Peptides, proteins, and extracellular matrix act synergistically to influence cellular function at the biotic-synthetic interface. However, identifying the individual and cooperative contributions of the various combinations and concentration regimes is extremely difficult. The confined channel deposition method we describe affords highly tunable orthogonal reactive concentration gradients that greatly expand the dynamic range, spatial control, and chemical versatility of the reactive silanes that can be controllably deposited. Using metal-free "dual click" immobilization chemistries, multiple peptides with a variety of functionality can be immobilized efficiently and reproducibly enabling optimal concentration profiling and the assessment of synergistic interactions.