Synthesis of Water Soluble Quantum Dots for Monitoring Carrier-DNA Nanoparticles in Plant Cells

Fluorescent quantum dots (QDs) have shown great promise for use as biolabels in cell and animal biology and more recently in plant sciences. An important use of QDs is for monitoring the dynamics, intracellular trafficking, and fate of carrier-DNA nanocomplexes in cell transfection and potentially in plant transformation. In this study, a low cost aqueous procedure has been developed to efficiently prepare biocompatible QDs for monitoring nanoparticle-mediated gene transfer in conjunction with molecular breeding of Jatropha curcas. Water-soluble CdSe nanoparticles were synthesized by self-assembly using L-Cysteine as stabilizer and optimal synthesis scheme established by fluorescence spectroscopy. The QDs were used to label chitosan-DNA nanoparticles via electrostatic interaction and the resultant QD-labeled chitosan-DNA complexes were shown to have superior fluorescence properties with red shift of emission and absorption spectra relative to the CdSe QDs alone. This system is being explored as a superior alternative to Agrobacterium-mediated genetic transformation of Jatropha curcas cells. PCR amplification of the full length of the carried reporter gene (GFP) suggests that the DNA was not digested in Jatropha curcas cells transfected with CdSe/CS-DNA complexes. Furthermore, GFP gene expression in the transfected callus cells, as evidenced by fluorescence detection, suggests that the target DNA was integrated into the plant genome.