
The Bioinert surface is ready-to-use. There is no pre-hydration step necessary. The surface will swell by itself once wetted with buffer or cell medium.
Both the flat, thin bottom material and the excellent optical quality of the ibidi Polymer Coverslip enable high-resolution microscopy without any disruptive autofluorescence.
ibiTreat, Uncoated, and Bioinert—A Surface Comparison
Excellent cell adhesion
Culture of adherent cells
ECM coatings possible
The hydrophilic ibiTreat surface provides excellent cell adhesion, even without a defined protein coating. However, ECM protein coatings can be done on ibiTreat without any restrictions. The ibiTreat surface is ideal for culture of adherent cells that do not need any specific coating.
Weak cell adhesion
Culture of adherent cells
ECM coatings possible
The hydrophobic Uncoated surface provides weak cell adhesion, if not previously coated with an ECM protein. ECM protein coatings can be done on the Uncoated surface without any restrictions. The Uncoated surface is ideal for the culture of adherent cells that require a specific coating.
The hydrophilic Bioinert surface hinders any protein attachment, thus inhibiting subsequent cell attachment. Unlike with the ibiTreat and Uncoated surfaces, a coating is not possible. The Bioinert surface is ideal for the culture of suspension cells and cell aggregates.
Application Example: Spheroid Culture and 3D Projection Using the Bioinert Surface
Spheroids were generated from the HT-1080 LifeAct cell line with an agarose-based liquid overlay technique and transferred to the µ-Dish 35 mm, high Bioinert for microscopy.
Confocal laser scanning image of an HT-1080 LifeAct spheroid. The image is a projection from a series of confocal sections. The rainbow color scale indicates the distance from the coverslip surface. Warm colors = close to the surface, cold colors = distant from the surface.
Application Example: Spheroid Culture and FDA/PI Staining Using the Bioinert Surface
The Bioinert surface is ideally suited for the short- and long-term 3D culture of spheroids and organoids. Since both specific and non-specific cell immobilization are inhibited, cells are forced into a suspended state, enabling formation of small and large spheroids. To assess the viability, the cells were stained using fluorescein diacetate (FDA), which marks viable cells, and propidium iodide (PI), which stains dead cells.
Confocal laser scanning section of a HepG2 spheroid. Spheroids of HepG2 cells were generated with an agarose-based liquid overlay technique and transferred to the µ-Dish 35 mm, high Bioinert. FDA (green) indicates living cells at the outer spheroid layers. PI (red) marks dead cells within the necrotic spheroid center. Scale bar is 200 µm.
Spheroids of different cell lines were generated by the liquid overlay method and transferred into the µ-Dish 35 mm, high Bioinert for FDA/PI staining and live cell imaging.
Live cell widefield fluorescence imaging of FDA/PI-stained different cell types as indicated. FDA (green) indicates living cells at the outer spheroid layers. PI (red) marks dead cells within the necrotic spheroid center. Note the different spheroid morphology, which depends on the cell type.
Frontal view and sideview of an FDA-PI-stained MCF-7 cell spheroid. Confocal laser scanning images are projected from an overlay of the serial confocal sections of the FDA signal. Scale bar is 100 µm.
Application Example: Cultivation of Adherent Cells on Different Surfaces
The µ-Dish 35 mm, high Bioinert is suitable for the cultivation of various adherent cell types (see figure below).
On the ibiTreat surface, all adherent cell types show a strong cell adhesion. A weaker cell adhesion is observed on the Uncoated surface since there is only a serum protein coating. On the Bioinert surface, cells do not attach at all and spheroid formation can be observed in most of the cell types. Depending on the cell-cell-adhesion of the specific cell type, spheroids are formed more or less homogeneously.
Different adherent cell types were seeded on the ibiTreat, Uncoated, and Bioinert surfaces, respectively. The cells were cultured in full growth medium without prior ECM protein coating. Images were taken 24 hours after seeding. Phase contrast microscopy, Scale bar is 300 µm.