Fabrication of a novel partially dissolving polymer microneedle patch for transdermal drug delivery

Polymer microneedles (MNs) have gained increasing attention as a minimally invasive method for efficiently delivering drugs and vaccines in a patient-friendly manner. Herein, an easy and mild process with O₂ plasma treatment was used to fabricate polyvinylpyrrolidone (PVP)-polyvinyl alcohol (PVA) MN patches, and efficient, sustained transdermal delivery was achieved. The diffusion rate of the entrained molecules could be controlled by adjusting the ratio of PVP-PVA. Optical coherence tomography was used to monitor the in vitro penetration in real time and to measure the penetration depth. Rhodamine 6G and fluorescein isothiocyanate-labeled bovine serum albumin (BSA-FITC) were used to explore the potential for using partially dissolving MNs as a transdermal delivery device. Confocal microscopy images revealed that the model drug can gradually diffuse from the puncture sites to a deeper depth. The drug-release profile also demonstrated that the PVP-PVA MNs can provide a successful and sustained release and that the transdermal delivery rate was regulated by the PVP-PVA ratio. Furthermore, the two-stage processing strategy developed in this study provides a simple and easy method for localizing the drug in the needle. The partially dissolving MNs developed in this study may serve as a promising device for controlled drug release and for biological storage applications.