Integrating an ex-vivo skin biointerface with electrochemical DNA biosensor for direct measurement of the protective effect of UV blocking agents.

Skin cancer is the most frequent kind of cancer in white people in many parts of the world. UV-induced DNA damage and genetic mutation can subsequently lead to skin cancer. Therefore development of new biosensing strategies for detection of UV-induced DNA damage is of great importance. Here we demonstrate a novel combination of an ex-vivo skin biointerface and an electrochemical DNA sensor for the direct detection of UV induced DNA damage and investigation the protective effect of various UV blockers (Zinc-oxide (ZnO), titanium-dioxide (TiO2 ) nanoparticles (NPs) and sunscreens) against DNA damage. A diazonium modified screen-printed carbon electrode immobilized with a DNA sequence related to the p53 tumour suppressor gene, the most commonly affected gene in human UV-induced skin cancer, was applied as an electrochemical DNA sensor. Electrochemical impedance spectroscopy (EIS) was employed for the detection of DNA damage induced by UV-A radiation by following the changes in charge transfer resistance (Rct ). The protective effects of UV blockers applied onto a pig skin surface (a suitable model representing human skin) were successfully detected by the DNA sensor. We observed that the naked skin has little UV protection showing an 18.2% decreases in ∆R/R values compared to the control, while applying both NPs and NP-formulated sunscreens could significantly reduce DNA damage, resulting in a decrease in ∆R/R values of 67.1% (ZnO NPs), 77.2% (TiO2 NPs), 77.1% (sunscreen 1) and 92.4% (sunscreen 2), respectively. Moreover, doping moisturising cream with NPs could provide a similar DNA protective effect. This new method is a biologically relevant alternative to animal testing and offers advantages such as fast, easy and inexpensive processing, in addition to its miniaturised dimension, and could be used for a range of applications in other sources of DNA damage and the protective effect of different UV blocking agents and other topical formulations.