Microneedles in biomedicine: Innovations, challenges, and future prospects.

The effective delivery of therapeutic drugs is fundamental to modern medical practice. However, conventional administration methods, primarily oral and parenteral injection, exhibit numerous limitations, including the suboptimal bioavailability of macromolecules and challenges related to patient compliance. The advent of microneedle (MN) technology is reshaping strategies in the biomedical field, effectively overcoming the constraints of traditional drug delivery and diagnostic approaches. Research indicates that MNs can penetrate the stratum corneum to form transient microchannels, facilitating the transdermal delivery of therapeutic agents while bypassing gastrointestinal and hepatic barriers. This customizable and personalized drug delivery system holds significant potential for clinical application. Beyond drug delivery, MNs also have the capacity to transform healthcare models through real-time biomarker monitoring enabled by contact with interstitial fluid. This technology demonstrates considerable promise in managing chronic conditions such as diabetes, while also opening avenues for applications in vaccination, tissue regeneration, and cancer therapy. Recent innovations include the development of stimulus-responsive MNs for precision medicine and their integration with wearable devices to achieve closed-loop therapeutic diagnostics. Despite the substantial promise of this field, challenges remain regarding clinical translation, particularly in relation to biocompatibility, mechanical strength, and drug stability. This review outlines MN classifications, design principles, and applications, emphasizing their expanding role not only in healthcare but also in precision medicine, global health, and food safety. By overcoming current barriers and integrating emerging technologies, MNs have the potential to transform diagnostic and therapeutic paradigms, delivering scalable, patient-centered solutions to a broad range of biomedical challenges.