Real-Time Nanobiosensors based on Semiconducting Nanostructures
New ways for the ultrasensitive detection of small molecules using electrical sensing methods based on label free electrical detection are needed for rapid and inexpensive detection of biomolecules such as antibiotics, proteins, DNA and enzymes. We are currently exploring real-time nanobiosensors based on different semiconducting nanostructures such as SnO2 nanowires, ZnO thin films and high aspect-ratio ZnO nanowalls. First successful results show the label-free detection of tetracycline via ZnO/Al2O3 nanowalls.
Semiconducting Nanostructure Fabrication
For mass production especially producing nanobiosensors based on single nanowire FET’s can be very complicated and time consuming. In contrast we demonstrate a novel approach for the batch fabrication of ultralong (mm range) high aspect ratio ZnO nanowalls (500 nm height, 50 nm width) on wafer scale. Such nanowalls are fabricated by an atomic layer deposition based spacer lithography (ASL) approach and deliver a precise control of position and geometry.
Detection of the antibiotic tetracycline by ultralong nanowalls
While most of the studies are related to basic research the here demonstrated highly sensitive ZnO/Al2O3 nanowalls will be used as a nanobiosensor for the electronic read-out of biomolecular/drug-target interactions for real time evidence of particular small molecules in an analyte. We use the ZnO/Al2O3 nanowall structures for the antibiotics detection by functionalizing them with operator DNA and specifically bound and electrically charged TetR sensor proteins. With this functionalized surface it is possible to detect tetracycline antibiotics. When tetracycline is present in the environment aqueous measurement solution of the sensor it binds to the TetR sensor protein which is then released from the sensor surface.
Furthermore we investigated a new and simple approach for a molecular controlled release based on atomic layer deposition (ALD) hybrid material.