Core-shell microneedle platform for transdermal and pulsatile drug/vaccine delivery and method of manufacturing the same

A drug delivery system comprising:

• an assembly including
• a substrate, and
• a plurality of microneedles extending from the substrate, each microneedle including:
• a shell including a biodegradable polymer, said shell having a tapered shape from a distal tip to a proximal base having a diameter larger than the distal tip,
• a core including a mixture of a therapeutic agent and a polymeric carrier,
• and
• a cap including a biodegradable polymer, the cap bonded to the base of the shell and enclosing the core within the shell, said cap and shell not including any therapeutic agent, and
• said assembly comprising:
• a water-soluble polymer layer between the cap and the substrate, said water-soluble polymer layer connecting the microneedles to the substrate with the tips of the microneedles directed away from the substrate,
• wherein the water-soluble polymer layer is configured to dissolve to release the microneedles from the substrate when the microneedles are inserted into the skin of a patient, leaving the microneedles embedded in the skin where the cap and shell of each of the plurality of microneedles degrade at a predetermined time to release the therapeutic agent therein into the skin of the patient.