Extensible and swellable hydrogel-forming microneedles for deep point-of-care sampling and drug deployment

Microneedles are considered to be an effective, convenient, non-invasive, biosafety and compliant medical technology for vaccinations, biomarker testing, medical aesthetics and other related fields. Nonetheless, further clinical and commercial translation of regular microneedles is hampered by challenges in manufacturability, cost variability, insufficient comfort, contamination and so on. Recent innovations in functional biomaterials and chemical engineering technologies have been applied to develop extensible and swellable hydrogel-forming microneedles, achieving precise and controlled drug delivery and localized sampling from the target tissues. In this review, we systematically summarize the latest development of the extensible and swellable hydrogel-forming microneedles, including deep point-of-care testing, drug deployment, wound healing and mucoadhesion improvement. In addition, further analysis of the challenges and prospects for clinical application of current strategies is well presented. It is believed that the combined efforts of engineering, material, pharmaceutical and clinical research will contribute to the future success of this clinical and commercial translation.