Recent progress of 3D-printed microneedles for transdermal drug delivery.

Microneedles as novel transdermal drug delivery systems have lately attracted extensive attention due to their distinguished properties, including improved patient compliance and self-administration, compared to traditional parenteral administrations such as intravenous injection, intramuscular injection and subcutaneous injection. However, the great difficulties of precisely manufacturing those microneedles and patches within micro scale have strongly retarded their commercialization and clinical applications, particularly for the personalized medicine. Recently, numerous researches of utilizing 3D-priting process to fabricate transdermal drug delivery systems have been reported, not only adopting versatile printing methodologies, but also utilizing with different formulation strategies, to fabricate both artificial cargo delivery systems and sophisticated bio-inspired microneedles. This review aims to summarize those lately reported studies and to elaborate their advantages and limitations, discussing promising potential applications as novel drug delivery systems.