DNA Biosensors for the Detection of Hippuricase Gene of Campylobacter Jejuni Based SPREETA and dotLab Platforms

DNA-biosensors allow rapid, real-time monitoring of hybridization with the target nucleic acids. These biosensors are gaining more attention over traditional diagnostic methods for their fast and responsive operation, and their cost effective design. Specificity of the system relies on oligonucleotide probes covalently immobilized on the sensing surface. We report the development of a biosensor based on direct covalent coupling of thiol and biotin labeled single-stranded DNA (ssDNA) on a Surface Plasmon Resonance (SPREETA™) and a laser optics (dotLab™) transduction platform to detect genomic DNA for Campylobacter jejuni. The laser optics platform (dotLab™) has been used for the first time to detect ssDNA target. The sensors used in this system consist of a polystyrene surface with neutravidin coated spots over which the biotin-labeled DNA is immobilized. The detection limit of both the sensor platforms has been analyzed and it was found that the dotLab™ system shows better detection limit up to 1 nM than the SPR system which has a detection limit of 10 nM. The reusability of the sensors has also been analyzed, and we found that there was negligible change in sensitivity after sensors regeneration (~9.7 x E-7 ?RI) with minimal damage to the immobilized probes. Non-specific binding was minimized using a spacer thiol to the thiolated probes and BSA in the laser optics system, to cover the non-avidinated polystyrene region. The spacer thiol, not only removes unbound ssDNA, but also creates a self-assembled monolayer thereby minimizing non-specificity. These findings highlight the potential of DNA biosensors in developing a sensitive, regenerative and robust platform for food safety and clinical investigations.&'