Electrochemical nanogenosensor design for the detection of pathogenic microorganisms

In this study, an electrochemical based nanogenosensor design for the detection of pathogenic microorganisms was carried out. Disposable pen tip electrodes (PGE) were used as sensor surfaces and these sensor surfaces were enriched with Graphene Oxide (GO) nanomaterials. In the designed nanogenosensor, 22 base length gene region of Escherichia coli (E. coli) bacteria were used as model microorganism. The model pathogenic microorganism E. coli was studied with both synthetic sequences and real samples. A nanomaterial called Graphene Oxide (GO) is used to improve sensibility and selectivity of the genosensor. Graphene is a two-dimensional nanomaterial consisting of honeycomb braided structures that hybridize to sp² of carbon atoms. Graphene Oxide (GO) is a graphene derivative obtained by oxidation of graphite. Since graphene oxide has different oxygen groups in its structure, it provides better bonding with other molecules. For this purpose, Graphene Oxide modification was performed by applying carbodimide chemistry to sensor surfaces for better bonding of Graphene Oxide to the surface. The GO coated sensor surfaces were covalently immobilized with the E. coli probe sequence, hybridizing with the E. coli target sequence and the Mycobacterium tuberculosis sequence with all bases different from the target sequence. Interactions on the sensor surface were analyzed by Electrochemical Impedance Spectroscopy (EIS) method in the presence of 5mM [Fe (CN) 6] 3- / 4-. The selectivity and optimization conditions of all nanogenosensors were obtained with synthetic sequences. Studies have been conducted to determine the optimal hybridization conditions (probe and target concentration, hybridization buffer, wash buffer, etc.). After the optimization conditions were obtained, PCR products (real samples) were used. The study continued with verification of nanogenosensor that is designed under optimum conditions. A faster, easier and more cost-effective nanogenosensor design was performed compared to other methods used in the diagnosis of hereditary and infectious diseases. These nanogenosensors, which increase their surface areas and sensitivity, have been found to be the basis of microchip technologies with their applicability to clinical diagnosis and a single-use system.