A novel transdermal delivery system for protein-based drugs uses photothermal ablation to increase the permeability of the skin by heating and perturbing the first skin layer, so that the drug can be delivered through a skin patch. Currently, the most effective method for protein-based drug delivery is through injection.
To enhance protein permeability into the skin, researchers prepared a transparent gel patch with gold nanorods on the gel surface and fluorescently labeled ovalbumin (FITC-OVA) inside the patch. The gel patch was placed on mouse skin to allow contact with the coated gold nanorods, and irradiated by a continuous-wave NIR laser.
Both in vivo and in vitro experiments were performed using gel patches with gold nanorods, gel patches without gold nanorods (control 1), and gel patches with gold nanorods but without any form of irradiation (control 2). The two controls did not produce any thermal ablation effect on the skin, but the NIR-irradiated gold nanorod patches increased the skin temperature to about 43 °C, resulting in enhanced translocation of FITC-OVA into the skin.
“Our experiments have shown that the photothermal effect on gold nanorods by irradiation of near-infrared light causes the skin to heat up and become more permeable,” said professor Takuro Niidome, leader of the research project at Kumamoto University. “It should be noted that our technique has yet to deliver any specific protein drugs, but we are confident that the research will contribute to the development of effective transdermal delivery systems.”
The research was published in the European Journal of Pharmaceutics and Biopharmaceutics (doi: 10.1016/j.ejpb.2017.06.005).