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In the past two decades, microneedles (MNs) patches as a promising platform have been extensively investigated for transdermal delivery of drug drugs, cells, and active substances and extraction of bio‐fluids. To realize painless, efficacious, and safe transdermal delivery, these MNs must penetrate the skin to the appropriate depth without breaking or bending. Therefore, effective prediction of mechanical properties such as skin penetration of microneedles is crucial for the material and structural design of MNs. In this article, a numerical simulation of the insertion process of the microneedle into various types of skin modeling is reported using the finite element method. The effective stress failure criterion has been coupled with the element deletion technique to predict the complete insertion process. The numerical results show a good agreement with the reported experimental data for the deformation and failure of the skin and the insertion force. [ABSTRACT FROM AUTHOR]

The transdermal drug delivery based on microneedles (MNs) provides a suitable and painless self-administration for diabetic patients. In this work, the hydrogel-forming MNs were firstly fabricated using poly(vinyl alcohol) (PVA) and chitosan (CS) as matrix. A hypoglycemic drug, metformin (Met), had been loaded into MIL-100(Fe). Then, both of free Met and Met-loaded MIL-100(Fe) were integrated into hydrogel-forming MNs for regulation of blood glucose levels (BGLs) on diabetic rats. After penetrated into the skin, the free Met could be firstly released from MNs. Due to the absorption of interstitial fluid and subsequent release of loaded Met from MIL-100(Fe), leading to a sustainable and long-term drug release behaviors. A notable hypoglycemic effect and low risk of hypoglycemia could be obtained on diabetic rat models in vivo . The as-fabricated hydrogel-forming MNs expected to become a new type of transdermal drug delivery platform for transdermal delivery of high-dose drugs to form a long-term hypoglycemic effect., (© 2024 IOP Publishing Ltd.)

Skin ulcers are one of the complications of diabetes. At present, the treatment of diabetic skin wounds is still not satisfactory, and the efficiency of drug delivery is limited by the depth of penetration. Herein, a synergistically flexible microneedle dressing is presented for effectively promoting diabetic wound healing. Metformin, as an anti-diabetic drug, can be loaded into microneedles, which can effectively pierce into the skin of diabetic rats to trigger a response for regulating blood glucose levels. A novel multifunctional nanosystem CaO 2 @polydopamine (CaO 2 @PDA) was introduced into polycaprolactone and gelatin (PCL/Gel) electrospun nanofiber films as microneedle back patches to inhibit inflammation, provide oxygen, and absorb the excess exudate. Besides, the CaO 2 @PDA in back patches also provided effective antibacterial properties against both S. aureus and E. coli . Additionally, the as-fabricated flexible microneedle dressings loaded with metformin and CaO 2 @PDA nanoparticles demonstrated a high level of CD31 and low level of TNF-α, leading to accelerated diabetic skin-wound closure. These distinctive features demonstrate that our microneedle system can be a facile candidate for efficient wound healing in patients with diabetes and may be applied in various biomedical fields.