A Method for Generation and Characterization of Orthogonal Three-Component Gradient Surfaces

In this paper, we present a method for generating orthogonal three-component gradients based on self-assembled monolayers on gold. Our proposed method uses a surface chemical reaction which follows first-order reaction kinetics. A quinone-presenting monolayer was subjected to two sequential reduction steps in perpendicular directions, to yield an orthogonal amine gradient on the surface. The three components were conjugated to the amine functionality during all reduction steps, yielding the surface with orthogonal three-component gradients. In our method, the ligand densities of different components can be precisely modulatory and predictable, and the resulting amine group is well suited to various conjugation reagents. Thus, we suggest that our proposed method can be used as a general platform for preparing three-component gradients consisting not only of small organic molecules but also of macro(bio)molecules such as proteins, oligonucleotides, and nanomaterials.