Introduction: Microneedles (MNs) are promising tools for wound healing by minimally penetrating the stratum corneum, enabling efficient drug delivery and tissue regeneration. Hydrogels are widely used as wound dressings for their excellent exudate absorption and moisture retention. In this study, we developed a hydrogel microneedle dressing by integrating a microneedle platform into a polyvinyl alcohol (PVA)-polyvinylpyrrolidone (PVP) hydrogel loaded with sildenafil, a drug shown to enhance wound healing. The hydrogel network was constructed using a freeze-thaw crosslinking method, with L(+)-tartaric acid as an acidifier to promote a robust network. This study aimed to develop a next-generation wound dressing, SHMN (Sildenafil-Hydrogel MNs), capable of efficiently delivering poorly soluble sildenafil while providing superior exudate absorption, moisture retention, and tissue regeneration.

Methods: The hydrogel was prepared by dissolving 10% w/v PVA and 25% w/v PVP in distilled water, with L(+)-tartaric acid added at various ratios to optimize crosslinking and reduce freeze-thaw cycles. Polyethylene glycol 400 (PEG 400) was included to enhance sildenafil solubility and permeability. Microneedles were fabricated by mold casting, pouring the solution into molds, vacuuming to fill cavities, and subjecting to one freeze-thaw cycle (−20 °C for 18 h, then 25 °C for 6 h). Mechanical properties, including elongation at break, Young’s modulus, and swelling ratio, were evaluated using hydrogel films. Morphology, mechanical strength, and physicochemical properties (DSC, FTIR, XRD) of SHMN were assessed. In vitro skin permeation was evaluated using Franz diffusion cells. For in vivo wound healing, full-thickness wounds were created on SD rat dorsal skin, and SHMN dressings were applied for 14 days.

Result: Addition of L(+)-tartaric acid improved Young’s modulus and swelling capacity, facilitating a well-organized hydrogel network within the PVA-PVP matrix. Mechanical strength of the microneedles increased dose-dependently. Franz cell studies confirmed PEG 400 enhanced drug solubilization and skin permeation. In vivo, the SHMN group showed significantly higher wound closure rates than controls. Histological analysis (H&E staining) showed superior healing in the SHMN group, with thicker epithelial layers, reduced inflammation, and increased collagen deposition.

Conclusion: Sildenafil-loaded PVA-PVP hydrogel microneedles exhibited sufficient mechanical strength for skin insertion and excellent wound healing activity. L(+)-tartaric acid promoted robust hydrogel network formation, supporting superior exudate absorption and moisture retention. PEG 400 enhanced sildenafil delivery to tissue, promoting strong regeneration. The SHMN system developed here shows promise as a patient-customized smart dressing for chronic and refractory wounds, combining efficient drug delivery with optimal wound environment management.