Design principles of microneedles for drug delivery and sampling applications

Microneedles technology is a powerful platform to achieve efficient transdermal delivery of bioactive molecules for local or systemic therapies attributing to their minimally invasive delivery mode that circumvents the use of hypodermic needles. Building on its success in transdermal delivery, the applications of microneedles have been expanded to non-dermatological purposes including oral, buccal, intramyocardial, and ocular delivery. Additionally, with the advancement of materials and analysis techniques, microneedle-integrated point-of-care devices have shown promise for fast and efficient biomolecular sampling for patient health monitoring and disease diagnosis. In this review, we discuss the design principles of microneedles to overcome the biological barriers of various administration routes for drug delivery, in addition to more recent innovations employing microneedles for biomolecular and cellular sampling applications.