An innovative nucleic acid based biosensor toward detection of Legionella pneumophila using DNA immobilization and hybridization: A novel genosensor

Legionella pneumophila is a causative agent of Pontiac fever and Legionaries' disease. L. pneumophila is a gram negative, fastidious and hard to grow bacterium. Since severe growth of this pathogen, molecular diagnostics based on DNA can be very important. Mip gene is one of the strongest constructed in Legionella pneumophila that targeted in several molecular detection methods. Also, L. pneumophila is one of the threatening pathogens that has many challenges for its rapid and specific detection. This study is an attempt to identify Legionella pneumophila specific genes using a DNA-based bioassay. In this work, gold nanostructures supported by cysteamine (Cys A/AuNPs) were deposited on the surface of gold electrode to engineer an innovative DNA based biosensor. The Cys A/AuNPs interface provides a large surface area for the effective immobilization of ssDNA, as well as it ascertains the bioactivity and stability of immobilized of pDNA. Field emission scanning electron microscope (FE-SEM), and EDS photoelectron spectroscopies were used to monitor the sensor fabrication. Cyclic voltammetry (CV) and square wave voltammetry (SWV) were used for electrochemical characterization of DNA immobilization and hybridization by cDNA as complementary target sequence. Obtained results showed good sensitivity, selectivity and stability. Finally, target DNA was quantified at a linear range from 1 mu M to 1 ZM and low limit of quantification (LLOQ) was 1 Zepto-molar. The results of this study indicate that nucleic acid based bioassay in the near future can be a good alternative to the detection of L. pneumophila.