Synthesis and Functionalization of Fluorescent Quantum Dot Bioconjugates for Cellular Imaging of Directed Gene Therapy

Herein, I optimize a method for synthesis and bioconjugation of water-soluble, fluorescent CdSe/ZnS quantum dots (QDs) for targeted cellular delivery of DNA. Core CdSe QDs were synthesized in high temperature organic solvents and passivated with a ZnS shell to increase quantum yield. The fluorescent QD nanoparticles were made water-soluble by enveloping them with an amphiphilic polymer. These aqueous nanoparticles were functionalized with tertiary amines to impart a positive charge, allowing electrostatic binding to negatively-charged DNA. The conjugated QDs were characterized using zeta potential and electrophoresis to gauge their ability to electrostatically bind DNA. The QDs were further modified by conjugation with Wheat Germ Agglutinin (WGA) (a carbohydrate-binding protein) in an aim to direct nanoparticle trafficking within the cell. I observed the effect of this conjugation to QDs in N2a (mouse neuroblastoma) cells using fluorescence microscopy and immunocytochemistry to visualize trafficking. The images were used to evaluate the potential of bioconjugated QDs as a targeted non-viral gene therapy vector