Design, preparation of microneedles and their applications in medical diagnosis and cosmetic regeneration

Abstract

The existence of the skin barrier severely limits the efficiency of transdermal drug delivery, while traditional administration methods also have problems such as low bioavailability and poor patient compliance. As a new generation of transdermal drug delivery technology, microneedles have been extensively studied due to their advantages of painlessness, minimal invasiveness, and precise controlled release. However, there are still many bottlenecks and controversies in their technical system that have not been thoroughly explored. This review systematically summarizes different types of microneedle design, namely solid, hollow, dissolvable, coated, and swelling types, as well as preparation technologies ranging from traditional etching and injection molding to emerging 3D printing and laser processing. It critically points out the shortcomings of current microneedle research in terms of balancing mechanical properties, controlling large-scale production costs, and adapting to complex physiological environments. In particular, aiming at issues such as insufficient mechanical strength of polymer microneedles, limited biocompatibility of metal and silicon-based materials, and reliability problems of intelligent responsive microneedles in practical applications, multi-dimensional optimization paths are proposed. This article further highlights the innovative applications of microneedles in vaccine delivery, chronic disease management, anti-tumor therapy, and cosmetic regenerative medicine, such as cutting-edge directions like stimulus-responsive microneedles enabling on-demand drug release and the synergistic effect of microneedles with nanocarriers. At the same time, it sharply points out the translational challenges faced by related technologies in moving from the laboratory to clinical practice. Finally, this article looks forward to the development opportunities of microneedles in personalized medicine and the integration of intelligent diagnosis and treatment, providing a critical perspective and theoretical basis for promoting their leap from technical concept to clinical practicality.