[[alternative]]GaN for DNA-sensing Applications

[[abstract]]In this report, the applicability of the III-nitride-based materials as a semiconductor-based biosensors is demonstrated. Generally, GaN is considered as potential candidate for optoelectronic material because it is a wide direct band gap (3.4 eV) semiconductor. Recently, a lot of interest has been developed on its sensor-application, e.g. high power FETs and microelectronic devices. Furthermore, group III-nitrides are known for their chemical inertness and bio-compatibility, which leads to the realization of biosensors based on III-nitrides semiconductor. In this work, GaN is used for the construction of a DNA-sensing material by immobilizing thiol-terminated oligonucleotides onto a mercaptosilane-modified GaN surface by using disulfide bonds.The covalent bond attachment of thiol-modified DNA oligomers to MPTS-modified GaN surface has proved by contact angle measurement, atomic force microscopy (AFM), X-ray photoelectron spectroscopy(XPS), confocal optical microscope(COM),and high-resolution transmission electron microscopy (HR-TEM).Using electrochemical impedance measurement, it is possible to observe the immobilized DNA molecules on the GaN surface and discriminate between ss and ds DNA. Quenching of photoluminescence signal has been observed when a ss-DNA modified GaN subjected to ds-DNA modification. This demonstrates that surface modified GaN can perform as a sensor for DNAs. Comparative to GaN this films, GaN NWs is one case have higher sensivity for DNA –sensing, which one highly desirable for bio-sensing applications.