Microneedle arrays for cutaneous and transcutaneous drug delivery, disease diagnosis, and cosmetic aid

The human skin passively transports small drug molecules through it. Sometimes, barriers are disrupted to deliver larger molecules for local and systemic effects. However, low dose requirements, restricted penetration of hydrophilic and high molecular weight drugs, and the necessity of specialised fabrication technologies forced scientists to develop novel means of immense utility. The cutaneous and transcutaneous applications of microneedles (MNs) have been investigated well. The patches, rollers, and devices are the active area of investigation in chemotherapy, dermatology, metabolic, and neuro-disorders. The process of skin pre-treatment, disease diagnosis, and molecular imaging have become simplified as MNs showed immense utility in near-infrared imaging, blood and interstitial fluid collection, and glucose, triglyceride, and mineral monitoring in a time-dependent manner. This article highlights the year-wise trends and the recent advancements of MNs with particular emphasis on their fabrication technologies, preferred types, and fabricating materials with their biocompatibility, drug delivery, i.e., most preferably chemotherapy, vaccination, anesthetisation, dermal and immunological disorders, diagnosis, and cosmetic uses along with the clinical pertinence. The market potential, safety concerns, regulatory aspects, and future opportunities are deliberately highlighted, along with the vast applicability of MNs in translating concepts to the clinics.