Ethidium bromide (EtBr) is one of the most used non-protein molecules in molecular biology, specifically for fluorescence-based detection of nucleic acids during gel electrophoresis. EtBr fluoresces when exposed to ultraviolet light, intensifying after binding to DNA. Although non-radioactive, the ability of EtBr to bind preferentially to the double strand structure and to enter the nucleus membrane of cells makes it a toxic substance, which can cause tumorigenesis due to the genetic damage induced by its interaction. Its reputation as a potential mutagen has created a need to minimize its use and eliminate the risks associated with exposure, as well as the potential environmental hazards associated with disposal. A key challenge in detection of EtBr contamination is the poor sensitivity of traditional methods based on, for example UV lamp which have been shown to have a LOD of 5 mM (500 ppm) which is quite high. In this work we develop nanogold-modified ultra-microelectrode-based sensors that are rapid, portable and exhibit a LOD of 12 nM (∼0.005 ppm). This is sufficient to confirm removal of EtBr following decontamination procedures. Recently, EtBr has been shown to be electrochemically active. In this work, we present the modification of ultra-micro electrode sensors with nanogold and subsequent detection of EtBr in phosphate buffer on a nanomolar level. The sensor can detect EtBr with a higher sensitivity and reliability than the classic UV lamp in a practical manner. Finally, we develop a portable electronics unit to allow remote monitoring. This novel sensor may offer a potential solution to test for and reduce potentials risks associated with both job-related risk and unwanted environmental release of EtBr.
Valente et al. (Fri,) studied this question.