Live bacteria microneedles for biomedical applications.

Bacteria play dual roles as both pathogenic agents and therapeutic agents. Their inherent motility, tumor-preferential colonization, and immunomodulatory properties confer significant disease prevention and treatment potential in fields such as intestinal therapy, oncology, and wound healing. However, challenges including bacterial biosafety concerns, delivery methods, and low colonization rates severely hinder their biomedical and clinical applications in disease treatment. Microneedles (MNs) are emerging as highly promising biomedical device options, offering the dual advantages of functional versatility and minimally invasive characteristics. MNs demonstrate substantial potential in treating various diseases, holding promises to elevate the application level of bacterial therapies. This review summarizes recent advances in MN-mediated live bacterial delivery systems, focusing on their applications in wound healing, cancer therapy, vaccination, and fungal infection treatment. The representative bacteria employed in MN-mediated delivery systems and their unique biology and mechanisms are also discussed. Finally, this review explores the key challenges and future development prospects in MN-mediated bacteria therapy.