Design, fabrication, and evaluation of antimicrobial sponge-hydrogel bilayer microneedles: An integrated system for transdermal insulin delivery and glucose sensing.

Diabetes mellitus is a chronic metabolic disorder that requires long-term management, as persistent hyperglycemia may lead to severe complications, thereby making real-time glucose monitoring and precise control essential. Traditional subcutaneous insulin injections are inconvenient, exhibit poor patient compliance and dosing accuracy, and do not provide real-time feedback, thereby hindering personalized therapy. Microneedles (MNs) offers a minimally invasive, user-friendly, and self-administered alternative; however, existing MN systems still exhibit low drug-loading capacity, insufficient controlled-release performance, a lack of glucose-monitoring capability, and inherent infection risks, which limit their application in long-term diabetes management. To address these limitations, we developed a novel antimicrobial sponge-hydrogel bilayer MNs system (ASMNs@PVA/SA-INS) that integrates insulin delivery, glucose sensing, and antimicrobial protection. The system comprises a polyvinyl alcohol/sodium alginate (PVA/SA) hydrogel layer for controlled insulin release and a sponge MN base functionalized silver nanoparticles to provide antibacterial activity. Experiments results demonstrated that over 83 % of insulin was released within 24 h, effectively controlling blood glucose for more than 8 h. Additionally, the system responded to glucose level changes within 10 min through a visible color change, indicating real-time sensing capability. This platform offers a promising strategy for intelligent and individualized diabetes management.