Abstract: A cell adhesion solution of a cross-linked polymer for substrates includes an amino acid polymer, a buffered cross-linking agent, and deionized water (DI H2O). In one example, the amino acid polymer is selected from a neutral or basic amino acid, such as poly 1-lysine or poly 1-arginine. In another example, the amino acid polymer includes poly 1-1sine. In another example, the amino acid polymer includes poly 1-1sine of molecular weight of 100,000 or higher. The cross-linking agent can be selected from an aldehyde functional group, a buffered formaldehyde solution or a 10% neutral buffered formalin solution.