A micro-needle array is provided that may be used to deliver a bioactive agent to a therapeutic target. The micro-needle array preferably includes a substrate, a plurality of micro-needles integral with the substrate, and a bioactive agent. At least one micro-needle preferably includes a top surface, a bottom surface, a side surface, and a cavity defined by an inner surface. The bioactive agent may be disposed on the substrate and the plurality of micro-needles. The at least one micro-needle may further include a slit connecting the cavity to an aperture, the slit extending from the top surface to the bottom surface.