Real-time monitoring of carbonarius DNA structured biochip by surface plasmon resonance imaging

Surface plasmon resonance imaging (SPRI) studies, performed on a specially designed system exploiting the Kretschmann configuration, have been carried out to develop a DNA sensor for the detection of gene mutations accounting for the analysis of a fungin species which can proliferate especially in cereals, producing toxic compounds such as mycotoxins. The SPRI system has been used in order to study the hybridization process of ssDNA carbonarius probes immobilized onto a bio-functionalized Au surface in order to detect in real time the mutations in a DNA fragment. The SPRI system is a good choice for real-time monitoring of hybridization dynamics on an array of immobilized oligonucleotide probes because of the high sensitivity in characterization of ultra-thin films adsorbed onto gold or other noble metal surfaces. Using this technique, local changes in the reflectivity of a thin metal film describe the hybridization process between the molecules tethered to the surface and those sent in solution in the test chamber. The increase in the greyscale levels of the images (representing the functionalized gold traps) during the hybridization process demonstrated the occurrence of the binding event. The process has been proven to be reversible and specific for the investigated probes, since no signal has been detected in the presence of a negative control which is a non-complementary target.