Disposable cysteine based electrochemical impedance biosensor for skin sensitization analysis

Abstract

Nowadays, the personal care and cosmetics market is one of the largest markets in the world. However, some potential cosmetic ingredients may cause skin sensitization. Animal testing is deemed as a perfect but controversial solution to skin sensitization analysis. The European Union (EU), which has the most stringent and protective regulations for cosmetic has agreed to ban all tests related to animals. This has wide ranging implications for cosmetic companies worldwide as a cosmetic product which has been successfully registered in the EU can be easily registered worldwide. Thus, in chemico, in silico or in vitro alternative methods for the prediction of skin sensitization need to be introduced. The main purpose of this work was to investigate the performance of an impedance skin sensitizer biosensor obtained using self-assembly of cysteine on screen printed carbon electrode (SPCE) modified with gold nanoparticles (AuNPs). The basis of the biosensor developed in this work was that the conjugation of allergen to cysteine-AuNPs on SPCE would result in the commencement of the skin sensitization process. A biosensor with good reproducibility (relative standard deviations of 8.43 %) and sensitivity was obtained when 50 mM of cysteine was deposited on the AuNPs and left for 24 hours on the SPCE. The biosensor managed to successfully differentiate between water soluble mild, medium and strong sensitizers based on the values of the changes in charge transfer resistance ( ΔRct). Different allergen concentrations did not significantly affect ΔRct readings (the range studied was between 10 to 90 mM). The biosensor in this research work was found to have the potential to be successfully used as an alternative method to animal testing for the detection of skin sensitizers.