Disposable genosensor, a new tool for the detection of NOS-terminator, a genetic element present in GMOs

Legislation enacted worldwide to regulate the presence of genetically modified organisms (GMOs) in crops, foods and ingredients, necessitated the development of reliable and sensitive methods for GMO detection. An indicator based electrochemical disposable genosensor for the voltammetric detection of NOS-terminator, a genetic element present in GMOs is described as a possible substitute method for the common technique of gel electrophoresis and fluorescent image analysis. The biosensor relies on the immobilization of the 25-mer single stranded oligonucleotides (probe) related to NOS-terminator DNA sequence and the relative binding of this sequence with the polymerase chain reaction (PCR) amplified samples from certified reference material (CRM) of Roundup Ready soybean (Fluka) at a screen printed electrode (SPE). The extent of hybridization between the probe and target DNA is determined by using square wave voltammetry (SWV) with moving average baseline correction and methylene blue (3,7-bis(dimethylamino)phenothiazin-5-ium chloride, MB), as the hybridization indicator. The difference between the MB signals, obtained from the hybrid modified and probe modified SPEs, is used to detect GMOs from PCR amplified DNA samples. Numerous factors affecting the hybridization and indicator binding reactions are optimized to maximize the sensitivity.