QCM-DNA biosensor based on plasma modified PT/TiO 2 nanocomposites.

A significant development in this field was recorded with the design of DNA biosensors. DNA biosensors are generally greatly enhanced for diagnostic applications, environment monitoring, genetic analysis, food controls, detection of genetically modified organisms, and bacteria or virus detection. As a mass-sensitive device capable of measuring subnanogram levels, the quartz crystal microbalance (QCM) is an important technology to design sensitive DNA biosensors. QCM sensor provides a number of excellent benefits as a label free recognition system such as rapid detection, easy adjustment, and cost effectiveness by reducing reagents and efforts.

QCM is an important instrument for in situ realtime characterization of solid/liquid interfaces. This technology has been widely used for the study of interactions of biological molecules to provide of rapid and highly sensitive information. Therefore, a lot of studies was directed onto the clarification of mechanism and kinetics of large biomolecules binding processes in real time.

In this work, we reported a sensitive QCM-DNA biosensor for GMOs detection using polymerized polythiophene/titanium dioxide (PT/TiO2) nanocomposites by plasma method. A significant decrease in the frequency change were observed on quartz crystal surface during QCM-DNA biosensor studies. Oxidation potentials of PT/TiO2 nanocomposites were examined in the Cyclic Voltammetry. In situ probe replacement procedure was reversibly changed the DNA strand targeted by a DNA biosensor design. The first step was provided immobilization by irreversible adsorption of a P35S based DNA/PT/TiO2 probe and CaMV35S based DNA target on a gold-covered quartz electrode surface of a 5 MHz microbalance. In the second step, the optimal DNA concentration was determined as experimental.