Synthesis and Assessment of DNA/Silver Nanoclusters Probes for Optimal and Selective Detection of Tristeza Virus Mild Strains

Citrus Tristeza virus (CTV) is one of the most destructive pathogens worldwide that exist as a mixture of malicious (Sever) and tolerable (Mild) strains. Mild strains of CTV can be used to immunize healthy plants from more Severe strains damage. Recently, innovative methods based on the fluorescent properties of DNA/silver nanoclusters have been developed for molecular detection purposes. In this study, a simple procedure was followed to create more active DNA/AgNCs probe for accurate and selective detection of Tristeza Mild-RNA. To this end, four distinct DNA emitter scaffolds (C12, Red, Green, Yellow) were tethered to the Mild capture sequence and investigated in various buffers in order to find highly emissive combinations. Then, to achieve specific and reliable results, several chemical additives, including organic solvents, PEG and organo-soluble salts were used to enhance control fluorescence signals and optimize the hybridization solution. The data showed that, under adjusted conditions, the target sensitivity is enhanced by a factor of five and the high discrimination between Mild and Severe RNAs were obtained. The emission ratio of the DNA/AgNCs was dropped in the presence of target RNAs and I-0/I intensity linearly ranged from 1.5 x 10(-8) M to 1.8 x 10(-6) M with the detection limit of 4.3 x 10(-9) M.