Advancing Transdermal Delivery by Zn/Ag-Electrode-Printed Iontophoretic Patch with Self-Generating Microcurrents

Abstract

This study aimed to evaluate Zn/Ag-electrode-printed patches for the transdermal delivery of small molecules through iontophoresis. The Zn/Ag-electrode-printed patches interact with biological liquid electrolytes and generate suitable microcurrents for the iontophoretic delivery of small molecules across the skin. In fluorescein permeation studies, Zn/Ag-electrode-printed patches increased the transdermal depth of fluorescein into the dermis, while the permeation of fluorescein was limited when Zn/C-electrode-printed patches were tested. Further permeation experiments were conducted with 3D skin models, which showed a similar trend to the above, indicating that Zn/Ag-electrode-printed patches had a higher penetration rate compared to the blank. Studies using acetyl hexapeptide-8 as a peptide drug model and sodium ascorbyl phosphate (SAP) as a hydrophilic derivative of ascorbic acid showed that the iontophoretic patch with Zn/Ag electrodes promoted more penetration of drugs than unprinted patches. The permeation of SAP exhibited a two-phase profile with a relatively rapid permeation followed by a sustained, slower permeation. The permeation of acetyl hexapeptide-8 was slower due to its higher molecular weight, but the iontophoretic patch increased the permeation up to 1.5 times more than the unprinted patch. The microcurrent generated by the patch drives the transport of small molecule components through the skin, for the controlled and efficient delivery of therapeutic agents. The flexible design, efficient microcurrent generation, and stable electrodes make the Zn/Ag-electrode-printed patch a promising tool for transdermal drug delivery.