DNA-Directed Self-Assembly Of Gold Nanoparticles And Its Biological Properties Studies

In recent years, biological nanoassemblies(NAs), constructed through self-assemblybased on gold nanoparticles(Au NPs), polymer and biomacromolecule, have been extensivelyapplied in drug delivery, gene regulation, tumor diagnose and therapy, etc. DNA, well knownfor its excellent biocompatibility, programmability and the specific bases recognition ability,has become one of the most robust candidates to direct Au NPs self-assembly. Regretfully,DNA-directed Au NPs NAs(Au NAs) haven’t received much application in biomedicine dueto its inadequate stability in saline and serum.In this thesis, “Core-Satellite”-shaped Au NAs(CSNAs) were constructed using twokinds of Au NPs with different sizes, based on the hybridization method of single-strandedDNA(ss DNA). On one hand, controllable self-assembly of CSNAs were realized throughadjusting the assembly parameters. On the other hand, biological stability of CSNAs in salineand serum, cytotoxicity and fluorescence labeling characteristic of the polyethylene glycol(PEG) modified CSNAs were studied. Major results of this thesis are listed below:1. Satellite-Au NPs of 3.9 nm and Core-Au NPs of 18.7 nm were prepared andconjugated with two complementary ss DNA(A’ and c A’) respectively, which finally directedthe self-assembly of CSNAs. It was found that the molar ratios of c A’ to Core-Au NPs andSatellite-Au NPs-A’ to Core-Au NPs-c A’ played an important role in the quantities of the“Satellite” of the CSNAs. Increasing the molar ratios of c A’ to Core-Au NPs orSatellite-Au NPs-A’ to Core-Au NPs-c A’ could raise the “Satellite” quantities of the CSNAs.2. Stability of the CSNAs in Na Cl solution and serum were studied. It was revealed thatCSNAs could well existed in saline for at least 12 h. Moreover, the CSNAs prepared at 1:160of Core-Au NPs-c A’ to Satellite-Au NPs-A’ could bear a salt concentration nearly triple of thatin saline. Meanwhile, stability test in 10% FBS showed the CSNAs could remain intactstructure in serum for 6 h, indicating the good nuclease-resisting ability of the CSNAs.3. Cytotoxicity and fluorescence labeling characteristic of PEG modified CSNAs wereexplored. Cell experiments revealed the PEG modified CSNAs could maintain ≧90% cellviability within 5~50 mmol/L. Fluorescence experiments indicated the fluoresceinisothiocyanate(FITC) labeled CSNAs could emit a yellow-green fluorescence under 488 nmexcitation light, which made it possible to detect CSNAs via fluorescence microscopy.