Layer-by-Layer (LbL) assembly of polyelectrolytes on solid sub- strates is a well-characterized, tunable approach [1] for generating functional thin films for a variety of applications, including drug and gene delivery [2e5] and tissue engineering [6,7]. For these applications, this technique is advantageous in that the incorpo- ration of a broad range of therapeutics (e.g., proteins, nucleic acids, and small-molecule drugs) is carried out under physiological con- ditions, non-covalently, thereby preserving the native properties of the cargo while stabilizing it for delivery. Furthermore, surface-