Ultrasensitive Electrochemical Biosensor For The Detection Of The MecA Gene Sequence In Methicillin Resistant Strains Of Staphylococcus Aureus Using Gold Nanoparticles

ObjectiveAn ultrasensitive and specific electrochemical biosensor for thedetection of the mecA gene, which is associated with methicillin resistantstrains, was successfully developed.Gold nanoparticles and alkaline phosphatase as the signalamplification, binding with electrochemical biosensors are used to theultrasensitive detection of the gene. This method is expected to be used todetect the actual bacteria in clinical specimens for clinical diagnosis.MethodsCapture probes were immobilized on the surface of a goldnanoparticles modified glassy carbon electrode. After hybridizationbetween with target probes and capture probes, dual labeled goldnanoparticles with alkaline phosphatase and detection probes were hybridized with target probes for sensitive detection of mecA genefragments. Dual labeled gold nanoparticles, which acted as ahigh-efficiency signal amplification strategy, were successfully prepared.The gold nanoparticles and dual labeled gold nanoparticles werecharacterized by transmission electron microscopy (TEM).ResultsDifferent concentrations of gene fragments were detected to inspectthe specificity and sensitivity of the proposed biosensor. This biosensordisplayed outstanding selectivity and a remarkable sensitivity LOD=23pM,S/N=3. Good linearity over the range of50pM to250pM wasdemonstrated. Moreover, the measurement process required less than2hours. This device was employed for the successful detection of mecAgene in methicillin resistant Staphylococcus aureus was confirmed byscanning electron microscopy (SEM), and electrochemical impedancespectroscopy (EIS). With the above amplification stratergy, the currentresponded to mecA gene linearly in the concentration range of50-250pM under optimal detection conditions with a detection limit of23pM.ConclusionA novel gene biosensor was developed for the electrochemicaldetection of the mecA gene, which was associated with methicillin resistantstrains. Dual marked gold nanoparticles with alkaline phosphatase and detection probe were successfully prepared and used for highly sensitivedetection of the mecA gene fragments. Under optimized detectionconditions, the proposed biosensor showed high sensitivity and a broadlinear range. More importantly, the whole detection time was performed in2h, which allows rapid identification of methicillin resistant strains andmay assist clinicians in making accurate decisions. Moreover, this proposedbiosensing strategy may be used to develop other biosensors for pathogenicbacterias and drug resistance analysis.