Evaluation of Softness in Proximity to the Surface of a Collagen Gel
In a cell culture, the gel strength (softness) of the culture scaffold is known to have an impact on cellular behavior. However, measuring the “softness” in a culture solution is not easy. In this experiment, a scanning probe microscope (SPM) was used to attempt to measure the “softness” of a collagen gel used as the scaffold for a cell culture.
Fig. 1 Force Curves in the Culture Solution
The collagen gel used in the cell culture was formed at multiple concentrations, and the force curve in the proximity of the gel surface in the culture solution was measured with an SPM (Fig. 1). In the force curve measurement, the smaller the force acting for a given proximity between the probe and the sample, the softer the sample surface indicated. Fig. 1 shows the measurement of the force (nN) acting between the probe and gel when the probe was pressed in a further 2 μm from the point of contact between the probe and the gel surface. A dependency on concentration of the softness was verified. It was evident that the lower the concentration, the softer the surface.
Fig. 2 Dependency on Concentration of the Softness of a Collagen Gel
Additionally, comparable measurements were performed on two different types of collagen gel (A and B), and the softness concentration dependency was quantified successfully (Fig. 2).
As shown, the softness of a gel in a culture solution can be measured using an SPM, and that as the collagen concentration rises, so too does the hardness of the gel surface.
By combining observations of the surface shape with information on the changes in cellular gene expression due to the gel strength, it is likely that SPM measurements of the quantitative softness may be applicable in research on culture scaffold.
(Samples provided by: Professor Koichi Morimoto and Professor Nobuhiro Kato, Faculty of Biology-Oriented Science and Technology, Kindai University)
