1. The solid surface on which cells grow: This is the most common usage. In this context, the substrate is typically a culture dish, flask, or plate made of a material like polystyrene or glass. These surfaces are often treated with adhesion factors like collagen, fibronectin, or laminin, which promote cell attachment and spreading.
2. The nutrients and factors that cells need to survive and proliferate: This is a broader definition and encompasses the culture medium, which is a liquid solution containing:
* Essential nutrients: sugars, amino acids, vitamins, and salts
* Growth factors: proteins that stimulate cell growth and division
* Buffers: maintain the pH of the medium
* Antibiotics: prevent bacterial contamination
Therefore, the "substrate" for cells in cell culture can be both the solid surface on which they grow and the liquid medium that provides them with nutrients and essential factors.
