Ultrasensitive Electrochemical Biosensor for the Detection of the mecA Gene Sequence in Methicillin Resistant Strains of Staphylococcus aureus Employing Gold Nanoparticles

An ultrasensitive and specific electrochemical biosensor for the determination of mecA gene, which is associated with methicillin resistant strains, was successfully developed. Capture probes were immobilized on the surface of a gold nanoparticle modified glassy carbon electrode. After target probes were hybridized with capture probes, dual labeled gold nanoparticles with alkaline phosphatase and detection probes were hybridized with target probes for sensitive detection of mecA gene fragments. Dual labeled gold nanoparticles, which acted as a high-efficiency signal amplification strategy, were successfully prepared. The gold nanoparticles and dual labeled gold nanoparticles were characterized by transmission electron microscopy. Different concentrations of gene fragments were detected to inspect the specificity and sensitivity of the proposed biosensor. This biosensor displayed outstanding selectivity and a remarkable sensitivity (LOD=23pM, S/N=3). Good linearity over the range of 50pM to 250pM was demonstrated. Moreover, the measurement process required less than 2hours. This device was employed for the successful determination of mecA gene from methicillin resistant Staphylococcus aureus.