Label-free optical biosensor for direct complex DNA detection using Vitis vinifera L.

The ability to detect and quantify small amounts of DNA in biological complex samples is a hot research area. Up until recently most of the work performed in this area used label-dependent protocols that increases its complexity and overall costs. The aim the work was to develop a label-free technology suitable for DNA detection and quantification using real complex DNA samples. The applicability of this system was tested using synthetic ssDNA targets that guaranteed the systems specificity, in the sense that only complementary sequences hybridized with the probe. When using real samples extracted from Vitis vinifera L. the system was able to successfully detect and quantify the DNA present without any of the time consuming and costly amplification steps. The detection and quantification limits of the proposed system were 60 ± 20 nM and 201 ± 20 nM, respectively for Target 1 concentrations between 31 and 350 nM. This method can easily be applied to other species and purposes, allowing the direct detection of DNA in a label-free environment with high accuracy and specificity.